fix: ship sharp binaries for Windows arm64 builds

Fixes #1675

.github/workflows/electron.yml

@@ -115,7 +115,9 @@ jobs:
           Write-Host "Spectre libs present: $($found.FullName)"
 
       - name: Install dependencies
-        run: npm ci
+        run: |
+          npm ci
+          node scripts/install-windows-sharp.cjs
 
       # Bundled plugins are counted as downloads in the plugin store, so a
       # build only fetches them when the pins change.

CHANGELOG.md

@@ -19,9 +19,21 @@
 - Plugins can set login rules: sign out after a time without activity, limit how long a session lasts, turn off remember me and require a second factor
 - A user who must have a second factor but has none can sign in only to set one up
 - Admins can redirect HTTP to HTTPS and send HSTS while HTTPS is on. Off by default so reverse proxies keep working
+- A plugin can answer all sync requests and use the replica store, change feed and linked server list, so sync no longer lives in the core app
+- The desktop app can hold several accounts, each with its own copy of a server's data. The app signs in as the active one and its auto session follows a switch
+- The linked server list holds one link per account, with room for more connection options per server
+- A plugin can carry SSH connections over its own stream, and core relays a host's connection over a socket for another Termix
+- Plugins can create a folder with a color and icon and remove it when it is empty
+- Another Termix server can manage this one with an API key, which can now ask for a one minute ticket to open plugin sockets as its user
+- FIDO2 security keys (ed25519-sk and ecdsa-sk) work through SSH Agent authentication when Termix runs in the desktop app. The key asks for a touch or PIN on your own machine
+- Pasting a security key file now explains how to use it instead of failing to decode it
+- Plugins can add a panel that sits beside a host tab, like a terminal. You can open, resize and move it
+- The desktop app can link to a server that requires a client certificate (mutual TLS). It uses a PFX or P12 file for sync and the certificate in your system store for the app window
+- Plugins can show a web page in a native view in the desktop app, for sites that do not load in an iframe
 
 ### Changed
 
+- Server and desktop sync moved out of the core app into a plugin, including the Sync screen, the link wizard and the first run step. Existing links and offline copies keep working
 - The icon rail, sidebar, tab bar, dock, Dashboard, Manage, Settings and command palette now come from a bundled layout. It can be swapped for another layout but not removed, and a fix to it no longer needs a Termix release
 - Your theme is saved to your account so your other devices use it too, unless you keep settings on this device only
 - The themes besides light and dark now come from a bundled themes plugin. It can be swapped but not removed, and Termix keeps a basic light and dark theme of its own
@@ -37,6 +49,12 @@
 - Importing hosts from a JSON or SSH config file and exporting hosts now come from the Import and Export plugin. Exports are now written to the audit log. Without the plugin there is no import or export
 - Generating and checking SSH keys in the credential editor and deploying a key to a host now come from the Credential Tools plugin. Deploys are now written to the audit log. Without the plugin those buttons are hidden
 
+### Fixed
+
+- Linking the desktop app to a server no longer stalls on the server dashboard after sign in
+- Exporting your data no longer fails when a plugin table has a text key, like saved passkeys
+- The Windows on ARM desktop app starts again instead of failing with a local server error
+
 ### Removed
 
 - The desktop app no longer has its own client tunnel and native Remote Desktop code

README.md

@@ -91,6 +91,7 @@ Plugins add everything else. The official ones ship with Termix, and admins can
 | [Snippets](https://github.com/Termix-SSH/Plugin-Snippets)                   | Save the commands you run often and run them in a terminal or on many hosts in one click.                                       |
 | [SSH Terminal](https://github.com/Termix-SSH/Plugin-SSH-Terminal)           | SSH terminal sessions with tabs, split screen, history, macros and a local terminal in the desktop app.                         |
 | [Step CA](https://github.com/Termix-SSH/Plugin-Step-CA)                     | Connect to hosts with short-lived SSH certificates from a smallstep step-ca server.                                             |
+| [Sync](https://github.com/Termix-SSH/Plugin-Sync)                           | Sync the desktop app with one or more servers, and manage other Termix servers as remote sites from a master.                   |
 | [Tailscale](https://github.com/Termix-SSH/Plugin-Tailscale)                 | Add tailnet devices as hosts and connect with Tailscale SSH.                                                                    |
 | [Termix Identity](https://github.com/Termix-SSH/Plugin-Termix-Identity)     | Publish your SSH public keys under a public handle and run your own SSH certificate authority.                                  |
 | [Tmux Monitor](https://github.com/Termix-SSH/Plugin-Tmux-Monitor)           | Browse and control tmux sessions, windows and panes across your hosts.                                                          |

electron/embedded-view.cjs

@@ -0,0 +1,165 @@
+const { isolatedUrl } = require("./isolated-window.cjs");
+
+function cleanBounds(bounds) {
+  const value = (n) => Math.max(0, Math.round(Number(n) || 0));
+  return {
+    x: value(bounds?.x),
+    y: value(bounds?.y),
+    width: value(bounds?.width),
+    height: value(bounds?.height),
+  };
+}
+
+/**
+ * Native web views drawn inside the main window, for pages that do not work
+ * in a sandboxed iframe. Each one is a WebContentsView in its own
+ * non-persistent session, with the same limits as an isolated window: no
+ * permissions, no downloads, http(s) and ws(s) only. The renderer owns the
+ * placement and sends the bounds of the element the view should cover.
+ */
+function createEmbeddedViews({ WebContentsView, session, getMainWindow }) {
+  const views = new Map();
+
+  function destroy(id) {
+    const entry = views.get(id);
+    if (!entry) return;
+    views.delete(id);
+    const main = getMainWindow();
+    if (main && !main.isDestroyed()) {
+      try {
+        main.contentView.removeChildView(entry.view);
+      } catch {
+        /* already detached */
+      }
+    }
+    if (!entry.view.webContents.isDestroyed()) entry.view.webContents.close();
+    void Promise.allSettled([
+      entry.session.clearStorageData(),
+      entry.session.clearCache(),
+      entry.session.closeAllConnections(),
+    ]);
+  }
+
+  function destroyAll() {
+    for (const id of [...views.keys()]) destroy(id);
+  }
+
+  function open(options = {}) {
+    const main = getMainWindow();
+    if (!main) throw new Error("No window to attach a view to");
+    const id = String(options.id || "");
+    if (!id) throw new Error("A view needs an id");
+    const url = isolatedUrl(options.url);
+    const existing = views.get(id);
+    if (existing) {
+      if (
+        existing.url === url.href &&
+        existing.ignoreCert === !!options.ignoreCert
+      ) {
+        setBounds(id, options.bounds);
+        setVisible(id, options.visible !== false);
+        return { success: true };
+      }
+      destroy(id);
+    }
+
+    const isolated = session.fromPartition(
+      `embedded-view-${id}-${Date.now()}`,
+      {
+        cache: false,
+      },
+    );
+    isolated.setPermissionRequestHandler((_c, _p, callback) => callback(false));
+    isolated.setPermissionCheckHandler(() => false);
+    isolated.on("will-download", (event) => event.preventDefault());
+    isolated.webRequest.onBeforeRequest((details, callback) => {
+      const protocol = new URL(details.url).protocol;
+      callback({
+        cancel: !["http:", "https:", "ws:", "wss:"].includes(protocol),
+      });
+    });
+
+    const view = new WebContentsView({
+      webPreferences: {
+        session: isolated,
+        sandbox: true,
+        contextIsolation: true,
+        nodeIntegration: false,
+        webviewTag: false,
+        webSecurity: true,
+      },
+    });
+    const canNavigate = (target) => {
+      try {
+        return target === "about:blank" || !!isolatedUrl(target);
+      } catch {
+        return false;
+      }
+    };
+    for (const name of ["will-navigate", "will-redirect"]) {
+      view.webContents.on(name, (event, target) => {
+        if (!canNavigate(target)) event.preventDefault();
+      });
+    }
+    view.webContents.setWindowOpenHandler(({ url: target }) =>
+      canNavigate(target)
+        ? {
+            action: "allow",
+            overrideBrowserWindowOptions: {
+              webPreferences: { session: isolated, sandbox: true },
+            },
+          }
+        : { action: "deny" },
+    );
+
+    views.set(id, {
+      view,
+      session: isolated,
+      url: url.href,
+      origin: url.origin,
+      ignoreCert: !!options.ignoreCert,
+    });
+    main.contentView.addChildView(view);
+    setBounds(id, options.bounds);
+    setVisible(id, options.visible !== false);
+    view.webContents.loadURL(url.href).catch(() => {});
+    return { success: true };
+  }
+
+  function setBounds(id, bounds) {
+    const entry = views.get(id);
+    if (entry) entry.view.setBounds(cleanBounds(bounds));
+  }
+
+  function setVisible(id, visible) {
+    const entry = views.get(id);
+    if (entry) entry.view.setVisible(!!visible);
+  }
+
+  function handleCertificateError(event, contents, url, callback) {
+    for (const entry of views.values()) {
+      if (entry.view.webContents !== contents) continue;
+      event.preventDefault();
+      let allowed = false;
+      try {
+        allowed = entry.ignoreCert && new URL(url).origin === entry.origin;
+      } catch {
+        /* malformed URL is refused */
+      }
+      callback(allowed);
+      return true;
+    }
+    return false;
+  }
+
+  return {
+    open,
+    setBounds,
+    setVisible,
+    destroy,
+    destroyAll,
+    handleCertificateError,
+  };
+}
+
+module.exports = { createEmbeddedViews, cleanBounds };

electron/linked-server.cjs

@@ -34,6 +34,8 @@ function setLinkedServer(config) {
     basicAuth:
       config.basicAuth && config.basicAuth.username ? config.basicAuth : null,
     allowInvalidCertificate: !!config.allowInvalidCertificate,
+    clientCert:
+      config.clientCert && config.clientCert.pfx ? config.clientCert : null,
   };
 }
 
@@ -45,6 +47,16 @@ function isLinkedOrigin(url) {
   return !!linked && getOrigin(url) === linked.origin;
 }
 
+// The PFX of the link's client certificate, for TLS this process makes itself
+// to the linked origin. Null for any other origin.
+function clientCertOptionsFor(url) {
+  if (!isLinkedOrigin(url) || !linked.clientCert) return {};
+  return {
+    pfx: Buffer.from(linked.clientCert.pfx, "base64"),
+    passphrase: linked.clientCert.passphrase || "",
+  };
+}
+
 function basicAuthValue(basicAuth) {
   return `Basic ${Buffer.from(
     `${basicAuth.username}:${basicAuth.password || ""}`,
@@ -99,6 +111,7 @@ module.exports = {
   setLinkedServer,
   getLinkedServer,
   isLinkedOrigin,
+  clientCertOptionsFor,
   applyLinkHeaders,
   linkedRequestHeaders,
   answerLogin,

electron/main.cjs

@@ -1,6 +1,7 @@
 const {
   app,
   BrowserWindow,
+  WebContentsView,
   shell,
   ipcMain,
   dialog,
@@ -459,6 +460,7 @@ function isInvalidCertificateAllowedForUrl(url) {
 function getTlsVerificationOptions(url) {
   return {
     rejectUnauthorized: !isInvalidCertificateAllowedForUrl(url),
+    ...linkedServer.clientCertOptionsFor(url),
   };
 }
 
@@ -496,12 +498,38 @@ app.commandLine.appendSwitch("--enable-features=NetworkService");
 
 let mainWindow = null;
 const { createIsolatedWindows } = require("./isolated-window.cjs");
+const { createEmbeddedViews } = require("./embedded-view.cjs");
 const isolatedWindows = createIsolatedWindows({
   BrowserWindow,
   session,
   getMainWindow: () => mainWindow,
 });
 
+const embeddedViews = createEmbeddedViews({
+  WebContentsView,
+  session,
+  getMainWindow: () => mainWindow,
+});
+
+// Only the app's own page may place native views, never a frame inside it.
+function fromMainFrame(event) {
+  return !!mainWindow && event.senderFrame === mainWindow.webContents.mainFrame;
+}
+
+ipcMain.handle("embedded-view-open", (event, options) => {
+  if (!fromMainFrame(event)) throw new Error("Not allowed");
+  return embeddedViews.open(options);
+});
+ipcMain.handle("embedded-view-bounds", (event, id, bounds) => {
+  if (fromMainFrame(event)) embeddedViews.setBounds(String(id), bounds);
+});
+ipcMain.handle("embedded-view-visible", (event, id, visible) => {
+  if (fromMainFrame(event)) embeddedViews.setVisible(String(id), visible);
+});
+ipcMain.handle("embedded-view-close", (event, id) => {
+  if (fromMainFrame(event)) embeddedViews.destroy(String(id));
+});
+
 // Requests from the embedded backend over the fork IPC channel (the other
 // direction from the "shutdown" message main already sends it). A plugin's
 // ctx.desktop.openIsolatedWindow is the one caller today.
@@ -690,6 +718,39 @@ ipcMain.handle("allow-invalid-certificate-for-origin", (_event, origin) => {
   }
 });
 
+// Mutual TLS for the linked server: Chromium asks which certificate from the
+// OS store to present. Other origins keep Chromium's default (none).
+const chosenClientCerts = new Map();
+
+app.on(
+  "select-client-certificate",
+  async (event, _webContents, url, list, callback) => {
+    if (!linkedServer.isLinkedOrigin(url) || !list.length) return;
+    event.preventDefault();
+    const origin = new URL(url).origin;
+    const remembered = list.find(
+      (cert) => cert.fingerprint === chosenClientCerts.get(origin),
+    );
+    let chosen = remembered || (list.length === 1 ? list[0] : null);
+    if (!chosen) {
+      const { response } = await dialog.showMessageBox(mainWindow, {
+        type: "question",
+        title: "Client certificate",
+        message: "Choose the certificate for this server",
+        detail: origin,
+        buttons: [
+          ...list.slice(0, 8).map((cert) => cert.subjectName),
+          "Cancel",
+        ],
+        cancelId: Math.min(list.length, 8),
+      });
+      chosen = list[response] || null;
+    }
+    if (chosen) chosenClientCerts.set(origin, chosen.fingerprint);
+    callback(chosen || undefined);
+  },
+);
+
 app.on(
   "certificate-error",
   (event, _webContents, url, error, certificate, callback) => {
@@ -697,6 +758,10 @@ app.on(
       isolatedWindows.handleCertificateError(event, _webContents, url, callback)
     )
       return;
+    if (
+      embeddedViews.handleCertificateError(event, _webContents, url, callback)
+    )
+      return;
     if (isWebEndpointCertificateAllowed(url)) {
       event.preventDefault();
       logToFile("Allowed invalid certificate for configured web endpoint", {
@@ -1474,7 +1539,14 @@ function createWindow() {
     }
   });
 
+  mainWindow.webContents.on("did-start-navigation", (details) => {
+    if (details.isMainFrame && !details.isSameDocument) {
+      embeddedViews.destroyAll();
+    }
+  });
+
   mainWindow.on("closed", () => {
+    embeddedViews.destroyAll();
     mainWindow = null;
   });
 

electron/preload.js

@@ -80,6 +80,16 @@ contextBridge.exposeInMainWorld("electronAPI", {
     ipcRenderer.invoke("start-drag-to-desktop", dragData),
   cleanupTempFile: (tempId) => ipcRenderer.invoke("cleanup-temp-file", tempId),
 
+  // Native web views placed over an element of the page (WebContentsView).
+  embeddedView: {
+    open: (options) => ipcRenderer.invoke("embedded-view-open", options),
+    setBounds: (id, bounds) =>
+      ipcRenderer.invoke("embedded-view-bounds", id, bounds),
+    setVisible: (id, visible) =>
+      ipcRenderer.invoke("embedded-view-visible", id, visible),
+    close: (id) => ipcRenderer.invoke("embedded-view-close", id),
+  },
+
   invoke: invokeAllowed,
 });
 

package.json

@@ -15,7 +15,7 @@
   "scripts": {
     "format": "prettier --write .",
     "format:check": "prettier --check .",
-    "postinstall": "node scripts/patch-app-builder-lib.cjs && node scripts/patch-better-sqlite3.cjs && node scripts/patch-nan.cjs && node scripts/patch-node-pty.cjs && node scripts/patch-ssh2-agent.cjs",
+    "postinstall": "node scripts/patch-app-builder-lib.cjs && node scripts/patch-better-sqlite3.cjs && node scripts/patch-nan.cjs && node scripts/patch-node-pty.cjs && node scripts/patch-ssh2-agent.cjs && node scripts/patch-ssh2-sk.cjs",
     "prepare": "husky || true",
     "prebuild": "node scripts/write-electron-build-info.cjs",
     "lint": "node scripts/generate-dialect-schema.cjs --check && eslint . && node scripts/check-importmap-csp.cjs && node scripts/check-core-plugin-ids.cjs && node scripts/check-sdk-ui-exports.cjs && node scripts/check-sdk-guide.cjs && node scripts/check-test-locations.cjs && node scripts/check-changelog.cjs && node scripts/check-env-catalog.cjs",

packages/plugin-sdk/CHANGELOG.md

@@ -1,5 +1,28 @@
 # Changelog
 
+## 1.0.17
+
+Plugin API 1.9.0.
+
+### Added
+
+- `app.registerCompanion` and `app.toggleCompanion`, so a plugin can add a panel beside any host tab. The user opens, resizes and moves it, and the tab keeps running
+- `NativeView` in `@termix-ssh/plugin-sdk/ui`, which shows a web page in a native view in the desktop app, for sites that do not work in an iframe
+
+## 1.0.16
+
+Plugin API 1.8.0.
+
+### Added
+
+- `ctx.sync.provide` and the `sync:provide` capability, so a plugin can answer every /sync request
+- `ctx.ssh.transports.provide` and the `ssh:transport` capability, so a plugin can carry SSH connections over its own stream
+- `ctx.hosts.folders.ensure` and `removeEmpty`
+
+### Removed
+
+- The sync screens and calls in `@termix-ssh/plugin-sdk/ui`: `LinkServerDialog`, `ProxySettingsFields`, `useSyncStatus`, `refreshSyncStatus`, `setSyncStatus`, `getSyncConflicts`, `getSyncErrors`, `retrySyncErrors`, `settleSyncConflict`, `syncNow`, `unlinkServer`, `updateSyncSettings` and their types. They moved into the sync plugin
+
 ## 1.0.15
 
 Plugin API 1.7.0.

packages/plugin-sdk/PLUGIN-GUIDE.md

@@ -1,6 +1,6 @@
 # Termix plugin guide
 
-SDK 1.0.15 | Plugin API 1.7.0
+SDK 1.0.17 | Plugin API 1.9.0
 
 This guide is for anyone, person or AI coding tool, building a Termix plugin. It ships inside
 `@termix-ssh/plugin-sdk`, so the copy in your `node_modules` always matches the SDK you have installed.
@@ -202,37 +202,40 @@ Bundled as ESM for Node 22+ into `dist/backend.js`. Backend imports of your own
 
 ### What ctx has
 
-| Member                 | Capability                       | What it does                                                   |
-| ---------------------- | -------------------------------- | -------------------------------------------------------------- |
-| `pluginId`, `manifest` | none                             | Your id and manifest                                           |
-| `log`                  | none                             | Log lines tagged with your plugin                              |
-| `db`                   | `db:own`                         | Your own tables                                                |
-| `kv`                   | `kv:own`                         | Small key value state                                          |
-| `files.dataDir()`      | `files:own`                      | A folder of your own                                           |
-| `settings`             | none                             | Your settings                                                  |
-| `secrets`              | `secrets:own`                    | Encrypted values per user, `seal`/`unseal` for your own tables |
-| `http`, `ws`           | `network:serve`                  | Routes and sockets                                             |
-| `rbac`                 | none                             | Check the actor's permissions                                  |
-| `hosts`                | `hosts:read`, `hosts:write`      | List, read, create, update and share hosts as the actor        |
-| `ssh`                  | `ssh:connect`, `credentials:use` | Connect to hosts through Termix's SSH pipeline                 |
-| `credentials`          | varies                           | The actor's saved keys, and protocol logins                    |
-| `services`             | per service                      | Call other plugins and offer your own                          |
-| `events`               | `events:core` for core topics    | Emit and listen for events                                     |
-| `notify`               | `notify:send`                    | Send alerts to the Alerts inbox                                |
-| `fetch`                | `network:outbound`               | Outbound HTTP with SSRF protection                             |
-| `process`              | `process:spawn`                  | Run programs on the server                                     |
-| `schedule`             | none                             | Timers that stop on disable and never overlap                  |
-| `audit.record`         | none                             | Write your own audit line                                      |
-| `sync`                 | none                             | Sync your tables to a linked desktop                           |
-| `auth`                 | `auth:provide`                   | Login methods, second factors, SSH auth types                  |
-| `auth.issueUserToken`  | `users:impersonate`              | A short-lived session for calling Termix's API as a user       |
-| `auth.policy`          | `auth:policy`                    | Login rules: idle timeout, session length, second factors      |
-| `users.getLocale`      | `users:read`                     | A user's UI language                                           |
-| `system`               | `system:tls`                     | The server's HTTPS certificate                                 |
-| `plugins.list()`       | `plugins:read`                   | Which plugins are installed                                    |
-| `asUser(userId, fn)`   | always audited                   | Run background work as a user                                  |
-| `currentActor()`       | none                             | The user the current call runs for                             |
-| `disposables.add(fn)`  | none                             | Extra cleanup on disable                                       |
+| Member                 | Capability                       | What it does                                                    |
+| ---------------------- | -------------------------------- | --------------------------------------------------------------- |
+| `pluginId`, `manifest` | none                             | Your id and manifest                                            |
+| `log`                  | none                             | Log lines tagged with your plugin                               |
+| `db`                   | `db:own`                         | Your own tables                                                 |
+| `kv`                   | `kv:own`                         | Small key value state                                           |
+| `files.dataDir()`      | `files:own`                      | A folder of your own                                            |
+| `settings`             | none                             | Your settings                                                   |
+| `secrets`              | `secrets:own`                    | Encrypted values per user, `seal`/`unseal` for your own tables  |
+| `http`, `ws`           | `network:serve`                  | Routes and sockets                                              |
+| `rbac`                 | none                             | Check the actor's permissions                                   |
+| `hosts`                | `hosts:read`, `hosts:write`      | List, read, create, update and share hosts as the actor         |
+| `ssh`                  | `ssh:connect`, `credentials:use` | Connect to hosts through Termix's SSH pipeline                  |
+| `credentials`          | varies                           | The actor's saved keys, and protocol logins                     |
+| `services`             | per service                      | Call other plugins and offer your own                           |
+| `events`               | `events:core` for core topics    | Emit and listen for events                                      |
+| `notify`               | `notify:send`                    | Send alerts to the Alerts inbox                                 |
+| `fetch`                | `network:outbound`               | Outbound HTTP with SSRF protection                              |
+| `process`              | `process:spawn`                  | Run programs on the server                                      |
+| `schedule`             | none                             | Timers that stop on disable and never overlap                   |
+| `audit.record`         | none                             | Write your own audit line                                       |
+| `sync`                 | none                             | Sync your tables to a linked desktop                            |
+| `auth`                 | `auth:provide`                   | Login methods, second factors, SSH auth types                   |
+| `auth.issueUserToken`  | `users:impersonate`              | A short-lived session for calling Termix's API as a user        |
+| `auth.policy`          | `auth:policy`                    | Login rules: idle timeout, session length, second factors       |
+| `sync.provide`         | `sync:provide`                   | Answers all /sync requests: server sync, linked desktops        |
+| `ssh.transports`       | `ssh:transport`                  | Carries a host's SSH connection over your own stream            |
+| `hosts.folders`        | `hosts:write`                    | Create a folder row with a color and icon, remove it when empty |
+| `users.getLocale`      | `users:read`                     | A user's UI language                                            |
+| `system`               | `system:tls`                     | The server's HTTPS certificate                                  |
+| `plugins.list()`       | `plugins:read`                   | Which plugins are installed                                     |
+| `asUser(userId, fn)`   | always audited                   | Run background work as a user                                   |
+| `currentActor()`       | none                             | The user the current call runs for                              |
+| `disposables.add(fn)`  | none                             | Extra cleanup on disable                                        |
 
 ### The actor
 
@@ -301,6 +304,9 @@ router.post("/notes", async (req, res) => {
 - `ctx.rbac.require("manage")` on a single route, `await ctx.rbac.has("manage")` in code. A full id like
   `hosts.edit` checks a core permission.
 - Host access: `ctx.hosts.checkAccess(hostId, "connect" | "view" | "edit" | "manage")`.
+- Transports: with `ssh:transport`, `ctx.ssh.transports.provide({ claims(hostId), open({ id, ip, port }) })`
+  returns a stream the SSH client uses instead of a direct, proxy or jump host connection. Core also serves
+  `/plugin-ws/core/ssh-relay?hostId=` for callers with connect access, so one Termix can relay to another.
 - Managed hosts: with `hosts:lock`, `ctx.hosts.locks.provide({ isLocked, note, allowManualCreate })` makes
   the hosts you manage read only for the UI, the API and other plugins (pins and order still work), and
   `allowManualCreate: () => false` blocks adding hosts by hand. Your own `ctx.hosts` writes still go
@@ -489,6 +495,7 @@ your plugin's error boundary and Suspense.
 | ---------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
 | `registerRailItem`                                                                 | A sidebar rail button                                             |
 | `registerTab`, `registerPanel`                                                     | A tab type or sidebar panel (id in `contributes.tabs` / `panels`) |
+| `registerCompanion`, `toggleCompanion`                                             | A panel beside any host tab, bound to its host and handle         |
 | `registerDashboardCard`                                                            | A dashboard card (`contributes.dashboardCards`)                   |
 | `registerHostAction`                                                               | A host button, palette entry or default connect                   |
 | `registerHostEditorSection`                                                        | Your own host editor section (host settings get one for free)     |
@@ -624,6 +631,9 @@ Build UI from `@termix-ssh/plugin-sdk/ui` so it matches Termix and follows the t
 exports with props is `ui.api.txt` in the Termix repo
 (https://github.com/Termix-SSH/Termix/blob/main/packages/plugin-sdk/ui.api.txt).
 
+- Web pages that break in an iframe: `NativeView` (props `url`, `ignoreCert`, `hidden`, `fallback`) shows the
+  page in a native view in the desktop app. It fills its element, hides while a dialog or menu is open and renders
+  `fallback` in a browser.
 - Square: panels, cards and containers have no rounded corners. Small controls may stay rounded.
 - Flat: borders, not shadows. Use theme tokens like `border-border`, `bg-background`,
   `text-muted-foreground`, `text-destructive`. One accent, `text-accent-brand`. Don't add colors.
@@ -707,6 +717,14 @@ lists them too). `evaluate` returns `allowRememberDevice`, `maxSessionSeconds`,
 refuses the login. A user who must have a second factor but has none gets a session that can only set one
 up, and `/users/me` reports `restriction: "second-factor-setup"`.
 
+Sync is answered by one plugin. `sync:provide` is high risk: `ctx.sync.provide({ handle })` takes over every
+request under `/sync` (an Express style handler, 404 when nothing provides it), and `ctx.sync.host` hands
+over the neutral parts core keeps: the replica store (`replica`), the change feed and push applier
+(`feed`), the linked server list (`links`, one per local user), desktop accounts (`accounts`), sessions
+(`sessions`), host lookups, plugin mirroring and the proxy settings the desktop app needs. A test passes its
+own `syncHost` to `createMockCtx`. An API key can ask `POST /users/ws-ticket/api-key` for a one minute
+ticket that opens plugin sockets as its user, which is how one server opens sessions through another.
+
 ## Testing
 
 ```ts
@@ -893,46 +911,48 @@ To run your own registry instead, see https://docs.termix.site/develop/registrie
 
 ## Capabilities
 
-| Capability               | Risk     | What it allows                                          |
-| ------------------------ | -------- | ------------------------------------------------------- |
-| `credentials:read`       | critical | Read stored secrets for hosts the user can reach        |
-| `system:tls`             | critical | Replace the HTTPS certificate, answer CA domain checks  |
-| `ssh:connect`            | high     | Run any command on hosts, with the user's access        |
-| `process:spawn`          | high     | Run programs on the Termix server                       |
-| `users:write`            | high     | Add users and change their roles                        |
-| `users:impersonate`      | high     | Act as another user, or get a session for them, audited |
-| `db:core-refs`           | high     | Query core users, roles and hosts tables (read only)    |
-| `auth:provide`           | high     | Add login methods, second factors, SSH auth types       |
-| `auth:policy`            | high     | Set login rules: idle timeout, session length, 2FA      |
-| `device:serial`          | high     | Open serial and USB ports on the server                 |
-| `desktop:local`          | high     | Use the user's own computer, desktop app only           |
-| `hosts:export`           | high     | Export hosts with their saved logins                    |
-| `notify:hub`             | high     | Receive every alert (the alerts hub only)               |
-| `ui:layout`              | high     | Replace the whole app layout                            |
-| `hosts:write`            | medium   | Add and edit hosts                                      |
-| `hosts:status-provide`   | medium   | Be the source of host status dots                       |
-| `hosts:activity-provide` | medium   | Be the source of the recent activity list               |
-| `hosts:lock`             | medium   | Make hosts it manages read only for everyone else       |
-| `network:probe`          | medium   | Check that a host answers on a TCP port                 |
-| `credentials:use`        | medium   | Connect with saved credentials without seeing them      |
-| `credentials:write`      | medium   | Save new credentials                                    |
-| `network:outbound`       | medium   | Outbound HTTP through `ctx.fetch`                       |
-| `network:serve`          | medium   | HTTP routes and sockets                                 |
-| `network:broadcast`      | medium   | Local network broadcasts, like Wake-on-LAN              |
-| `users:read`             | medium   | Usernames, roles and UI language                        |
-| `events:core`            | medium   | Listen to core events                                   |
-| `notify:send`            | medium   | Send alerts                                             |
-| `audit:read`             | medium   | Read the audit log                                      |
-| `desktop:window`         | medium   | Open windows in the desktop app                         |
-| `hosts:read`             | low      | Read hosts the user can see                             |
-| `db:own`                 | low      | Your own tables                                         |
-| `kv:own`                 | low      | Small key value state                                   |
-| `files:own`              | low      | Your own folder on disk                                 |
-| `secrets:own`            | low      | Your own encrypted secrets                              |
-| `settings:read-core`     | low      | Read Termix server settings                             |
-| `plugins:read`           | low      | See installed plugins                                   |
-| `ui:surface`             | low      | Add tabs, panels and settings                           |
-| `ui:theme`               | low      | Add color themes, CSS only                              |
+| Capability               | Risk     | What it allows                                                |
+| ------------------------ | -------- | ------------------------------------------------------------- |
+| `credentials:read`       | critical | Read stored secrets for hosts the user can reach              |
+| `system:tls`             | critical | Replace the HTTPS certificate, answer CA domain checks        |
+| `ssh:connect`            | high     | Run any command on hosts, with the user's access              |
+| `process:spawn`          | high     | Run programs on the Termix server                             |
+| `users:write`            | high     | Add users and change their roles                              |
+| `users:impersonate`      | high     | Act as another user, or get a session for them, audited       |
+| `db:core-refs`           | high     | Query core users, roles and hosts tables (read only)          |
+| `auth:provide`           | high     | Add login methods, second factors, SSH auth types             |
+| `auth:policy`            | high     | Set login rules: idle timeout, session length, 2FA            |
+| `sync:provide`           | high     | Run sync: answer every /sync request                          |
+| `device:serial`          | high     | Open serial and USB ports on the server                       |
+| `desktop:local`          | high     | Use the user's own computer, desktop app only                 |
+| `hosts:export`           | high     | Export hosts with their saved logins                          |
+| `notify:hub`             | high     | Receive every alert (the alerts hub only)                     |
+| `ui:layout`              | high     | Replace the whole app layout                                  |
+| `hosts:write`            | medium   | Add and edit hosts                                            |
+| `hosts:status-provide`   | medium   | Be the source of host status dots                             |
+| `hosts:activity-provide` | medium   | Be the source of the recent activity list                     |
+| `ssh:transport`          | high     | Carry SSH connections for hosts it claims over its own stream |
+| `hosts:lock`             | medium   | Make hosts it manages read only for everyone else             |
+| `network:probe`          | medium   | Check that a host answers on a TCP port                       |
+| `credentials:use`        | medium   | Connect with saved credentials without seeing them            |
+| `credentials:write`      | medium   | Save new credentials                                          |
+| `network:outbound`       | medium   | Outbound HTTP through `ctx.fetch`                             |
+| `network:serve`          | medium   | HTTP routes and sockets                                       |
+| `network:broadcast`      | medium   | Local network broadcasts, like Wake-on-LAN                    |
+| `users:read`             | medium   | Usernames, roles and UI language                              |
+| `events:core`            | medium   | Listen to core events                                         |
+| `notify:send`            | medium   | Send alerts                                                   |
+| `audit:read`             | medium   | Read the audit log                                            |
+| `desktop:window`         | medium   | Open windows in the desktop app                               |
+| `hosts:read`             | low      | Read hosts the user can see                                   |
+| `db:own`                 | low      | Your own tables                                               |
+| `kv:own`                 | low      | Small key value state                                         |
+| `files:own`              | low      | Your own folder on disk                                       |
+| `secrets:own`            | low      | Your own encrypted secrets                                    |
+| `settings:read-core`     | low      | Read Termix server settings                                   |
+| `plugins:read`           | low      | See installed plugins                                         |
+| `ui:surface`             | low      | Add tabs, panels and settings                                 |
+| `ui:theme`               | low      | Add color themes, CSS only                                    |
 
 An update that adds a capability waits for an admin to approve it.
 

packages/plugin-sdk/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@termix-ssh/plugin-sdk",
-  "version": "1.0.15",
+  "version": "1.0.17",
   "description": "The contract between Termix core and a plugin: types, the capability catalog and the manifest schema.",
   "license": "Apache-2.0",
   "repository": {

packages/plugin-sdk/schema/manifest.schema.json

@@ -152,6 +152,8 @@
           "users:write",
           "auth:provide",
           "auth:policy",
+          "sync:provide",
+          "ssh:transport",
           "system:tls",
           "device:serial",
           "hosts:write",

packages/plugin-sdk/src/backend.ts

@@ -236,6 +236,429 @@ export interface SyncEntityRegistration {
  */
 export interface PluginSync {
   registerEntity: (entity: SyncEntityRegistration) => void;
+  /** Needs sync:provide. Takes over /sync/v2 and /sync/link. Removed on deactivate. */
+  provide: (provider: PluginSyncProvider) => () => void;
+  /** Needs sync:provide. The replica store, change feed and link registry. */
+  readonly host: PluginSyncHost;
+}
+
+/**
+ * The plugin that owns server and desktop sync. Core forwards every request
+ * under /sync to `handle` (an Express style handler) and answers 404 when no
+ * plugin provides it. Call `next()` to let core answer instead.
+ */
+export interface PluginSyncProvider {
+  handle: (
+    req: unknown,
+    res: unknown,
+    next: (error?: unknown) => void,
+  ) => void | Promise<void>;
+}
+
+/** A kind of data that syncs, as the sync provider sees it. */
+export interface SyncEntityInfo {
+  type: string;
+  owner: string;
+  order: number;
+  readOnly: boolean;
+  /** Whether the row would show in a load even if it exists. */
+  covers?: (syncId: string) => boolean;
+}
+
+/** A row ready for the wire, with its content hash. */
+export interface SyncWireRow {
+  syncId: string;
+  wire: SyncRow;
+  hash: string;
+}
+
+export interface SyncRecordInfo {
+  entityType: string;
+  syncId: string;
+  revision: number;
+  hash: string | null;
+  deleted: boolean;
+  error: string | null;
+  errorHash: string | null;
+  seq: number;
+}
+
+export interface SyncConflictInfo {
+  id: number;
+  entityType: string;
+  syncId: string;
+  localRow: string;
+  createdAt: string;
+}
+
+export interface SyncAccountInfo {
+  id: string;
+  username: string;
+  isAdmin: boolean;
+  active: boolean;
+}
+
+export interface SyncProxyHeader {
+  name: string;
+  value: string;
+}
+
+export interface SyncBasicAuth {
+  username: string;
+  password: string;
+}
+
+/** Extra per server connection options. Kept open so new ones need no migration. */
+export type SyncLinkOptions = Record<string, unknown>;
+
+/** One server a desktop is linked to, with a replica of its data. */
+export interface SyncLinkInfo {
+  id: number;
+  /** The local user the replica belongs to. */
+  userId: string;
+  serverUrl: string;
+  serverName: string | null;
+  serverVersion: string | null;
+  sessionToken: string | null;
+  customHeaders: SyncProxyHeader[];
+  basicAuth: SyncBasicAuth | null;
+  allowInvalidCertificate: boolean;
+  remoteUserId: string | null;
+  remoteUsername: string | null;
+  account: {
+    remoteUserId?: string;
+    username?: string;
+    isAdmin?: boolean;
+    roles?: string[];
+    permissions?: string[];
+  } | null;
+  disabledTypes: string[];
+  /** Extra connection options for this server, kept open for new ones. */
+  options: SyncLinkOptions;
+  knownTypes: string[];
+  cursor: number;
+  status: "idle" | "syncing" | "offline" | "error" | "signed_out";
+  lastError: string | null;
+  linkedAt: string;
+  lastSyncAt: string | null;
+}
+
+export interface SyncLinkCreate {
+  userId: string;
+  serverUrl: string;
+  serverName?: string | null;
+  serverVersion?: string | null;
+  sessionToken: string;
+  customHeaders?: SyncProxyHeader[];
+  basicAuth?: SyncBasicAuth | null;
+  allowInvalidCertificate?: boolean;
+  remoteUserId?: string | null;
+  remoteUsername?: string | null;
+}
+
+export type SyncLinkPatch = Partial<
+  Pick<
+    SyncLinkInfo,
+    | "serverName"
+    | "serverVersion"
+    | "sessionToken"
+    | "customHeaders"
+    | "basicAuth"
+    | "allowInvalidCertificate"
+    | "remoteUserId"
+    | "remoteUsername"
+    | "account"
+    | "disabledTypes"
+    | "options"
+    | "knownTypes"
+    | "cursor"
+    | "status"
+    | "lastError"
+    | "lastSyncAt"
+  >
+>;
+
+export type SyncRemoteErrorKind =
+  "offline" | "tls" | "proxy" | "basic_auth" | "signed_out" | "server";
+
+export interface SyncRemoteError extends Error {
+  readonly kind: SyncRemoteErrorKind;
+  readonly status?: number;
+}
+
+export interface SyncRemoteTarget {
+  serverUrl: string;
+  sessionToken?: string | null;
+  customHeaders?: SyncProxyHeader[];
+  basicAuth?: SyncBasicAuth | null;
+  allowInvalidCertificate?: boolean;
+}
+
+export interface SyncRemoteRequest {
+  method?: string;
+  body?: unknown;
+  timeoutMs?: number;
+  signal?: AbortSignal;
+}
+
+export interface SyncPushOp {
+  entityType: string;
+  syncId: string;
+  baseRevision: number;
+  op: "upsert" | "delete";
+  row?: SyncRow;
+}
+
+export type SyncPushResult =
+  | { syncId: string; entityType: string; status: "ok"; revision: number }
+  | {
+      syncId: string;
+      entityType: string;
+      status: "conflict";
+      revision: number;
+      deleted: boolean;
+      row: SyncRow | null;
+    }
+  | { syncId: string; entityType: string; status: "rejected"; reason: string };
+
+export interface SyncRemotePlugin {
+  id: string;
+  name: string;
+  version: string;
+  source: string;
+  artifact: boolean;
+  enabled: boolean;
+  active: boolean;
+  desktop: string;
+  syncEntities: string[];
+  granted: string[];
+}
+
+/**
+ * What the sync provider gets from core: the replica store, the change feed,
+ * the linked server registry, sessions and a few helpers. Core keeps all of
+ * it neutral; the provider decides when and how to use it. Needs sync:provide.
+ */
+export interface PluginSyncHost {
+  /** True on the desktop app's own backend. */
+  readonly embedded: boolean;
+  info: { appName: () => Promise<string>; version: () => string };
+
+  entities: {
+    list: () => SyncEntityInfo[];
+    get: (type: string) => SyncEntityInfo | undefined;
+    /** Registers core's own entities once. */
+    ensureCore: () => Promise<void>;
+    onChanged: (listener: () => void) => () => void;
+    onLocalWrite: (listener: () => void) => () => void;
+  };
+
+  /** Rows and bookkeeping of one local user's replica. */
+  replica: {
+    resolvers: (userId: string, onMissing?: () => void) => unknown;
+    loadRows: (
+      type: string,
+      userId: string,
+      resolvers: unknown,
+    ) => Promise<{ rows: Map<string, SyncWireRow>; failed: Set<string> }>;
+    loadRow: (
+      type: string,
+      userId: string,
+      syncId: string,
+      resolvers: unknown,
+    ) => Promise<SyncWireRow | null>;
+    writeRow: (
+      type: string,
+      userId: string,
+      wire: SyncRow,
+      resolvers: unknown,
+    ) => Promise<void>;
+    deleteRow: (type: string, userId: string, syncId: string) => Promise<void>;
+    orderSelfReferences: (type: string, rows: SyncRow[]) => SyncRow[];
+    counts: (userId: string) => Promise<Record<string, number>>;
+    wipe: (userId: string) => Promise<void>;
+    regenerateSyncIds: (userId: string) => Promise<void>;
+    removeSharedCopies: (userId: string) => Promise<void>;
+    records: {
+      list: (userId: string) => Promise<Map<string, SyncRecordInfo>>;
+      put: (
+        userId: string,
+        type: string,
+        syncId: string,
+        values: { revision: number; hash: string | null; deleted: boolean },
+      ) => Promise<void>;
+      setError: (
+        userId: string,
+        type: string,
+        syncId: string,
+        reason: string,
+        hash: string,
+      ) => Promise<void>;
+      clearErrors: (userId: string) => Promise<void>;
+      listErrors: (userId: string) => Promise<SyncRecordInfo[]>;
+      deleteForUser: (userId: string) => Promise<void>;
+      key: (type: string, syncId: string) => string;
+    };
+    conflicts: {
+      save: (
+        userId: string,
+        type: string,
+        syncId: string,
+        row: SyncRow,
+        revision: number,
+      ) => Promise<void>;
+      list: (userId: string) => Promise<SyncConflictInfo[]>;
+      get: (userId: string, id: number) => Promise<SyncConflictInfo | null>;
+      delete: (userId: string, id: number) => Promise<void>;
+    };
+  };
+
+  /** The server side: what changed for an account and what a desktop pushed. */
+  feed: {
+    withUserLock: <T>(userId: string, run: () => Promise<T>) => Promise<T>;
+    changes: (
+      userId: string,
+      cursor: number,
+      limit: number,
+      types?: string[],
+    ) => Promise<{
+      records: Array<{
+        seq: number;
+        entityType: string;
+        syncId: string;
+        revision: number;
+        deleted: boolean;
+        row: SyncRow | null;
+      }>;
+      hasMore: boolean;
+      nextCursor: number;
+      entityTypes: Array<{
+        type: string;
+        owner: string;
+        order: number;
+        readOnly: boolean;
+      }>;
+    }>;
+    parsePushOps: (body: unknown) => Promise<SyncPushOp[] | null>;
+    applyPush: (userId: string, ops: SyncPushOp[]) => Promise<SyncPushResult[]>;
+    /** Streams a change notice to the account's open event streams. */
+    listen: (userId: string, res: unknown) => Promise<() => void>;
+  };
+
+  /**
+   * The linked server registry, kept in core so it is there before plugins.
+   * One link per local user. Without a user, the active account is meant.
+   */
+  links: {
+    list: () => Promise<SyncLinkInfo[]>;
+    get: (userId?: string) => Promise<SyncLinkInfo | null>;
+    create: (link: SyncLinkCreate) => Promise<SyncLinkInfo>;
+    update: (
+      patch: SyncLinkPatch,
+      userId?: string,
+    ) => Promise<SyncLinkInfo | null>;
+    remove: (userId?: string) => Promise<void>;
+  };
+
+  /** Desktop accounts: the local user and the replica user of each server. */
+  accounts: {
+    list: () => Promise<SyncAccountInfo[]>;
+    /** A new empty account, ready to be linked to a server. */
+    create: () => Promise<string>;
+    /** Which account the app signs in as from now on. */
+    setActive: (userId: string) => Promise<void>;
+    activeId: () => Promise<string | null>;
+    /** Deletes an account and all its data. The last one cannot go. */
+    remove: (userId: string) => Promise<void>;
+  };
+
+  http: {
+    json: <T>(
+      target: SyncRemoteTarget,
+      pathname: string,
+      request?: SyncRemoteRequest,
+    ) => Promise<T>;
+    fetch: (
+      target: SyncRemoteTarget,
+      pathname: string,
+      request?: SyncRemoteRequest,
+    ) => Promise<{
+      ok: boolean;
+      status: number;
+      body: AsyncIterable<Uint8Array> | null;
+    }>;
+    normalizeServerUrl: (input: string) => string | null;
+    isRemoteError: (error: unknown) => error is SyncRemoteError;
+  };
+
+  sessions: {
+    /** A long lived session for a linked desktop. Shows in the account's sessions. */
+    issueDesktop: (
+      userId: string,
+      options: { days: number; deviceInfo: string },
+    ) => Promise<string>;
+    revoke: (sessionId: string) => Promise<void>;
+    find: (
+      sessionId: string,
+    ) => Promise<{ expiresAt: string; deviceInfo: string | null } | null>;
+    findUser: (
+      userId: string,
+    ) => Promise<{ id: string; username: string } | null>;
+    /** The user and session behind a token, or null when it is not valid. */
+    verify: (
+      token: string,
+    ) => Promise<{ userId: string; sessionId?: string } | null>;
+    /** Sets the sign in cookie on a response, like a login does. A name sets another cookie. */
+    setCookie: (
+      req: unknown,
+      res: unknown,
+      value: string,
+      options?: { name?: string; days?: number },
+    ) => void;
+    /** Removes the sign in cookie, without ending the session behind it. */
+    clearCookie: (req: unknown, res: unknown, name?: string) => void;
+    /** Express middleware that signs the request in and sets userId and sessionId. */
+    middleware: () => unknown;
+    /** Express middleware that lets a request through only on a desktop. */
+    desktopOnly: () => unknown;
+  };
+
+  hosts: {
+    findForSync: (
+      userId: string,
+      syncId: string,
+    ) => Promise<{ id: number; name: string | null } | null>;
+    statusBySyncId: (userId: string) => Promise<Record<string, unknown>>;
+  };
+
+  plugins: {
+    listForDesktop: () => Promise<{
+      plugins: SyncRemotePlugin[];
+      registryKeys: unknown;
+    }>;
+    /** Sends a plugin archive; false when there is no such plugin to share. */
+    sendPackage: (pluginId: string, res: unknown) => Promise<boolean>;
+    mirror: (link: SyncLinkInfo) => Promise<void>;
+    lastRemote: () => SyncRemotePlugin[];
+    localNames: () => Map<string, string>;
+  };
+
+  desktop: {
+    /** Tells the app's main process how to reach the linked origin. */
+    applyProxy: (link: SyncLinkInfo | null) => Promise<void>;
+    deviceName: () => string;
+  };
+
+  alerts: {
+    send: (alert: {
+      title: string;
+      body: string;
+      severity: "info" | "warning" | "error";
+      category: string;
+      dedupeKey: string;
+      link?: { tab: string };
+    }) => Promise<void>;
+  };
 }
 
 /**
@@ -972,6 +1395,18 @@ export interface PluginHosts {
   activity: PluginHostActivityApi;
   /** Read only hosts this plugin manages. */
   locks: PluginHostLocksApi;
+  /** Folder rows for the acting user. Needs hosts:write. */
+  folders: PluginHostFoldersApi;
+}
+
+export interface PluginHostFoldersApi {
+  /** Creates the folder row if missing and sets its color and icon. */
+  ensure: (
+    name: string,
+    style?: { color?: string | null; icon?: string | null },
+  ) => Promise<void>;
+  /** Removes the folder row and subfolders once no host is left in them. */
+  removeEmpty: (name: string) => Promise<boolean>;
 }
 
 export interface PluginHostImportOptions {
@@ -1354,7 +1789,29 @@ export interface PluginNetwork {
   ) => Promise<boolean>;
 }
 
+/**
+ * A way to reach some hosts other than a plain TCP connection. `claims` is
+ * asked for every connection, so it must be quick. `open` returns a stream
+ * the SSH client runs over, like a relayed socket.
+ */
+export interface PluginSshTransportProvider {
+  claims: (hostId: number) => boolean;
+  open: (host: {
+    id: number;
+    ip: string;
+    port: number;
+  }) => Promise<import("node:stream").Duplex>;
+}
+
+export interface PluginSshTransports {
+  /** Needs ssh:transport. Removed on deactivate. */
+  provide: (provider: PluginSshTransportProvider) => () => void;
+}
+
 export interface PluginSsh {
+  /** Other ways to reach hosts, used by every connection to them. */
+  transports: PluginSshTransports;
+
   /**
    * Whether a TCP port answers through the host's jump host chain. Chains are
    * shared and closed when idle. The acting user must be able to connect to

packages/plugin-sdk/src/capabilities.ts

@@ -48,6 +48,8 @@ export const CAPABILITY_CATALOG: readonly CapabilityInfo[] = [
   entry("db:core-refs", "high"),
   entry("auth:provide", "high"),
   entry("auth:policy", "high"),
+  entry("sync:provide", "high"),
+  entry("ssh:transport", "high"),
   entry("device:serial", "high"),
   entry("notify:hub", "high"),
   entry("ui:layout", "high"),

packages/plugin-sdk/src/frontend.ts

@@ -814,6 +814,46 @@ export interface SettingsComponentProps {
   running: boolean;
 }
 
+/** What a companion starts with. Read from the plugin's own settings. */
+export interface CompanionDefaults {
+  /** Open by itself the first time a matching tab shows. */
+  open?: boolean;
+  side?: "left" | "right" | "bottom";
+  /** Pixels of width, or height at the bottom. */
+  size?: number;
+  /** Show the edge button that opens and closes it. Default true. */
+  edgeButton?: boolean;
+}
+
+export interface CompanionProps {
+  /** The tab it sits beside. */
+  tab: PluginTabRecord;
+  host?: PluginHostRecord;
+  /** The host in the shape the connection APIs take. */
+  sshHost?: Record<string, unknown>;
+  /** The tab's surface handle (see TabHandle), read at call time. */
+  getHandle: () => TabHandle | null;
+  side: "left" | "right" | "bottom";
+  /** False while the tab is in the background or the panel is closed. */
+  isVisible: boolean;
+  close: () => void;
+  setSide: (side: "left" | "right" | "bottom") => void;
+}
+
+export interface CompanionOptions {
+  icon?: IconComponent;
+  titleKey?: string;
+  order?: number;
+  /** Tab types it applies to. Any tab with a host when empty. */
+  tabTypes?: string[];
+  when?: (tab: PluginTabRecord, host?: PluginHostRecord) => boolean;
+  /**
+   * A hook returning the starting state. It runs in the plugin's scope, so it
+   * can read the plugin's settings.
+   */
+  useDefaults?: () => CompanionDefaults;
+}
+
 export type ActionHandler = (...args: never[]) => unknown;
 
 export interface ActionSlotDefinition {
@@ -1068,6 +1108,18 @@ export interface TermixApp extends TermixAppInfo {
     component: ComponentType<TabProps>,
     options?: TabOptions,
   ) => Disposer;
+  /**
+   * A panel that sits beside any host tab the options match (a terminal, a
+   * desktop, ...), bound to that tab's host. The user opens, resizes and moves
+   * it; the tab keeps running underneath.
+   */
+  registerCompanion: (
+    id: string,
+    component: ComponentType<CompanionProps>,
+    options?: CompanionOptions,
+  ) => Disposer;
+  /** Opens a companion on a tab, or closes it when it is showing. */
+  toggleCompanion: (tab: PluginTabRecord, id?: string) => void;
   registerHostEditorSection: (
     section: HostEditorSectionContribution,
   ) => Disposer;

packages/plugin-sdk/src/manifest.ts

@@ -37,7 +37,7 @@ export {
  * "^1.2" needs 1.2 or later). engine.termix is checked against the core
  * version by the server.
  */
-export const PLUGIN_API_VERSION = "1.7.0";
+export const PLUGIN_API_VERSION = "1.9.0";
 
 /** The API major, the default engine.api for a new plugin. */
 export const SUPPORTED_PLUGIN_API_VERSION = String(

packages/plugin-sdk/src/testing.ts

@@ -68,7 +68,7 @@ import type {
   PluginSshKeyCredential,
   PluginSshKeyCredentialInput,
 } from "./backend.js";
-import type { SyncEntityRegistration } from "./backend.js";
+import type { PluginSyncHost, SyncEntityRegistration } from "./backend.js";
 import type { PluginDatabase } from "./backend.js";
 import type {
   PluginExternalClientRequest,
@@ -104,6 +104,8 @@ export interface FakeScheduledJob {
 
 export interface FakeContextOptions {
   pluginId?: string;
+  /** What ctx.sync.host answers, for a sync provider's tests. */
+  syncHost?: Partial<PluginSyncHost>;
   manifest?: Partial<PluginManifest>;
   /** Acting user returned by currentActor and used by asUser. */
   actor?: string;
@@ -756,6 +758,12 @@ export function createFakeContext(
       registerEntity: (entity) => {
         syncEntities.push(entity);
       },
+      provide: () => () => {},
+      get host() {
+        if (!options.syncHost)
+          throw new Error("Pass syncHost to use ctx.sync.host");
+        return options.syncHost as PluginSyncHost;
+      },
     },
 
     registry: {
@@ -1062,6 +1070,10 @@ export function createFakeContext(
           };
         },
       },
+      folders: {
+        ensure: async () => {},
+        removeEmpty: async () => true,
+      },
       locks: {
         provide: (provider) => {
           hostLockProviders.push(provider);
@@ -1140,6 +1152,7 @@ export function createFakeContext(
     },
 
     ssh: {
+      transports: { provide: () => () => {} },
       probe: async (hostId, probeOptions) =>
         options.reachable?.(hostId, probeOptions?.port) ?? false,
       connect: async (host, connectOptions) => {
@@ -1582,6 +1595,8 @@ export function createFakeContext(
 
 export interface MockContextOptions {
   pluginId?: string;
+  /** What ctx.sync.host answers, for a sync provider's tests. */
+  syncHost?: Partial<PluginSyncHost>;
   manifest?: Partial<PluginManifest>;
   /** Capabilities the plugin is granted. Anything else throws. */
   capabilities?: string[];
@@ -1744,6 +1759,7 @@ export function createMockCtx(
 
   const base = createFakeContext({
     pluginId: options.pluginId,
+    syncHost: options.syncHost,
     actor: options.actor,
     settings: options.settings,
     coreSettings: options.coreSettings,
@@ -1996,6 +2012,16 @@ export function createMockCtx(
           return ctx.hosts.activity.provide(provider);
         },
       },
+      folders: {
+        ensure: async (name, style) => {
+          require("hosts:write");
+          return ctx.hosts.folders.ensure(name, style);
+        },
+        removeEmpty: async (name) => {
+          require("hosts:write");
+          return ctx.hosts.folders.removeEmpty(name);
+        },
+      },
       locks: {
         provide: (provider) => {
           require("hosts:lock");
@@ -2029,6 +2055,12 @@ export function createMockCtx(
 
     ssh: {
       ...ctx.ssh,
+      transports: {
+        provide: (provider) => {
+          require("ssh:transport");
+          return ctx.ssh.transports.provide(provider);
+        },
+      },
       probe: async (hostId, probeOptions) => {
         require("ssh:connect");
         return ctx.ssh.probe(hostId, probeOptions);

packages/plugin-sdk/ui.api.txt

@@ -176,7 +176,6 @@ LANGUAGES (value): readonly { code: string; label: string; }[]
 Label (value): ({ className, ...props }: LabelProps & RefAttributes<HTMLLabelElement>) => Element
 LineChart (value): ({ series, timestamps, domain, yFormatter, height, className, }: LineChartProps) => Element
 LineChartSeries (type): LineChartSeries
-LinkServerDialog (value): ({ open, onOpenChange, onLinked, relogin, }: LinkServerDialogProps) => Element
 LinkedAccountInfo (type): LinkedAccountInfo
 ListBadge (value): ({ tone, className, children, }: { tone?: "destructive" | "muted" | "brand" | "warning" | "success"; className?: string; children: ReactNode; }) => Element
 ListRow (value): ({ title, icon, badges, meta, stripe, tone, color, selected, active, dimmed, leading, trailing, actions, onClick, className, children, ...rest }: { title: ReactNode; icon?: ReactNode; badges?: ReactNode; meta?: ReactNode; stripe?: number; tone?: ListRowTone; color?: string; selected?: boolean; active?: boolean; dimmed?: boolean; leading?: ReactNode; trailing?: ReactNode; actions?: ReactNode; onClick?: () => void; className?: string; children?: ReactNode; } & Omit<HTMLAttributes<HTMLDivElement>, "title" | "children" | "onClick">) => Element
@@ -197,6 +196,8 @@ ManagerSearch (value): ({ value, onChange, placeholder, count, extra, }: { value
 Meter (value): ({ percent, className, }: { percent: number; className?: string; }) => Element
 MetricCard (value): ({ title, icon, action, children, bodyClassName, scroll, scrollMax, }: { title: string; icon: ReactNode; action?: ReactNode; children: ReactNode; bodyClassName?: string; scroll?: boolean; scrollMax?: number; }) => Element
 MiniStat (value): ({ caption, value, valueClassName, className, }: { caption: ReactNode; value: ReactNode; valueClassName?: string; className?: string; }) => Element
+NativeView (value): ({ url, ignoreCert, hidden, fallback, className, style, }: NativeViewProps) => Element
+NativeViewProps (type): NativeViewProps
 NumberField (value): ({ label, value, onChange, placeholder, hint, error, min, max, disabled, className, }: { label: string; value: number; onChange: (value: number) => void; placeholder?: string; hint?: ReactNode; error?: string; min?: number; max?: number; disabled?: boolean; className?: string; }) => Element
 OPEN_PLUGINS_EVENT (value): "termix:open-plugins"
 OpenTabRecord (type): OpenTabRecord
@@ -227,7 +228,6 @@ PopoverAnchor (value): ({ ...props }: PopoverAnchorProps & RefAttributes<HTMLDiv
 PopoverContent (value): ({ className, align, sideOffset, ...props }: PopoverContentProps & RefAttributes<HTMLDivElement>) => Element
 PopoverTrigger (value): ({ ...props }: PopoverTriggerProps & RefAttributes<HTMLButtonElement>) => Element
 ProxyNode (type): ProxyNode
-ProxySettingsFields (value): ({ customHeaders, basicAuth, onChange, }: ProxySettingsFieldsProps) => Element
 RadialGauge (value): ({ value, label, caption, size, strokeWidth, className, colorClassName, }: RadialGaugeProps) => Element
 RadialGaugeProps (type): RadialGaugeProps
 RailGroup (type): RailGroup
@@ -288,12 +288,6 @@ SurfaceKind (type): SurfaceKind
 SurfaceScope (value): ({ kind, onEditingChange, onClose, className, children, }: { kind?: SurfaceKind; onClose?: () => void; onEditingChange?: (editing: EditingWidth) => void; className?: string; children: ReactNode; }) => Element
 Switch (value): ({ className, ...props }: SwitchProps & RefAttributes<HTMLButtonElement>) => Element
 SwitchRow (value): ({ label, description, badge, checked, onChange, disabled, defaultKey, rowId, }: { label: string; description?: ReactNode; badge?: string; checked: boolean; onChange: (value: boolean) => void; disabled?: boolean; defaultKey?: string; rowId?: string; }) => Element
-SyncBasicAuth (type): SyncBasicAuth
-SyncConflictItem (type): SyncConflictItem
-SyncEntityInfo (type): SyncEntityInfo
-SyncErrorItem (type): SyncErrorItem
-SyncProxyHeader (type): SyncProxyHeader
-SyncStatus (type): SyncStatus
 TOTPDialog (value): ({ isOpen, prompt, mode, waiting, onSubmit, onCancel, backgroundColor, }: TOTPDialogProps) => Element
 Tab (type): Tab
 TabShellCallbacks (type): TabShellCallbacks
@@ -443,8 +437,6 @@ getSessionTimeoutMinutes (value): () => Promise<number>
 getSessions (value): () => Promise<{ sessions: { id: string; userId: string; username?: string; deviceType: string; deviceInfo: string; createdAt: string; expiresAt: string; lastActiveAt: string; isRevoked?: boolean; isCurrentSession?: boolean; }[]; }>
 getStatusCheckSettings (value): () => Promise<{ statusCheckInterval: number; }>
 getStatusClasses (value): (status: boolean | "online" | "offline" | "unknown", scheme: StatusColorScheme, variant: "dot" | "stripe" | "badge", loading?: boolean) => string
-getSyncConflicts (value): () => Promise<SyncConflictItem[]>
-getSyncErrors (value): () => Promise<SyncErrorItem[]>
 getTabType (value): (id: string) => TabTypeDef
 getTlsStatus (value): () => Promise<TlsStatus>
 getUpdateChannel (value): () => Promise<UpdateChannelState>
@@ -509,7 +501,6 @@ quickConnectTargets (value): (all: HostActionDef[], host: Host) => HostActionDef
 railItemLabel (value): (id: string, t: (key: string) => string) => string
 readFromClipboard (value): () => Promise<string>
 recordHostActionPreference (value): (hostId: string, action: TabType) => void
-refreshSyncStatus (value): () => void
 registerLayout (value): (item: RegisteredLayout) => () => void
 registerTabCloseGuard (value): (tabId: string, guard: Guard) => () => void
 releaseUrlFrom (value): (info: VersionInfo) => string
@@ -532,7 +523,6 @@ resolveConnectionOrigin (value): (host: OriginResolvableHost, options?: { defaul
 resolveHostDefaults (value): (where: { hostId?: number; folder?: string; parentHostId?: number; }, adminTargetUserId?: string) => Promise<Record<string, ResolvedHostDefault>>
 resolveHostTabType (value): (host: Host, preferredType?: TabType) => TabType
 resolveRemoteHostId (value): (syncId: string) => Promise<number>
-retrySyncErrors (value): () => Promise<SyncStatus>
 revokeAllUserSessions (value): (userId: string) => Promise<{ success: boolean; message: string; }>
 revokeCredentialAccess (value): (credentialId: number, accessId: number) => Promise<void>
 revokeFolderAccess (value): (ruleId: number) => Promise<void>
@@ -556,21 +546,17 @@ setDeveloperMode (value): (enabled: boolean) => Promise<void>
 setHostAuthOverride (value): (hostId: number, protocol: string, credentialId: number, sharedCopySyncId?: string) => Promise<{ success: boolean; protocol: string; credentialId: number; }>
 setNotificationPrivateEndpoints (value): (hosts: string[]) => Promise<string[]>
 setPluginOptions (value): (pluginId: string, options: { autoUpdate?: boolean; pinned?: boolean; channel?: PluginChannel; }) => Promise<{ autoUpdate: boolean; pinnedVersion: string; channel: PluginChannel; }>
-setSyncStatus (value): (next: SyncStatus) => void
 setUpdateChannel (value): (channel: UpdateChannel) => Promise<UpdateChannelState>
-settleSyncConflict (value): (id: number, keep: "mine" | "server") => Promise<void>
 shareCredential (value): (credentialId: number, targets: ShareTarget[], permissionLevel: CredentialPermissionLevel, durationHours?: number) => Promise<{ success: boolean; expiresAt: string; }>
 shareFolder (value): (folder: string, shareData: { targets: ShareTarget[]; permissionLevel: SharePermissionLevel; durationHours?: number; }) => Promise<{ success: boolean; expiresAt: string; hostsShared: number; hostsTotal: number; hostResults: { hostId: number; shared: boolean; reason?: string; }[]; }>
 shareHost (value): (hostId: number, shareData: { targets: ShareTarget[]; permissionLevel: SharePermissionLevel; durationHours?: number; }, syncId?: string) => Promise<{ success: boolean; expiresAt: string; results: { type: "role" | "user"; id: string | number; accessId: number; created: boolean; }[]; }>
 shell (value): TabShellCallbacks
 splitDefaultKey (value): (fullKey: string) => [string, string]
 sshHostToHost (value): (h: SSHHostWithStatus) => Host
-syncNow (value): () => Promise<SyncStatus>
 tabIcon (value): (type: TabType) => Element
 tabJumpHotkeyKeys (value): () => string[]
 takePendingManageRequest (value): () => ManageRequest
 unlinkExternalFromPasswordAccount (value): (userId: string) => Promise<{ success: boolean; message: string; }>
-unlinkServer (value): (keepData: boolean) => Promise<SyncStatus>
 updateCredential (value): (credentialId: number, credentialData: Record<string, unknown>) => Promise<Record<string, unknown>>
 updateExternalAutoProvision (value): (enabled: boolean) => Promise<Record<string, unknown>>
 updateFolderMetadata (value): (name: string, color?: string, icon?: string, credentialId?: number, localOnly?: boolean) => Promise<void>
@@ -588,7 +574,6 @@ updateSSHHost (value): (hostId: number, hostData: HostData) => Promise<Host>
 updateSecondFactorAfterExternalLogin (value): (enabled: boolean) => Promise<Record<string, unknown>>
 updateSessionTimeout (value): (timeoutHours: number) => Promise<void>
 updateStatusCheckSettings (value): (settings: { statusCheckInterval: number; }) => Promise<void>
-updateSyncSettings (value): (settings: { disabledTypes?: string[]; customHeaders?: SyncProxyHeader[]; basicAuth?: SyncBasicAuth; allowInvalidCertificate?: boolean; }) => Promise<SyncStatus>
 uploadTlsCertificate (value): (payload: { certificate: string; privateKey: string; }) => Promise<TlsStatus & { success: boolean; reloadMessage?: string; }>
 usageBarColor (value): (percent: number) => string
 usageColor (value): (percent: number) => string
@@ -601,6 +586,7 @@ useChooseTheme (value): () => (themeId: string) => void
 useConfirm (value): () => (options: ConfirmOptions) => Promise<boolean>
 useConnectionGate (value): () => ConnectionGateController
 useConnectionLog (value): () => ConnectionLogContextType
+useDesktopLinked (value): () => boolean
 useDesktopUpdate (value): () => DesktopUpdateState
 useEditorDefaultKeys (value): () => Map<string, EditorDefaultKey>
 useHostActions (value): () => HostActionDef[]
@@ -635,7 +621,6 @@ useSshAuthEditors (value): () => SshAuthEditorDef[]
 useSshAuthProviders (value): () => { providers: SshAuthTypeOption[]; loaded: boolean; find: (type: string) => SshAuthTypeOption; }
 useStatusColorScheme (value): () => StatusColorScheme
 useSurfaceKind (value): () => SurfaceKind
-useSyncStatus (value): () => any
 useTabHandlesVersion (value): () => number
 useTabs (value): () => TabContextType
 useTabsSafe (value): () => TabContextType

scripts/check-sdk-ui-exports.cjs

@@ -197,7 +197,6 @@ const ALLOWED = [
   "Label",
   "LineChart",
   "LineChartSeries",
-  "LinkServerDialog",
   "LinkedAccountInfo",
   "ListBadge",
   "ListRow",
@@ -218,6 +217,8 @@ const ALLOWED = [
   "Meter",
   "MetricCard",
   "MiniStat",
+  "NativeView",
+  "NativeViewProps",
   "NumberField",
   "OPEN_PLUGINS_EVENT",
   "OpenTabRecord",
@@ -248,7 +249,6 @@ const ALLOWED = [
   "PopoverContent",
   "PopoverTrigger",
   "ProxyNode",
-  "ProxySettingsFields",
   "RadialGauge",
   "RadialGaugeProps",
   "RailGroup",
@@ -309,12 +309,6 @@ const ALLOWED = [
   "SurfaceScope",
   "Switch",
   "SwitchRow",
-  "SyncBasicAuth",
-  "SyncConflictItem",
-  "SyncEntityInfo",
-  "SyncErrorItem",
-  "SyncProxyHeader",
-  "SyncStatus",
   "TOTPDialog",
   "Tab",
   "TabShellCallbacks",
@@ -464,8 +458,6 @@ const ALLOWED = [
   "getSessions",
   "getStatusCheckSettings",
   "getStatusClasses",
-  "getSyncConflicts",
-  "getSyncErrors",
   "getTabType",
   "getTlsStatus",
   "getUpdateChannel",
@@ -530,7 +522,6 @@ const ALLOWED = [
   "railItemLabel",
   "readFromClipboard",
   "recordHostActionPreference",
-  "refreshSyncStatus",
   "registerLayout",
   "registerTabCloseGuard",
   "releaseUrlFrom",
@@ -553,7 +544,6 @@ const ALLOWED = [
   "resolveHostDefaults",
   "resolveHostTabType",
   "resolveRemoteHostId",
-  "retrySyncErrors",
   "revokeAllUserSessions",
   "revokeCredentialAccess",
   "revokeFolderAccess",
@@ -577,21 +567,17 @@ const ALLOWED = [
   "setHostAuthOverride",
   "setNotificationPrivateEndpoints",
   "setPluginOptions",
-  "setSyncStatus",
   "setUpdateChannel",
-  "settleSyncConflict",
   "shareCredential",
   "shareFolder",
   "shareHost",
   "shell",
   "splitDefaultKey",
   "sshHostToHost",
-  "syncNow",
   "tabIcon",
   "tabJumpHotkeyKeys",
   "takePendingManageRequest",
   "unlinkExternalFromPasswordAccount",
-  "unlinkServer",
   "updateCredential",
   "updateExternalAutoProvision",
   "updateFolderMetadata",
@@ -609,7 +595,6 @@ const ALLOWED = [
   "updateSessionTimeout",
   "updateHttpsSettings",
   "updateStatusCheckSettings",
-  "updateSyncSettings",
   "uploadTlsCertificate",
   "usageBarColor",
   "usageColor",
@@ -622,6 +607,7 @@ const ALLOWED = [
   "useConfirm",
   "useConnectionGate",
   "useConnectionLog",
+  "useDesktopLinked",
   "useDesktopUpdate",
   "useEditorDefaultKeys",
   "useHostActions",
@@ -656,7 +642,6 @@ const ALLOWED = [
   "useSshAuthProviders",
   "useStatusColorScheme",
   "useSurfaceKind",
-  "useSyncStatus",
   "useTabHandlesVersion",
   "useTabs",
   "useTabsSafe",

scripts/install-windows-sharp.cjs

@@ -0,0 +1,26 @@
+const fs = require("node:fs");
+const path = require("node:path");
+const { execFileSync } = require("node:child_process");
+
+function findPackage(start) {
+  let directory = path.dirname(start);
+  while (directory !== path.dirname(directory)) {
+    const manifest = path.join(directory, "package.json");
+    if (fs.existsSync(manifest)) return JSON.parse(fs.readFileSync(manifest));
+    directory = path.dirname(directory);
+  }
+  throw new Error("Could not locate the installed sharp package manifest");
+}
+
+// The build runs on x64 but ships arm64 and ia32 too, so npm ci alone
+// only installs the x64 binary.
+const sharpPackage = findPackage(require.resolve("sharp"));
+const packages = [
+  "@img/sharp-win32-arm64",
+  "@img/sharp-win32-ia32",
+  "@img/sharp-win32-x64",
+].map((name) => `${name}@${sharpPackage.optionalDependencies[name]}`);
+
+execFileSync("npm.cmd", ["install", "--force", "--no-save", ...packages], {
+  stdio: "inherit",
+});

scripts/patch-ssh2-sk.cjs

@@ -0,0 +1,149 @@
+const fs = require("node:fs");
+
+const SK_ED = "sk-ssh-ed25519@openssh.com";
+const SK_EC = "sk-ecdsa-sha2-nistp256@openssh.com";
+
+function replaceOnce(source, from, to, label) {
+  const first = source.indexOf(from);
+  if (first === -1 || source.indexOf(from, first + 1) !== -1) {
+    throw new Error(`ssh2 changed (${label}); review the security key patch`);
+  }
+  return source.replace(from, () => to);
+}
+
+function patchKeyParserSource(source) {
+  if (source.includes("// termix-sk")) return source;
+  let out = replaceOnce(
+    source,
+    `    case 'ecdsa-sha2-nistp521':
+      return true;
+    case 'ssh-ed25519':
+      if (eddsaSupported)
+        return true;`,
+    `    case 'ecdsa-sha2-nistp521':
+      return true;
+    case '${SK_EC}': // termix-sk
+      return true;
+    case '${SK_ED}':
+    case 'ssh-ed25519':
+      if (eddsaSupported)
+        return true;`,
+    "key types",
+  );
+  out = replaceOnce(
+    out,
+    `    default:
+      return new Error(\`Unsupported OpenSSH public key type: \${baseType}\`);
+  }
+
+  return new OpenSSH_Public(`,
+    `    case '${SK_ED}':
+    case '${SK_EC}': {
+      // Public blob only; the security key signs, so there is no private half.
+      const rest = data.subarray(data._pos || 0);
+      const typeLen = Buffer.byteLength(baseType);
+      pubSSH = Buffer.allocUnsafe(4 + typeLen + rest.length);
+      writeUInt32BE(pubSSH, typeLen, 0);
+      pubSSH.utf8Write(baseType, 4, typeLen);
+      pubSSH.set(rest, 4 + typeLen);
+      algo = baseType === '${SK_ED}' ? null : 'sha256';
+      break;
+    }
+    default:
+      return new Error(\`Unsupported OpenSSH public key type: \${baseType}\`);
+  }
+
+  return new OpenSSH_Public(`,
+    "parseDER",
+  );
+  return out;
+}
+
+function patchAgentSource(source) {
+  if (source.includes("skTrailer")) return source;
+  return replaceOnce(
+    source,
+    `              binaryParser.init(signature, 0);
+              binaryParser.readString(true);
+              signature = binaryParser.readString();
+              binaryParser.clear();`,
+    `              binaryParser.init(signature, 0);
+              binaryParser.readString(true);
+              signature = binaryParser.readString();
+              // Security key signatures end with flags and a counter.
+              const skTrailer = signature === undefined
+                ? undefined
+                : binaryParser.readRaw();
+              binaryParser.clear();
+              if (skTrailer && skTrailer.length)
+                signature.skTrailer = Buffer.from(skTrailer);`,
+    "agent sign response",
+  );
+}
+
+function patchProtocolSource(source) {
+  if (source.includes("skTrailer")) return source;
+  const start = source.indexOf("  authPK(username, pubKey, keyAlgo, cbSign) {");
+  const end = source.indexOf("  authHostbased(", start);
+  if (start === -1 || end === -1) {
+    throw new Error("ssh2 changed (authPK); review the security key patch");
+  }
+  let region = source.slice(start, end);
+  region = replaceOnce(
+    region,
+    `      signature = convertSignature(signature, keyType);`,
+    `      const skTrailer = signature && signature.skTrailer;
+      signature = convertSignature(signature, keyType);`,
+    "authPK sign",
+  );
+  region = replaceOnce(
+    region,
+    `          + 4 + algoLen + 4 + sigLen
+      );`,
+    `          + 4 + algoLen + 4 + sigLen + (skTrailer ? skTrailer.length : 0)
+      );`,
+    "authPK alloc",
+  );
+  region = replaceOnce(
+    region,
+    `      writeUInt32BE(packet, 4 + algoLen + 4 + sigLen, p += pubKeyLen);`,
+    `      writeUInt32BE(
+        packet,
+        4 + algoLen + 4 + sigLen + (skTrailer ? skTrailer.length : 0),
+        p += pubKeyLen
+      );`,
+    "authPK length",
+  );
+  region = replaceOnce(
+    region,
+    `      packet.set(signature, p += 4);`,
+    `      packet.set(signature, p += 4);
+      if (skTrailer)
+        packet.set(skTrailer, p + sigLen);`,
+    "authPK copy",
+  );
+  return source.slice(0, start) + region + source.slice(end);
+}
+
+if (require.main === module) {
+  const targets = [
+    ["ssh2/lib/protocol/keyParser.js", patchKeyParserSource],
+    ["ssh2/lib/agent.js", patchAgentSource],
+    ["ssh2/lib/protocol/Protocol.js", patchProtocolSource],
+  ];
+  for (const [id, patch] of targets) {
+    const target = require.resolve(id);
+    const source = fs.readFileSync(target, "utf8");
+    const result = patch(source);
+    if (result !== source) fs.writeFileSync(target, result);
+  }
+  console.log(
+    "[patch-ssh2-sk] Security key public keys and signatures enabled",
+  );
+}
+
+module.exports = {
+  patchKeyParserSource,
+  patchAgentSource,
+  patchProtocolSource,
+};

src/backend/database/database.ts

@@ -27,8 +27,7 @@ import hostSidebarPreferencesRoutes from "./routes/host-sidebar-preferences.js";
 import credentialSidebarPreferencesRoutes from "./routes/credential-sidebar-preferences.js";
 import uiPreferencesRoutes from "./routes/ui-preferences.js";
 import { registerAuditLogRoutes } from "./routes/audit-log-routes.js";
-import syncRoutes from "../sync/server/routes.js";
-import syncLinkRoutes from "../sync/client/routes.js";
+import { syncForwarder } from "../sync/provider.js";
 import { syncChangeWatcher } from "../sync/server/change-watcher.js";
 import dashboardRoutes from "./routes/dashboard-routes.js";
 import {
@@ -36,6 +35,7 @@ import {
   mountPluginLegacyPaths,
 } from "./routes/plugin-api-routes.js";
 import { attachPluginWebSockets } from "../plugins/ws.js";
+import { registerSshRelay } from "../hosts/ssh-relay.js";
 import pluginRoutes from "./routes/plugins.js";
 import { createPluginAssetsRouter } from "../plugins/assets.js";
 import { getPluginRuntime } from "../plugins/index.js";
@@ -1625,8 +1625,7 @@ app.use("/host-sidebar/preferences", hostSidebarPreferencesRoutes);
 app.use("/credential-sidebar/preferences", credentialSidebarPreferencesRoutes);
 app.use("/ui-preferences", uiPreferencesRoutes);
 registerAuditLogRoutes(app, authenticateJWT);
-app.use("/sync", syncRoutes);
-app.use("/sync", syncLinkRoutes);
+app.use("/sync", syncForwarder);
 app.use("/dashboard", dashboardRoutes);
 app.use("/plugins", pluginRoutes);
 app.use(
@@ -1900,6 +1899,7 @@ const httpServer = http.createServer(app);
 // Plugin sockets ride this server at /plugin-ws/<id>/<path>. Anything else is
 // left alone, so core's own upgrade handling is unaffected.
 attachPluginWebSockets(httpServer);
+registerSshRelay();
 
 httpServer.on("error", (err: NodeJS.ErrnoException) => {
   if (err.code === "EADDRINUSE") {

src/backend/database/repositories/host-folder-repository.ts

@@ -236,6 +236,29 @@ export class HostFolderRepository {
       .where(and(eq(hosts.userId, userId), folderMatch(hosts.folder)));
   }
 
+  /** Drops the folder rows (and subfolders) only when no host is left in them. */
+  async deleteEmptyFolderRecords(
+    userId: string,
+    folderName: string,
+  ): Promise<boolean> {
+    if ((await this.listHostsInFolder(userId, folderName)).length > 0) {
+      return false;
+    }
+    await deleteReturning(
+      this.context,
+      sshFolders,
+      and(
+        eq(sshFolders.userId, userId),
+        or(
+          eq(sshFolders.name, folderName),
+          like(sshFolders.name, `${folderName} / %`),
+        ),
+      ),
+    );
+    await this.afterWrite();
+    return true;
+  }
+
   async deleteHostsAndFolderRecords(
     userId: string,
     folderName: string,

src/backend/database/routes/desktop-auto-session.ts

@@ -61,15 +61,23 @@ export function isNativeTokenExportRequest(req: Request): boolean {
  * during testing, or a household sharing one install) -- a user in that
  * state deserves to get into the app they installed, not a confusing,
  * unexplained dead end. So this always returns a single, deterministic
- * user: the admin account if one exists, else the earliest-registered
- * account. It never returns null.
+ * user: the account the user switched to if it still exists, else the admin
+ * account if one exists, else the earliest-registered account. It never
+ * returns null when there are users.
  */
 export function resolveDesktopAutoSessionUser(
   allUsers: UserRecord[],
+  preferredId?: string | null,
 ): UserRecord | null {
   if (allUsers.length === 0) return null;
   if (allUsers.length === 1) return allUsers[0];
 
+  // An account the user switched to on purpose, while it still exists.
+  const preferred = preferredId
+    ? allUsers.find((user) => user.id === preferredId)
+    : undefined;
+  if (preferred) return preferred;
+
   const admin = allUsers.find((user) => user.isAdmin);
   if (admin) return admin;
 

src/backend/database/routes/user-socket-ticket-routes.ts

@@ -61,4 +61,38 @@ export function registerUserSocketTicketRoutes(
       res.status(500).json({ error: "Failed to issue a socket ticket" });
     }
   });
+
+  /**
+   * @openapi
+   * /users/ws-ticket/api-key:
+   *   post:
+   *     summary: Get a WebSocket ticket for an API key
+   *     description: For another Termix server that manages this one with an API key. Returns a token that is valid for one minute and only opens plugin WebSockets, as the key's user. It cannot call any other route.
+   *     tags:
+   *       - Users
+   *     responses:
+   *       200:
+   *         description: The ticket.
+   *       401:
+   *         description: The request did not use an API key.
+   *       500:
+   *         description: Failed to issue the ticket.
+   */
+  router.post("/ws-ticket/api-key", authenticateJWT, async (req, res) => {
+    const authReq = req as AuthenticatedRequest;
+    if (!authReq.apiKeyId) {
+      return res.status(401).json({ error: "An API key is required" });
+    }
+    try {
+      const ticket = await authManager.issueApiKeySocketTicket(
+        authReq.userId,
+        authReq.apiKeyId,
+      );
+      res.setHeader("Cache-Control", "no-store");
+      res.json({ ticket });
+    } catch (err) {
+      authLogger.error("Failed to issue an API key socket ticket", err);
+      res.status(500).json({ error: "Failed to issue a socket ticket" });
+    }
+  });
 }

src/backend/database/routes/users.ts

@@ -27,6 +27,7 @@ import { registerUserSettingsRoutes } from "./user-settings-routes.js";
 import { registerTlsRoutes } from "./tls-routes.js";
 import { registerUserSessionRoutes } from "./user-session-routes.js";
 import { registerUserSocketTicketRoutes } from "./user-socket-ticket-routes.js";
+import { shownIdentity } from "../../sync/shown-identity.js";
 import { registerUserExternalAccountRoutes } from "./user-external-account-routes.js";
 import { registerUserPasswordResetRoutes } from "./user-password-reset-routes.js";
 import { registerUserAdminRoutes } from "./user-admin-routes.js";
@@ -568,30 +569,6 @@ router.post("/logout", authenticateJWT, async (req, res) => {
   }
 });
 
-/**
- * On a desktop linked to a server, the account it is signed in to there.
- * That account is who the user is; the local profile only mirrors it.
- */
-async function describeDesktopLink(userId: string) {
-  if (process.env.ELECTRON_EMBEDDED !== "true") return null;
-  try {
-    const { getLink } = await import("../../sync/client/link-store.js");
-    const link = await getLink();
-    if (!link || link.userId !== userId) return null;
-    return {
-      serverUrl: link.serverUrl,
-      serverName: link.serverName,
-      username: link.account?.username ?? link.remoteUsername,
-      isAdmin: !!link.account?.isAdmin,
-      roles: link.account?.roles ?? [],
-      permissions: link.account?.permissions ?? [],
-      status: link.status,
-    };
-  } catch {
-    return null;
-  }
-}
-
 /**
  * @openapi
  * /users/me:
@@ -624,18 +601,19 @@ router.get("/me", authenticateJWT, async (req: Request, res: Response) => {
 
     const hasPassword = user.passwordHash && user.passwordHash.trim() !== "";
     const isDualAuth = hasPassword && isExternalAccount(user);
+    const shown = await shownIdentity(user);
 
     res.json({
       userId: user.id,
-      username: user.username,
-      is_admin: !!user.isAdmin,
+      username: shown.username,
+      is_admin: shown.isAdmin,
       is_external: isExternalAccount(user),
       is_dual_auth: isDualAuth,
       // Any second factor; the name is what 2.8 clients read.
       totp_enabled: await createCurrentUserAuthRepository().hasSecondFactor(
         user.id,
       ),
-      linked: await describeDesktopLink(user.id),
+      linked: shown.linked,
       // "second-factor-setup" while the login policy wants a factor set up.
       restriction: (req as AuthenticatedRequest).sessionRestriction ?? null,
     });
@@ -743,7 +721,11 @@ router.post("/internal/auto-session", async (req, res) => {
 
     const userRepository = createCurrentUserRepository();
     const allUsers = await userRepository.listAll();
-    const userRecord = resolveDesktopAutoSessionUser(allUsers);
+    const { getSavedActiveUserId } = await import("../../sync/accounts.js");
+    const userRecord = resolveDesktopAutoSessionUser(
+      allUsers,
+      await getSavedActiveUserId(),
+    );
     if (!userRecord) {
       return res.status(403).json({
         error: "No local users exist",
@@ -754,10 +736,11 @@ router.post("/internal/auto-session", async (req, res) => {
     if (existingToken) {
       const existingPayload = await authManager.verifyJWTToken(existingToken);
       if (existingPayload?.userId === userRecord.id) {
+        const shownNow = await shownIdentity(userRecord);
         return res.json({
           success: true,
-          is_admin: !!userRecord.isAdmin,
-          username: userRecord.username,
+          is_admin: shownNow.isAdmin,
+          username: shownNow.username,
           token: existingToken,
         });
       }
@@ -769,10 +752,11 @@ router.post("/internal/auto-session", async (req, res) => {
       rememberMe: true,
     });
 
+    const shown = await shownIdentity(userRecord);
     const response = {
       success: true,
-      is_admin: !!userRecord.isAdmin,
-      username: userRecord.username,
+      is_admin: shown.isAdmin,
+      username: shown.username,
       token,
     };
 

src/backend/hosts/connect/transport-providers.ts

@@ -0,0 +1,51 @@
+/**
+ * Other ways to reach a host, provided by plugins through
+ * ctx.ssh.transports.provide. A provider claims some hosts by id and hands the
+ * pipeline an open stream to them instead of a TCP connection, for example a
+ * relay through another Termix server. The first provider that claims a host
+ * wins, and nothing else (jump hosts, proxies) is tried for it.
+ */
+
+import type { Duplex } from "node:stream";
+import type { PluginSshTransportProvider } from "@termix-ssh/plugin-sdk/backend";
+
+interface Entry {
+  pluginId: string;
+  provider: PluginSshTransportProvider;
+}
+
+const providers = new Map<symbol, Entry>();
+
+export function provideSshTransport(
+  pluginId: string,
+  provider: PluginSshTransportProvider,
+): () => void {
+  const key = Symbol(pluginId);
+  providers.set(key, { pluginId, provider });
+  return () => {
+    providers.delete(key);
+  };
+}
+
+/** Test seam. */
+export function clearSshTransports(): void {
+  providers.clear();
+}
+
+/** Opens a stream to the host if a provider claims it, else null. */
+export async function openProvidedTransport(host: {
+  id: number;
+  ip: string;
+  port: number;
+}): Promise<Duplex | null> {
+  for (const { provider } of providers.values()) {
+    let claimed = false;
+    try {
+      claimed = provider.claims(host.id);
+    } catch {
+      claimed = false;
+    }
+    if (claimed) return provider.open(host);
+  }
+  return null;
+}

src/backend/hosts/connect/transport.ts

@@ -1,6 +1,6 @@
 /**
- * How the bytes get to a host: port knocking, a jump host chain or a SOCKS5
- * proxy, in that order. Sets config.sock and
+ * How the bytes get to a host: a transport a plugin provides, else port
+ * knocking, a jump host chain or a SOCKS5 proxy, in that order. Sets config.sock and
  * returns the jump client so the caller can close it with the connection.
  */
 
@@ -13,6 +13,7 @@ import {
 } from "../../utils/socks5-helper.js";
 import type { ProxyNode } from "../../../types/index.js";
 import { createJumpHostChain } from "../jump-host-chain.js";
+import { openProvidedTransport } from "./transport-providers.js";
 import { resolveSshConnectConfigHost } from "../ssh-dns.js";
 import { performPortKnocking } from "../terminal-auth-helpers.js";
 import type {
@@ -59,7 +60,7 @@ export interface OpenTransportOptions {
 
 export interface OpenedTransport {
   jumpClient: Client | null;
-  via: "direct" | "proxy" | "jump";
+  via: "direct" | "proxy" | "jump" | "provided";
 }
 
 function forwardThrough(
@@ -94,6 +95,16 @@ export async function openSshTransport(
   config: MutableConnectConfig,
   options: OpenTransportOptions = {},
 ): Promise<OpenedTransport> {
+  const provided = await openProvidedTransport({
+    id: host.id,
+    ip: host.ip,
+    port: host.port || 22,
+  });
+  if (provided) {
+    config.sock = provided;
+    return { jumpClient: null, via: "provided" };
+  }
+
   if (
     options.portKnock !== false &&
     Array.isArray(host.portKnockSequence) &&

src/backend/hosts/ssh-relay.ts

@@ -0,0 +1,110 @@
+/**
+ * A relay to a host's SSH port, for another Termix server that manages this
+ * one. It opens a WebSocket at /plugin-ws/core/ssh-relay with an API key
+ * ticket, names a host, and the bytes of an SSH connection run through it.
+ * This server reaches the host the way it always does, jump hosts, proxy and
+ * port knocking included, so the other server never needs a route to it. The
+ * SSH session itself stays between that server and the host.
+ *
+ * The caller needs connect access to the host, the same as for a session.
+ */
+
+import net from "node:net";
+import type { Duplex } from "node:stream";
+import { createWebSocketStream, type WebSocket } from "ws";
+import type { PluginWebSocketConnection } from "@termix-ssh/plugin-sdk/backend";
+import { resolveHostById } from "./host-resolver.js";
+import { openSshTransport } from "./connect/transport.js";
+import type { MutableConnectConfig, SshConnectHost } from "./connect/types.js";
+import { sshLogger } from "../utils/logger.js";
+import { registerCoreWsRoute } from "../plugins/ws.js";
+
+const MAX_RELAYS_PER_USER = 100;
+const open = new Map<string, number>();
+
+function close(ws: WebSocket, code: number, reason: string): void {
+  try {
+    ws.close(code, reason);
+  } catch {
+    // Already closed.
+  }
+}
+
+async function handleRelay(
+  connection: PluginWebSocketConnection,
+): Promise<void> {
+  const ws = connection.socket as WebSocket;
+  const url = String((connection.request as { url?: string }).url ?? "");
+  const hostId = Number(
+    new URL(url, "http://relay").searchParams.get("hostId"),
+  );
+  const userId = connection.userId;
+
+  if (!userId || !Number.isSafeInteger(hostId) || hostId <= 0) {
+    close(ws, 1008, "A host is required");
+    return;
+  }
+  if ((open.get(userId) ?? 0) >= MAX_RELAYS_PER_USER) {
+    close(ws, 1013, "Too many connections");
+    return;
+  }
+
+  const host = await resolveHostById(hostId, userId);
+  if (!host) {
+    close(ws, 1008, "Host not found or access denied");
+    return;
+  }
+
+  open.set(userId, (open.get(userId) ?? 0) + 1);
+  let stream: Duplex | null = null;
+  let jumpEnd: (() => void) | null = null;
+  let done = false;
+  const finish = () => {
+    if (done) return;
+    done = true;
+    open.set(userId, Math.max(0, (open.get(userId) ?? 1) - 1));
+    stream?.destroy();
+    jumpEnd?.();
+    close(ws, 1000, "Closed");
+  };
+  ws.once("close", finish);
+
+  try {
+    const sshHost = host as unknown as SshConnectHost;
+    const config = {
+      host: sshHost.ip,
+      port: sshHost.port || 22,
+    } as MutableConnectConfig;
+    const { jumpClient } = await openSshTransport(sshHost, config);
+    jumpEnd = () => jumpClient?.end();
+    stream = (config.sock as Duplex | undefined) ?? null;
+    if (!stream) {
+      stream = net.connect({
+        host: String(config.host),
+        port: Number(config.port),
+      });
+    }
+    const pipe = createWebSocketStream(ws);
+    stream.once("error", finish);
+    stream.once("close", finish);
+    pipe.once("error", finish);
+    stream.pipe(pipe);
+    pipe.pipe(stream);
+  } catch (error) {
+    sshLogger.warn("A relay could not reach its host", {
+      operation: "ssh_relay_open",
+      hostId,
+      error: error instanceof Error ? error.message : String(error),
+    });
+    finish();
+  }
+}
+
+let registered = false;
+
+/** Mounts the relay once, for servers that other Termix servers manage. */
+export function registerSshRelay(): void {
+  if (registered) return;
+  registered = true;
+  registerCoreWsRoute("/ssh-relay", handleRelay);
+}

src/backend/plugins/ctx-desktop-local.ts

@@ -157,6 +157,7 @@ export function createPluginDesktopLocal(deps: Deps): PluginDesktopLocal {
           customHeaders: link.customHeaders,
           basicAuth: link.basicAuth,
           allowInvalidCertificate: link.allowInvalidCertificate,
+          clientCert: link.clientCert,
         },
         pathname,
       );

src/backend/plugins/ctx-hosts.ts

@@ -1041,6 +1041,31 @@ export function createPluginHosts({ manifest, bag, audit }: Deps): PluginHosts {
       },
     },
 
+    folders: {
+      ensure: async (name, style) => {
+        await requireWrite();
+        const userId = actingUser();
+        const { createCurrentHostFolderRepository } =
+          await import("../database/repositories/factory.js");
+        await createCurrentHostFolderRepository().upsertMetadata(
+          userId,
+          name,
+          style?.color ?? null,
+          style?.icon ?? null,
+        );
+      },
+      removeEmpty: async (name) => {
+        await requireWrite();
+        const userId = actingUser();
+        const { createCurrentHostFolderRepository } =
+          await import("../database/repositories/factory.js");
+        return createCurrentHostFolderRepository().deleteEmptyFolderRecords(
+          userId,
+          name,
+        );
+      },
+    },
+
     activity: {
       provide: (provider) => {
         if (!declared.includes("hosts:activity-provide")) {

src/backend/plugins/ctx-ssh-auth.ts

@@ -43,6 +43,7 @@ import {
   registerSecondFactor,
 } from "../auth/registry.js";
 import { provideAuthPolicy } from "../auth/policy.js";
+import { provideSshTransport } from "../hosts/connect/transport-providers.js";
 import type { VerifiedIdentity } from "../auth/types.js";
 import type {
   MutableConnectConfig,
@@ -296,6 +297,26 @@ export function createPluginSsh({ manifest, bag, audit }: Deps): PluginSsh {
     }`;
 
   return {
+    transports: {
+      provide: (provider) => {
+        if (!declared.includes("ssh:transport")) {
+          throw capabilityRefused(pluginId, "ssh:transport");
+        }
+        const remove = provideSshTransport(pluginId, provider);
+        void audit(
+          "ssh_transport_provide",
+          `${pluginId} carries host connections`,
+          {
+            success: true,
+          },
+        );
+        const drop = bag.add(remove, "ssh transport");
+        return () => {
+          drop();
+          remove();
+        };
+      },
+    },
     probe: async (hostId, probeOptions) => {
       await assertCapability(pluginId, "ssh:connect", declared);
       if (!Number.isInteger(hostId) || hostId <= 0) return false;

src/backend/plugins/ctx.ts

@@ -54,6 +54,9 @@ import {
 } from "@termix-ssh/plugin-sdk/backend";
 import type { PluginTableDefinition } from "@termix-ssh/plugin-sdk/db";
 import * as syncRegistry from "./sync-registry.js";
+import { provideSync } from "../sync/provider.js";
+import { createSyncHost } from "../sync/host.js";
+import type { PluginSyncHost } from "@termix-ssh/plugin-sdk/backend";
 import {
   needsExplicitPersist,
   resolveDatabaseDialect,
@@ -189,6 +192,34 @@ export function createPluginContext(
   handle: PluginHandle,
 ): PluginContext {
   const pluginId = manifest.id;
+  let syncHost: PluginSyncHost | undefined;
+  const syncApi: PluginContext["sync"] = {
+    registerEntity: (entity) => {
+      const dispose = syncRegistry.registerEntity(pluginId, entity);
+      handle.bag.add(dispose, `sync entity ${entity.type}`);
+    },
+    provide: (provider) => {
+      if (!manifest.capabilities.includes("sync:provide")) {
+        throw capabilityRefused(pluginId, "sync:provide");
+      }
+      const remove = provideSync(pluginId, provider);
+      const drop = handle.bag.add(remove, "sync provider");
+      return () => {
+        drop();
+        remove();
+      };
+    },
+  } as PluginContext["sync"];
+  // Not enumerable, so tools that walk the context do not trip the check.
+  Object.defineProperty(syncApi, "host", {
+    enumerable: false,
+    get() {
+      if (!manifest.capabilities.includes("sync:provide")) {
+        throw capabilityRefused(pluginId, "sync:provide");
+      }
+      return (syncHost ??= createSyncHost());
+    },
+  });
   const auditCall = (
     action: string,
     details: string,
@@ -520,12 +551,7 @@ export function createPluginContext(
       },
     },
 
-    sync: {
-      registerEntity: (entity) => {
-        const dispose = syncRegistry.registerEntity(pluginId, entity);
-        handle.bag.add(dispose, `sync entity ${entity.type}`);
-      },
-    },
+    sync: syncApi,
 
     kv: {
       get: (key) => kvGet(key),

src/backend/plugins/user-data.ts

@@ -27,7 +27,7 @@ export interface UserOwnedTable {
   otherUserColumns: string[];
   /** refHost columns. */
   hostColumns: string[];
-  /** Columns that travel, as SQL names. The primary key and secrets do not. */
+  /** Columns that travel, as SQL names. Auto ids and secrets do not. */
   columns: string[];
   /** The owner column is the primary key: one row per user. */
   userIsKey: boolean;
@@ -57,9 +57,7 @@ export function listUserOwnedTables(): UserOwnedTable[] {
         .filter(
           ([, column]) =>
             column === user[1] ||
-            (column.type !== "id" &&
-              !column.primaryKey &&
-              column.type !== "encryptedText"),
+            (column.type !== "id" && column.type !== "encryptedText"),
         )
         .map(([property, column]) => columnName(property, column)),
       userIsKey: !!user[1].primaryKey,

src/backend/plugins/ws.ts

@@ -54,6 +54,8 @@ interface Route {
   rawHandler?: RawUpgradeHandler;
   /** Sockets handed to rawHandler, destroyed when the route goes away. */
   rawSockets?: Set<Duplex>;
+  /** Core's own socket: served under /plugin-ws/core/, no plugin grant. */
+  core?: boolean;
 }
 
 /** Largest frame a plugin socket accepts. ws defaults to 100MB. */
@@ -163,7 +165,10 @@ async function handlePluginUpgrade(
   // checked per upgrade rather than at registration, and a revoke takes effect
   // on the next connection without a restart.
   const { hasCapability } = await import("./permissions.js");
-  if (!(await hasCapability(route.pluginId, "network:serve", route.declared))) {
+  if (
+    !route.core &&
+    !(await hasCapability(route.pluginId, "network:serve", route.declared))
+  ) {
     reject(socket, 403, "Forbidden");
     return true;
   }
@@ -303,6 +308,32 @@ export function registerPluginWsRoute(
   return () => disposeRoute(routeKey, pluginId, normalized);
 }
 
+/**
+ * A socket core itself serves, at /plugin-ws/core/<path>, so it rides the same
+ * proxy rules and token checks as plugin sockets. Authenticated like them.
+ */
+export function registerCoreWsRoute(
+  path: string,
+  handler: PluginWebSocketHandler,
+): () => void {
+  const routeKey = key("core", path);
+  const normalized = normalizePath(path);
+  if (routes.has(routeKey)) return () => {};
+  routes.set(routeKey, {
+    pluginId: "core",
+    path: normalized,
+    options: {},
+    declared: [],
+    handler,
+    core: true,
+  });
+  servers.set(
+    routeKey,
+    new WebSocketServer({ noServer: true, maxPayload: MAX_PAYLOAD_BYTES }),
+  );
+  return () => disposeRoute(routeKey, "core", normalized);
+}
+
 export function registerPluginWsUpgrade(
   pluginId: string,
   path: string,

src/backend/starter.ts

@@ -265,17 +265,15 @@ async function provisionLocalDesktopUserIfNeeded(): Promise<void> {
       });
     }
 
-    // After plugins, so their sync entities are registered before a pass.
+    // Sync itself starts with the plugin that provides it.
     if (process.env.ELECTRON_EMBEDDED === "true") {
       try {
-        const { startDesktopSync } = await import("./sync/client/engine.js");
-        startDesktopSync();
         const { startDesktopUpdateCheck } =
           await import("./updates/desktop-update-check.js");
         startDesktopUpdateCheck();
       } catch (error) {
-        systemLogger.warn("Desktop sync failed to start", {
-          operation: "sync_start",
+        systemLogger.warn("Desktop update check failed to start", {
+          operation: "update_check_start",
           error: getErrorMessage(error),
         });
       }

src/backend/sync/accounts.ts

@@ -0,0 +1,94 @@
+/**
+ * Accounts on a desktop. Each local user is one account: the plain local one,
+ * or the replica of a linked server. Exactly one is active, and the app signs
+ * in as it. Switching only changes which user the desktop auto session picks,
+ * so no data is shared between accounts.
+ */
+
+import crypto from "crypto";
+import {
+  createCurrentRoleRepository,
+  createCurrentSettingsRepository,
+  createCurrentUserRepository,
+} from "../database/repositories/factory.js";
+import { resolveDesktopAutoSessionUser } from "../database/routes/desktop-auto-session.js";
+import { AuthManager } from "../utils/auth-manager.js";
+
+const ACTIVE_KEY = "desktop_active_user";
+
+/** The user the desktop signs in as. Falls back to the usual single-user pick. */
+export async function getActiveUserId(): Promise<string | null> {
+  const users = await createCurrentUserRepository().listAll();
+  if (users.length === 0) return null;
+  const saved = await createCurrentSettingsRepository().get(ACTIVE_KEY);
+  return resolveDesktopAutoSessionUser(users, saved)?.id ?? null;
+}
+
+export async function setActiveUserId(userId: string): Promise<void> {
+  const user = await createCurrentUserRepository().findById(userId);
+  if (!user) throw new Error("No such account");
+  await createCurrentSettingsRepository().set(ACTIVE_KEY, userId);
+}
+
+/** Saved choice only, for the auto session route. */
+export async function getSavedActiveUserId(): Promise<string | null> {
+  return createCurrentSettingsRepository().get(ACTIVE_KEY);
+}
+
+export interface DesktopAccount {
+  id: string;
+  username: string;
+  isAdmin: boolean;
+  active: boolean;
+}
+
+export async function listAccounts(): Promise<DesktopAccount[]> {
+  const users = await createCurrentUserRepository().listAll();
+  const active = await getActiveUserId();
+  return users.map((user) => ({
+    id: user.id,
+    username: user.username,
+    isAdmin: !!user.isAdmin,
+    active: user.id === active,
+  }));
+}
+
+/** A new empty account for another server to be linked to. */
+export async function createAccount(): Promise<string> {
+  const users = createCurrentUserRepository();
+  const id = crypto.randomUUID();
+  await users.create({
+    id,
+    username: `server-${id.slice(0, 8)}`,
+    passwordHash: "",
+    isAdmin: true,
+  });
+  try {
+    await createCurrentRoleRepository().assignRoleNameToUser({
+      userId: id,
+      roleName: "admin",
+      grantedBy: id,
+    });
+  } catch {
+    // The account still works; admin is also set on the user row.
+  }
+  await AuthManager.getInstance().registerUser(
+    id,
+    crypto.randomBytes(32).toString("hex"),
+  );
+  return id;
+}
+
+/** Deletes an account and everything it owns. The last account stays. */
+export async function removeAccount(userId: string): Promise<void> {
+  const users = await createCurrentUserRepository().listAll();
+  if (users.length <= 1) throw new Error("The last account cannot be removed");
+  const active = await getActiveUserId();
+  const { deleteUserAndRelatedData } =
+    await import("../database/routes/delete-user-data.js");
+  await deleteUserAndRelatedData(userId);
+  if (active === userId) {
+    const next = users.find((user) => user.id !== userId);
+    if (next) await setActiveUserId(next.id);
+  }
+}

src/backend/sync/client/device.ts

@@ -0,0 +1,5 @@
+import os from "os";
+
+export function defaultDeviceName(): string {
+  return os.hostname() || "Termix Desktop";
+}

src/backend/sync/client/electron-proxy.ts

@@ -14,7 +14,11 @@ export async function applyElectronProxyConfig(
   link:
     | (Pick<
         SyncLink,
-        "serverUrl" | "customHeaders" | "basicAuth" | "allowInvalidCertificate"
+        | "serverUrl"
+        | "customHeaders"
+        | "basicAuth"
+        | "allowInvalidCertificate"
+        | "clientCert"
       > & { sessionToken?: string | null; status?: string })
     | null,
 ): Promise<void> {
@@ -30,6 +34,7 @@ export async function applyElectronProxyConfig(
           headers: link.customHeaders ?? [],
           basicAuth: link.basicAuth ?? null,
           allowInvalidCertificate: !!link.allowInvalidCertificate,
+          clientCert: link.clientCert ?? null,
         }
       : null,
   );

src/backend/sync/client/engine.ts

@@ -1,780 +0,0 @@
-/**
- * The linked desktop's side of sync.
- *
- * A pass pushes local edits, then pulls what changed on the server after the
- * saved cursor, then backfills any entity type this device has never pulled
- * (first link, a feature switched on, a category turned back on). Local
- * edits are found the same way the server finds changes: by comparing each
- * row's hash with the one recorded at the last sync.
- */
-
-import os from "os";
-import type { SyncRow } from "@termix-ssh/plugin-sdk/backend";
-import {
-  getEntity,
-  listEntities,
-  onEntitiesChanged,
-  type RegisteredSyncEntity,
-} from "../../plugins/sync-registry.js";
-import { syncLogger } from "../../utils/logger.js";
-import { sendCoreAlert } from "../../notify/core-notify.js";
-import { registerCoreSyncEntities } from "../entities.js";
-import {
-  createResolvers,
-  deleteStoredRow,
-  loadWireRow,
-  loadWireRows,
-  writeWireRow,
-} from "../store.js";
-import {
-  listRecords,
-  putRecord,
-  recordKey,
-  saveConflict,
-  setRecordError,
-  type SyncRecord,
-} from "../records.js";
-import { orderSelfReferences } from "../wire.js";
-import { onLocalWrite } from "../server/change-watcher.js";
-import { getLink, updateLink, type SyncLink } from "./link-store.js";
-import { RemoteError, remoteFetch, remoteJson } from "./http.js";
-import { mirrorPlugins } from "./plugins.js";
-import { applyElectronProxyConfig } from "./electron-proxy.js";
-
-export interface RemoteChange {
-  seq: number;
-  entityType: string;
-  syncId: string;
-  revision: number;
-  deleted: boolean;
-  row: SyncRow | null;
-}
-
-interface ChangesPage {
-  changes: RemoteChange[];
-  nextCursor: number;
-  hasMore: boolean;
-  entityTypes: Array<{
-    type: string;
-    owner: string;
-    order: number;
-    readOnly: boolean;
-  }>;
-}
-
-interface PushOp {
-  entityType: string;
-  syncId: string;
-  baseRevision: number;
-  op: "upsert" | "delete";
-  row?: SyncRow;
-}
-
-type PushResult =
-  | { syncId: string; entityType: string; status: "ok"; revision: number }
-  | {
-      syncId: string;
-      entityType: string;
-      status: "conflict";
-      revision: number;
-      deleted: boolean;
-      row: SyncRow | null;
-    }
-  | { syncId: string; entityType: string; status: "rejected"; reason: string };
-
-const MAX_BATCH_OPS = 200;
-const MAX_BATCH_BYTES = 1_000_000;
-const MAX_PAGES = 500;
-const SAFETY_INTERVAL_MS = 5 * 60_000;
-const REFRESH_CHECK_MS = 24 * 60 * 60_000;
-const DELETED_HASH = "deleted";
-
-export interface EngineState {
-  running: boolean;
-  /** Local changes found in the last pass that the server has not taken. */
-  pending: number;
-  /** Entity types the server runs, from the last pull. */
-  serverTypes: Array<{ type: string; owner: string; readOnly: boolean }>;
-  lastPassAt: string | null;
-}
-
-/** An entity this device could sync: registered here, and on the server. */
-function syncable(
-  entity: RegisteredSyncEntity,
-  link: SyncLink,
-  serverTypes: Set<string> | null,
-): boolean {
-  if (link.disabledTypes.includes(entity.type)) return false;
-  if (serverTypes && !serverTypes.has(entity.type)) return false;
-  return true;
-}
-
-function sortChanges(changes: RemoteChange[]): RemoteChange[] {
-  const byType = new Map<string, RemoteChange[]>();
-  for (const change of changes) {
-    const list = byType.get(change.entityType) ?? [];
-    list.push(change);
-    byType.set(change.entityType, list);
-  }
-  const types = [...byType.keys()].sort(
-    (a, b) => (getEntity(a)?.order ?? 1e6) - (getEntity(b)?.order ?? 1e6),
-  );
-  const out: RemoteChange[] = [];
-  for (const type of types) {
-    const list = byType.get(type)!;
-    const entity = getEntity(type);
-    // Only the latest record of each row matters.
-    const latest = new Map<string, RemoteChange>();
-    for (const change of list) latest.set(change.syncId, change);
-    const live = [...latest.values()].filter((change) => !change.deleted);
-    const gone = [...latest.values()].filter((change) => change.deleted);
-    if (entity) {
-      const bySyncId = new Map(live.map((change) => [change.syncId, change]));
-      const ordered = orderSelfReferences(
-        entity,
-        live.map((change) => ({
-          ...(change.row ?? {}),
-          syncId: change.syncId,
-        })),
-      );
-      out.push(...ordered.map((row) => bySyncId.get(row.syncId as string)!));
-    } else {
-      out.push(...live);
-    }
-    out.push(...gone);
-  }
-  return out;
-}
-
-export class SyncEngine {
-  private running = false;
-  private again = false;
-  private timer: NodeJS.Timeout | null = null;
-  private safety: NodeJS.Timeout | null = null;
-  private backoffMs = 0;
-  private events: AbortController | null = null;
-  private eventsFor: string | null = null;
-  private lastRefreshCheck = 0;
-  private serverTypes: Set<string> | null = null;
-  private stopFns: Array<() => void> = [];
-  private alerted = false;
-  readonly state: EngineState = {
-    running: false,
-    pending: 0,
-    serverTypes: [],
-    lastPassAt: null,
-  };
-
-  start(): void {
-    if (this.safety) return;
-    registerCoreSyncEntities();
-    this.safety = setInterval(() => this.request(0), SAFETY_INTERVAL_MS);
-    this.safety.unref?.();
-    this.stopFns.push(onLocalWrite(() => this.request(2000)));
-    // A plugin that came up may bring entity types to backfill.
-    this.stopFns.push(onEntitiesChanged(() => this.request(3000)));
-    this.request(3000);
-  }
-
-  stop(): void {
-    if (this.safety) clearInterval(this.safety);
-    if (this.timer) clearTimeout(this.timer);
-    this.safety = this.timer = null;
-    this.closeEvents();
-    for (const stop of this.stopFns.splice(0)) stop();
-  }
-
-  /** Runs a pass after `delayMs`, folding requests that arrive meanwhile. */
-  request(delayMs = 0): void {
-    if (this.timer) {
-      if (delayMs > 0) return;
-      clearTimeout(this.timer);
-    }
-    this.timer = setTimeout(() => {
-      this.timer = null;
-      void this.run();
-    }, delayMs);
-    this.timer.unref?.();
-  }
-
-  /** Runs a pass now and waits for it. */
-  async syncNow(): Promise<void> {
-    if (this.running) {
-      this.again = true;
-      while (this.running) await new Promise((r) => setTimeout(r, 100));
-      return;
-    }
-    await this.run();
-  }
-
-  /** Forgets what the server runs, after a relink or unlink. */
-  reset(): void {
-    this.serverTypes = null;
-    this.state.serverTypes = [];
-    this.state.pending = 0;
-    this.alerted = false;
-    this.backoffMs = 0;
-    this.closeEvents();
-  }
-
-  private async run(): Promise<void> {
-    if (this.running) {
-      this.again = true;
-      return;
-    }
-    this.running = this.state.running = true;
-    try {
-      await this.pass();
-    } finally {
-      this.running = this.state.running = false;
-      this.state.lastPassAt = new Date().toISOString();
-      if (this.again) {
-        this.again = false;
-        this.request(0);
-      }
-    }
-  }
-
-  private async pass(): Promise<void> {
-    const link = await getLink();
-    if (!link?.sessionToken) {
-      this.closeEvents();
-      return;
-    }
-    await updateLink({ status: "syncing" });
-
-    try {
-      await this.refreshSession(link);
-      const fresh = (await getLink())!;
-      await mirrorPlugins(fresh);
-
-      // A first pass pulls before it pushes, so rows both sides already
-      // have are matched up instead of sent back as edits.
-      const firstPass = fresh.knownTypes.length === 0;
-      if (!firstPass) {
-        await this.push(fresh);
-        await this.pull(fresh);
-      }
-      await this.backfill((await getLink())!);
-      if (firstPass) await this.push((await getLink())!);
-
-      this.backoffMs = 0;
-      this.alerted = false;
-      await updateLink({
-        status: "idle",
-        lastError: null,
-        lastSyncAt: new Date().toISOString(),
-      });
-      const done = (await getLink())!;
-      await applyElectronProxyConfig(done).catch(() => {});
-      this.openEvents(done);
-    } catch (error) {
-      await this.fail(error);
-    }
-  }
-
-  private async fail(error: unknown): Promise<void> {
-    const remote = error instanceof RemoteError ? error : null;
-    const message = error instanceof Error ? error.message : String(error);
-    syncLogger.warn("Sync pass failed", {
-      operation: "sync_pass",
-      kind: remote?.kind ?? "internal",
-      error: message,
-    });
-
-    if (remote?.kind === "signed_out") {
-      const link = await updateLink({
-        status: "signed_out",
-        lastError: message,
-      });
-      await applyElectronProxyConfig(link).catch(() => {});
-      this.closeEvents();
-      if (!this.alerted) {
-        this.alerted = true;
-        await sendCoreAlert({
-          title: "Sync is paused",
-          body: "This device was signed out of the server it syncs with. Sign in again from Sync to keep going.",
-          severity: "warning",
-          category: "termix.sync.signed_out",
-          dedupeKey: "sync:signed_out",
-          audience: "admins",
-          link: { tab: "sync" },
-        });
-      }
-      return;
-    }
-
-    const offline = remote?.kind === "offline";
-    await updateLink({
-      status: offline ? "offline" : "error",
-      lastError: message,
-    });
-    this.backoffMs = Math.min(
-      this.backoffMs ? this.backoffMs * 2 : 15_000,
-      10 * 60_000,
-    );
-    this.request(this.backoffMs);
-  }
-
-  private async refreshSession(link: SyncLink): Promise<void> {
-    if (Date.now() - this.lastRefreshCheck < REFRESH_CHECK_MS) return;
-    const result = await remoteJson<{ token: string | null }>(
-      link,
-      "/sync/v2/session/refresh",
-      { method: "POST", body: {} },
-    );
-    this.lastRefreshCheck = Date.now();
-    if (result.token) await updateLink({ sessionToken: result.token });
-  }
-
-  /** Local rows the server does not have in this form yet. */
-  async outbox(link: SyncLink): Promise<{
-    ops: PushOp[];
-    hashes: Map<string, string>;
-  }> {
-    const records = await listRecords(link.userId);
-    const resolvers = createResolvers(link.userId);
-    const ops: PushOp[] = [];
-    const hashes = new Map<string, string>();
-
-    for (const entity of listEntities()) {
-      if (entity.readOnly) continue;
-      if (!link.knownTypes.includes(entity.type)) continue;
-      if (!syncable(entity, link, this.serverTypes)) continue;
-
-      const { rows, failed } = await loadWireRows(
-        entity,
-        link.userId,
-        resolvers,
-      );
-      for (const row of rows.values()) {
-        const key = recordKey(entity.type, row.syncId);
-        const record = records.get(key);
-        if (record && !record.deleted && record.hash === row.hash) continue;
-        // Unavailable server rows can recover without another local edit.
-        if (record?.errorHash === row.hash && record.error !== "unavailable") {
-          continue;
-        }
-        ops.push({
-          entityType: entity.type,
-          syncId: row.syncId,
-          baseRevision: record?.revision ?? 0,
-          op: "upsert",
-          row: row.wire,
-        });
-        hashes.set(key, row.hash);
-      }
-
-      for (const record of records.values()) {
-        if (record.entityType !== entity.type || record.deleted) continue;
-        if (record.revision === 0) continue;
-        if (rows.has(record.syncId) || failed.has(record.syncId)) continue;
-        if (entity.covers && !entity.covers(record.syncId)) continue;
-        if (
-          record.errorHash === DELETED_HASH &&
-          record.error !== "unavailable"
-        ) {
-          continue;
-        }
-        ops.push({
-          entityType: entity.type,
-          syncId: record.syncId,
-          baseRevision: record.revision,
-          op: "delete",
-        });
-      }
-    }
-    return { ops, hashes };
-  }
-
-  private async push(link: SyncLink): Promise<void> {
-    const { ops, hashes } = await this.outbox(link);
-    this.state.pending = ops.length;
-    if (ops.length === 0) return;
-
-    for (const batch of batches(ops)) {
-      const { results } = await remoteJson<{ results: PushResult[] }>(
-        link,
-        "/sync/v2/push",
-        { method: "POST", body: { ops: batch }, timeoutMs: 120_000 },
-      );
-      const byKey = new Map(
-        batch.map((op) => [recordKey(op.entityType, op.syncId), op]),
-      );
-      for (const result of results) {
-        const key = recordKey(result.entityType, result.syncId);
-        const op = byKey.get(key);
-        if (!op) continue;
-        await this.settle(link, op, result, hashes.get(key) ?? null);
-      }
-      this.state.pending = Math.max(0, this.state.pending - batch.length);
-    }
-  }
-
-  private async settle(
-    link: SyncLink,
-    op: PushOp,
-    result: PushResult,
-    hash: string | null,
-  ): Promise<void> {
-    const userId = link.userId;
-    const entity = getEntity(op.entityType);
-    if (!entity) return;
-
-    if (result.status === "ok") {
-      await putRecord(userId, op.entityType, op.syncId, {
-        revision: result.revision,
-        hash: op.op === "delete" ? null : hash,
-        deleted: op.op === "delete",
-      });
-      return;
-    }
-
-    if (result.status === "rejected") {
-      await setRecordError(
-        userId,
-        op.entityType,
-        op.syncId,
-        result.reason,
-        hash ?? DELETED_HASH,
-      );
-      return;
-    }
-
-    // A live row the server could not send says nothing; keep ours to retry.
-    if (!result.deleted && !result.row) return;
-
-    // Conflict: the server moved on since this device last saw the row. Its
-    // version wins here, and a local edit it replaced is kept for the user.
-    if (op.op === "upsert" && op.row) {
-      await saveConflict(
-        userId,
-        op.entityType,
-        op.syncId,
-        op.row,
-        result.revision,
-      );
-    }
-    const resolvers = createResolvers(userId);
-    if (result.deleted) {
-      await deleteStoredRow(entity, userId, op.syncId);
-      await putRecord(userId, op.entityType, op.syncId, {
-        revision: result.revision,
-        hash: null,
-        deleted: true,
-      });
-      return;
-    }
-    await writeWireRow(
-      entity,
-      userId,
-      { ...result.row, syncId: op.syncId },
-      resolvers,
-    );
-    const written = await loadWireRow(entity, userId, op.syncId, resolvers);
-    await putRecord(userId, op.entityType, op.syncId, {
-      revision: result.revision,
-      hash: written?.hash ?? null,
-      deleted: false,
-    });
-  }
-
-  private async fetchChanges(
-    link: SyncLink,
-    cursor: number,
-    types?: string[],
-  ): Promise<{ changes: RemoteChange[]; cursor: number }> {
-    const all: RemoteChange[] = [];
-    let next = cursor;
-    for (let page = 0; page < MAX_PAGES; page++) {
-      const query = new URLSearchParams({
-        cursor: String(next),
-        limit: "1000",
-      });
-      if (types?.length) query.set("types", types.join(","));
-      const result = await remoteJson<ChangesPage>(
-        link,
-        `/sync/v2/changes?${query.toString()}`,
-        { timeoutMs: 120_000 },
-      );
-      all.push(...result.changes);
-      next = result.nextCursor;
-      this.learnTypes(result);
-      if (!result.hasMore) break;
-    }
-    return { changes: all, cursor: next };
-  }
-
-  private learnTypes(page: ChangesPage): void {
-    this.serverTypes = new Set(page.entityTypes.map((entry) => entry.type));
-    this.state.serverTypes = page.entityTypes.map((entry) => ({
-      type: entry.type,
-      owner: entry.owner,
-      readOnly: entry.readOnly,
-    }));
-  }
-
-  private async pull(link: SyncLink): Promise<void> {
-    const { changes, cursor } = await this.fetchChanges(link, link.cursor);
-    const known = new Set(link.knownTypes);
-    await this.apply(
-      link,
-      changes.filter(
-        (change) =>
-          known.has(change.entityType) &&
-          !link.disabledTypes.includes(change.entityType),
-      ),
-      false,
-    );
-    await updateLink({ cursor });
-  }
-
-  /** Pulls every row of types this device has not pulled before. */
-  private async backfill(link: SyncLink): Promise<void> {
-    if (!this.serverTypes) {
-      // Only the entity types are wanted, so a one-row page is enough.
-      this.learnTypes(
-        await remoteJson<ChangesPage>(
-          link,
-          `/sync/v2/changes?cursor=${link.cursor}&limit=1`,
-          { timeoutMs: 120_000 },
-        ),
-      );
-    }
-    const fresh = listEntities()
-      .map((entity) => entity.type)
-      .filter(
-        (type) =>
-          !link.knownTypes.includes(type) &&
-          !link.disabledTypes.includes(type) &&
-          this.serverTypes?.has(type),
-      );
-    if (fresh.length === 0) return;
-
-    const { changes, cursor } = await this.fetchChanges(link, 0, fresh);
-    await this.apply(link, changes, true);
-    const current = (await getLink())!;
-    await updateLink({
-      knownTypes: [...new Set([...current.knownTypes, ...fresh])],
-      // On a first pass the backfill is the whole pull, so it sets the cursor.
-      ...(link.knownTypes.length === 0 ? { cursor } : {}),
-    });
-  }
-
-  /**
-   * Writes pulled changes. `adopt` is for a first pull of a type: a local row
-   * with no record yet takes the server's version without a conflict.
-   */
-  private async apply(
-    link: SyncLink,
-    changes: RemoteChange[],
-    adopt: boolean,
-  ): Promise<void> {
-    if (changes.length === 0) return;
-    const userId = link.userId;
-    const records = await listRecords(userId);
-    let missed = false;
-    const resolvers = createResolvers(userId, () => {
-      missed = true;
-    });
-    const retry: RemoteChange[] = [];
-
-    for (const change of sortChanges(changes)) {
-      const entity = getEntity(change.entityType);
-      if (!entity) continue;
-      const key = recordKey(change.entityType, change.syncId);
-      const record = records.get(key);
-      if (record && record.revision >= change.revision) continue;
-
-      try {
-        if (!entity.readOnly) {
-          await this.keepLocalEdit(
-            entity,
-            userId,
-            change,
-            record,
-            adopt,
-            resolvers,
-          );
-        }
-        if (change.deleted) {
-          await deleteStoredRow(entity, userId, change.syncId);
-          await putRecord(userId, change.entityType, change.syncId, {
-            revision: change.revision,
-            hash: null,
-            deleted: true,
-          });
-          continue;
-        }
-        missed = false;
-        await writeWireRow(
-          entity,
-          userId,
-          { ...(change.row ?? {}), syncId: change.syncId },
-          resolvers,
-        );
-        if (missed) retry.push(change);
-        await this.recordApplied(entity, userId, change, resolvers);
-      } catch (error) {
-        syncLogger.warn("Could not apply a synced change", {
-          operation: "sync_apply",
-          entityType: change.entityType,
-          syncId: change.syncId,
-          error: error instanceof Error ? error.message : String(error),
-        });
-      }
-    }
-
-    // Rows that pointed at something written later in the same pull.
-    for (const change of retry) {
-      const entity = getEntity(change.entityType)!;
-      try {
-        await writeWireRow(
-          entity,
-          userId,
-          { ...(change.row ?? {}), syncId: change.syncId },
-          resolvers,
-        );
-        await this.recordApplied(entity, userId, change, resolvers);
-      } catch {
-        // The first write stands.
-      }
-    }
-  }
-
-  private async recordApplied(
-    entity: RegisteredSyncEntity,
-    userId: string,
-    change: RemoteChange,
-    resolvers: ReturnType<typeof createResolvers>,
-  ): Promise<void> {
-    const written = entity.readOnly
-      ? null
-      : await loadWireRow(entity, userId, change.syncId, resolvers);
-    await putRecord(userId, change.entityType, change.syncId, {
-      revision: change.revision,
-      hash: written?.hash ?? null,
-      deleted: false,
-    });
-  }
-
-  /** Saves a local edit the incoming change is about to replace. */
-  private async keepLocalEdit(
-    entity: RegisteredSyncEntity,
-    userId: string,
-    change: RemoteChange,
-    record: SyncRecord | undefined,
-    adopt: boolean,
-    resolvers: ReturnType<typeof createResolvers>,
-  ): Promise<void> {
-    if (!record && adopt) return;
-    const local = await loadWireRow(
-      entity,
-      userId,
-      change.syncId,
-      resolvers,
-    ).catch(() => null);
-    if (!local) return;
-    if (record && !record.deleted && record.hash === local.hash) return;
-    await saveConflict(
-      userId,
-      change.entityType,
-      change.syncId,
-      local.wire,
-      change.revision,
-    );
-  }
-
-  private openEvents(link: SyncLink): void {
-    const key = `${link.serverUrl}|${link.sessionToken}`;
-    if (this.events && this.eventsFor === key) return;
-    this.closeEvents();
-    const controller = new AbortController();
-    this.events = controller;
-    this.eventsFor = key;
-    void this.listen(link, controller);
-  }
-
-  private closeEvents(): void {
-    this.events?.abort();
-    this.events = null;
-    this.eventsFor = null;
-  }
-
-  private async listen(
-    link: SyncLink,
-    controller: AbortController,
-  ): Promise<void> {
-    try {
-      const response = await remoteFetch(link, "/sync/v2/events", {
-        signal: controller.signal,
-      });
-      if (!response.ok || !response.body)
-        throw new Error(`HTTP ${response.status}`);
-      const decoder = new TextDecoder();
-      let buffer = "";
-      for await (const chunk of response.body) {
-        buffer += decoder.decode(chunk as Uint8Array, { stream: true });
-        let index;
-        while ((index = buffer.indexOf("\n\n")) >= 0) {
-          const block = buffer.slice(0, index);
-          buffer = buffer.slice(index + 2);
-          if (/^event: change$/m.test(block)) this.request(500);
-        }
-      }
-    } catch {
-      // Dropped or refused: the safety interval still syncs, and the next
-      // successful pass reopens the stream.
-    }
-    if (this.events === controller) {
-      this.events = null;
-      this.eventsFor = null;
-      if (!controller.signal.aborted) {
-        setTimeout(() => this.request(0), 30_000).unref?.();
-      }
-    }
-  }
-
-  /** Where the link's proxy settings have to reach outside the backend. */
-  async applyProxyConfig(): Promise<void> {
-    await applyElectronProxyConfig(await getLink());
-  }
-}
-
-function* batches(ops: PushOp[]): Generator<PushOp[]> {
-  let batch: PushOp[] = [];
-  let bytes = 0;
-  for (const op of ops) {
-    const size = JSON.stringify(op).length;
-    if (
-      batch.length > 0 &&
-      (batch.length >= MAX_BATCH_OPS || bytes + size > MAX_BATCH_BYTES)
-    ) {
-      yield batch;
-      batch = [];
-      bytes = 0;
-    }
-    batch.push(op);
-    bytes += size;
-  }
-  if (batch.length > 0) yield batch;
-}
-
-let engine: SyncEngine | null = null;
-
-export function getSyncEngine(): SyncEngine {
-  if (!engine) engine = new SyncEngine();
-  return engine;
-}
-
-/** Starts syncing on a desktop. A server install never links. */
-export function startDesktopSync(): void {
-  if (process.env.ELECTRON_EMBEDDED !== "true") return;
-  const instance = getSyncEngine();
-  instance.start();
-  void instance.applyProxyConfig().catch(() => {});
-}
-
-export function defaultDeviceName(): string {
-  return os.hostname() || "Termix Desktop";
-}

src/backend/sync/client/http.ts

@@ -9,7 +9,7 @@
 
 import { Agent, ProxyAgent, fetch as undiciFetch } from "undici";
 import type { Dispatcher } from "undici";
-import type { BasicAuth, ProxyHeader } from "./link-store.js";
+import type { BasicAuth, ClientCert, ProxyHeader } from "./link-store.js";
 
 export interface RemoteTarget {
   serverUrl: string;
@@ -17,6 +17,7 @@ export interface RemoteTarget {
   customHeaders?: ProxyHeader[];
   basicAuth?: BasicAuth | null;
   allowInvalidCertificate?: boolean;
+  clientCert?: ClientCert | null;
 }
 
 export type RemoteErrorKind =
@@ -24,6 +25,8 @@ export type RemoteErrorKind =
   | "offline"
   /** TLS failed and the certificate is not allowed. */
   | "tls"
+  /** The server wants a client certificate and none was accepted. */
+  | "client_cert"
   /** A proxy answered instead of Termix (its login page, a 404 page). */
   | "proxy"
   /** The proxy wants basic auth. */
@@ -53,6 +56,13 @@ const TLS_CODES = new Set([
   "CERT_UNTRUSTED",
 ]);
 
+const CLIENT_CERT_CODES = new Set([
+  "ERR_SSL_TLSV13_ALERT_CERTIFICATE_REQUIRED",
+  "ERR_SSL_SSLV3_ALERT_BAD_CERTIFICATE",
+  "ERR_SSL_TLSV1_ALERT_UNKNOWN_CA",
+  "ERR_SSL_SSLV3_ALERT_HANDSHAKE_FAILURE",
+]);
+
 function envProxy(url: string): string | null {
   const proxy =
     process.env.https_proxy ||
@@ -84,10 +94,16 @@ const dispatchers = new Map<string, Dispatcher>();
 function dispatcherFor(target: RemoteTarget): Dispatcher {
   const insecure = !!target.allowInvalidCertificate;
   const proxy = envProxy(target.serverUrl);
-  const key = `${insecure}|${proxy ?? ""}`;
+  const cert = target.clientCert;
+  const key = `${insecure}|${proxy ?? ""}|${cert ? `${cert.passphrase}|${cert.pfx}` : ""}`;
   let dispatcher = dispatchers.get(key);
   if (!dispatcher) {
-    const tls = insecure ? { rejectUnauthorized: false } : {};
+    const tls = {
+      ...(insecure ? { rejectUnauthorized: false } : {}),
+      ...(cert
+        ? { pfx: Buffer.from(cert.pfx, "base64"), passphrase: cert.passphrase }
+        : {}),
+    };
     dispatcher = proxy
       ? new ProxyAgent({ uri: proxy, requestTls: tls })
       : new Agent({ connect: tls });
@@ -141,10 +157,22 @@ export function requestHeaders(target: RemoteTarget): Record<string, string> {
   return headers;
 }
 
-function describeNetworkError(error: unknown): RemoteError {
+// A server that requires a client certificate often just drops the
+// connection when it gets none, or one it does not accept.
+const DROPPED_CODES = new Set(["UND_ERR_SOCKET", "ECONNRESET"]);
+
+function describeNetworkError(
+  error: unknown,
+  target?: RemoteTarget,
+): RemoteError {
   const cause = (error as { cause?: { code?: string; message?: string } })
     ?.cause;
   const code = cause?.code ?? (error as { code?: string })?.code ?? "";
+  const droppedOverTls =
+    DROPPED_CODES.has(code) && target?.serverUrl.startsWith("https:");
+  if (CLIENT_CERT_CODES.has(code) || droppedOverTls) {
+    return new RemoteError("client_cert", cause?.message || code);
+  }
   if (TLS_CODES.has(code) || /certificate/i.test(cause?.message ?? "")) {
     return new RemoteError("tls", cause?.message || code);
   }
@@ -193,7 +221,7 @@ export async function remoteFetch(
       signal: controller.signal,
     });
   } catch (error) {
-    throw describeNetworkError(error);
+    throw describeNetworkError(error, target);
   } finally {
     if (timeout) clearTimeout(timeout);
   }
@@ -228,7 +256,7 @@ export async function remoteStreamFetch(
       signal: request.signal,
     } as never);
   } catch (error) {
-    throw describeNetworkError(error);
+    throw describeNetworkError(error, target);
   }
 }
 

src/backend/sync/client/link-store.ts

@@ -1,9 +1,13 @@
 /**
- * The desktop's link to a server, one row in sync_link. Secrets (the session
- * token, proxy headers, basic auth) are stored encrypted with the system key.
+ * The desktop's links to servers, one row each in sync_link and at most one
+ * per local user, since each link has its own replica user. Secrets (the
+ * session token, proxy headers, basic auth) are stored encrypted with the
+ * system key. Without a user, a call means the active account's link.
  */
 
+import { createSecureContext } from "node:tls";
 import { eq } from "drizzle-orm";
+import { getActiveUserId } from "../accounts.js";
 import { syncLink } from "../../database/db/schema.js";
 import { createCurrentRepositoryContext } from "../../database/repositories/factory.js";
 import { DatabaseSaveTrigger } from "../../utils/database-save-trigger.js";
@@ -33,6 +37,14 @@ export interface BasicAuth {
   password: string;
 }
 
+/** A PFX/P12 client certificate for servers that require mutual TLS. */
+export interface ClientCert {
+  /** Base64 of the PFX/P12 file. */
+  pfx: string;
+  passphrase: string;
+  name: string | null;
+}
+
 export interface SyncLink {
   id: number;
   userId: string;
@@ -43,11 +55,14 @@ export interface SyncLink {
   customHeaders: ProxyHeader[];
   basicAuth: BasicAuth | null;
   allowInvalidCertificate: boolean;
+  clientCert: ClientCert | null;
   remoteUserId: string | null;
   remoteUsername: string | null;
   account: LinkAccount | null;
   /** Entity types switched off on this device. */
   disabledTypes: string[];
+  /** Extra connection options for this server, kept open for new ones. */
+  options: Record<string, unknown>;
   /** Entity types this device has fully pulled at least once. */
   knownTypes: string[];
   cursor: number;
@@ -90,7 +105,11 @@ async function fromRow(row: Row): Promise<SyncLink> {
       sessionToken = null;
     }
   }
-  const scope = parseJson<{ disabled?: string[] }>(row.scope, {});
+  const scope = parseJson<{
+    disabled?: string[];
+    options?: Record<string, unknown>;
+    clientCert?: string;
+  }>(row.scope, {});
   return {
     id: row.id,
     userId: row.userId,
@@ -101,10 +120,16 @@ async function fromRow(row: Row): Promise<SyncLink> {
     customHeaders: await decryptJson<ProxyHeader[]>(row.customHeaders, []),
     basicAuth: await decryptJson<BasicAuth | null>(row.basicAuth, null),
     allowInvalidCertificate: !!row.allowInvalidCertificate,
+    clientCert: await decryptJson<ClientCert | null>(
+      scope.clientCert ?? null,
+      null,
+    ),
     remoteUserId: row.remoteUserId,
     remoteUsername: row.remoteUsername,
     account: parseJson<LinkAccount | null>(row.account, null),
     disabledTypes: Array.isArray(scope.disabled) ? scope.disabled : [],
+    options:
+      scope.options && typeof scope.options === "object" ? scope.options : {},
     knownTypes: parseJson<string[]>(row.knownTypes, []),
     cursor: Number(row.cursor) || 0,
     status: (row.status as LinkStatus) || "idle",
@@ -114,8 +139,20 @@ async function fromRow(row: Row): Promise<SyncLink> {
   };
 }
 
-export async function getLink(): Promise<SyncLink | null> {
-  const [row] = await db().select().from(syncLink).limit(1);
+export async function listLinks(): Promise<SyncLink[]> {
+  const rows = await db().select().from(syncLink);
+  return Promise.all(rows.map(fromRow));
+}
+
+/** The link of one local user, or of the active account when none is given. */
+export async function getLink(userId?: string): Promise<SyncLink | null> {
+  const owner = userId ?? (await getActiveUserId());
+  if (!owner) return null;
+  const [row] = await db()
+    .select()
+    .from(syncLink)
+    .where(eq(syncLink.userId, owner))
+    .limit(1);
   return row ? fromRow(row) : null;
 }
 
@@ -128,12 +165,40 @@ export interface NewLink {
   customHeaders?: ProxyHeader[];
   basicAuth?: BasicAuth | null;
   allowInvalidCertificate?: boolean;
+  clientCert?: ClientCert | null;
   remoteUserId?: string | null;
   remoteUsername?: string | null;
 }
 
+/** Throws when the PFX is unreadable or the passphrase is wrong. */
+export function assertClientCert(cert: ClientCert): void {
+  try {
+    createSecureContext({
+      pfx: Buffer.from(cert.pfx, "base64"),
+      passphrase: cert.passphrase,
+    });
+  } catch {
+    throw new Error("The client certificate or its passphrase is not valid");
+  }
+}
+
+async function sealScope(
+  disabled: string[],
+  options: Record<string, unknown>,
+  clientCert: ClientCert | null,
+): Promise<string> {
+  return JSON.stringify({
+    disabled,
+    options,
+    ...(clientCert
+      ? { clientCert: await encryptSystemSecret(JSON.stringify(clientCert)) }
+      : {}),
+  });
+}
+
 export async function createLink(link: NewLink): Promise<SyncLink> {
-  await db().delete(syncLink);
+  if (link.clientCert) assertClientCert(link.clientCert);
+  await db().delete(syncLink).where(eq(syncLink.userId, link.userId));
   await db()
     .insert(syncLink)
     .values({
@@ -149,6 +214,7 @@ export async function createLink(link: NewLink): Promise<SyncLink> {
         ? await encryptSystemSecret(JSON.stringify(link.basicAuth))
         : null,
       allowInvalidCertificate: !!link.allowInvalidCertificate,
+      scope: link.clientCert ? await sealScope([], {}, link.clientCert) : null,
       remoteUserId: link.remoteUserId ?? null,
       remoteUsername: link.remoteUsername ?? null,
       cursor: 0,
@@ -157,7 +223,7 @@ export async function createLink(link: NewLink): Promise<SyncLink> {
       linkedAt: new Date().toISOString(),
     });
   await DatabaseSaveTrigger.forceSave("sync_link");
-  return (await getLink())!;
+  return (await getLink(link.userId))!;
 }
 
 export interface LinkPatch {
@@ -167,10 +233,12 @@ export interface LinkPatch {
   customHeaders?: ProxyHeader[];
   basicAuth?: BasicAuth | null;
   allowInvalidCertificate?: boolean;
+  clientCert?: ClientCert | null;
   remoteUserId?: string | null;
   remoteUsername?: string | null;
   account?: LinkAccount | null;
   disabledTypes?: string[];
+  options?: Record<string, unknown>;
   knownTypes?: string[];
   cursor?: number;
   status?: LinkStatus;
@@ -178,9 +246,13 @@ export interface LinkPatch {
   lastSyncAt?: string | null;
 }
 
-export async function updateLink(patch: LinkPatch): Promise<SyncLink | null> {
-  const current = await getLink();
+export async function updateLink(
+  patch: LinkPatch,
+  userId?: string,
+): Promise<SyncLink | null> {
+  const current = await getLink(userId);
   if (!current) return null;
+  if (patch.clientCert) assertClientCert(patch.clientCert);
   const set: Partial<Row> = {};
   if (patch.serverName !== undefined) set.serverName = patch.serverName;
   if (patch.serverVersion !== undefined)
@@ -210,8 +282,16 @@ export async function updateLink(patch: LinkPatch): Promise<SyncLink | null> {
   if (patch.account !== undefined) {
     set.account = patch.account ? JSON.stringify(patch.account) : null;
   }
-  if (patch.disabledTypes !== undefined) {
-    set.scope = JSON.stringify({ disabled: patch.disabledTypes });
+  if (
+    patch.disabledTypes !== undefined ||
+    patch.options !== undefined ||
+    patch.clientCert !== undefined
+  ) {
+    set.scope = await sealScope(
+      patch.disabledTypes ?? current.disabledTypes,
+      patch.options ?? current.options,
+      patch.clientCert === undefined ? current.clientCert : patch.clientCert,
+    );
   }
   if (patch.knownTypes !== undefined) {
     set.knownTypes = JSON.stringify(patch.knownTypes);
@@ -224,10 +304,12 @@ export async function updateLink(patch: LinkPatch): Promise<SyncLink | null> {
     await db().update(syncLink).set(set).where(eq(syncLink.id, current.id));
     DatabaseSaveTrigger.triggerSave("sync_link");
   }
-  return getLink();
+  return getLink(current.userId);
 }
 
-export async function deleteLink(): Promise<void> {
-  await db().delete(syncLink);
+export async function deleteLink(userId?: string): Promise<void> {
+  const owner = userId ?? (await getActiveUserId());
+  if (!owner) return;
+  await db().delete(syncLink).where(eq(syncLink.userId, owner));
   await DatabaseSaveTrigger.forceSave("sync_link");
 }

src/backend/sync/client/routes.ts

@@ -1,761 +0,0 @@
-/**
- * The desktop's own sync routes, under /sync/link. They only exist in the
- * embedded desktop backend; on a server they answer 404.
- */
-
-import express, {
-  type NextFunction,
-  type Request,
-  type Response,
-} from "express";
-import { and, eq, isNotNull } from "drizzle-orm";
-import type { SyncRow } from "@termix-ssh/plugin-sdk/backend";
-import type { AuthenticatedRequest } from "../../../types/index.js";
-import { AuthManager } from "../../utils/auth-manager.js";
-import { syncLogger } from "../../utils/logger.js";
-import { hosts, sshCredentials } from "../../database/db/schema.js";
-import { createCurrentRepositoryContext } from "../../database/repositories/factory.js";
-import { getPluginRuntime } from "../../plugins/index.js";
-import { getEntity, listEntities } from "../../plugins/sync-registry.js";
-import { registerCoreSyncEntities } from "../entities.js";
-import {
-  createResolvers,
-  deleteStoredRow,
-  listStoredRows,
-  regenerateSyncIds,
-  writeWireRow,
-} from "../store.js";
-import {
-  clearRecordErrors,
-  deleteConflict,
-  deleteRecordsForUser,
-  getConflict,
-  listConflicts,
-  listRecordErrors,
-} from "../records.js";
-import { SYNC_PROTOCOL_VERSION } from "../protocol.js";
-import {
-  createLink,
-  deleteLink,
-  getLink,
-  updateLink,
-  type BasicAuth,
-  type ProxyHeader,
-  type SyncLink,
-} from "./link-store.js";
-import {
-  normalizeServerUrl,
-  RemoteError,
-  remoteJson,
-  type RemoteTarget,
-} from "./http.js";
-import { defaultDeviceName, getSyncEngine } from "./engine.js";
-import { applyElectronProxyConfig } from "./electron-proxy.js";
-import { lastRemotePlugins } from "./plugins.js";
-
-const router = express.Router();
-const authManager = AuthManager.getInstance();
-const authenticateJWT = authManager.createAuthMiddleware();
-
-function desktopOnly(_req: Request, res: Response, next: NextFunction) {
-  if (process.env.ELECTRON_EMBEDDED !== "true") {
-    res.status(404).json({ error: "Not found" });
-    return;
-  }
-  next();
-}
-
-const guard = [desktopOnly, authenticateJWT];
-
-function userOf(req: Request): string {
-  return (req as AuthenticatedRequest).userId;
-}
-
-function readHeaders(value: unknown): ProxyHeader[] {
-  if (!Array.isArray(value)) return [];
-  return value
-    .filter(
-      (header): header is ProxyHeader =>
-        !!header &&
-        typeof header.name === "string" &&
-        typeof header.value === "string" &&
-        /^[A-Za-z0-9-]{1,100}$/.test(header.name.trim()),
-    )
-    .map((header) => ({ name: header.name.trim(), value: header.value }))
-    .slice(0, 20);
-}
-
-function readBasicAuth(value: unknown): BasicAuth | null {
-  if (!value || typeof value !== "object") return null;
-  const { username, password } = value as Record<string, unknown>;
-  if (typeof username !== "string" || !username) return null;
-  return {
-    username,
-    password: typeof password === "string" ? password : "",
-  };
-}
-
-function readTarget(body: Record<string, unknown>): RemoteTarget | null {
-  const serverUrl =
-    typeof body.serverUrl === "string"
-      ? normalizeServerUrl(body.serverUrl)
-      : null;
-  if (!serverUrl) return null;
-  return {
-    serverUrl,
-    customHeaders: readHeaders(body.customHeaders),
-    basicAuth: readBasicAuth(body.basicAuth),
-    allowInvalidCertificate: body.allowInvalidCertificate === true,
-  };
-}
-
-/** What the sync panel can show about each entity type. */
-function describeEntities(link: SyncLink | null) {
-  registerCoreSyncEntities();
-  const names = new Map<string, string>();
-  for (const plugin of getPluginRuntime().loader.list()) {
-    names.set(plugin.id, plugin.manifest.name);
-  }
-  for (const plugin of lastRemotePlugins()) {
-    if (!names.has(plugin.id)) names.set(plugin.id, plugin.name);
-  }
-  const serverTypes = getSyncEngine().state.serverTypes;
-  const seen = new Set<string>();
-  const entries = [
-    ...listEntities().map((entity) => ({
-      type: entity.type,
-      owner: entity.owner,
-      readOnly: !!entity.readOnly,
-    })),
-    ...serverTypes,
-  ];
-  return entries
-    .filter((entry) => {
-      if (seen.has(entry.type) || entry.type === "accountProfile") return false;
-      seen.add(entry.type);
-      return true;
-    })
-    .map((entry) => ({
-      type: entry.type,
-      owner: entry.owner,
-      ownerName:
-        entry.owner === "core" ? null : (names.get(entry.owner) ?? entry.owner),
-      readOnly: entry.readOnly,
-      onServer: serverTypes.some((server) => server.type === entry.type),
-      onDevice: !!getEntity(entry.type),
-      enabled: !link?.disabledTypes.includes(entry.type),
-    }));
-}
-
-async function statusBody() {
-  const link = await getLink();
-  const engine = getSyncEngine();
-  if (!link) {
-    return { linked: false, entities: describeEntities(null) };
-  }
-  return {
-    linked: true,
-    serverUrl: link.serverUrl,
-    serverName: link.serverName,
-    serverVersion: link.serverVersion,
-    account: link.account ?? {
-      username: link.remoteUsername ?? undefined,
-    },
-    status: engine.state.running ? "syncing" : link.status,
-    lastError: link.lastError,
-    linkedAt: link.linkedAt,
-    lastSyncAt: link.lastSyncAt,
-    pending: engine.state.pending,
-    conflicts: (await listConflicts(link.userId)).length,
-    errors: (await listRecordErrors(link.userId)).length,
-    firstSyncDone: link.knownTypes.length > 0,
-    allowInvalidCertificate: link.allowInvalidCertificate,
-    customHeaders: link.customHeaders.map((header) => ({
-      name: header.name,
-      value: "",
-      set: true,
-    })),
-    basicAuth: link.basicAuth
-      ? { username: link.basicAuth.username, password: "", set: true }
-      : null,
-    entities: describeEntities(link),
-  };
-}
-
-/** Removes read-only copies of what other users shared with the account. */
-async function removeSharedCopies(userId: string): Promise<void> {
-  const db = createCurrentRepositoryContext().drizzle;
-  const sharedHosts = await db
-    .select({ id: hosts.id })
-    .from(hosts)
-    .where(and(eq(hosts.userId, userId), isNotNull(hosts.sharedSource)));
-  const { deleteOwnedHost } = await import("../../hosts/delete-host.js");
-  for (const host of sharedHosts) await deleteOwnedHost(userId, host.id);
-
-  const sharedCredentials = await db
-    .select({ id: sshCredentials.id })
-    .from(sshCredentials)
-    .where(
-      and(
-        eq(sshCredentials.userId, userId),
-        isNotNull(sshCredentials.sharedSource),
-      ),
-    );
-  const { deleteOwnedCredential } =
-    await import("../../hosts/delete-credential.js");
-  for (const credential of sharedCredentials) {
-    await deleteOwnedCredential(userId, credential.id);
-  }
-}
-
-/** Deletes every row that syncs, keeping local-only ones. */
-async function wipeSyncedData(userId: string): Promise<void> {
-  const entities = [...listEntities()].reverse();
-  for (const entity of entities) {
-    if (entity.readOnly) continue;
-    try {
-      if (entity.load) {
-        for (const row of await entity.load(userId)) {
-          await entity.erase?.(userId, String(row.syncId));
-        }
-        continue;
-      }
-      if (!entity.table || entity.singleton) continue;
-      for (const row of await listStoredRows(entity, userId)) {
-        if (entity.shouldSync && entity.shouldSync(row) === false) continue;
-        if (typeof row.syncId !== "string") continue;
-        await deleteStoredRow(entity, userId, row.syncId);
-      }
-    } catch (error) {
-      syncLogger.warn("Could not clear synced data", {
-        operation: "sync_wipe",
-        entityType: entity.type,
-        error: error instanceof Error ? error.message : String(error),
-      });
-    }
-  }
-}
-
-function problemFor(error: unknown) {
-  if (!(error instanceof RemoteError)) {
-    return { problem: "unreachable", message: String(error) };
-  }
-  switch (error.kind) {
-    case "tls":
-      return { problem: "tls_untrusted", message: error.message };
-    case "basic_auth":
-      return { problem: "basic_auth_required", message: error.message };
-    case "proxy":
-      return error.status === 404
-        ? { problem: "not_termix", message: error.message }
-        : { problem: "proxy_login", message: error.message };
-    case "signed_out":
-    case "server":
-      // A Termix older than 2.9 has no /sync/v2 and answers with an error.
-      return { problem: "version_mismatch", message: error.message };
-    default:
-      return { problem: "unreachable", message: error.message };
-  }
-}
-
-/**
- * @openapi
- * /sync/link/status:
- *   get:
- *     summary: This desktop's link to a server
- *     description: Desktop only. Whether the app is linked, to which server and account, how syncing is going, and which kinds of data sync.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The link status.
- */
-router.get("/link/status", ...guard, async (_req: Request, res: Response) => {
-  try {
-    res.json(await statusBody());
-  } catch (error) {
-    syncLogger.error("Failed to read sync status", error, {
-      operation: "sync_status",
-    });
-    res.status(500).json({ error: "Failed to read sync status" });
-  }
-});
-
-/**
- * @openapi
- * /sync/link/probe:
- *   post:
- *     summary: Check a server address before linking
- *     description: Desktop only. Tries the server with the given proxy settings and says what is in the way, if anything. On success the proxy settings are also applied to the desktop's browser session so the sign-in page loads.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The server's name and version, or the problem found.
- */
-router.post("/link/probe", ...guard, async (req: Request, res: Response) => {
-  const target = readTarget(req.body ?? {});
-  if (!target) return res.json({ ok: false, problem: "invalid_url" });
-  try {
-    const info = await remoteJson<{
-      termix?: boolean;
-      name?: string;
-      version?: string;
-      protocol?: number;
-    }>(target, "/sync/v2/info", { timeoutMs: 15_000 });
-    if (!info?.termix) return res.json({ ok: false, problem: "not_termix" });
-    if (info.protocol !== SYNC_PROTOCOL_VERSION) {
-      return res.json({
-        ok: false,
-        problem: "version_mismatch",
-        version: info.version,
-      });
-    }
-    await applyElectronProxyConfig({
-      serverUrl: target.serverUrl,
-      customHeaders: target.customHeaders ?? [],
-      basicAuth: target.basicAuth ?? null,
-      allowInvalidCertificate: !!target.allowInvalidCertificate,
-    }).catch(() => {});
-    res.json({
-      ok: true,
-      serverUrl: target.serverUrl,
-      name: info.name ?? "Termix",
-      version: info.version ?? null,
-    });
-  } catch (error) {
-    res.json({ ok: false, ...problemFor(error) });
-  }
-});
-
-/**
- * @openapi
- * /sync/link/preview:
- *   get:
- *     summary: How much this desktop has that would sync
- *     description: Desktop only. Row counts per kind of data, shown before choosing whether to merge this desktop's data into the account or replace it.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Counts per entity type.
- */
-router.get("/link/preview", ...guard, async (req: Request, res: Response) => {
-  const userId = userOf(req);
-  registerCoreSyncEntities();
-  const counts: Record<string, number> = {};
-  for (const entity of listEntities()) {
-    if (entity.readOnly) continue;
-    try {
-      if (entity.load) {
-        counts[entity.type] = (await entity.load(userId)).length;
-        continue;
-      }
-      if (!entity.table) continue;
-      counts[entity.type] = (await listStoredRows(entity, userId)).filter(
-        (row) => !entity.shouldSync || entity.shouldSync(row) !== false,
-      ).length;
-    } catch {
-      counts[entity.type] = 0;
-    }
-  }
-  res.json({ counts });
-});
-
-/**
- * @openapi
- * /sync/link/complete:
- *   post:
- *     summary: Link this desktop to a server account
- *     description: Desktop only. Takes the session from signing in to the server, trades it for a long-lived desktop session, and starts syncing. "merge" uploads this desktop's data into the account; "replace" deletes it here first and takes the account's.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Linked; the new status.
- *       400:
- *         description: Missing server or session.
- *       502:
- *         description: The server refused the session.
- */
-router.post("/link/complete", ...guard, async (req: Request, res: Response) => {
-  const userId = userOf(req);
-  const body = req.body ?? {};
-  const target = readTarget(body);
-  const token = typeof body.token === "string" ? body.token : "";
-  const mode = body.mode === "replace" ? "replace" : "merge";
-  if (!target || !token) {
-    return res.status(400).json({ error: "Missing server or session" });
-  }
-
-  try {
-    const deviceName =
-      typeof body.deviceName === "string" && body.deviceName.trim()
-        ? body.deviceName.trim()
-        : defaultDeviceName();
-    const linked = await remoteJson<{
-      token: string;
-      user: { id: string; username: string };
-      server?: { version?: string | null };
-    }>({ ...target, sessionToken: token }, "/sync/v2/link", {
-      method: "POST",
-      body: { deviceName },
-    });
-
-    const previous = await getLink();
-    if (previous) {
-      await removeSharedCopies(previous.userId);
-      await deleteRecordsForUser(previous.userId);
-    }
-    if (mode === "replace") {
-      await wipeSyncedData(userId);
-    }
-    await deleteRecordsForUser(userId);
-
-    const link = await createLink({
-      userId,
-      serverUrl: target.serverUrl,
-      serverName: typeof body.serverName === "string" ? body.serverName : null,
-      serverVersion: linked.server?.version ?? null,
-      sessionToken: linked.token,
-      customHeaders: target.customHeaders,
-      basicAuth: target.basicAuth,
-      allowInvalidCertificate: target.allowInvalidCertificate,
-      remoteUserId: linked.user.id,
-      remoteUsername: linked.user.username,
-    });
-    const engine = getSyncEngine();
-    engine.reset();
-    await applyElectronProxyConfig(link).catch(() => {});
-    engine.request(0);
-    res.json(await statusBody());
-  } catch (error) {
-    syncLogger.warn("Linking to a server failed", {
-      operation: "sync_link_complete",
-      error: error instanceof Error ? error.message : String(error),
-    });
-    res.status(502).json({ ...problemFor(error) });
-  }
-});
-
-/**
- * @openapi
- * /sync/link/relogin:
- *   post:
- *     summary: Sign this desktop back in after its session ended
- *     description: Desktop only. Takes a new sign-in session for the same account and resumes syncing where it stopped.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Signed in again; the new status.
- *       409:
- *         description: The sign-in was for a different account.
- */
-router.post("/link/relogin", ...guard, async (req: Request, res: Response) => {
-  const token = typeof req.body?.token === "string" ? req.body.token : "";
-  const link = await getLink();
-  if (!link || !token) return res.status(400).json({ error: "Not linked" });
-  try {
-    const linked = await remoteJson<{
-      token: string;
-      user: { id: string; username: string };
-    }>({ ...link, sessionToken: token }, "/sync/v2/link", {
-      method: "POST",
-      body: { deviceName: defaultDeviceName() },
-    });
-    if (link.remoteUserId && linked.user.id !== link.remoteUserId) {
-      return res.status(409).json({ error: "different_account" });
-    }
-    await updateLink({
-      sessionToken: linked.token,
-      status: "idle",
-      lastError: null,
-    });
-    getSyncEngine().request(0);
-    res.json(await statusBody());
-  } catch (error) {
-    res.status(502).json({ ...problemFor(error) });
-  }
-});
-
-/**
- * @openapi
- * /sync/link/unlink:
- *   post:
- *     summary: Unlink this desktop from its server
- *     description: Desktop only. Ends the desktop's session on the server when it can be reached. With keepData the synced data stays on this device as its own; otherwise it is deleted. Copies of what others shared with the account are always removed.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Unlinked.
- */
-router.post("/link/unlink", ...guard, async (req: Request, res: Response) => {
-  const keepData = req.body?.keepData !== false;
-  const link = await getLink();
-  if (!link) return res.json(await statusBody());
-  const userId = link.userId;
-  try {
-    await remoteJson(link, "/sync/v2/unlink", {
-      method: "POST",
-      body: {},
-      timeoutMs: 10_000,
-    }).catch(() => {});
-
-    const engine = getSyncEngine();
-    engine.reset();
-    await removeSharedCopies(userId);
-    if (keepData) {
-      // New syncIds so this data reads as new if it is ever linked again.
-      for (const entity of listEntities()) {
-        if (!entity.readOnly) await regenerateSyncIds(entity, userId);
-      }
-    } else {
-      await wipeSyncedData(userId);
-    }
-    await deleteRecordsForUser(userId);
-    await deleteLink();
-    await applyElectronProxyConfig(null).catch(() => {});
-    res.json(await statusBody());
-  } catch (error) {
-    syncLogger.error("Unlinking failed", error, { operation: "sync_unlink" });
-    res.status(500).json({ error: "Failed to unlink" });
-  }
-});
-
-/**
- * @openapi
- * /sync/link/sync:
- *   post:
- *     summary: Sync now
- *     description: Desktop only. Runs a sync pass and waits for it.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The status after the pass.
- */
-router.post("/link/sync", ...guard, async (_req: Request, res: Response) => {
-  await getSyncEngine().syncNow();
-  res.json(await statusBody());
-});
-
-/**
- * @openapi
- * /sync/link/settings:
- *   put:
- *     summary: Change what syncs and how the server is reached
- *     description: Desktop only. disabledTypes lists the kinds of data that stay on this device. Proxy headers and basic auth left blank keep their saved values.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The new status.
- *       400:
- *         description: Not linked.
- */
-router.put("/link/settings", ...guard, async (req: Request, res: Response) => {
-  const link = await getLink();
-  if (!link) return res.status(400).json({ error: "Not linked" });
-  const body = req.body ?? {};
-  const patch: Parameters<typeof updateLink>[0] = {};
-
-  if (Array.isArray(body.disabledTypes)) {
-    const disabled = body.disabledTypes.filter(
-      (type: unknown): type is string =>
-        typeof type === "string" && type !== "accountProfile",
-    );
-    const changed = new Set([
-      ...disabled.filter((type: string) => !link.disabledTypes.includes(type)),
-      ...link.disabledTypes.filter((type) => !disabled.includes(type)),
-    ]);
-    patch.disabledTypes = disabled;
-    // A type switched back on is pulled again in full.
-    patch.knownTypes = link.knownTypes.filter((type) => !changed.has(type));
-  }
-  if (Array.isArray(body.customHeaders)) {
-    const saved = new Map(link.customHeaders.map((h) => [h.name, h.value]));
-    patch.customHeaders = (body.customHeaders as unknown[])
-      .filter(
-        (header): header is { name: string; value?: string } =>
-          !!header && typeof (header as { name?: unknown }).name === "string",
-      )
-      .map((header) => ({
-        name: header.name,
-        value: header.value || saved.get(header.name) || "",
-      }))
-      .filter((header) => header.value);
-    patch.customHeaders = readHeaders(patch.customHeaders);
-  }
-  if (body.basicAuth === null) {
-    patch.basicAuth = null;
-  } else if (body.basicAuth && typeof body.basicAuth === "object") {
-    const next = readBasicAuth(body.basicAuth);
-    if (next && !next.password && link.basicAuth) {
-      next.password = link.basicAuth.password;
-    }
-    patch.basicAuth = next;
-  }
-  if (typeof body.allowInvalidCertificate === "boolean") {
-    patch.allowInvalidCertificate = body.allowInvalidCertificate;
-  }
-
-  const updated = await updateLink(patch);
-  await applyElectronProxyConfig(updated).catch(() => {});
-  getSyncEngine().request(0);
-  res.json(await statusBody());
-});
-
-/**
- * @openapi
- * /sync/link/conflicts:
- *   get:
- *     summary: Local edits that lost to a newer edit on the server
- *     description: Desktop only. The server's version was kept; each entry holds this device's version so it can be restored.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The conflicts, oldest first.
- */
-router.get("/link/conflicts", ...guard, async (req: Request, res: Response) => {
-  const conflicts = await listConflicts(userOf(req));
-  res.json({
-    conflicts: conflicts.map((conflict) => {
-      let row: SyncRow = {};
-      try {
-        row = JSON.parse(conflict.localRow);
-      } catch {
-        row = {};
-      }
-      return {
-        id: conflict.id,
-        entityType: conflict.entityType,
-        syncId: conflict.syncId,
-        name: row.name ?? row.title ?? row.label ?? row.ip ?? conflict.syncId,
-        createdAt: conflict.createdAt,
-      };
-    }),
-  });
-});
-
-/**
- * @openapi
- * /sync/link/conflicts/{id}:
- *   post:
- *     summary: Settle a conflict
- *     description: Desktop only. keep "mine" puts this device's version back, and the next sync sends it to the server. keep "server" drops it.
- *     tags:
- *       - Sync
- *     parameters:
- *       - in: path
- *         name: id
- *         required: true
- *         schema:
- *           type: integer
- *     responses:
- *       200:
- *         description: Settled.
- *       404:
- *         description: No such conflict.
- */
-router.post(
-  "/link/conflicts/:id",
-  ...guard,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    const conflict = await getConflict(userId, Number(req.params.id));
-    if (!conflict) return res.status(404).json({ error: "Not found" });
-    try {
-      if (req.body?.keep === "mine") {
-        const entity = getEntity(conflict.entityType);
-        if (entity && !entity.readOnly) {
-          const row = JSON.parse(conflict.localRow) as SyncRow;
-          await writeWireRow(
-            entity,
-            userId,
-            { ...row, syncId: conflict.syncId },
-            createResolvers(userId),
-          );
-        }
-      }
-      await deleteConflict(userId, conflict.id);
-      getSyncEngine().request(0);
-      res.json({ success: true });
-    } catch (error) {
-      syncLogger.warn("Could not settle a sync conflict", {
-        operation: "sync_conflict",
-        error: error instanceof Error ? error.message : String(error),
-      });
-      res.status(500).json({ error: "Failed to settle conflict" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/link/errors:
- *   get:
- *     summary: Changes the server refused
- *     description: Desktop only. Each entry names the record and why the server refused it. A refused change is not sent again until it changes or is retried.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The refused changes.
- */
-router.get("/link/errors", ...guard, async (req: Request, res: Response) => {
-  const errors = await listRecordErrors(userOf(req));
-  res.json({
-    errors: errors.map((record) => ({
-      entityType: record.entityType,
-      syncId: record.syncId,
-      reason: record.error,
-    })),
-  });
-});
-
-/**
- * @openapi
- * /sync/link/errors/retry:
- *   post:
- *     summary: Send refused changes again
- *     description: Desktop only. Clears every refusal and syncs.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The status after the pass.
- */
-router.post(
-  "/link/errors/retry",
-  ...guard,
-  async (req: Request, res: Response) => {
-    await clearRecordErrors(userOf(req));
-    await getSyncEngine().syncNow();
-    res.json(await statusBody());
-  },
-);
-
-/**
- * @openapi
- * /sync/link/session:
- *   get:
- *     summary: The linked server and session, for connecting to it directly
- *     description: Desktop only. Used when a host is set to connect through the server rather than from this device.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The server address and session token, or nulls when not linked.
- */
-router.get("/link/session", ...guard, async (_req: Request, res: Response) => {
-  const link = await getLink();
-  if (!link?.sessionToken || link.status === "signed_out") {
-    return res.json({ serverUrl: null, token: null });
-  }
-  res.json({ serverUrl: link.serverUrl, token: link.sessionToken });
-});
-
-export default router;

src/backend/sync/host.ts

@@ -0,0 +1,544 @@
+/**
+ * What the sync provider plugin gets from core through ctx.sync.host: the
+ * replica store, the change feed, the linked server registry, sessions and
+ * a few helpers. Core stays neutral; the plugin decides what to do with it.
+ */
+
+import fs from "fs";
+import os from "os";
+import path from "path";
+import * as tar from "tar";
+import { and, eq, isNotNull } from "drizzle-orm";
+import type { NextFunction, Request, Response } from "express";
+import type { PluginSyncHost, SyncRow } from "@termix-ssh/plugin-sdk/backend";
+import { resolvePluginDesktopMode } from "@termix-ssh/plugin-sdk/manifest";
+import { AuthManager } from "../utils/auth-manager.js";
+import { getLocalVersion } from "../utils/app-version.js";
+import { syncLogger } from "../utils/logger.js";
+import { sendCoreAlert } from "../notify/core-notify.js";
+import { getPluginRuntime } from "../plugins/index.js";
+import {
+  getEntity,
+  listEntities,
+  onEntitiesChanged,
+  type RegisteredSyncEntity,
+} from "../plugins/sync-registry.js";
+import {
+  createCurrentHostRepository,
+  createCurrentHostResolutionRepository,
+  createCurrentPluginPermissionGrantRepository,
+  createCurrentPluginRepository,
+  createCurrentRepositoryContext,
+  createCurrentSessionRepository,
+  createCurrentSettingsRepository,
+  createCurrentUserRepository,
+} from "../database/repositories/factory.js";
+import { resolveBrandingSettings } from "../database/routes/branding-settings.js";
+import { hosts, sshCredentials } from "../database/db/schema.js";
+import {
+  createResolvers,
+  deleteStoredRow,
+  listStoredRows,
+  loadWireRow,
+  loadWireRows,
+  regenerateSyncIds,
+  writeWireRow,
+  type Resolvers,
+} from "./store.js";
+import {
+  clearRecordErrors,
+  deleteConflict,
+  deleteRecordsForUser,
+  getConflict,
+  listChanges,
+  listConflicts,
+  listRecordErrors,
+  listRecords,
+  putRecord,
+  recordKey,
+  saveConflict,
+  setRecordError,
+} from "./records.js";
+import { orderSelfReferences } from "./wire.js";
+import { onLocalWrite } from "./server/write-listeners.js";
+import {
+  createLink,
+  deleteLink,
+  getLink,
+  listLinks,
+  updateLink,
+} from "./client/link-store.js";
+import {
+  createAccount,
+  getActiveUserId,
+  listAccounts,
+  removeAccount,
+  setActiveUserId,
+} from "./accounts.js";
+import {
+  normalizeServerUrl,
+  RemoteError,
+  remoteFetch,
+  remoteJson,
+} from "./client/http.js";
+import { applyElectronProxyConfig } from "./client/electron-proxy.js";
+import { lastRemotePlugins, mirrorPlugins } from "./client/plugins.js";
+import { defaultDeviceName } from "./client/device.js";
+
+function entityOf(type: string): RegisteredSyncEntity {
+  const entity = getEntity(type);
+  if (!entity) throw new Error(`Unknown sync entity "${type}"`);
+  return entity;
+}
+
+function info(entity: RegisteredSyncEntity) {
+  return {
+    type: entity.type,
+    owner: entity.owner,
+    order: entity.order,
+    readOnly: !!entity.readOnly,
+    covers: entity.covers,
+  };
+}
+
+/** Deletes every row that syncs, keeping local-only ones. */
+async function wipeSyncedData(userId: string): Promise<void> {
+  const entities = [...listEntities()].reverse();
+  for (const entity of entities) {
+    if (entity.readOnly) continue;
+    try {
+      if (entity.load) {
+        for (const row of await entity.load(userId)) {
+          await entity.erase?.(userId, String(row.syncId));
+        }
+        continue;
+      }
+      if (!entity.table || entity.singleton) continue;
+      for (const row of await listStoredRows(entity, userId)) {
+        if (entity.shouldSync && entity.shouldSync(row) === false) continue;
+        if (typeof row.syncId !== "string") continue;
+        await deleteStoredRow(entity, userId, row.syncId);
+      }
+    } catch (error) {
+      syncLogger.warn("Could not clear synced data", {
+        operation: "sync_wipe",
+        entityType: entity.type,
+        error: error instanceof Error ? error.message : String(error),
+      });
+    }
+  }
+}
+
+/** Removes read-only copies of what other users shared with the account. */
+async function removeSharedCopies(userId: string): Promise<void> {
+  const db = createCurrentRepositoryContext().drizzle;
+  const sharedHosts = await db
+    .select({ id: hosts.id })
+    .from(hosts)
+    .where(and(eq(hosts.userId, userId), isNotNull(hosts.sharedSource)));
+  const { deleteOwnedHost } = await import("../hosts/delete-host.js");
+  for (const host of sharedHosts) await deleteOwnedHost(userId, host.id);
+
+  const sharedCredentials = await db
+    .select({ id: sshCredentials.id })
+    .from(sshCredentials)
+    .where(
+      and(
+        eq(sshCredentials.userId, userId),
+        isNotNull(sshCredentials.sharedSource),
+      ),
+    );
+  const { deleteOwnedCredential } =
+    await import("../hosts/delete-credential.js");
+  for (const credential of sharedCredentials) {
+    await deleteOwnedCredential(userId, credential.id);
+  }
+}
+
+async function ensureCoreEntities(): Promise<void> {
+  const { registerCoreSyncEntities } = await import("./entities.js");
+  registerCoreSyncEntities();
+}
+
+async function counts(userId: string): Promise<Record<string, number>> {
+  await ensureCoreEntities();
+  const result: Record<string, number> = {};
+  for (const entity of listEntities()) {
+    if (entity.readOnly) continue;
+    try {
+      if (entity.load) {
+        result[entity.type] = (await entity.load(userId)).length;
+        continue;
+      }
+      if (!entity.table) continue;
+      result[entity.type] = (await listStoredRows(entity, userId)).filter(
+        (row) => !entity.shouldSync || entity.shouldSync(row) !== false,
+      ).length;
+    } catch {
+      result[entity.type] = 0;
+    }
+  }
+  return result;
+}
+
+async function listPluginsForDesktop() {
+  const records = new Map(
+    (await createCurrentPluginRepository().listAll()).map((record) => [
+      record.id,
+      record,
+    ]),
+  );
+  const grants = createCurrentPluginPermissionGrantRepository();
+  const plugins = [];
+  for (const plugin of getPluginRuntime().loader.list()) {
+    plugins.push({
+      id: plugin.id,
+      name: plugin.manifest.name,
+      version: plugin.manifest.version,
+      source: plugin.source,
+      // A bundled plugin updated from a signed .tmxplug can be mirrored.
+      artifact: !!plugin.artifact,
+      enabled: records.get(plugin.id)?.state === "enabled",
+      active: plugin.state === "active",
+      desktop: resolvePluginDesktopMode(plugin.manifest),
+      syncEntities: plugin.manifest.contributes?.syncEntities ?? [],
+      granted: (await grants.listByPlugin(plugin.id)).map(
+        (grant) => grant.capability,
+      ),
+    });
+  }
+  const { customRegistryKeys } = await import("../plugins/registries.js");
+  return { plugins, registryKeys: await customRegistryKeys() };
+}
+
+async function sendPackage(
+  pluginId: string,
+  target: unknown,
+): Promise<boolean> {
+  const res = target as Response;
+  const plugin = getPluginRuntime()
+    .loader.list()
+    .find((candidate) => candidate.id === pluginId);
+  if (!plugin || (plugin.source !== "user" && !plugin.artifact)) return false;
+  const artifact = plugin.artifact ?? "";
+  res.setHeader("Content-Type", "application/gzip");
+  if (fs.existsSync(artifact)) {
+    const sig = `${artifact}.sig`;
+    if (fs.existsSync(sig)) {
+      res.setHeader(
+        "X-Termix-Signature",
+        Buffer.from(await fs.promises.readFile(sig, "utf8")).toString("base64"),
+      );
+    }
+    fs.createReadStream(artifact).pipe(res);
+    return true;
+  }
+  const temp = path.join(
+    os.tmpdir(),
+    `termix-plugin-${pluginId}-${Date.now()}.tmxplug`,
+  );
+  await tar.c({ gzip: true, cwd: plugin.dir, file: temp }, ["."]);
+  const stream = fs.createReadStream(temp);
+  stream.on("close", () => void fs.promises.rm(temp, { force: true }));
+  stream.pipe(res);
+  return true;
+}
+
+export function createSyncHost(): PluginSyncHost {
+  const authManager = AuthManager.getInstance();
+
+  return {
+    embedded: process.env.ELECTRON_EMBEDDED === "true",
+    info: {
+      appName: async () => {
+        try {
+          return (
+            await resolveBrandingSettings(createCurrentSettingsRepository())
+          ).appName;
+        } catch {
+          return "Termix";
+        }
+      },
+      version: () => getLocalVersion(),
+    },
+
+    entities: {
+      list: () => listEntities().map(info),
+      get: (type) => {
+        const entity = getEntity(type);
+        return entity ? info(entity) : undefined;
+      },
+      ensureCore: () => ensureCoreEntities(),
+      onChanged: (listener) => onEntitiesChanged(listener),
+      onLocalWrite: (listener) => onLocalWrite(listener),
+    },
+
+    replica: {
+      resolvers: (userId, onMissing) => createResolvers(userId, onMissing),
+      loadRows: async (type, userId, resolvers) => {
+        const result = await loadWireRows(
+          entityOf(type),
+          userId,
+          resolvers as Resolvers,
+        );
+        return { rows: result.rows, failed: result.failed };
+      },
+      loadRow: (type, userId, syncId, resolvers) =>
+        loadWireRow(entityOf(type), userId, syncId, resolvers as Resolvers),
+      writeRow: async (type, userId, wire, resolvers) => {
+        await writeWireRow(
+          entityOf(type),
+          userId,
+          wire,
+          resolvers as Resolvers,
+        );
+      },
+      deleteRow: async (type, userId, syncId) => {
+        await deleteStoredRow(entityOf(type), userId, syncId);
+      },
+      orderSelfReferences: (type, rows) =>
+        orderSelfReferences(entityOf(type), rows as SyncRow[]),
+      counts: (userId) => counts(userId),
+      wipe: (userId) => wipeSyncedData(userId),
+      regenerateSyncIds: async (userId) => {
+        for (const entity of listEntities()) {
+          if (!entity.readOnly) await regenerateSyncIds(entity, userId);
+        }
+      },
+      removeSharedCopies: (userId) => removeSharedCopies(userId),
+      records: {
+        list: (userId) => listRecords(userId) as never,
+        put: (userId, type, syncId, values) =>
+          putRecord(userId, type, syncId, values),
+        setError: (userId, type, syncId, reason, hash) =>
+          setRecordError(userId, type, syncId, reason, hash),
+        clearErrors: (userId) => clearRecordErrors(userId),
+        listErrors: (userId) => listRecordErrors(userId) as never,
+        deleteForUser: (userId) => deleteRecordsForUser(userId),
+        key: (type, syncId) => recordKey(type, syncId),
+      },
+      conflicts: {
+        save: (userId, type, syncId, row, revision) =>
+          saveConflict(userId, type, syncId, row, revision),
+        list: (userId) => listConflicts(userId) as never,
+        get: (userId, id) => getConflict(userId, id) as never,
+        delete: (userId, id) => deleteConflict(userId, id),
+      },
+    },
+
+    feed: {
+      withUserLock: async (userId, run) => {
+        const { withUserLock } = await import("./server/feed.js");
+        return withUserLock(userId, run);
+      },
+      changes: async (userId, cursor, limit, types) => {
+        const { withUserLock, reconcileUser } =
+          await import("./server/feed.js");
+        const page = await withUserLock(userId, async () => {
+          const { wire } = await reconcileUser(userId);
+          const records = await listChanges(userId, cursor, limit + 1, types);
+          return { wire, records };
+        });
+        const hasMore = page.records.length > limit;
+        const records = [];
+        for (const record of page.records.slice(0, limit)) {
+          if (!getEntity(record.entityType)) continue;
+          const row = record.deleted
+            ? null
+            : (page.wire.get(recordKey(record.entityType, record.syncId)) ??
+              null);
+          // A live record with no row failed to serialize; it comes again once
+          // it changes, rather than arriving as a delete.
+          if (!record.deleted && !row) continue;
+          records.push({
+            seq: record.seq,
+            entityType: record.entityType,
+            syncId: record.syncId,
+            revision: record.revision,
+            deleted: !!record.deleted,
+            row,
+          });
+        }
+        const slice = page.records.slice(0, limit);
+        return {
+          records,
+          hasMore,
+          nextCursor: slice.length ? slice[slice.length - 1].seq : cursor,
+          entityTypes: listEntities().map((entity) => ({
+            type: entity.type,
+            owner: entity.owner,
+            order: entity.order,
+            readOnly: !!entity.readOnly,
+          })),
+        } as never;
+      },
+      parsePushOps: async (body) => {
+        const { parsePushOps } = await import("./server/push.js");
+        return parsePushOps(body) as never;
+      },
+      applyPush: async (userId, ops) => {
+        const { withUserLock } = await import("./server/feed.js");
+        const { applyPush } = await import("./server/push.js");
+        return withUserLock(userId, () =>
+          applyPush(userId, ops as never),
+        ) as never;
+      },
+      listen: async (userId, res) => {
+        const { addListener } = await import("./server/feed.js");
+        return addListener(userId, res as Response);
+      },
+    },
+
+    links: {
+      list: () => listLinks() as never,
+      get: (userId) => getLink(userId) as never,
+      create: (link) => createLink(link) as never,
+      update: (patch, userId) => updateLink(patch, userId) as never,
+      remove: (userId) => deleteLink(userId),
+    },
+
+    accounts: {
+      list: () => listAccounts(),
+      create: () => createAccount(),
+      setActive: (userId) => setActiveUserId(userId),
+      activeId: () => getActiveUserId(),
+      remove: (userId) => removeAccount(userId),
+    },
+
+    http: {
+      json: (target, pathname, request) =>
+        remoteJson(target, pathname, request),
+      fetch: ((target, pathname, request) =>
+        remoteFetch(target, pathname, request)) as never,
+      normalizeServerUrl,
+      isRemoteError: ((error: unknown) =>
+        error instanceof RemoteError) as never,
+    },
+
+    sessions: {
+      issueDesktop: (userId, options) =>
+        authManager.generateJWTToken(userId, {
+          expiresIn: `${options.days}d`,
+          deviceType: "desktop",
+          deviceInfo: options.deviceInfo,
+        }),
+      revoke: async (sessionId) => {
+        await authManager.revokeSession(sessionId);
+      },
+      find: async (sessionId) => {
+        const session =
+          await createCurrentSessionRepository().findById(sessionId);
+        return session
+          ? { expiresAt: session.expiresAt, deviceInfo: session.deviceInfo }
+          : null;
+      },
+      findUser: async (userId) => {
+        const user = await createCurrentUserRepository().findById(userId);
+        return user ? { id: user.id, username: user.username } : null;
+      },
+      verify: async (token) => {
+        const payload = await authManager.verifyJWTToken(token);
+        return payload
+          ? { userId: payload.userId, sessionId: payload.sessionId }
+          : null;
+      },
+      setCookie: (req, res, value, options) => {
+        (res as Response).cookie(
+          options?.name ?? "jwt",
+          value,
+          authManager.getSecureCookieOptions(
+            req as Request,
+            (options?.days ?? 30) * 24 * 60 * 60 * 1000,
+          ),
+        );
+      },
+      clearCookie: (req, res, name) => {
+        (res as Response).clearCookie(
+          name ?? "jwt",
+          authManager.getClearCookieOptions(req as Request),
+        );
+      },
+      middleware: () => authManager.createAuthMiddleware(),
+      desktopOnly: () => (_req: Request, res: Response, next: NextFunction) => {
+        if (process.env.ELECTRON_EMBEDDED !== "true") {
+          res.status(404).json({ error: "Not found" });
+          return;
+        }
+        next();
+      },
+    },
+
+    hosts: {
+      findForSync: async (userId, syncId) => {
+        const hostId =
+          await createCurrentHostResolutionRepository().findHostIdBySyncId(
+            syncId,
+          );
+        if (hostId === null) return null;
+        const { PermissionManager } =
+          await import("../utils/permission-manager.js");
+        const access = await PermissionManager.getInstance().canAccessHost(
+          userId,
+          hostId,
+          "connect",
+        );
+        if (!access.hasAccess) return null;
+        const row = await createCurrentHostRepository().findById(hostId);
+        return { id: hostId, name: row?.name ?? row?.ip ?? null };
+      },
+      statusBySyncId: async (userId) => {
+        const { hostStatus } =
+          await import("../plugins/host-status-provider.js");
+        const { PermissionManager } =
+          await import("../utils/permission-manager.js");
+        const statuses = await hostStatus.statusesFor(userId, null);
+        const entries = [...statuses.entries()];
+        const allowed =
+          await PermissionManager.getInstance().filterAccessibleHostIds(
+            userId,
+            entries.map(([id]) => id),
+          );
+        const hostRepository = createCurrentHostRepository();
+        const result: Record<string, unknown> = {};
+        for (const [id, entry] of entries) {
+          if (!allowed.has(id)) continue;
+          const row = await hostRepository.findById(id);
+          if (row?.syncId) result[row.syncId] = entry;
+        }
+        return result;
+      },
+    },
+
+    plugins: {
+      listForDesktop: listPluginsForDesktop as never,
+      sendPackage,
+      mirror: (link) => mirrorPlugins(link as never),
+      lastRemote: () => lastRemotePlugins() as never,
+      localNames: () => {
+        const names = new Map<string, string>();
+        for (const plugin of getPluginRuntime().loader.list()) {
+          names.set(plugin.id, plugin.manifest.name);
+        }
+        return names;
+      },
+    },
+
+    desktop: {
+      applyProxy: (link) => applyElectronProxyConfig(link as never),
+      deviceName: defaultDeviceName,
+    },
+
+    alerts: {
+      send: (alert) =>
+        sendCoreAlert({
+          title: alert.title,
+          body: alert.body,
+          severity: alert.severity,
+          category: alert.category,
+          dedupeKey: alert.dedupeKey,
+          audience: "admins",
+          link: alert.link,
+        } as never),
+    },
+  };
+}

src/backend/sync/protocol.ts

@@ -1,2 +0,0 @@
-/** Bumped when a desktop and server can no longer understand each other. */
-export const SYNC_PROTOCOL_VERSION = 1;

src/backend/sync/provider.ts

@@ -0,0 +1,80 @@
+/**
+ * The sync provider: a plugin that answers /sync/v2 and /sync/link through
+ * ctx.sync.provide. Core only forwards. With no provider the paths answer 404,
+ * so a server without it looks like one that never had sync.
+ */
+
+import type { NextFunction, Request, RequestHandler, Response } from "express";
+import type { PluginSyncProvider } from "@termix-ssh/plugin-sdk/backend";
+import { syncLogger } from "../utils/logger.js";
+
+interface Entry {
+  pluginId: string;
+  provider: PluginSyncProvider;
+}
+
+const providers = new Map<symbol, Entry>();
+
+export function provideSync(
+  pluginId: string,
+  provider: PluginSyncProvider,
+): () => void {
+  const key = Symbol(pluginId);
+  providers.set(key, { pluginId, provider });
+  return () => {
+    providers.delete(key);
+  };
+}
+
+/** Test seam. */
+export function clearSyncProviders(): void {
+  providers.clear();
+}
+
+export function hasSyncProvider(): boolean {
+  return providers.size > 0;
+}
+
+/** Sends the request to the first provider that does not pass. */
+export const syncForwarder: RequestHandler = (
+  req: Request,
+  res: Response,
+  next: NextFunction,
+) => {
+  const entries = [...providers.values()];
+  const run = (index: number): void => {
+    const entry = entries[index];
+    if (!entry) {
+      next();
+      return;
+    }
+    const pass = (error?: unknown): void => {
+      if (error) next(error);
+      else run(index + 1);
+    };
+    try {
+      const result = entry.provider.handle(req, res, pass);
+      if (result && typeof result.catch === "function") {
+        result.catch((error: unknown) => fail(entry, error, res, next));
+      }
+    } catch (error) {
+      fail(entry, error, res, next);
+    }
+  };
+  run(0);
+};
+
+function fail(
+  entry: Entry,
+  error: unknown,
+  res: Response,
+  next: NextFunction,
+): void {
+  syncLogger.warn("Sync provider failed", {
+    operation: "sync_provider",
+    pluginId: entry.pluginId,
+    error: error instanceof Error ? error.message : String(error),
+  });
+  if (res.headersSent) next(error);
+  else res.status(500).json({ error: "Sync is not available right now" });
+}

src/backend/sync/server/change-watcher.ts

@@ -1,14 +1,8 @@
 import type { NextFunction, Request, Response } from "express";
 import { markChanged } from "./feed.js";
+import { notifyLocalWrite } from "./write-listeners.js";
 
 const READS = new Set(["GET", "HEAD", "OPTIONS"]);
-const writeListeners = new Set<() => void>();
-
-/** Called after every successful write request, for a linked desktop's engine. */
-export function onLocalWrite(listener: () => void): () => void {
-  writeListeners.add(listener);
-  return () => writeListeners.delete(listener);
-}
 
 /**
  * Any successful write may change what a linked desktop should have, so it
@@ -23,7 +17,7 @@ export function syncChangeWatcher(
     res.on("finish", () => {
       if (res.statusCode >= 400) return;
       markChanged();
-      for (const listener of writeListeners) listener();
+      notifyLocalWrite();
     });
   }
   next();

src/backend/sync/server/routes.ts

@@ -1,605 +0,0 @@
-import express, { type Request, type Response } from "express";
-import fs from "fs";
-import path from "path";
-import os from "os";
-import * as tar from "tar";
-import type { AuthenticatedRequest } from "../../../types/index.js";
-import { AuthManager } from "../../utils/auth-manager.js";
-import { syncLogger } from "../../utils/logger.js";
-import { getLocalVersion } from "../../utils/app-version.js";
-import { getEntity, listEntities } from "../../plugins/sync-registry.js";
-import { getPluginRuntime } from "../../plugins/index.js";
-import { resolvePluginDesktopMode } from "@termix-ssh/plugin-sdk/manifest";
-import {
-  createCurrentSessionRepository,
-  createCurrentSettingsRepository,
-  createCurrentUserRepository,
-  createCurrentPluginRepository,
-  createCurrentPluginPermissionGrantRepository,
-} from "../../database/repositories/factory.js";
-import { resolveBrandingSettings } from "../../database/routes/branding-settings.js";
-import { registerCoreSyncEntities } from "../entities.js";
-import { listChanges, recordKey } from "../records.js";
-import { addListener, reconcileUser, withUserLock } from "./feed.js";
-import { applyPush, parsePushOps } from "./push.js";
-import { SYNC_PROTOCOL_VERSION } from "../protocol.js";
-
-const SESSION_DAYS = 365;
-const REFRESH_WITHIN_MS = 60 * 24 * 60 * 60 * 1000;
-const MAX_PAGE = 1000;
-
-const router = express.Router();
-const authManager = AuthManager.getInstance();
-const authenticateJWT = authManager.createAuthMiddleware();
-
-registerCoreSyncEntities();
-
-function userOf(req: Request): string {
-  return (req as AuthenticatedRequest).userId;
-}
-
-/** A non-negative integer query value, the fallback when absent, null when malformed. */
-function queryInt(value: unknown, fallback: number): number | null {
-  if (value === undefined) return fallback;
-  const parsed = Number(value);
-  return typeof value === "string" &&
-    /^\d+$/.test(value) &&
-    Number.isSafeInteger(parsed)
-    ? parsed
-    : null;
-}
-
-/**
- * @openapi
- * /sync/v2/info:
- *   get:
- *     summary: Describe this server to a desktop that wants to link to it
- *     description: Public. Lets the desktop app confirm it reached Termix and not a proxy's login page, and that the sync protocol matches.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Server name, version and sync protocol version.
- */
-router.get("/v2/info", async (_req: Request, res: Response) => {
-  let name = "Termix";
-  try {
-    name = (await resolveBrandingSettings(createCurrentSettingsRepository()))
-      .appName;
-  } catch {
-    // The default name is fine.
-  }
-  res.setHeader("X-Termix-Sync", String(SYNC_PROTOCOL_VERSION));
-  res.json({
-    termix: true,
-    name,
-    version: getLocalVersion(),
-    protocol: SYNC_PROTOCOL_VERSION,
-  });
-});
-
-/**
- * @openapi
- * /sync/v2/link:
- *   post:
- *     summary: Link a desktop to this account
- *     description: Trades the short login session the desktop just signed in with for a long-lived desktop session, which shows in the account's sessions list and is revoked like any other. The login session is ended.
- *     tags:
- *       - Sync
- *     requestBody:
- *       content:
- *         application/json:
- *           schema:
- *             type: object
- *             properties:
- *               deviceName:
- *                 type: string
- *     responses:
- *       200:
- *         description: The desktop session token and the account it belongs to.
- *       401:
- *         description: Not signed in.
- *       403:
- *         description: API keys cannot link a desktop.
- */
-router.post(
-  "/v2/link",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    if ((req as AuthenticatedRequest).apiKeyId) {
-      return res.status(403).json({ error: "API keys cannot link a desktop" });
-    }
-    try {
-      const user = await createCurrentUserRepository().findById(userId);
-      if (!user) return res.status(401).json({ error: "User not found" });
-      const rawName =
-        typeof req.body?.deviceName === "string" ? req.body.deviceName : "";
-      const deviceName = rawName.trim().slice(0, 100) || "Termix Desktop";
-      const token = await authManager.generateJWTToken(userId, {
-        expiresIn: `${SESSION_DAYS}d`,
-        deviceType: "desktop",
-        deviceInfo: `${deviceName} (sync)`,
-      });
-      const loginSession = (req as AuthenticatedRequest).sessionId;
-      if (loginSession) await authManager.revokeSession(loginSession);
-      res.json({
-        token,
-        user: { id: user.id, username: user.username },
-        server: { version: getLocalVersion() },
-      });
-    } catch (error) {
-      syncLogger.error("Failed to link a desktop", error, {
-        operation: "sync_link",
-        userId,
-      });
-      res.status(500).json({ error: "Failed to link" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/session/refresh:
- *   post:
- *     summary: Keep a linked desktop's session from expiring
- *     description: Returns a fresh desktop session when the current one ends within 60 days, and ends the old one. Otherwise returns null and the desktop keeps its token.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The new token, or null.
- *       401:
- *         description: Session revoked or expired.
- */
-router.post(
-  "/v2/session/refresh",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    const sessionId = (req as AuthenticatedRequest).sessionId;
-    try {
-      if (!sessionId) return res.json({ token: null });
-      const session =
-        await createCurrentSessionRepository().findById(sessionId);
-      if (!session) return res.status(401).json({ error: "Session not found" });
-      const remaining = new Date(session.expiresAt).getTime() - Date.now();
-      if (remaining > REFRESH_WITHIN_MS) return res.json({ token: null });
-      const token = await authManager.generateJWTToken(userId, {
-        expiresIn: `${SESSION_DAYS}d`,
-        deviceType: "desktop",
-        deviceInfo: session.deviceInfo,
-      });
-      await authManager.revokeSession(sessionId);
-      res.json({ token });
-    } catch (error) {
-      syncLogger.error("Failed to refresh a desktop session", error, {
-        operation: "sync_session_refresh",
-        userId,
-      });
-      res.status(500).json({ error: "Failed to refresh session" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/unlink:
- *   post:
- *     summary: End a linked desktop's session
- *     description: Called by a desktop when it unlinks, so its session stops working here right away.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The session was ended.
- */
-router.post(
-  "/v2/unlink",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const sessionId = (req as AuthenticatedRequest).sessionId;
-    try {
-      if (sessionId) await authManager.revokeSession(sessionId);
-      res.json({ success: true });
-    } catch (error) {
-      syncLogger.error("Failed to end a desktop session", error, {
-        operation: "sync_unlink",
-      });
-      res.status(500).json({ error: "Failed to unlink" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/changes:
- *   get:
- *     summary: Pull what changed for this account after a cursor
- *     description: Returns records in change order. Each has the entity type, syncId, revision, whether it is deleted, and the row when it is not. Records of entity types this server does not currently run are skipped but still move the cursor.
- *     tags:
- *       - Sync
- *     parameters:
- *       - in: query
- *         name: cursor
- *         schema:
- *           type: integer
- *       - in: query
- *         name: limit
- *         schema:
- *           type: integer
- *       - in: query
- *         name: types
- *         description: Comma-separated entity types, to backfill only those.
- *         schema:
- *           type: string
- *     responses:
- *       200:
- *         description: A page of changes, the next cursor and whether more remain.
- *       400:
- *         description: The cursor or limit is not a non-negative integer.
- *       500:
- *         description: Failed to read changes.
- */
-router.get(
-  "/v2/changes",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    const cursor = queryInt(req.query.cursor, 0);
-    const pageSize = queryInt(req.query.limit, MAX_PAGE);
-    if (cursor === null || pageSize === null) {
-      return res.status(400).json({ error: "Invalid cursor or limit" });
-    }
-    const limit = Math.min(MAX_PAGE, Math.max(1, pageSize));
-    const types =
-      typeof req.query.types === "string" && req.query.types
-        ? req.query.types.split(",").filter(Boolean)
-        : undefined;
-
-    try {
-      const page = await withUserLock(userId, async () => {
-        const { wire } = await reconcileUser(userId);
-        const records = await listChanges(userId, cursor, limit + 1, types);
-        return { wire, records };
-      });
-      const hasMore = page.records.length > limit;
-      const records = page.records.slice(0, limit);
-      const changes = [];
-      for (const record of records) {
-        if (!getEntity(record.entityType)) continue;
-        const row = record.deleted
-          ? null
-          : (page.wire.get(recordKey(record.entityType, record.syncId)) ??
-            null);
-        // A live record with no row failed to serialize; it comes again once it
-        // changes, rather than arriving as a delete.
-        if (!record.deleted && !row) continue;
-        changes.push({
-          seq: record.seq,
-          entityType: record.entityType,
-          syncId: record.syncId,
-          revision: record.revision,
-          deleted: !!record.deleted,
-          row,
-        });
-      }
-      res.json({
-        changes,
-        nextCursor: records.length ? records[records.length - 1].seq : cursor,
-        hasMore,
-        entityTypes: listEntities().map((entity) => ({
-          type: entity.type,
-          owner: entity.owner,
-          order: entity.order,
-          readOnly: !!entity.readOnly,
-        })),
-      });
-    } catch (error) {
-      syncLogger.error("Failed to read sync changes", error, {
-        operation: "sync_changes",
-        userId,
-      });
-      res.status(500).json({ error: "Failed to read changes" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/push:
- *   post:
- *     summary: Push a desktop's changes
- *     description: Each op carries the revision the desktop last saw. Ops are applied in dependency order and each gets its own result, ok with the new revision, conflict with the server's version, or rejected with a reason.
- *     tags:
- *       - Sync
- *     requestBody:
- *       content:
- *         application/json:
- *           schema:
- *             type: object
- *             properties:
- *               ops:
- *                 type: array
- *                 items:
- *                   type: object
- *     responses:
- *       200:
- *         description: One result per op, in the order sent.
- *       400:
- *         description: Malformed ops, or more than 500.
- *       500:
- *         description: Failed to apply changes.
- */
-router.post(
-  "/v2/push",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    const ops = parsePushOps(req.body);
-    if (!ops) return res.status(400).json({ error: "Invalid ops" });
-    try {
-      const results = await withUserLock(userId, () => applyPush(userId, ops));
-      res.json({ results });
-    } catch (error) {
-      syncLogger.error("Failed to apply pushed changes", error, {
-        operation: "sync_push",
-        userId,
-      });
-      res.status(500).json({ error: "Failed to apply changes" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/events:
- *   get:
- *     summary: Stream a notice whenever this account's data changes
- *     description: Server-sent events. A "change" event means there is something new to pull. Comments are sent every 25 seconds to keep proxies from closing the stream.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: An event stream.
- */
-router.get("/v2/events", authenticateJWT, (req: Request, res: Response) => {
-  const userId = userOf(req);
-  res.setHeader("Content-Type", "text/event-stream");
-  res.setHeader("Cache-Control", "no-cache, no-transform");
-  res.setHeader("Connection", "keep-alive");
-  res.setHeader("X-Accel-Buffering", "no");
-  res.flushHeaders?.();
-  res.write(`event: ready\ndata: {}\n\n`);
-  const remove = addListener(userId, res);
-  req.on("close", remove);
-});
-
-/**
- * @openapi
- * /sync/v2/hosts/{syncId}:
- *   get:
- *     summary: This server's id for a host, by its sync id
- *     description: For a linked desktop that asks the server to act on a host (a tunnel through it), which needs the server's own id. Only for hosts the caller can connect to.
- *     tags:
- *       - Sync
- *     parameters:
- *       - in: path
- *         name: syncId
- *         required: true
- *         schema:
- *           type: string
- *     responses:
- *       200:
- *         description: The host's id and name.
- *       404:
- *         description: No such host the caller can connect to.
- */
-router.get(
-  "/v2/hosts/:syncId",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    try {
-      const { createCurrentHostResolutionRepository } =
-        await import("../../database/repositories/factory.js");
-      const hostId =
-        await createCurrentHostResolutionRepository().findHostIdBySyncId(
-          String(req.params.syncId),
-        );
-      if (hostId === null) return res.status(404).json({ error: "Not found" });
-      const { PermissionManager } =
-        await import("../../utils/permission-manager.js");
-      const access = await PermissionManager.getInstance().canAccessHost(
-        userId,
-        hostId,
-        "connect",
-      );
-      if (!access.hasAccess)
-        return res.status(404).json({ error: "Not found" });
-      const { createCurrentHostRepository } =
-        await import("../../database/repositories/factory.js");
-      const row = await createCurrentHostRepository().findById(hostId);
-      res.json({ id: hostId, name: row?.name ?? row?.ip ?? null });
-    } catch (error) {
-      syncLogger.error("Failed to look up a host by sync id", error, {
-        operation: "sync_host_lookup",
-      });
-      res.status(500).json({ error: "Failed to look up host" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/host-status:
- *   get:
- *     summary: Status of the hosts this account can see, keyed by sync id
- *     description: For a linked desktop whose hosts connect through this server, so it can show their status against its own copies.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: Status entries by host sync id.
- */
-router.get(
-  "/v2/host-status",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const userId = userOf(req);
-    try {
-      const { hostStatus } =
-        await import("../../plugins/host-status-provider.js");
-      const { PermissionManager } =
-        await import("../../utils/permission-manager.js");
-      const { createCurrentHostRepository } =
-        await import("../../database/repositories/factory.js");
-      const statuses = await hostStatus.statusesFor(userId, null);
-      const entries = [...statuses.entries()];
-      const allowed =
-        await PermissionManager.getInstance().filterAccessibleHostIds(
-          userId,
-          entries.map(([id]) => id),
-        );
-      const hostRepository = createCurrentHostRepository();
-      const result: Record<string, unknown> = {};
-      for (const [id, entry] of entries) {
-        if (!allowed.has(id)) continue;
-        const row = await hostRepository.findById(id);
-        if (row?.syncId) result[row.syncId] = entry;
-      }
-      res.json(result);
-    } catch (error) {
-      syncLogger.error("Failed to read host status for sync", error, {
-        operation: "sync_host_status",
-      });
-      res.status(500).json({ error: "Failed to read host status" });
-    }
-  },
-);
-
-async function listPluginsForDesktop() {
-  return getPluginRuntime().loader.list();
-}
-
-/**
- * @openapi
- * /sync/v2/plugins:
- *   get:
- *     summary: The features this server runs, for a linked desktop to mirror
- *     description: Every installed plugin with its version, where it came from, whether it is on, how a desktop should treat it and which sync entities it owns. registryKeys lists the signing keys of the custom registries an admin added, so plugins from them load on the desktop.
- *     tags:
- *       - Sync
- *     responses:
- *       200:
- *         description: The plugin list.
- */
-router.get(
-  "/v2/plugins",
-  authenticateJWT,
-  async (_req: Request, res: Response) => {
-    try {
-      const records = new Map(
-        (await createCurrentPluginRepository().listAll()).map((record) => [
-          record.id,
-          record,
-        ]),
-      );
-      const grants = createCurrentPluginPermissionGrantRepository();
-      const plugins = [];
-      for (const plugin of await listPluginsForDesktop()) {
-        plugins.push({
-          id: plugin.id,
-          name: plugin.manifest.name,
-          version: plugin.manifest.version,
-          source: plugin.source,
-          // A bundled plugin updated from a signed .tmxplug can be mirrored.
-          artifact: !!plugin.artifact,
-          enabled: records.get(plugin.id)?.state === "enabled",
-          active: plugin.state === "active",
-          desktop: resolvePluginDesktopMode(plugin.manifest),
-          syncEntities: plugin.manifest.contributes?.syncEntities ?? [],
-          granted: (await grants.listByPlugin(plugin.id)).map(
-            (grant) => grant.capability,
-          ),
-        });
-      }
-      const { customRegistryKeys } =
-        await import("../../plugins/registries.js");
-      res.json({ plugins, registryKeys: await customRegistryKeys() });
-    } catch (error) {
-      syncLogger.error("Failed to list plugins for sync", error, {
-        operation: "sync_plugins",
-      });
-      res.status(500).json({ error: "Failed to list plugins" });
-    }
-  },
-);
-
-/**
- * @openapi
- * /sync/v2/plugins/{id}/package:
- *   get:
- *     summary: Download an installed plugin so a linked desktop can install it
- *     description: Only for plugins installed on this server, or bundled ones replaced by a signed update. Sends the original .tmxplug when there is one, with its signature in the X-Termix-Signature header, otherwise a fresh archive of the plugin folder.
- *     tags:
- *       - Sync
- *     parameters:
- *       - in: path
- *         name: id
- *         required: true
- *         schema:
- *           type: string
- *     responses:
- *       200:
- *         description: The plugin archive.
- *       404:
- *         description: No installed plugin with that id.
- */
-router.get(
-  "/v2/plugins/:id/package",
-  authenticateJWT,
-  async (req: Request, res: Response) => {
-    const pluginId = String(req.params.id);
-    try {
-      const plugin = (await listPluginsForDesktop()).find(
-        (candidate) => candidate.id === pluginId,
-      );
-      if (!plugin || (plugin.source !== "user" && !plugin.artifact)) {
-        return res.status(404).json({ error: "Plugin not found" });
-      }
-      const artifact = plugin.artifact ?? "";
-      res.setHeader("Content-Type", "application/gzip");
-      if (fs.existsSync(artifact)) {
-        const sig = `${artifact}.sig`;
-        if (fs.existsSync(sig)) {
-          res.setHeader(
-            "X-Termix-Signature",
-            Buffer.from(await fs.promises.readFile(sig, "utf8")).toString(
-              "base64",
-            ),
-          );
-        }
-        return fs.createReadStream(artifact).pipe(res);
-      }
-      const temp = path.join(
-        os.tmpdir(),
-        `termix-plugin-${pluginId}-${Date.now()}.tmxplug`,
-      );
-      await tar.c({ gzip: true, cwd: plugin.dir, file: temp }, ["."]);
-      const stream = fs.createReadStream(temp);
-      stream.on("close", () => void fs.promises.rm(temp, { force: true }));
-      stream.pipe(res);
-    } catch (error) {
-      syncLogger.error("Failed to package a plugin for sync", error, {
-        operation: "sync_plugin_package",
-        pluginId,
-      });
-      if (!res.headersSent) {
-        res.status(500).json({ error: "Failed to package plugin" });
-      }
-    }
-  },
-);
-
-export default router;

src/backend/sync/server/write-listeners.ts

@@ -0,0 +1,11 @@
+const writeListeners = new Set<() => void>();
+
+/** Called after every successful write request, for a linked desktop's engine. */
+export function onLocalWrite(listener: () => void): () => void {
+  writeListeners.add(listener);
+  return () => writeListeners.delete(listener);
+}
+
+export function notifyLocalWrite(): void {
+  for (const listener of writeListeners) listener();
+}

src/backend/sync/shown-identity.ts

@@ -0,0 +1,40 @@
+/**
+ * On a desktop linked to a server, the account it is signed in to there.
+ * That account is who the user is; the local profile only mirrors it.
+ */
+export async function describeDesktopLink(userId: string) {
+  if (process.env.ELECTRON_EMBEDDED !== "true") return null;
+  try {
+    const { getLink } = await import("./client/link-store.js");
+    const link = await getLink(userId);
+    if (!link) return null;
+    return {
+      serverUrl: link.serverUrl,
+      serverName: link.serverName,
+      username: link.account?.username ?? link.remoteUsername,
+      isAdmin: !!link.account?.isAdmin,
+      roles: link.account?.roles ?? [],
+      permissions: link.account?.permissions ?? [],
+      status: link.status,
+    };
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Who the app shows. On a desktop linked to a server that is the account it
+ * is signed in to there, not the local user that holds the copy of its data.
+ */
+export async function shownIdentity(user: {
+  id: string;
+  username: string;
+  isAdmin: boolean | null;
+}) {
+  const linked = await describeDesktopLink(user.id);
+  return {
+    linked,
+    username: linked?.username || user.username,
+    isAdmin: linked ? linked.isAdmin : !!user.isAdmin,
+  };
+}

src/backend/tests/database/routes/desktop-auto-session.test.ts

@@ -136,6 +136,22 @@ describe("isNativeTokenExportRequest", () => {
 });
 
 describe("resolveDesktopAutoSessionUser", () => {
+  it("returns the account the user switched to, while it exists", () => {
+    const admin = makeUser({ id: "admin", isAdmin: true });
+    const chosen = makeUser({ id: "chosen" });
+    expect(resolveDesktopAutoSessionUser([admin, chosen], "chosen")).toBe(
+      chosen,
+    );
+  });
+
+  it("falls back to the usual pick when the chosen account is gone", () => {
+    const admin = makeUser({ id: "admin", isAdmin: true });
+    const other = makeUser({ id: "other" });
+    expect(resolveDesktopAutoSessionUser([admin, other], "deleted")).toBe(
+      admin,
+    );
+  });
+
   it("returns the sole local user regardless of having a real password", () => {
     const user = makeUser({ passwordHash: "$2a$10$realbcryptvaluehere" });
     expect(resolveDesktopAutoSessionUser([user])).toBe(user);

src/backend/tests/database/routes/user-socket-ticket-routes.test.ts

@@ -25,6 +25,10 @@ const issueSocketTicket = vi.fn(
   async (userId: string, sessionId: string) => `ticket:${userId}:${sessionId}`,
 );
 
+const issueApiKeySocketTicket = vi.fn(
+  async (userId: string, keyId: string) => `key-ticket:${userId}:${keyId}`,
+);
+
 const authenticate: RequestHandler = (req, _res, next) => {
   Object.assign(req, {
     userId: "u1",
@@ -38,7 +42,10 @@ function app() {
   const router = express.Router();
   registerUserSocketTicketRoutes(router, {
     authenticateJWT: authenticate,
-    authManager: { issueSocketTicket } as unknown as AuthManager,
+    authManager: {
+      issueSocketTicket,
+      issueApiKeySocketTicket,
+    } as unknown as AuthManager,
   });
   const server = express();
   server.use(cookieParser());
@@ -50,6 +57,7 @@ beforeEach(() => {
   state.sessionId = "s1";
   state.apiKeyId = undefined;
   issueSocketTicket.mockClear();
+  issueApiKeySocketTicket.mockClear();
 });
 
 describe("POST /users/ws-ticket", () => {
@@ -98,3 +106,23 @@ describe("POST /users/ws-ticket", () => {
     expect(issueSocketTicket).not.toHaveBeenCalled();
   });
 });
+
+describe("POST /users/ws-ticket/api-key", () => {
+  it("gives an API key a ticket as its user", async () => {
+    state.sessionId = undefined;
+    state.apiKeyId = "key-1";
+
+    const res = await request(app()).post("/users/ws-ticket/api-key");
+
+    expect(res.status).toBe(200);
+    expect(res.body.ticket).toBe("key-ticket:u1:key-1");
+    expect(res.headers["cache-control"]).toBe("no-store");
+  });
+
+  it("refuses a login session, which has its own ticket", async () => {
+    const res = await request(app()).post("/users/ws-ticket/api-key");
+
+    expect(res.status).toBe(401);
+    expect(issueApiKeySocketTicket).not.toHaveBeenCalled();
+  });
+});

src/backend/tests/electron/embedded-view.test.ts

@@ -0,0 +1,164 @@
+import { createRequire } from "node:module";
+import { EventEmitter } from "node:events";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const { createEmbeddedViews, cleanBounds } = createRequire(import.meta.url)(
+  "../../../../electron/embedded-view.cjs",
+);
+
+const views: FakeView[] = [];
+
+class FakeView {
+  webContents = Object.assign(new EventEmitter(), {
+    setWindowOpenHandler: vi.fn(),
+    loadURL: vi.fn().mockResolvedValue(undefined),
+    isDestroyed: () => false,
+    close: vi.fn(),
+  });
+  setBounds = vi.fn();
+  setVisible = vi.fn();
+  constructor(public options: { webPreferences: Record<string, unknown> }) {
+    views.push(this);
+  }
+}
+
+const bounds = { x: 10.4, y: 20.6, width: 300, height: 200 };
+let contentView: {
+  addChildView: ReturnType<typeof vi.fn>;
+  removeChildView: ReturnType<typeof vi.fn>;
+};
+let session: EventEmitter & Record<string, ReturnType<typeof vi.fn>>;
+let manager: ReturnType<typeof createEmbeddedViews>;
+
+beforeEach(() => {
+  views.length = 0;
+  contentView = { addChildView: vi.fn(), removeChildView: vi.fn() };
+  session = Object.assign(new EventEmitter(), {
+    setPermissionRequestHandler: vi.fn(),
+    setPermissionCheckHandler: vi.fn(),
+    clearStorageData: vi.fn().mockResolvedValue(undefined),
+    clearCache: vi.fn().mockResolvedValue(undefined),
+    closeAllConnections: vi.fn().mockResolvedValue(undefined),
+    webRequest: { onBeforeRequest: vi.fn() },
+  });
+  manager = createEmbeddedViews({
+    WebContentsView: FakeView,
+    session: { fromPartition: vi.fn(() => session) },
+    getMainWindow: () => ({ contentView, isDestroyed: () => false }),
+  });
+});
+
+describe("embedded views", () => {
+  it("opens a locked down view at the given bounds", () => {
+    manager.open({ id: "a", url: "https://pve.example:8006/", bounds });
+    const [view] = views;
+    expect(view.options.webPreferences).toMatchObject({
+      sandbox: true,
+      contextIsolation: true,
+      nodeIntegration: false,
+      webviewTag: false,
+    });
+    expect(contentView.addChildView).toHaveBeenCalledWith(view);
+    expect(view.setBounds).toHaveBeenCalledWith({
+      x: 10,
+      y: 21,
+      width: 300,
+      height: 200,
+    });
+    expect(view.webContents.loadURL).toHaveBeenCalledWith(
+      "https://pve.example:8006/",
+    );
+    const handler = session.setPermissionRequestHandler.mock.calls[0][0];
+    const allow = vi.fn();
+    handler(null, "media", allow);
+    expect(allow).toHaveBeenCalledWith(false);
+  });
+
+  it("refuses urls that are not plain http or https", () => {
+    expect(() =>
+      manager.open({ id: "a", url: "file:///etc/passwd", bounds }),
+    ).toThrow();
+    expect(() =>
+      manager.open({ id: "a", url: "https://u:p@host/", bounds }),
+    ).toThrow();
+  });
+
+  it("moves and hides an open view, and closes it", () => {
+    manager.open({ id: "a", url: "https://x.example/", bounds });
+    manager.setBounds("a", { x: 1, y: 2, width: 3, height: 4 });
+    manager.setVisible("a", false);
+    const [view] = views;
+    expect(view.setBounds).toHaveBeenLastCalledWith({
+      x: 1,
+      y: 2,
+      width: 3,
+      height: 4,
+    });
+    expect(view.setVisible).toHaveBeenLastCalledWith(false);
+    manager.destroy("a");
+    expect(contentView.removeChildView).toHaveBeenCalledWith(view);
+    expect(view.webContents.close).toHaveBeenCalled();
+    expect(session.clearStorageData).toHaveBeenCalled();
+  });
+
+  it("reuses a view for the same url and replaces it for a new one", () => {
+    manager.open({ id: "a", url: "https://x.example/", bounds });
+    manager.open({ id: "a", url: "https://x.example/", bounds });
+    expect(views).toHaveLength(1);
+    manager.open({ id: "a", url: "https://y.example/", bounds });
+    expect(views).toHaveLength(2);
+    expect(contentView.removeChildView).toHaveBeenCalledWith(views[0]);
+  });
+
+  it("accepts an invalid certificate only for its own origin and only when asked", () => {
+    manager.open({
+      id: "a",
+      url: "https://x.example/",
+      ignoreCert: true,
+      bounds,
+    });
+    manager.open({ id: "b", url: "https://z.example/", bounds });
+    const check = (index: number, url: string) => {
+      const event = { preventDefault: vi.fn() };
+      const callback = vi.fn();
+      const handled = manager.handleCertificateError(
+        event,
+        views[index].webContents,
+        url,
+        callback,
+      );
+      return { handled, allowed: callback.mock.calls[0]?.[0] };
+    };
+    expect(check(0, "https://x.example/page")).toEqual({
+      handled: true,
+      allowed: true,
+    });
+    expect(check(0, "https://other.example/")).toEqual({
+      handled: true,
+      allowed: false,
+    });
+    expect(check(1, "https://z.example/")).toEqual({
+      handled: true,
+      allowed: false,
+    });
+    expect(
+      manager.handleCertificateError({}, {}, "https://x.example/", vi.fn()),
+    ).toBe(false);
+  });
+
+  it("closes everything", () => {
+    manager.open({ id: "a", url: "https://x.example/", bounds });
+    manager.open({ id: "b", url: "https://y.example/", bounds });
+    manager.destroyAll();
+    expect(contentView.removeChildView).toHaveBeenCalledTimes(2);
+  });
+
+  it("keeps bounds as whole, non negative numbers", () => {
+    expect(cleanBounds({ x: -5, y: "x", width: 9.5, height: 1 })).toEqual({
+      x: 0,
+      y: 0,
+      width: 10,
+      height: 1,
+    });
+  });
+});

src/backend/tests/electron/linked-certificate.test.ts

@@ -6,6 +6,7 @@ import { describe, expect, it } from "vitest";
 const require = createRequire(import.meta.url);
 const linkedServer = require("../../../../electron/linked-server.cjs") as {
   setLinkedServer: (config: unknown) => void;
+  clientCertOptionsFor: (url: string) => Record<string, unknown>;
 };
 
 const source = fs.readFileSync(
@@ -59,3 +60,26 @@ describe("linked server certificate exception", () => {
     });
   });
 });
+
+describe("linked server client certificate", () => {
+  const clientCert = {
+    pfx: Buffer.from("pfx-bytes").toString("base64"),
+    passphrase: "pw",
+  };
+
+  it("hands the PFX to TLS made for the linked origin only", () => {
+    linkedServer.setLinkedServer({ origin: ORIGIN, clientCert });
+    expect(linkedServer.clientCertOptionsFor(TERMINAL)).toEqual({
+      pfx: Buffer.from("pfx-bytes"),
+      passphrase: "pw",
+    });
+    expect(
+      linkedServer.clientCertOptionsFor("https://elsewhere.example/"),
+    ).toEqual({});
+  });
+
+  it("offers nothing when the link has no certificate", () => {
+    linkedServer.setLinkedServer({ origin: ORIGIN });
+    expect(linkedServer.clientCertOptionsFor(TERMINAL)).toEqual({});
+  });
+});

src/backend/tests/hosts/connect/transport-providers.test.ts

@@ -0,0 +1,103 @@
+import { PassThrough } from "node:stream";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+  performPortKnocking: vi.fn(),
+  createJumpHostChain: vi.fn(),
+  createSocks5Connection: vi.fn(),
+}));
+
+vi.mock("../../../utils/logger.js", () => {
+  const log = { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() };
+  return { logger: log, sshLogger: log };
+});
+vi.mock("../../../hosts/terminal-auth-helpers.js", () => ({
+  performPortKnocking: mocks.performPortKnocking,
+}));
+vi.mock("../../../hosts/jump-host-chain.js", () => ({
+  createJumpHostChain: mocks.createJumpHostChain,
+}));
+vi.mock("../../../utils/socks5-helper.js", () => ({
+  createSocks5Connection: mocks.createSocks5Connection,
+}));
+vi.mock("../../../hosts/ssh-dns.js", () => ({
+  resolveSshConnectConfigHost: async (config: unknown) => config,
+}));
+
+const { clearSshTransports, openProvidedTransport, provideSshTransport } =
+  await import("../../../hosts/connect/transport-providers.js");
+const { openSshTransport } =
+  await import("../../../hosts/connect/transport.js");
+
+const host = { id: 7, ip: "10.0.0.7", port: 22, username: "root" };
+
+afterEach(() => {
+  clearSshTransports();
+  vi.clearAllMocks();
+});
+
+describe("ssh transport providers", () => {
+  it("opens nothing when no provider claims the host", async () => {
+    provideSshTransport("a", { claims: () => false, open: vi.fn() });
+    expect(await openProvidedTransport(host)).toBeNull();
+  });
+
+  it("hands back the claiming provider's stream", async () => {
+    const stream = new PassThrough();
+    const open = vi.fn(async () => stream);
+    provideSshTransport("a", { claims: (id) => id === 7, open });
+    expect(await openProvidedTransport(host)).toBe(stream);
+    expect(open).toHaveBeenCalledWith(host);
+    expect(await openProvidedTransport({ ...host, id: 8 })).toBeNull();
+  });
+
+  it("treats a provider that throws while claiming as not claiming", async () => {
+    provideSshTransport("a", {
+      claims: () => {
+        throw new Error("boom");
+      },
+      open: vi.fn(),
+    });
+    expect(await openProvidedTransport(host)).toBeNull();
+  });
+
+  it("stops using a provider once it is removed", async () => {
+    const remove = provideSshTransport("a", {
+      claims: () => true,
+      open: async () => new PassThrough(),
+    });
+    remove();
+    expect(await openProvidedTransport(host)).toBeNull();
+  });
+});
+
+describe("openSshTransport with a provider", () => {
+  it("uses the provided stream and skips knocking, jump hosts and proxies", async () => {
+    const stream = new PassThrough();
+    provideSshTransport("a", { claims: () => true, open: async () => stream });
+    const config: Record<string, unknown> = {};
+    const result = await openSshTransport(
+      {
+        ...host,
+        portKnockSequence: [{ port: 1 }],
+        jumpHosts: [{ hostId: 1 }],
+        useSocks5: true,
+        socks5Host: "proxy",
+        userId: "u1",
+      } as never,
+      config as never,
+    );
+    expect(result).toEqual({ jumpClient: null, via: "provided" });
+    expect(config.sock).toBe(stream);
+    expect(mocks.performPortKnocking).not.toHaveBeenCalled();
+    expect(mocks.createJumpHostChain).not.toHaveBeenCalled();
+    expect(mocks.createSocks5Connection).not.toHaveBeenCalled();
+  });
+
+  it("connects directly when nothing claims the host", async () => {
+    const config: Record<string, unknown> = {};
+    const result = await openSshTransport(host as never, config as never);
+    expect(result.via).toBe("direct");
+    expect(config.sock).toBeUndefined();
+  });
+});

src/backend/tests/hosts/ssh-relay.test.ts

@@ -0,0 +1,138 @@
+import net from "node:net";
+import type { AddressInfo } from "node:net";
+import http from "node:http";
+import { PassThrough } from "node:stream";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { WebSocket, WebSocketServer } from "ws";
+
+const mocks = vi.hoisted(() => ({
+  resolveHostById: vi.fn(),
+  openSshTransport: vi.fn(),
+  handler: null as null | ((connection: unknown) => Promise<void>),
+}));
+
+vi.mock("../../utils/logger.js", () => {
+  const log = { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() };
+  return { sshLogger: log, logger: log };
+});
+vi.mock("../../hosts/host-resolver.js", () => ({
+  resolveHostById: mocks.resolveHostById,
+}));
+vi.mock("../../hosts/connect/transport.js", () => ({
+  openSshTransport: mocks.openSshTransport,
+}));
+vi.mock("../../plugins/ws.js", () => ({
+  registerCoreWsRoute: (_path: string, handler: never) => {
+    mocks.handler = handler;
+    return () => {};
+  },
+}));
+
+const { registerSshRelay } = await import("../../hosts/ssh-relay.js");
+
+let echo: net.Server;
+let echoPort = 0;
+let relayServer: http.Server;
+let wss: WebSocketServer;
+let relayUrl = "";
+
+beforeEach(async () => {
+  vi.clearAllMocks();
+  registerSshRelay();
+
+  echo = net.createServer((socket) => socket.pipe(socket));
+  await new Promise<void>((resolve) => echo.listen(0, "127.0.0.1", resolve));
+  echoPort = (echo.address() as AddressInfo).port;
+
+  relayServer = http.createServer();
+  wss = new WebSocketServer({ server: relayServer });
+  wss.on("connection", (socket, request) => {
+    void mocks.handler?.({ userId: "user-1", request, socket });
+  });
+  await new Promise<void>((resolve) =>
+    relayServer.listen(0, "127.0.0.1", resolve),
+  );
+  relayUrl = `ws://127.0.0.1:${(relayServer.address() as AddressInfo).port}`;
+
+  mocks.resolveHostById.mockResolvedValue({
+    id: 5,
+    ip: "127.0.0.1",
+    port: echoPort,
+  });
+  mocks.openSshTransport.mockResolvedValue({ jumpClient: null, via: "direct" });
+});
+
+afterEach(async () => {
+  wss.close();
+  await new Promise((resolve) => relayServer.close(resolve));
+  await new Promise((resolve) => echo.close(resolve));
+});
+
+function open(query: string): Promise<{
+  socket: WebSocket;
+  closed: Promise<{ code: number; reason: string }>;
+}> {
+  return new Promise((resolve) => {
+    const socket = new WebSocket(`${relayUrl}/${query}`);
+    const closed = new Promise<{ code: number; reason: string }>((done) =>
+      socket.once("close", (code, reason) =>
+        done({ code, reason: reason.toString() }),
+      ),
+    );
+    socket.once("open", () => resolve({ socket, closed }));
+  });
+}
+
+describe("ssh relay", () => {
+  it("carries bytes to the host and back", async () => {
+    const { socket } = await open("?hostId=5");
+    const received = new Promise<string>((resolve) =>
+      socket.once("message", (data) => resolve(data.toString())),
+    );
+    socket.send(Buffer.from("SSH-2.0-test\r\n"));
+    expect(await received).toBe("SSH-2.0-test\r\n");
+    expect(mocks.resolveHostById).toHaveBeenCalledWith(5, "user-1");
+    socket.close();
+  });
+
+  it("uses the stream the transport made, such as a jump host channel", async () => {
+    const channel = new PassThrough();
+    const end = vi.fn();
+    mocks.openSshTransport.mockImplementation(
+      async (_host: unknown, config: { sock?: unknown }) => {
+        config.sock = channel;
+        return { jumpClient: { end }, via: "jump" };
+      },
+    );
+    const { socket } = await open("?hostId=5");
+    const received = new Promise<string>((resolve) =>
+      socket.once("message", (data) => resolve(data.toString())),
+    );
+    socket.send("ping");
+    expect(await received).toBe("ping");
+    socket.close();
+    await vi.waitFor(() => expect(end).toHaveBeenCalled());
+  });
+
+  it("refuses a host the user can't connect to", async () => {
+    mocks.resolveHostById.mockResolvedValue(null);
+    const { closed } = await open("?hostId=5");
+    expect(await closed).toMatchObject({
+      code: 1008,
+      reason: "Host not found or access denied",
+    });
+    expect(mocks.openSshTransport).not.toHaveBeenCalled();
+  });
+
+  it("needs a host id", async () => {
+    const { closed } = await open("");
+    expect((await closed).code).toBe(1008);
+    expect(mocks.resolveHostById).not.toHaveBeenCalled();
+  });
+
+  it("closes the socket when the host can't be reached", async () => {
+    mocks.openSshTransport.mockRejectedValue(new Error("no route"));
+    const { closed } = await open("?hostId=5");
+    expect((await closed).code).toBe(1000);
+  });
+});

src/backend/tests/hosts/ssh2-sk-patch.test.ts

@@ -0,0 +1,111 @@
+import { createRequire } from "node:module";
+import { readFileSync } from "node:fs";
+import { generateKeyPairSync } from "node:crypto";
+import { expect, it } from "vitest";
+const require = createRequire(import.meta.url);
+const ssh2 = require("ssh2");
+const {
+  patchKeyParserSource,
+  patchAgentSource,
+  patchProtocolSource,
+} = require("../../../../scripts/patch-ssh2-sk.cjs");
+
+const SK_ED = "sk-ssh-ed25519@openssh.com";
+
+function str(value: Buffer | string): Buffer {
+  const buf = Buffer.isBuffer(value) ? value : Buffer.from(value);
+  const len = Buffer.alloc(4);
+  len.writeUInt32BE(buf.length);
+  return Buffer.concat([len, buf]);
+}
+
+function skPublicBlob(): Buffer {
+  const { publicKey } = generateKeyPairSync("ed25519");
+  const raw = publicKey.export({ format: "der", type: "spki" }).subarray(-32);
+  return Buffer.concat([str(SK_ED), str(raw), str("ssh:")]);
+}
+
+it("patches are idempotent on the installed dependency", () => {
+  const files: Array<[string, (s: string) => string]> = [
+    ["ssh2/lib/protocol/keyParser.js", patchKeyParserSource],
+    ["ssh2/lib/agent.js", patchAgentSource],
+    ["ssh2/lib/protocol/Protocol.js", patchProtocolSource],
+  ];
+  for (const [id, patch] of files) {
+    const source = readFileSync(require.resolve(id), "utf8");
+    const result = patch(source);
+    expect(patch(result)).toBe(result);
+  }
+});
+
+it("fails explicitly when the dependency changes", () => {
+  expect(() => patchKeyParserSource("changed")).toThrow("review");
+  expect(() => patchAgentSource("changed")).toThrow("review");
+  expect(() => patchProtocolSource("changed")).toThrow("review");
+});
+
+it("parses a security key public blob and keeps it byte for byte", () => {
+  const blob = skPublicBlob();
+  const key = ssh2.utils.parseKey(blob);
+  expect(key).not.toBeInstanceOf(Error);
+  expect(key.type).toBe(SK_ED);
+  expect(Buffer.compare(key.getPublicSSH(), blob)).toBe(0);
+});
+
+it("sends flags and counter after the signature in publickey auth", async () => {
+  const blob = skPublicBlob();
+  const key = ssh2.utils.parseKey(blob);
+  const trailer = Buffer.from([0x01, 0, 0, 0, 7]);
+  const signature = Buffer.alloc(64, 9);
+  (signature as Buffer & { skTrailer?: Buffer }).skTrailer = trailer;
+
+  class FakeAgent extends ssh2.BaseAgent {
+    getIdentities(cb: (err: Error | null, keys?: unknown[]) => void) {
+      cb(null, [key]);
+    }
+    sign(
+      _key: unknown,
+      _data: Buffer,
+      _opts: unknown,
+      cb: (err: Error | null, sig?: Buffer) => void,
+    ) {
+      cb(null, signature);
+    }
+  }
+
+  const hostKey = ssh2.utils.generateKeyPairSync("ed25519").private;
+  const received = await new Promise<Buffer>((resolve) => {
+    const server = new ssh2.Server({ hostKeys: [hostKey] }, (client: any) => {
+      client.on("authentication", (ctx: any) => {
+        if (ctx.method !== "publickey") return ctx.reject(["publickey"]);
+        if (!ctx.signature) return ctx.accept();
+        resolve(
+          Buffer.concat([
+            Buffer.from(ctx.key.data),
+            Buffer.from(ctx.signature),
+          ]),
+        );
+        ctx.reject();
+      });
+      client.on("error", () => {});
+    });
+    server.listen(0, "127.0.0.1", () => {
+      const conn = new ssh2.Client();
+      conn.on("error", () => {});
+      conn.on("close", () => server.close());
+      conn.connect({
+        host: "127.0.0.1",
+        port: server.address().port,
+        username: "u",
+        agent: new FakeAgent(),
+        readyTimeout: 5000,
+      });
+    });
+  });
+  expect(
+    Buffer.compare(
+      received,
+      Buffer.concat([blob, Buffer.alloc(64, 9), trailer]),
+    ),
+  ).toBe(0);
+});

src/backend/tests/plugins/ctx-hosts.test.ts

@@ -30,6 +30,8 @@ const h = vi.hoisted(() => ({
   existingAccess: [] as Array<{ id: number }>,
   revoked: [] as number[],
   protocolWrites: [] as Array<{ hostId: number; protocols: string[] }>,
+  folderCalls: [] as Array<unknown[]>,
+  folderEmpty: true,
   roles: [] as Array<{
     id: number;
     name: string;
@@ -96,6 +98,15 @@ vi.mock("../../database/repositories/factory.js", () => ({
   createCurrentUserRepository: () => ({
     listAll: async () => h.users,
   }),
+  createCurrentHostFolderRepository: () => ({
+    upsertMetadata: async (...args: unknown[]) => {
+      h.folderCalls.push(["ensure", ...args]);
+    },
+    deleteEmptyFolderRecords: async (...args: unknown[]) => {
+      h.folderCalls.push(["remove", ...args]);
+      return h.folderEmpty;
+    },
+  }),
   createCurrentHostRepository: () => ({
     createEncryptedForUser: async (
       userId: string,
@@ -961,3 +972,45 @@ describe("ctx.hosts.locks", () => {
     expect(h.updates).toHaveLength(1);
   });
 });
+
+describe("ctx.hosts.folders", () => {
+  beforeEach(() => {
+    h.granted = new Set(["hosts:write"]);
+    h.actor = "user-1";
+    h.folderCalls = [];
+    h.folderEmpty = true;
+  });
+
+  it("needs hosts:write", async () => {
+    h.granted = new Set();
+    const hosts = createPluginHosts({
+      manifest: manifest(["hosts:write"]),
+      audit: vi.fn(async () => {}),
+    });
+    await expect(hosts.folders.ensure("Site")).rejects.toThrow(
+      PluginCapabilityError,
+    );
+  });
+
+  it("creates the folder row for the acting user with its style", async () => {
+    const hosts = createPluginHosts({
+      manifest: manifest(["hosts:write"]),
+      audit: vi.fn(async () => {}),
+    });
+    await hosts.folders.ensure("Site", { icon: "cloud-cog" });
+    expect(h.folderCalls).toEqual([
+      ["ensure", "user-1", "Site", null, "cloud-cog"],
+    ]);
+  });
+
+  it("removes only an empty folder", async () => {
+    const hosts = createPluginHosts({
+      manifest: manifest(["hosts:write"]),
+      audit: vi.fn(async () => {}),
+    });
+    expect(await hosts.folders.removeEmpty("Site")).toBe(true);
+    h.folderEmpty = false;
+    expect(await hosts.folders.removeEmpty("Site")).toBe(false);
+    expect(h.folderCalls[0]).toEqual(["remove", "user-1", "Site"]);
+  });
+});

src/backend/tests/plugins/user-data.test.ts

@@ -155,6 +155,30 @@ describe("plugin user data", () => {
     });
   });
 
+  it("exports a table with a text primary key", async () => {
+    const credentials = defineTable("credential", {
+      id: varchar(64).primaryKey(),
+      userId: refUser().notNull(),
+      label: text(),
+    });
+    for (const statement of createTableSql("sqlite", "fixture", credentials)) {
+      sqlite.exec(statement);
+    }
+    registerTable("fixture", credentials);
+    sqlite.exec(
+      "INSERT INTO p_fixture_credential (id, user_id, label) VALUES ('abc', 'u1', 'key')",
+    );
+
+    const file = new Database(":memory:");
+    file.exec("CREATE TABLE users (id TEXT PRIMARY KEY)");
+    file.exec("CREATE TABLE ssh_data (id INTEGER PRIMARY KEY)");
+    file.exec("INSERT INTO users (id) VALUES ('u1')");
+    await writeUserPluginTables(file, "u1");
+    expect(file.prepare("SELECT * FROM p_fixture_credential").all()).toEqual([
+      { id: "abc", user_id: "u1", label: "key" },
+    ]);
+  });
+
   it("writes large tables in chunks and lets the event loop run between them", async () => {
     const insert = sqlite.prepare(
       "INSERT INTO p_fixture_bookmark (user_id, path) VALUES ('u1', ?)",

src/backend/tests/plugins/ws.test.ts

@@ -154,6 +154,26 @@ describe("ctx.ws routing", () => {
     if (result.outcome === "open") result.socket.close();
   });
 
+  it("serves a socket core owns without any plugin grant", async () => {
+    state.granted = new Set();
+    const seen: string[] = [];
+    ws.registerCoreWsRoute("/relay", ({ userId }) => {
+      seen.push(userId);
+    });
+
+    const base = await startServer();
+    const signedIn = await connect(
+      `${base}/plugin-ws/core/relay`,
+      authProtocols(state.validToken),
+    );
+    const anonymous = await connect(`${base}/plugin-ws/core/relay`);
+
+    expect(signedIn.outcome).toBe("open");
+    expect(anonymous.outcome).toBe(401);
+    expect(seen).toEqual([state.userId]);
+    if (signedIn.outcome === "open") signedIn.socket.close();
+  });
+
   it("404s a path nothing registered", async () => {
     const base = await startServer();
 

src/backend/tests/sync/accounts.test.ts

@@ -0,0 +1,116 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+  users: [] as Array<{
+    id: string;
+    username: string;
+    isAdmin: boolean;
+    registeredAt: string;
+  }>,
+  saved: null as string | null,
+  create: vi.fn(),
+  assignRole: vi.fn(),
+  registerUser: vi.fn(),
+  deleteUserAndRelatedData: vi.fn(),
+  set: vi.fn(),
+}));
+
+vi.mock("../../database/repositories/factory.js", () => ({
+  createCurrentUserRepository: () => ({
+    listAll: async () => mocks.users,
+    findById: async (id: string) =>
+      mocks.users.find((u) => u.id === id) ?? null,
+    create: mocks.create,
+  }),
+  createCurrentRoleRepository: () => ({
+    assignRoleNameToUser: mocks.assignRole,
+  }),
+  createCurrentSettingsRepository: () => ({
+    get: async () => mocks.saved,
+    set: async (key: string, value: string) => {
+      mocks.set(key, value);
+      mocks.saved = value;
+    },
+  }),
+}));
+vi.mock("../../utils/auth-manager.js", () => ({
+  AuthManager: { getInstance: () => ({ registerUser: mocks.registerUser }) },
+}));
+vi.mock("../../database/routes/delete-user-data.js", () => ({
+  deleteUserAndRelatedData: mocks.deleteUserAndRelatedData,
+}));
+
+const {
+  createAccount,
+  getActiveUserId,
+  listAccounts,
+  removeAccount,
+  setActiveUserId,
+} = await import("../../sync/accounts.js");
+
+function user(
+  id: string,
+  isAdmin = false,
+  registeredAt = "2026-01-01T00:00:00Z",
+) {
+  return { id, username: id, isAdmin, registeredAt };
+}
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mocks.saved = null;
+  mocks.users = [
+    user("local", true),
+    user("work", false, "2026-02-01T00:00:00Z"),
+  ];
+});
+
+describe("desktop accounts", () => {
+  it("signs in as the usual user until one is chosen", async () => {
+    expect(await getActiveUserId()).toBe("local");
+    await setActiveUserId("work");
+    expect(await getActiveUserId()).toBe("work");
+  });
+
+  it("will not switch to an account that does not exist", async () => {
+    await expect(setActiveUserId("nope")).rejects.toThrow("No such account");
+    expect(mocks.set).not.toHaveBeenCalled();
+  });
+
+  it("lists the accounts with the active one marked", async () => {
+    await setActiveUserId("work");
+    expect(await listAccounts()).toEqual([
+      expect.objectContaining({ id: "local", active: false }),
+      expect.objectContaining({ id: "work", active: true }),
+    ]);
+  });
+
+  it("makes an empty admin account with its own data key", async () => {
+    const id = await createAccount();
+    expect(mocks.create).toHaveBeenCalledWith(
+      expect.objectContaining({ id, isAdmin: true, passwordHash: "" }),
+    );
+    expect(mocks.assignRole).toHaveBeenCalledWith(
+      expect.objectContaining({ userId: id, roleName: "admin" }),
+    );
+    expect(mocks.registerUser).toHaveBeenCalledWith(id, expect.any(String));
+  });
+
+  it("removes an account and its data", async () => {
+    await removeAccount("work");
+    expect(mocks.deleteUserAndRelatedData).toHaveBeenCalledWith("work");
+  });
+
+  it("moves to another account when the active one is removed", async () => {
+    await setActiveUserId("work");
+    mocks.set.mockClear();
+    await removeAccount("work");
+    expect(mocks.set).toHaveBeenCalledWith("desktop_active_user", "local");
+  });
+
+  it("keeps the last account", async () => {
+    mocks.users = [user("local", true)];
+    await expect(removeAccount("local")).rejects.toThrow("last account");
+    expect(mocks.deleteUserAndRelatedData).not.toHaveBeenCalled();
+  });
+});

src/backend/tests/sync/client/client-cert.test.ts

@@ -0,0 +1,204 @@
+import { execFileSync } from "node:child_process";
+import fs from "node:fs";
+import https from "node:https";
+import os from "node:os";
+import path from "node:path";
+import type { AddressInfo } from "node:net";
+import { sql } from "drizzle-orm";
+import {
+  afterAll,
+  afterEach,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  vi,
+} from "vitest";
+
+const state = vi.hoisted(() => ({ drizzle: null as unknown }));
+
+vi.mock("../../../database/db/index.js", () => ({
+  getDb: () => state.drizzle,
+  getSqlite: () => null,
+}));
+vi.mock("../../../utils/database-save-trigger.js", () => ({
+  DatabaseSaveTrigger: {
+    triggerSave: vi.fn(),
+    forceSave: vi.fn(async () => {}),
+  },
+}));
+vi.mock("../../../utils/system-crypto.js", () => ({
+  SystemCrypto: {
+    getInstance: () => ({ getEncryptionKey: async () => Buffer.alloc(32, 5) }),
+  },
+}));
+
+const { TestSqliteDatabase } =
+  await import("../../database/repositories/test-support.js");
+const { createLink, getLink, updateLink } =
+  await import("../../../sync/client/link-store.js");
+const { RemoteError, remoteJson } =
+  await import("../../../sync/client/http.js");
+
+function hasOpenssl(): boolean {
+  try {
+    execFileSync("openssl", ["version"], { stdio: "ignore" });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+const openssl = hasOpenssl();
+const PASSPHRASE = "pfx-pass";
+let dir = "";
+let pfx = "";
+let serverKey = "";
+let serverCert = "";
+let clientCert = "";
+
+function run(args: string[]) {
+  execFileSync("openssl", args, { cwd: dir, stdio: "ignore" });
+}
+
+function selfSigned(name: string) {
+  run([
+    "req",
+    "-x509",
+    "-newkey",
+    "rsa:2048",
+    "-nodes",
+    "-days",
+    "2",
+    "-keyout",
+    `${name}.key`,
+    "-out",
+    `${name}.crt`,
+    "-subj",
+    `/CN=${name}`,
+  ]);
+}
+
+beforeAll(() => {
+  if (!openssl) return;
+  dir = fs.mkdtempSync(path.join(os.tmpdir(), "termix-mtls-"));
+  selfSigned("server");
+  selfSigned("client");
+  run([
+    "pkcs12",
+    "-export",
+    "-inkey",
+    "client.key",
+    "-in",
+    "client.crt",
+    "-out",
+    "client.p12",
+    "-passout",
+    `pass:${PASSPHRASE}`,
+  ]);
+  pfx = fs.readFileSync(path.join(dir, "client.p12")).toString("base64");
+  serverKey = fs.readFileSync(path.join(dir, "server.key"), "utf8");
+  serverCert = fs.readFileSync(path.join(dir, "server.crt"), "utf8");
+  clientCert = fs.readFileSync(path.join(dir, "client.crt"), "utf8");
+});
+
+afterAll(() => {
+  if (dir) fs.rmSync(dir, { recursive: true, force: true });
+});
+
+describe.skipIf(!openssl)("client certificates", () => {
+  let server: https.Server;
+  let base: string;
+
+  beforeAll(async () => {
+    server = https.createServer(
+      {
+        key: serverKey,
+        cert: serverCert,
+        ca: [clientCert],
+        requestCert: true,
+        rejectUnauthorized: true,
+      },
+      (_req, res) => {
+        res.setHeader("Content-Type", "application/json");
+        res.end(JSON.stringify({ ok: true }));
+      },
+    );
+    await new Promise<void>((resolve) =>
+      server.listen(0, "127.0.0.1", resolve),
+    );
+    base = `https://127.0.0.1:${(server.address() as AddressInfo).port}`;
+  });
+
+  afterAll(() => new Promise<void>((resolve) => server.close(() => resolve())));
+
+  it("presents the PFX to a server that requires one", async () => {
+    const result = await remoteJson<{ ok: boolean }>(
+      {
+        serverUrl: base,
+        allowInvalidCertificate: true,
+        clientCert: { pfx, passphrase: PASSPHRASE, name: "client.p12" },
+      },
+      "/x",
+    );
+    expect(result.ok).toBe(true);
+  });
+
+  it("reports a missing client certificate as its own error", async () => {
+    const error = await remoteJson(
+      { serverUrl: base, allowInvalidCertificate: true },
+      "/x",
+    ).catch((e) => e);
+    expect(error).toBeInstanceOf(RemoteError);
+    expect((error as InstanceType<typeof RemoteError>).kind).toBe(
+      "client_cert",
+    );
+  });
+
+  describe("on the link", () => {
+    let db: InstanceType<typeof TestSqliteDatabase>;
+
+    beforeEach(async () => {
+      db = new TestSqliteDatabase("sqlite");
+      state.drizzle = (await db.connect()).drizzle;
+      await db.run(
+        sql`INSERT INTO users (id, username, password_hash) VALUES ('local', 'local', '')`,
+      );
+    });
+
+    afterEach(async () => {
+      await db.close();
+    });
+
+    it("stores the PFX encrypted and keeps it through other updates", async () => {
+      await createLink({
+        userId: "local",
+        serverUrl: "https://termix.example",
+        sessionToken: "t",
+        clientCert: { pfx, passphrase: PASSPHRASE, name: "client.p12" },
+      });
+      const raw = await db.query(sql`SELECT scope FROM sync_link`);
+      expect(JSON.stringify(raw)).not.toContain(pfx.slice(0, 40));
+
+      await updateLink({ disabledTypes: ["hosts"] }, "local");
+      const link = await getLink("local");
+      expect(link?.clientCert?.pfx).toBe(pfx);
+      expect(link?.disabledTypes).toEqual(["hosts"]);
+
+      await updateLink({ clientCert: null }, "local");
+      expect((await getLink("local"))?.clientCert).toBeNull();
+    });
+
+    it("rejects a PFX with the wrong passphrase", async () => {
+      await expect(
+        createLink({
+          userId: "local",
+          serverUrl: "https://termix.example",
+          sessionToken: "t",
+          clientCert: { pfx, passphrase: "nope", name: null },
+        }),
+      ).rejects.toThrow(/not valid/);
+    });
+  });
+});

src/backend/tests/sync/client/link-store.test.ts

@@ -21,8 +21,9 @@ vi.mock("../../../utils/system-crypto.js", () => ({
 
 const { TestSqliteDatabase } =
   await import("../../database/repositories/test-support.js");
-const { createLink, deleteLink, getLink, updateLink } =
+const { createLink, deleteLink, getLink, listLinks, updateLink } =
   await import("../../../sync/client/link-store.js");
+const { setActiveUserId } = await import("../../../sync/accounts.js");
 
 let db: InstanceType<typeof TestSqliteDatabase>;
 
@@ -96,3 +97,79 @@ describe("the desktop's link", () => {
     expect(await updateLink({ cursor: 1 })).toBeNull();
   });
 });
+
+describe("several links", () => {
+  beforeEach(async () => {
+    await db.run(sql`UPDATE users SET is_admin = 1 WHERE id = 'local'`);
+    await db.run(
+      sql`INSERT INTO users (id, username, password_hash) VALUES ('second', 'second', '')`,
+    );
+  });
+
+  it("keeps one link per local user", async () => {
+    await createLink({
+      userId: "local",
+      serverUrl: "https://a",
+      sessionToken: "a",
+    });
+    await createLink({
+      userId: "second",
+      serverUrl: "https://b",
+      sessionToken: "b",
+    });
+    expect((await listLinks()).map((link) => link.serverUrl).sort()).toEqual([
+      "https://a",
+      "https://b",
+    ]);
+    expect((await getLink("second"))?.serverUrl).toBe("https://b");
+    expect((await getLink("local"))?.serverUrl).toBe("https://a");
+  });
+
+  it("answers for the active account when no user is given", async () => {
+    await createLink({
+      userId: "local",
+      serverUrl: "https://a",
+      sessionToken: "a",
+    });
+    await createLink({
+      userId: "second",
+      serverUrl: "https://b",
+      sessionToken: "b",
+    });
+    expect((await getLink())?.serverUrl).toBe("https://a");
+    await setActiveUserId("second");
+    expect((await getLink())?.serverUrl).toBe("https://b");
+  });
+
+  it("changes and removes only the link it is asked about", async () => {
+    await createLink({
+      userId: "local",
+      serverUrl: "https://a",
+      sessionToken: "a",
+    });
+    await createLink({
+      userId: "second",
+      serverUrl: "https://b",
+      sessionToken: "b",
+    });
+    await updateLink({ cursor: 9, status: "offline" }, "second");
+    expect((await getLink("local"))?.cursor).toBe(0);
+    expect((await getLink("second"))?.cursor).toBe(9);
+    await deleteLink("second");
+    expect(await getLink("second")).toBeNull();
+    expect((await getLink("local"))?.serverUrl).toBe("https://a");
+  });
+
+  it("stores connection options without touching the type switches", async () => {
+    await createLink({
+      userId: "local",
+      serverUrl: "https://a",
+      sessionToken: "a",
+    });
+    await updateLink({ disabledTypes: ["hosts"] }, "local");
+    await updateLink({ options: { clientCertificate: "work" } }, "local");
+    const link = await getLink("local");
+    expect(link?.options).toEqual({ clientCertificate: "work" });
+    expect(link?.disabledTypes).toEqual(["hosts"]);
+  });
+});

src/backend/tests/sync/entity-labels.test.ts

@@ -1,26 +0,0 @@
-import { afterEach, describe, expect, it, vi } from "vitest";
-import fs from "node:fs";
-
-vi.mock("../../database/db/index.js", () => ({}));
-
-import { registerCoreSyncEntities } from "../../sync/entities.js";
-import {
-  listEntityTypes,
-  resetSyncRegistry,
-} from "../../plugins/sync-registry.js";
-
-afterEach(() => resetSyncRegistry());
-
-describe("core sync entities", () => {
-  it("each has a label in the Sync panel", () => {
-    registerCoreSyncEntities();
-    const en = JSON.parse(
-      fs.readFileSync(
-        new URL("../../../ui/locales/en.json", import.meta.url),
-        "utf8",
-      ),
-    );
-    const missing = listEntityTypes().filter((type) => !en.sync.entities[type]);
-    expect(missing).toEqual([]);
-  });
-});

src/backend/tests/sync/host.test.ts

@@ -0,0 +1,217 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+  listChanges: vi.fn(),
+  findHostIdBySyncId: vi.fn(),
+  canAccessHost: vi.fn(),
+  findById: vi.fn(),
+  getLink: vi.fn(),
+  generateJWTToken: vi.fn(),
+  revokeSession: vi.fn(),
+}));
+
+vi.mock("../../utils/auth-manager.js", () => ({
+  AuthManager: {
+    getInstance: () => ({
+      createAuthMiddleware: () => vi.fn(),
+      generateJWTToken: mocks.generateJWTToken,
+      revokeSession: mocks.revokeSession,
+    }),
+  },
+}));
+vi.mock("../../utils/logger.js", () => ({
+  syncLogger: { error: vi.fn(), warn: vi.fn() },
+}));
+vi.mock("../../utils/app-version.js", () => ({
+  getLocalVersion: () => "26.10.3",
+}));
+vi.mock("../../notify/core-notify.js", () => ({ sendCoreAlert: vi.fn() }));
+vi.mock("../../plugins/index.js", () => ({ getPluginRuntime: vi.fn() }));
+vi.mock("../../plugins/sync-registry.js", () => ({
+  getEntity: vi.fn(),
+  listEntities: () => [{ type: "hosts", owner: "core", order: 10 }],
+  onEntitiesChanged: vi.fn(),
+}));
+vi.mock("../../database/repositories/factory.js", () => ({
+  createCurrentHostRepository: () => ({ findById: mocks.findById }),
+  createCurrentHostResolutionRepository: () => ({
+    findHostIdBySyncId: mocks.findHostIdBySyncId,
+  }),
+  createCurrentPluginPermissionGrantRepository: vi.fn(),
+  createCurrentPluginRepository: vi.fn(),
+  createCurrentRepositoryContext: vi.fn(),
+  createCurrentSessionRepository: vi.fn(),
+  createCurrentSettingsRepository: vi.fn(),
+  createCurrentUserRepository: vi.fn(),
+}));
+vi.mock("../../database/routes/branding-settings.js", () => ({
+  resolveBrandingSettings: async () => ({ appName: "Termix" }),
+}));
+vi.mock("../../utils/permission-manager.js", () => ({
+  PermissionManager: {
+    getInstance: () => ({ canAccessHost: mocks.canAccessHost }),
+  },
+}));
+vi.mock("../../sync/entities.js", () => ({
+  registerCoreSyncEntities: vi.fn(),
+}));
+vi.mock("../../sync/store.js", () => ({}));
+vi.mock("../../sync/wire.js", () => ({}));
+vi.mock("../../sync/records.js", () => ({
+  listChanges: mocks.listChanges,
+  recordKey: (type: string, id: string) => `${type}\u0000${id}`,
+}));
+vi.mock("../../sync/server/write-listeners.js", () => ({
+  onLocalWrite: vi.fn(),
+}));
+vi.mock("../../sync/accounts.js", () => ({
+  createAccount: vi.fn(),
+  getActiveUserId: vi.fn(),
+  listAccounts: vi.fn(),
+  removeAccount: vi.fn(),
+  setActiveUserId: vi.fn(),
+}));
+vi.mock("../../sync/server/feed.js", () => ({
+  withUserLock: (_userId: string, fn: () => unknown) => fn(),
+  reconcileUser: async () => ({ wire: new Map() }),
+  addListener: vi.fn(),
+}));
+vi.mock("../../sync/server/push.js", () => ({}));
+vi.mock("../../sync/client/link-store.js", () => ({
+  getLink: mocks.getLink,
+  listLinks: vi.fn(),
+  createLink: vi.fn(),
+  updateLink: vi.fn(),
+  deleteLink: vi.fn(),
+}));
+vi.mock("../../sync/client/http.js", () => ({
+  normalizeServerUrl: vi.fn(),
+  RemoteError: class RemoteError extends Error {},
+  remoteFetch: vi.fn(),
+  remoteJson: vi.fn(),
+}));
+vi.mock("../../sync/client/electron-proxy.js", () => ({
+  applyElectronProxyConfig: vi.fn(),
+}));
+vi.mock("../../sync/client/plugins.js", () => ({
+  lastRemotePlugins: () => [],
+  mirrorPlugins: vi.fn(),
+}));
+
+const { createSyncHost } = await import("../../sync/host.js");
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mocks.listChanges.mockResolvedValue([]);
+});
+
+describe("host.feed.changes", () => {
+  it("answers an empty page with the entity types past the newest change", async () => {
+    const cursor = Number.MAX_SAFE_INTEGER;
+    const page = await createSyncHost().feed.changes("user-1", cursor, 1000);
+    expect(page).toEqual({
+      records: [],
+      hasMore: false,
+      nextCursor: cursor,
+      entityTypes: [
+        { type: "hosts", owner: "core", order: 10, readOnly: false },
+      ],
+    });
+  });
+
+  it("asks for one more row than the limit to know if more remain", async () => {
+    await createSyncHost().feed.changes("user-1", 0, 1000);
+    expect(mocks.listChanges).toHaveBeenCalledWith(
+      "user-1",
+      0,
+      1001,
+      undefined,
+    );
+  });
+
+  it("leaves out records of types this server does not run", async () => {
+    mocks.listChanges.mockResolvedValue([
+      { seq: 5, entityType: "gone", syncId: "a", revision: 1, deleted: false },
+    ]);
+    const page = await createSyncHost().feed.changes("user-1", 0, 10);
+    expect(page.records).toEqual([]);
+    expect(page.nextCursor).toBe(5);
+  });
+});
+
+describe("host.hosts.findForSync", () => {
+  beforeEach(() => {
+    mocks.findHostIdBySyncId.mockResolvedValue(41);
+    mocks.canAccessHost.mockImplementation(async (_user, _host, action) => ({
+      hasAccess: action === "connect",
+    }));
+    mocks.findById.mockResolvedValue({ name: "Shared host", ip: "10.0.0.1" });
+  });
+
+  it("resolves the server ID for a connect only recipient", async () => {
+    const found = await createSyncHost().hosts.findForSync(
+      "recipient",
+      "host-sync-id",
+    );
+    expect(mocks.canAccessHost).toHaveBeenCalledWith(
+      "recipient",
+      41,
+      "connect",
+    );
+    expect(found).toEqual({ id: 41, name: "Shared host" });
+  });
+
+  it("does not disclose a host the caller cannot connect to", async () => {
+    mocks.canAccessHost.mockResolvedValue({ hasAccess: false });
+    expect(await createSyncHost().hosts.findForSync("u", "s")).toBeNull();
+  });
+
+  it("returns null for a missing sync ID", async () => {
+    mocks.findHostIdBySyncId.mockResolvedValue(null);
+    expect(await createSyncHost().hosts.findForSync("u", "s")).toBeNull();
+    expect(mocks.canAccessHost).not.toHaveBeenCalled();
+  });
+});
+
+describe("host.sessions", () => {
+  it("issues a long desktop session that shows in the sessions list", async () => {
+    mocks.generateJWTToken.mockResolvedValue("token");
+    const token = await createSyncHost().sessions.issueDesktop("u1", {
+      days: 365,
+      deviceInfo: "Laptop (sync)",
+    });
+    expect(token).toBe("token");
+    expect(mocks.generateJWTToken).toHaveBeenCalledWith("u1", {
+      expiresIn: "365d",
+      deviceType: "desktop",
+      deviceInfo: "Laptop (sync)",
+    });
+  });
+
+  it("answers 404 outside the desktop app", () => {
+    const previous = process.env.ELECTRON_EMBEDDED;
+    delete process.env.ELECTRON_EMBEDDED;
+    const res = { status: vi.fn().mockReturnThis(), json: vi.fn() };
+    const next = vi.fn();
+    (
+      createSyncHost().sessions.desktopOnly() as (
+        req: unknown,
+        res: unknown,
+        next: () => void,
+      ) => void
+    )({}, res, next);
+    expect(res.status).toHaveBeenCalledWith(404);
+    expect(next).not.toHaveBeenCalled();
+    if (previous !== undefined) process.env.ELECTRON_EMBEDDED = previous;
+  });
+});
+
+describe("host.links", () => {
+  it("reads the linked server registry", async () => {
+    mocks.getLink.mockResolvedValue({ id: 1, serverUrl: "https://a.example" });
+    expect(await createSyncHost().links.get()).toEqual({
+      id: 1,
+      serverUrl: "https://a.example",
+    });
+  });
+});

src/backend/tests/sync/provider.test.ts

@@ -0,0 +1,66 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("../../utils/logger.js", () => ({
+  syncLogger: { warn: vi.fn() },
+}));
+
+const { clearSyncProviders, hasSyncProvider, provideSync, syncForwarder } =
+  await import("../../sync/provider.js");
+
+function response() {
+  const res = {
+    headersSent: false,
+    status: vi.fn(() => res),
+    json: vi.fn(() => res),
+  };
+  return res;
+}
+
+beforeEach(() => clearSyncProviders());
+
+describe("sync forwarder", () => {
+  it("passes through when nothing provides sync", () => {
+    const next = vi.fn();
+    syncForwarder({} as never, response() as never, next);
+    expect(hasSyncProvider()).toBe(false);
+    expect(next).toHaveBeenCalledWith();
+  });
+
+  it("hands the request to the provider", () => {
+    const handle = vi.fn();
+    provideSync("a", { handle });
+    const next = vi.fn();
+    syncForwarder({} as never, response() as never, next);
+    expect(handle).toHaveBeenCalledOnce();
+    expect(next).not.toHaveBeenCalled();
+  });
+
+  it("moves on when the provider calls next", () => {
+    provideSync("a", { handle: (_req, _res, pass) => pass() });
+    const second = vi.fn();
+    provideSync("b", { handle: second });
+    syncForwarder({} as never, response() as never, vi.fn());
+    expect(second).toHaveBeenCalledOnce();
+  });
+
+  it("answers 500 when the provider throws", async () => {
+    provideSync("a", {
+      handle: async () => {
+        throw new Error("boom");
+      },
+    });
+    const res = response();
+    syncForwarder({} as never, res as never, vi.fn());
+    await Promise.resolve();
+    await Promise.resolve();
+    expect(res.status).toHaveBeenCalledWith(500);
+  });
+
+  it("stops forwarding after the provider is removed", () => {
+    const remove = provideSync("a", { handle: vi.fn() });
+    remove();
+    const next = vi.fn();
+    syncForwarder({} as never, response() as never, next);
+    expect(next).toHaveBeenCalledWith();
+  });
+});

src/backend/tests/sync/server/changes.test.ts

@@ -1,75 +0,0 @@
-import { beforeEach, expect, it, vi } from "vitest";
-
-const { listChanges } = vi.hoisted(() => ({ listChanges: vi.fn() }));
-vi.mock("../../../utils/auth-manager.js", () => ({
-  AuthManager: { getInstance: () => ({ createAuthMiddleware: () => vi.fn() }) },
-}));
-vi.mock("../../../utils/logger.js", () => ({ syncLogger: { error: vi.fn() } }));
-vi.mock("../../../utils/app-version.js", () => ({ getLocalVersion: vi.fn() }));
-vi.mock("../../../plugins/index.js", () => ({ getPluginRuntime: vi.fn() }));
-vi.mock("../../../plugins/sync-registry.js", () => ({
-  getEntity: vi.fn(),
-  listEntities: () => [{ type: "hosts", owner: "core", order: 10 }],
-}));
-vi.mock("../../../database/repositories/factory.js", () => ({}));
-vi.mock("../../../sync/entities.js", () => ({
-  registerCoreSyncEntities: vi.fn(),
-}));
-vi.mock("../../../sync/records.js", () => ({
-  listChanges,
-  recordKey: vi.fn(),
-}));
-vi.mock("../../../sync/server/feed.js", () => ({
-  withUserLock: (_userId: string, fn: () => unknown) => fn(),
-  reconcileUser: async () => ({ wire: new Map() }),
-}));
-vi.mock("../../../sync/server/push.js", () => ({}));
-vi.mock("../../../database/routes/branding-settings.js", () => ({}));
-
-import router from "../../../sync/server/routes.js";
-
-const route = router.stack.find(
-  (layer) => layer.route?.path === "/v2/changes",
-)!.route!;
-const handler = route.stack[route.stack.length - 1].handle;
-
-beforeEach(() => {
-  vi.clearAllMocks();
-  listChanges.mockResolvedValue([]);
-});
-
-async function changes(query: Record<string, string>) {
-  const res = { status: vi.fn().mockReturnThis(), json: vi.fn() };
-  await handler({ userId: "user-1", query } as never, res as never, vi.fn());
-  return res;
-}
-
-it("answers an empty page with the entity types past the newest change", async () => {
-  const cursor = String(Number.MAX_SAFE_INTEGER);
-  const res = await changes({ cursor, limit: "1000" });
-  expect(res.status).not.toHaveBeenCalled();
-  expect(res.json).toHaveBeenCalledWith({
-    changes: [],
-    nextCursor: Number.MAX_SAFE_INTEGER,
-    hasMore: false,
-    entityTypes: [{ type: "hosts", owner: "core", order: 10, readOnly: false }],
-  });
-});
-
-it("defaults a missing cursor and limit", async () => {
-  await changes({});
-  expect(listChanges).toHaveBeenCalledWith("user-1", 0, 1001, undefined);
-});
-
-it.each([
-  { cursor: "abc" },
-  { cursor: "-1" },
-  { cursor: "1.5" },
-  { cursor: "Infinity" },
-  { limit: "1.5" },
-  { limit: "-5" },
-])("rejects a malformed query %o", async (query) => {
-  const res = await changes(query);
-  expect(res.status).toHaveBeenCalledWith(400);
-  expect(listChanges).not.toHaveBeenCalled();
-});

src/backend/tests/sync/server/host-lookup.test.ts

@@ -1,74 +0,0 @@
-import { beforeEach, expect, it, vi } from "vitest";
-
-const { findHostIdBySyncId, canAccessHost } = vi.hoisted(() => ({
-  findHostIdBySyncId: vi.fn(),
-  canAccessHost: vi.fn(),
-}));
-vi.mock("../../../utils/auth-manager.js", () => ({
-  AuthManager: { getInstance: () => ({ createAuthMiddleware: () => vi.fn() }) },
-}));
-vi.mock("../../../utils/logger.js", () => ({ syncLogger: { error: vi.fn() } }));
-vi.mock("../../../utils/app-version.js", () => ({ getLocalVersion: vi.fn() }));
-vi.mock("../../../plugins/index.js", () => ({ getPluginRuntime: vi.fn() }));
-vi.mock("../../../database/repositories/factory.js", () => ({
-  createCurrentHostResolutionRepository: () => ({ findHostIdBySyncId }),
-  createCurrentHostRepository: () => ({
-    findById: async () => ({ name: "Shared host" }),
-  }),
-}));
-vi.mock("../../../utils/permission-manager.js", () => ({
-  PermissionManager: { getInstance: () => ({ canAccessHost }) },
-}));
-vi.mock("../../../sync/entities.js", () => ({
-  registerCoreSyncEntities: vi.fn(),
-}));
-vi.mock("../../../sync/records.js", () => ({}));
-vi.mock("../../../sync/server/feed.js", () => ({}));
-vi.mock("../../../sync/server/push.js", () => ({}));
-vi.mock("../../../database/routes/branding-settings.js", () => ({}));
-
-import router from "../../../sync/server/routes.js";
-
-const route = router.stack.find(
-  (layer) => layer.route?.path === "/v2/hosts/:syncId",
-)!.route!;
-const handler = route.stack[route.stack.length - 1].handle;
-
-beforeEach(() => {
-  vi.clearAllMocks();
-  findHostIdBySyncId.mockResolvedValue(41);
-  canAccessHost.mockImplementation(async (_user, _host, action) => ({
-    hasAccess: action === "connect",
-  }));
-});
-
-async function lookup() {
-  const res = { status: vi.fn().mockReturnThis(), json: vi.fn() };
-  await handler(
-    { userId: "recipient", params: { syncId: "host-sync-id" } } as never,
-    res as never,
-    vi.fn(),
-  );
-  return res;
-}
-
-it("resolves the server ID for a connect-only recipient", async () => {
-  const res = await lookup();
-  expect(findHostIdBySyncId).toHaveBeenCalledWith("host-sync-id");
-  expect(canAccessHost).toHaveBeenCalledWith("recipient", 41, "connect");
-  expect(res.json).toHaveBeenCalledWith({ id: 41, name: "Shared host" });
-});
-
-it("does not disclose a host the caller cannot connect to", async () => {
-  canAccessHost.mockResolvedValue({ hasAccess: false });
-  const res = await lookup();
-  expect(res.status).toHaveBeenCalledWith(404);
-  expect(res.json).toHaveBeenCalledWith({ error: "Not found" });
-});
-
-it("returns 404 for a missing sync ID", async () => {
-  findHostIdBySyncId.mockResolvedValue(null);
-  const res = await lookup();
-  expect(res.status).toHaveBeenCalledWith(404);
-  expect(canAccessHost).not.toHaveBeenCalled();
-});

src/backend/tests/sync/shown-identity.test.ts

@@ -0,0 +1,59 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const getLink = vi.hoisted(() => vi.fn());
+vi.mock("../../sync/client/link-store.js", () => ({ getLink }));
+
+const { shownIdentity } = await import("../../sync/shown-identity.js");
+
+const local = { id: "u1", username: "server-ab12", isAdmin: true };
+
+beforeEach(() => {
+  process.env.ELECTRON_EMBEDDED = "true";
+  getLink.mockReset();
+});
+
+afterEach(() => {
+  delete process.env.ELECTRON_EMBEDDED;
+});
+
+describe("who the app shows", () => {
+  it("shows the local user when nothing is linked", async () => {
+    getLink.mockResolvedValue(null);
+    expect(await shownIdentity(local)).toMatchObject({
+      username: "server-ab12",
+      isAdmin: true,
+      linked: null,
+    });
+  });
+
+  it("shows the account on the server once linked, with its own admin flag", async () => {
+    getLink.mockResolvedValue({
+      serverUrl: "https://home.example",
+      serverName: "Home",
+      remoteUsername: "luke",
+      account: { username: "luke", isAdmin: false },
+      status: "idle",
+    });
+    expect(await shownIdentity(local)).toMatchObject({
+      username: "luke",
+      isAdmin: false,
+    });
+    expect(getLink).toHaveBeenCalledWith("u1");
+  });
+
+  it("shows the sign in name until the account has synced", async () => {
+    getLink.mockResolvedValue({
+      serverUrl: "https://home.example",
+      remoteUsername: "luke",
+      account: null,
+      status: "syncing",
+    });
+    expect((await shownIdentity(local)).username).toBe("luke");
+  });
+
+  it("is the local user on a server", async () => {
+    delete process.env.ELECTRON_EMBEDDED;
+    expect((await shownIdentity(local)).username).toBe("server-ab12");
+    expect(getLink).not.toHaveBeenCalled();
+  });
+});

src/backend/tests/sync/two-way.test.ts

@@ -1,768 +0,0 @@
-/**
- * A server and linked desktops, each with its own database, syncing through
- * the real engine and the real /sync/v2 routes. Only the network, auth and
- * the crypto keys are faked.
- */
-
-import express from "express";
-import request from "supertest";
-import { and, eq, sql } from "drizzle-orm";
-import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
-import type { DatabaseContext } from "../../database/repositories/database-context.js";
-
-const state = vi.hoisted(() => ({
-  current: null as null | { drizzle: unknown },
-  server: null as null | { drizzle: unknown },
-  allow: true,
-  sharedHostIds: new Set<number>(),
-  paths: [] as string[],
-}));
-
-const SERVER_USER = "srv-user";
-
-vi.mock("../../database/db/index.js", () => ({
-  getDb: () => state.current!.drizzle,
-  getSqlite: () => null,
-}));
-vi.mock("../../utils/database-save-trigger.js", () => ({
-  DatabaseSaveTrigger: {
-    triggerSave: vi.fn(),
-    forceSave: vi.fn(async () => {}),
-    batched: <T>(work: T) => work,
-  },
-}));
-vi.mock("../../utils/system-crypto.js", () => ({
-  SystemCrypto: {
-    getInstance: () => ({
-      getEncryptionKey: async () => Buffer.alloc(32, 7),
-      getJWTSecret: async () => "secret",
-    }),
-  },
-}));
-vi.mock("../../utils/data-crypto.js", () => ({
-  DataCrypto: {
-    getUserDataKey: () => Buffer.alloc(32, 3),
-    decryptRecord: (_table: string, record: unknown) => record,
-  },
-}));
-vi.mock("../../utils/permission-manager.js", () => ({
-  PermissionManager: {
-    getInstance: () => ({
-      hasPermission: async () => state.allow,
-      canAccessHost: async (_userId: string, hostId: number) => ({
-        hasAccess: state.sharedHostIds.has(hostId),
-      }),
-      getUserPermissions: async () => [],
-    }),
-  },
-}));
-vi.mock("../../utils/shared-host-secrets-manager.js", () => ({
-  SharedHostSecretsManager: {
-    getInstance: () => ({
-      resyncHost: async () => {},
-      resyncHostsForCredential: async () => {},
-    }),
-  },
-}));
-vi.mock("../../utils/shared-credential-secrets-manager.js", () => ({
-  SharedCredentialSecretsManager: {
-    getInstance: () => ({ resyncCredential: async () => {} }),
-  },
-}));
-vi.mock("../../hosts/delete-host.js", async () => {
-  const { hosts } = await import("../../database/db/schema.js");
-  const { eq: equals } = await import("drizzle-orm");
-  return {
-    deleteOwnedHost: async (_userId: string, id: number) => {
-      await (state.current!.drizzle as DatabaseContext["drizzle"])
-        .delete(hosts)
-        .where(equals(hosts.id, id));
-      return { id, name: "" };
-    },
-  };
-});
-vi.mock("../../hosts/delete-credential.js", async () => {
-  const { sshCredentials } = await import("../../database/db/schema.js");
-  const { eq: equals } = await import("drizzle-orm");
-  return {
-    deleteOwnedCredential: async (_userId: string, id: number) => {
-      await (state.current!.drizzle as DatabaseContext["drizzle"])
-        .delete(sshCredentials)
-        .where(equals(sshCredentials.id, id));
-      return { name: null };
-    },
-  };
-});
-vi.mock("../../utils/auth-manager.js", () => ({
-  AuthManager: {
-    getInstance: () => ({
-      createAuthMiddleware:
-        () => (req: { userId?: string }, _res: unknown, next: () => void) => {
-          req.userId = SERVER_USER;
-          next();
-        },
-      generateJWTToken: async () => "desktop-session",
-      revokeSession: async () => true,
-    }),
-  },
-}));
-vi.mock("../../notify/core-notify.js", () => ({ sendCoreAlert: vi.fn() }));
-vi.mock("../../sync/client/plugins.js", () => ({
-  mirrorPlugins: async () => {},
-  lastRemotePlugins: () => [],
-  isServerManaged: () => false,
-}));
-vi.mock("../../sync/client/http.js", async (importOriginal) => {
-  const actual =
-    await importOriginal<typeof import("../../sync/client/http.js")>();
-  return {
-    ...actual,
-    // The event stream is not under test.
-    remoteFetch: () => new Promise(() => {}),
-    remoteJson: async (
-      _target: unknown,
-      path: string,
-      init: { method?: string; body?: unknown } = {},
-    ) => {
-      state.paths.push(path);
-      const previous = state.current;
-      state.current = state.server;
-      try {
-        const agent = request(app);
-        const method = (init.method ?? "GET").toLowerCase() as "get" | "post";
-        const response = await agent[method](path).send(
-          init.body as object | undefined,
-        );
-        if (response.status >= 400) {
-          throw new actual.RemoteError(
-            "server",
-            response.body?.error ?? "error",
-            response.status,
-          );
-        }
-        return response.body;
-      } finally {
-        state.current = previous;
-      }
-    },
-  };
-});
-
-const { TestSqliteDatabase } =
-  await import("../database/repositories/test-support.js");
-const schema = await import("../../database/db/schema.js");
-const { default: syncRouter } = await import("../../sync/server/routes.js");
-const { SyncEngine } = await import("../../sync/client/engine.js");
-const { createLink, getLink, updateLink } =
-  await import("../../sync/client/link-store.js");
-const { markChanged, reconcileUser, resetFeed } =
-  await import("../../sync/server/feed.js");
-const { resetSeqAllocator, listConflicts, getConflict, deleteConflict } =
-  await import("../../sync/records.js");
-const { createResolvers, writeWireRow } = await import("../../sync/store.js");
-const { getEntity } = await import("../../plugins/sync-registry.js");
-const { FieldCrypto } = await import("../../utils/field-crypto.js");
-const { syncLogger } = await import("../../utils/logger.js");
-const { pluginEvents, TOPICS } = await import("../../plugins/events.js");
-
-const app = express();
-app.use(express.json({ limit: "5mb" }));
-app.use("/sync", syncRouter);
-
-type Db = InstanceType<typeof TestSqliteDatabase>;
-interface Side {
-  db: Db;
-  ctx: DatabaseContext;
-  userId: string;
-}
-
-let server: Side;
-let desktops: Side[] = [];
-
-async function side(userId: string): Promise<Side> {
-  const db = new TestSqliteDatabase("sqlite");
-  const ctx = await db.connect();
-  await db.run(
-    sql`INSERT INTO users (id, username, password_hash, is_admin) VALUES (${userId}, ${userId}, '', 1)`,
-  );
-  return { db, ctx, userId };
-}
-
-async function on<T>(where: Side, fn: () => Promise<T>): Promise<T> {
-  const previous = state.current;
-  state.current = where.ctx;
-  try {
-    return await fn();
-  } finally {
-    state.current = previous;
-  }
-}
-
-function db(where: Side) {
-  return where.ctx.drizzle;
-}
-
-async function addHost(
-  where: Side,
-  values: Partial<typeof schema.hosts.$inferInsert> & { name: string },
-) {
-  await db(where)
-    .insert(schema.hosts)
-    .values({
-      userId: where.userId,
-      ip: "10.0.0.1",
-      port: 22,
-      username: "root",
-      authType: "password",
-      syncId: `host-${values.name}`,
-      ...values,
-    });
-  // Stands in for the change watcher a write request would trip.
-  if (where === server) markChanged();
-}
-
-async function hostsOf(where: Side) {
-  return db(where)
-    .select()
-    .from(schema.hosts)
-    .where(eq(schema.hosts.userId, where.userId));
-}
-
-async function linkDesktop(
-  desktop: Side,
-): Promise<InstanceType<typeof SyncEngine>> {
-  await on(desktop, () =>
-    createLink({
-      userId: desktop.userId,
-      serverUrl: "https://termix.example",
-      sessionToken: "desktop-session",
-    }),
-  );
-  return new SyncEngine();
-}
-
-async function pass(desktop: Side, engine: InstanceType<typeof SyncEngine>) {
-  await on(desktop, () => engine.syncNow());
-  const link = await on(desktop, () => getLink());
-  expect(link?.lastError ?? null).toBeNull();
-}
-
-beforeEach(async () => {
-  resetFeed();
-  resetSeqAllocator();
-  state.allow = true;
-  state.sharedHostIds.clear();
-  state.paths = [];
-  server = await side(SERVER_USER);
-  state.server = server.ctx;
-  desktops = [await side("desk-a"), await side("desk-b")];
-});
-
-afterEach(async () => {
-  for (const s of [server, ...desktops]) await s.db.close();
-});
-
-describe("linking a desktop", () => {
-  it("merges both sides, translating references and keeping secrets", async () => {
-    const [desk] = desktops;
-    await on(desk, async () => {
-      await db(desk).insert(schema.sshCredentials).values({
-        userId: desk.userId,
-        name: "deploy key",
-        authType: "password",
-        username: "deploy",
-        syncId: "cred-1",
-      });
-      const [cred] = await db(desk).select().from(schema.sshCredentials);
-      await writeWireRow(
-        getEntity("hosts")!,
-        desk.userId,
-        {
-          syncId: "host-desk",
-          name: "desk",
-          ip: "10.0.0.2",
-          port: 22,
-          username: "root",
-          authType: "credential",
-          password: "s3cret",
-          credentialSyncId: cred.syncId,
-        },
-        createResolvers(desk.userId),
-      );
-    });
-    await on(server, () => addHost(server, { name: "srv" }));
-
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    const serverHosts = await on(server, () => hostsOf(server));
-    expect(serverHosts.map((h) => h.name).sort()).toEqual(["desk", "srv"]);
-    const pushed = serverHosts.find((h) => h.name === "desk")!;
-    const [serverCred] = await db(server).select().from(schema.sshCredentials);
-    expect(serverCred.syncId).toBe("cred-1");
-    expect(pushed.credentialId).toBe(serverCred.id);
-    // Stored encrypted, never as plaintext.
-    expect(pushed.password).not.toBe("s3cret");
-    expect(pushed.password).toContain('"iv"');
-
-    const deskHosts = await on(desk, () => hostsOf(desk));
-    expect(deskHosts.map((h) => h.name).sort()).toEqual(["desk", "srv"]);
-  });
-
-  it("adopts the server's version of rows both sides already have", async () => {
-    const [desk] = desktops;
-    await on(desk, () => addHost(desk, { name: "same", ip: "old" }));
-    await on(server, () => addHost(server, { name: "same", ip: "new" }));
-
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    const [host] = await on(desk, () => hostsOf(desk));
-    expect(host.ip).toBe("new");
-    expect(await on(desk, () => listConflicts(desk.userId))).toEqual([]);
-  });
-
-  it("never asks for a cursor past what the server's seq column holds", async () => {
-    const [desk] = desktops;
-    await on(server, () => addHost(server, { name: "srv" }));
-
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    const cursors = state.paths
-      .filter((path) => path.startsWith("/sync/v2/changes?"))
-      .map((path) =>
-        Number(new URLSearchParams(path.split("?")[1]).get("cursor")),
-      );
-    expect(cursors.length).toBeGreaterThan(0);
-    expect(Math.max(...cursors)).toBeLessThanOrEqual(2_147_483_647);
-  });
-});
-
-describe("a synced host", () => {
-  it("publishes host.created when it is written for the first time only", async () => {
-    const [desk] = desktops;
-    const seen: unknown[] = [];
-    const off = pluginEvents.on(TOPICS.hostCreated, (payload) => {
-      seen.push(payload);
-    });
-    const wire = {
-      syncId: "host-new",
-      name: "new",
-      ip: "10.0.0.2",
-      port: 22,
-      username: "root",
-      authType: "password",
-    };
-    try {
-      await on(desk, async () => {
-        const resolvers = createResolvers(desk.userId);
-        const first = await writeWireRow(
-          getEntity("hosts")!,
-          desk.userId,
-          wire,
-          resolvers,
-        );
-        await writeWireRow(
-          getEntity("hosts")!,
-          desk.userId,
-          { ...wire, name: "renamed" },
-          resolvers,
-        );
-        expect(seen).toEqual([{ hostId: first.id, userId: desk.userId }]);
-      });
-    } finally {
-      off();
-    }
-  });
-});
-
-describe("after linking", () => {
-  it("sends edits and deletes both ways", async () => {
-    const [desk] = desktops;
-    await on(server, () => addHost(server, { name: "a" }));
-    await on(server, () => addHost(server, { name: "b" }));
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    await on(desk, async () => {
-      await db(desk)
-        .update(schema.hosts)
-        .set({ ip: "10.9.9.9" })
-        .where(eq(schema.hosts.syncId, "host-a"));
-    });
-    await on(server, async () => {
-      await db(server)
-        .delete(schema.hosts)
-        .where(eq(schema.hosts.syncId, "host-b"));
-      markChanged();
-    });
-    await pass(desk, engine);
-
-    const serverHosts = await on(server, () => hostsOf(server));
-    expect(serverHosts.map((h) => [h.name, h.ip])).toEqual([["a", "10.9.9.9"]]);
-    const deskHosts = await on(desk, () => hostsOf(desk));
-    expect(deskHosts.map((h) => h.name)).toEqual(["a"]);
-
-    await on(desk, async () => {
-      await db(desk)
-        .delete(schema.hosts)
-        .where(eq(schema.hosts.syncId, "host-a"));
-    });
-    await pass(desk, engine);
-    expect(await on(server, () => hostsOf(server))).toEqual([]);
-  });
-
-  it("never sends a host kept on this device only", async () => {
-    const [desk] = desktops;
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-    await on(desk, () => addHost(desk, { name: "mine", localOnly: true }));
-    await pass(desk, engine);
-
-    expect(await on(server, () => hostsOf(server))).toEqual([]);
-    expect((await on(desk, () => hostsOf(desk))).map((h) => h.name)).toEqual([
-      "mine",
-    ]);
-  });
-
-  it("keeps a local edit that lost to a newer server edit, and can restore it", async () => {
-    const [desk] = desktops;
-    await on(server, () => addHost(server, { name: "a" }));
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    await on(desk, () =>
-      db(desk)
-        .update(schema.hosts)
-        .set({ ip: "desk-edit" })
-        .where(eq(schema.hosts.syncId, "host-a")),
-    );
-    await on(server, async () => {
-      await db(server)
-        .update(schema.hosts)
-        .set({ ip: "server-edit" })
-        .where(eq(schema.hosts.syncId, "host-a"));
-      markChanged();
-    });
-    await pass(desk, engine);
-
-    const [local] = await on(desk, () => hostsOf(desk));
-    expect(local.ip).toBe("server-edit");
-    const conflicts = await on(desk, () => listConflicts(desk.userId));
-    expect(conflicts).toHaveLength(1);
-    expect(JSON.parse(conflicts[0].localRow).ip).toBe("desk-edit");
-
-    // Keep mine: put it back, and the next pass sends it.
-    await on(desk, async () => {
-      const conflict = (await getConflict(desk.userId, conflicts[0].id))!;
-      await writeWireRow(
-        getEntity("hosts")!,
-        desk.userId,
-        { ...JSON.parse(conflict.localRow), syncId: conflict.syncId },
-        createResolvers(desk.userId),
-      );
-      await deleteConflict(desk.userId, conflict.id);
-    });
-    await pass(desk, engine);
-    const [serverHost] = await on(server, () => hostsOf(server));
-    expect(serverHost.ip).toBe("desk-edit");
-  });
-
-  it("does not let one refused change hold up the rest", async () => {
-    const [desk] = desktops;
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    await on(desk, async () => {
-      await addHost(desk, { name: "one" });
-      await db(desk).insert(schema.sshCredentials).values({
-        userId: desk.userId,
-        name: "cred",
-        authType: "password",
-        syncId: "cred-x",
-      });
-    });
-    // The server refuses host changes only.
-    const hostPermissions = getEntity("hosts")!.permissions;
-    const credentialPermissions = getEntity("sshCredentials")!.permissions;
-    getEntity("sshCredentials")!.permissions = undefined;
-    state.allow = false;
-    try {
-      await pass(desk, engine);
-    } finally {
-      getEntity("hosts")!.permissions = hostPermissions;
-      getEntity("sshCredentials")!.permissions = credentialPermissions;
-    }
-
-    expect(await on(server, () => hostsOf(server))).toEqual([]);
-    const creds = await db(server).select().from(schema.sshCredentials);
-    expect(creds.map((c) => c.name)).toEqual(["cred"]);
-    const [record] = await on(desk, () =>
-      db(desk)
-        .select()
-        .from(schema.syncRecords)
-        .where(
-          and(
-            eq(schema.syncRecords.entityType, "hosts"),
-            eq(schema.syncRecords.syncId, "host-one"),
-          ),
-        ),
-    );
-    expect(record.error).toBe("permission");
-  });
-
-  it("leaves a switched-off kind of data alone, and catches up when it is back on", async () => {
-    const [desk] = desktops;
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    const link = (await on(desk, () => getLink()))!;
-    await on(desk, () =>
-      updateLink({
-        disabledTypes: ["hosts"],
-        knownTypes: link.knownTypes.filter((type) => type !== "hosts"),
-      }),
-    );
-    await on(server, () => addHost(server, { name: "later" }));
-    await on(desk, () => addHost(desk, { name: "private" }));
-    await pass(desk, engine);
-
-    expect((await on(desk, () => hostsOf(desk))).map((h) => h.name)).toEqual([
-      "private",
-    ]);
-    expect(
-      (await on(server, () => hostsOf(server))).map((h) => h.name),
-    ).toEqual(["later"]);
-
-    await on(desk, () => updateLink({ disabledTypes: [] }));
-    await pass(desk, engine);
-    await pass(desk, engine);
-    const names = (await on(desk, () => hostsOf(desk)))
-      .map((h) => h.name)
-      .sort();
-    expect(names).toEqual(["later", "private"]);
-    expect(
-      (await on(server, () => hostsOf(server))).map((h) => h.name).sort(),
-    ).toEqual(["later", "private"]);
-  });
-});
-
-describe("a server row that cannot be read", () => {
-  async function recordOf(where: Side, syncId: string) {
-    const [record] = await on(where, () =>
-      db(where)
-        .select()
-        .from(schema.syncRecords)
-        .where(
-          and(
-            eq(schema.syncRecords.entityType, "hosts"),
-            eq(schema.syncRecords.syncId, syncId),
-          ),
-        ),
-    );
-    return record;
-  }
-
-  it.each(["upsert", "delete"] as const)(
-    "retries a local %s after the server row becomes readable",
-    async (op) => {
-      const [desk] = desktops;
-      await on(server, () => addHost(server, { name: "a" }));
-      const engine = await linkDesktop(desk);
-      await pass(desk, engine);
-
-      await on(desk, () =>
-        (op === "delete"
-          ? db(desk).delete(schema.hosts)
-          : db(desk).update(schema.hosts).set({ ip: "desk-edit" })
-        ).where(eq(schema.hosts.syncId, "host-a")),
-      );
-      await on(server, async () => {
-        await db(server)
-          .update(schema.hosts)
-          .set({ ip: "server-edit" })
-          .where(eq(schema.hosts.syncId, "host-a"));
-        await reconcileUser(SERVER_USER, { force: true });
-        // Then its secret stops decrypting, as under a different key.
-        const [host] = await hostsOf(server);
-        await db(server)
-          .update(schema.hosts)
-          .set({
-            password: FieldCrypto.encryptField(
-              "s3cret",
-              Buffer.alloc(32, 9),
-              String(host.id),
-              "password",
-            ),
-          })
-          .where(eq(schema.hosts.id, host.id));
-      });
-
-      const warn = vi.spyOn(syncLogger, "warn");
-      try {
-        await pass(desk, engine);
-        expect(warn).toHaveBeenCalledWith(
-          expect.any(String),
-          expect.objectContaining({
-            entityType: "hosts",
-            syncId: "host-a",
-            error: expect.any(String),
-          }),
-        );
-      } finally {
-        warn.mockRestore();
-      }
-
-      const [local] = await on(desk, () => hostsOf(desk));
-      expect(local?.ip).toBe(op === "upsert" ? "desk-edit" : undefined);
-      expect(await on(desk, () => listConflicts(desk.userId))).toEqual([]);
-      expect((await recordOf(desk, "host-a")).error).toBe("unavailable");
-
-      // Restore the same server content without another local edit or a new
-      // server revision. The failed operation must still be retried.
-      await on(server, () =>
-        db(server)
-          .update(schema.hosts)
-          .set({ password: null })
-          .where(eq(schema.hosts.syncId, "host-a")),
-      );
-      await on(server, () => reconcileUser(SERVER_USER, { force: true }));
-      await pass(desk, engine);
-      const [after] = await on(desk, () => hostsOf(desk));
-      expect(after?.ip).toBe("server-edit");
-      expect((await recordOf(desk, "host-a")).error).toBeNull();
-      const conflicts = await on(desk, () => listConflicts(desk.userId));
-      expect(conflicts.map((c) => JSON.parse(c.localRow).ip)).toEqual(
-        op === "upsert" ? ["desk-edit"] : [],
-      );
-    },
-  );
-
-  it("keeps the local row when a conflict carries no row", async () => {
-    const [desk] = desktops;
-    await on(server, () => addHost(server, { name: "a" }));
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    await on(desk, async () => {
-      const link = (await getLink())!;
-      const settle = (
-        engine as unknown as {
-          settle: (...args: unknown[]) => Promise<void>;
-        }
-      ).settle.bind(engine);
-      await settle(
-        link,
-        {
-          entityType: "hosts",
-          syncId: "host-a",
-          baseRevision: 1,
-          op: "upsert",
-          row: { syncId: "host-a", name: "a" },
-        },
-        {
-          entityType: "hosts",
-          syncId: "host-a",
-          status: "conflict",
-          revision: 2,
-          deleted: false,
-          row: null,
-        },
-        "hash",
-      );
-    });
-
-    expect((await on(desk, () => hostsOf(desk))).map((h) => h.name)).toEqual([
-      "a",
-    ]);
-    const record = await recordOf(desk, "host-a");
-    expect(record.deleted).toBe(false);
-    expect(record.revision).toBe(1);
-  });
-});
-
-describe("hosts shared with the account", () => {
-  it("arrive on the desktop with their text columns as stored", async () => {
-    const [desk] = desktops;
-    await on(server, async () => {
-      await server.db.run(
-        sql`INSERT INTO users (id, username, password_hash, is_admin) VALUES ('owner', 'owner', '', 0)`,
-      );
-      await db(server).insert(schema.hosts).values({
-        userId: "owner",
-        name: "theirs",
-        ip: "10.0.0.5",
-        port: 22,
-        username: "root",
-        authType: "none",
-        forceKeyboardInteractive: "true",
-        syncId: "host-theirs",
-      });
-      const [host] = await db(server).select().from(schema.hosts);
-      await db(server).insert(schema.hostAccess).values({
-        hostId: host.id,
-        userId: SERVER_USER,
-        grantedBy: "owner",
-        permissionLevel: "view",
-      });
-      state.sharedHostIds.add(host.id);
-      markChanged();
-    });
-
-    const engine = await linkDesktop(desk);
-    await pass(desk, engine);
-
-    const [copy] = await on(desk, () => hostsOf(desk));
-    expect(copy?.name).toBe("theirs");
-    expect(copy.forceKeyboardInteractive).toBe("true");
-    expect(JSON.parse(copy.sharedSource!)).toMatchObject({
-      owner: "owner",
-      permissionLevel: "view",
-    });
-  });
-});
-
-describe("two desktops on one account", () => {
-  it("converge on edits, creates and deletes made offline on each", async () => {
-    const [a, b] = desktops;
-    await on(server, () => addHost(server, { name: "shared-one" }));
-    await on(server, () => addHost(server, { name: "shared-two" }));
-    const engineA = await linkDesktop(a);
-    const engineB = await linkDesktop(b);
-    await pass(a, engineA);
-    await pass(b, engineB);
-
-    // Offline on both.
-    await on(a, () => addHost(a, { name: "from-a" }));
-    await on(a, () =>
-      db(a)
-        .update(schema.hosts)
-        .set({ ip: "10.1.1.1" })
-        .where(eq(schema.hosts.syncId, "host-shared-one")),
-    );
-    await on(b, () =>
-      db(b)
-        .delete(schema.hosts)
-        .where(eq(schema.hosts.syncId, "host-shared-two")),
-    );
-    await on(b, () => addHost(b, { name: "from-b" }));
-
-    await pass(a, engineA);
-    await pass(b, engineB);
-    await pass(a, engineA);
-
-    const view = async (where: Side) =>
-      (await on(where, () => hostsOf(where)))
-        .map((h) => `${h.name}:${h.ip}`)
-        .sort();
-    const expected = [
-      "from-a:10.0.0.1",
-      "from-b:10.0.0.1",
-      "shared-one:10.1.1.1",
-    ];
-    expect(await view(server)).toEqual(expected);
-    expect(await view(a)).toEqual(expected);
-    expect(await view(b)).toEqual(expected);
-  });
-});

src/backend/tests/utils/auth-manager-token.test.ts

@@ -214,6 +214,30 @@ describe("AuthManager token handling", () => {
     expect(payload?.userId).toBe("user-1");
   });
 
+  it("gives an API key a ticket on a short session that only a socket takes", async () => {
+    mocks.created.length = 0;
+    const ticket = await authManager.issueApiKeySocketTicket(
+      "user-1",
+      "key-12345678",
+    );
+    const payload = jwt.decode(ticket) as Record<string, number | string>;
+
+    expect(payload.userId).toBe("user-1");
+    expect(payload.purpose).toBe("ws");
+    expect(Number(payload.exp) - Number(payload.iat)).toBe(60);
+
+    const [session] = mocks.created;
+    expect(session.userId).toBe("user-1");
+    expect(session.id).toBe(payload.sessionId);
+    expect(session.deviceInfo).toBe("api-key: socket key-1234");
+    const lifetime =
+      new Date(String(session.expiresAt)).getTime() -
+      new Date(String(session.createdAt)).getTime();
+    expect(lifetime).toBe(120_000);
+
+    expect(await authManager.verifyJWTToken(ticket)).toBeNull();
+  });
+
   it("rejects a socket ticket whose session has expired", async () => {
     const ticket = await authManager.issueSocketTicket("user-1", "expired");
     expect(

src/backend/tests/utils/ssh-key-utils.test.ts

@@ -10,6 +10,7 @@ import {
   isPrivateKeyPassphraseError,
   getFriendlyKeyTypeName,
   validateKeyPair,
+  isSecurityKeyFile,
 } from "../../utils/ssh-key-utils.js";
 
 const { parsePrivateKey } = sshpk;
@@ -224,3 +225,43 @@ describe("PKCS#8 runtime key normalization", () => {
     ).toThrow();
   });
 });
+
+describe("security key files", () => {
+  const str = (v: string | Buffer) => {
+    const b = Buffer.from(v);
+    const l = Buffer.alloc(4);
+    l.writeUInt32BE(b.length);
+    return Buffer.concat([l, b]);
+  };
+  const skFile = (type: string) => {
+    const body = Buffer.concat([
+      Buffer.from("openssh-key-v1\u0000"),
+      str("none"),
+      str("none"),
+      str(""),
+      Buffer.from([0, 0, 0, 1]),
+      str(Buffer.concat([str(type), str(Buffer.alloc(32, 1)), str("ssh:")])),
+      str(Buffer.alloc(16)),
+    ]).toString("base64");
+    return `-----BEGIN OPENSSH PRIVATE KEY-----
+${body}
+-----END OPENSSH PRIVATE KEY-----`;
+  };
+
+  it("detects sk key files", () => {
+    expect(isSecurityKeyFile(skFile("sk-ssh-ed25519@openssh.com"))).toBe(true);
+    expect(
+      isSecurityKeyFile(skFile("sk-ecdsa-sha2-nistp256@openssh.com")),
+    ).toBe(true);
+  });
+
+  it("ignores normal keys", () => {
+    expect(isSecurityKeyFile(ED25519_PRIVATE)).toBe(false);
+  });
+
+  it("explains how to use a security key instead of failing to decode", () => {
+    expect(() =>
+      preparePrivateKeyForSSH2(skFile("sk-ssh-ed25519@openssh.com")),
+    ).toThrow("ssh-add");
+  });
+});

src/backend/upgrade/boot-migrations.ts

@@ -48,8 +48,8 @@ export const runPluginDataMigrations = DatabaseSaveTrigger.batched(
  */
 async function applyHostDefaults(): Promise<void> {
   try {
-    const { getLink } = await import("../sync/client/link-store.js");
-    if (await getLink().catch(() => null)) return;
+    const { listLinks } = await import("../sync/client/link-store.js");
+    if ((await listLinks().catch(() => [])).length > 0) return;
     const { recomputeEverything } =
       await import("../hosts/defaults/recompute.js");
     recomputeEverything("plugins started");

src/backend/utils/auth-manager.ts

@@ -472,6 +472,24 @@ class AuthManager {
     } as jwt.SignOptions);
   }
 
+  /**
+   * A one minute socket ticket for an API key. The key has no login session,
+   * so a two minute session a plugin could have minted carries the ticket. It
+   * can open plugin sockets and call nothing else.
+   */
+  async issueApiKeySocketTicket(
+    userId: string,
+    keyId: string,
+  ): Promise<string> {
+    const { token } = await this.issuePluginSession(userId, {
+      pluginId: "api-key",
+      purpose: `socket ${keyId.slice(0, 8)}`,
+      ttlSeconds: 120,
+    });
+    const sessionId = (jwt.decode(token) as JWTPayload).sessionId!;
+    return this.issueSocketTicket(userId, sessionId);
+  }
+
   /**
    * A session a plugin mints for a user, to call core's API as them. It is
    * an ordinary session row, so it verifies, expires and shows up like a

src/backend/utils/ssh-key-utils.ts

@@ -245,10 +245,30 @@ function getUnsupportedPrivateKeyError(privateKeyData: string): string {
   return "Unsupported private key format. Use an OpenSSH, PEM, or PuTTY PPK v2 RSA/DSA private key.";
 }
 
+const SECURITY_KEY_ERROR =
+  "This is a security key (FIDO2) key file. It only holds a handle, so the key itself must sign on your device. Load it with ssh-add and use SSH agent authentication in the desktop app.";
+
+/** An OpenSSH private key file for a FIDO2 security key (sk-ssh-ed25519, sk-ecdsa). */
+export function isSecurityKeyFile(privateKeyData: string): boolean {
+  const match = privateKeyData.match(
+    /-----BEGIN OPENSSH PRIVATE KEY-----([\s\S]*?)-----END OPENSSH PRIVATE KEY-----/,
+  );
+  if (!match) return false;
+  try {
+    const body = Buffer.from(match[1].replace(/\s+/g, ""), "base64");
+    return /sk-(?:ssh-ed25519|ecdsa-sha2-nistp256)@openssh\.com/.test(
+      body.toString("latin1"),
+    );
+  } catch {
+    return false;
+  }
+}
+
 export function preparePrivateKeyForSSH2(
   privateKeyData: string,
   passphrase?: string,
 ): Buffer {
+  if (isSecurityKeyFile(privateKeyData)) throw new Error(SECURITY_KEY_ERROR);
   let cleanKey = normalizePrivateKeyText(privateKeyData);
   if (
     /^-----BEGIN (?:ENCRYPTED )?PRIVATE KEY-----/.test(cleanKey) &&

src/main.tsx

@@ -14,6 +14,7 @@ import {
   Auth,
   getStoredAuth,
   clearStoredAuth,
+  storeAuth,
   markDesktopManualLogout,
   clearDesktopManualLogout,
 } from "@/auth/Auth";
@@ -195,7 +196,12 @@ function App() {
     if (phase !== "verifying") return;
     appReadyPromise
       .then(() => getUserInfo())
-      .then(async () => {
+      .then(async (info) => {
+        // The stored name can be an earlier account, after a switch or rename.
+        if (info.username) {
+          setAuthUsername(info.username);
+          storeAuth(info.username);
+        }
         if (isElectron()) {
           try {
             const token = await getCurrentToken();

src/types/onboarding.ts

@@ -10,7 +10,6 @@
 
 export const CORE_ONBOARDING_STEPS = {
   plugins: 1,
-  "desktop-sync": 1,
   "desktop-updates": 1,
   security: 1,
 } as const;
@@ -24,7 +23,6 @@ export type CoreOnboardingStepKey = keyof typeof CORE_ONBOARDING_STEPS;
  */
 export const LEGACY_SEEN: Readonly<Record<string, number>> = Object.freeze({
   plugins: 1,
-  "desktop-sync": 1,
   preset: 1,
   appearance: 1,
   security: 1,

src/ui/api/sync-api.ts

@@ -1,155 +0,0 @@
-import { authApi } from "@/main-axios";
-
-export type SyncState = "idle" | "syncing" | "offline" | "error" | "signed_out";
-
-export interface SyncProxyHeader {
-  name: string;
-  value: string;
-  /** A saved header whose value is not sent back. */
-  set?: boolean;
-}
-
-export interface SyncBasicAuth {
-  username: string;
-  password: string;
-  set?: boolean;
-}
-
-export interface SyncEntityInfo {
-  type: string;
-  owner: string;
-  ownerName: string | null;
-  readOnly: boolean;
-  onServer: boolean;
-  onDevice: boolean;
-  enabled: boolean;
-}
-
-export interface SyncStatus {
-  linked: boolean;
-  serverUrl?: string;
-  serverName?: string | null;
-  serverVersion?: string | null;
-  account?: {
-    username?: string;
-    isAdmin?: boolean;
-    roles?: string[];
-    permissions?: string[];
-  };
-  status?: SyncState;
-  lastError?: string | null;
-  linkedAt?: string;
-  lastSyncAt?: string | null;
-  pending?: number;
-  conflicts?: number;
-  errors?: number;
-  firstSyncDone?: boolean;
-  allowInvalidCertificate?: boolean;
-  customHeaders?: SyncProxyHeader[];
-  basicAuth?: SyncBasicAuth | null;
-  entities: SyncEntityInfo[];
-}
-
-export type ProbeProblem =
-  | "invalid_url"
-  | "unreachable"
-  | "tls_untrusted"
-  | "basic_auth_required"
-  | "proxy_login"
-  | "not_termix"
-  | "version_mismatch"
-  | "different_account";
-
-export interface ProbeResult {
-  ok: boolean;
-  serverUrl?: string;
-  name?: string;
-  version?: string | null;
-  problem?: ProbeProblem;
-  message?: string;
-}
-
-export interface ServerTarget {
-  serverUrl: string;
-  customHeaders?: SyncProxyHeader[];
-  basicAuth?: SyncBasicAuth | null;
-  allowInvalidCertificate?: boolean;
-}
-
-export interface SyncConflictItem {
-  id: number;
-  entityType: string;
-  syncId: string;
-  name: string;
-  createdAt: string;
-}
-
-export interface SyncErrorItem {
-  entityType: string;
-  syncId: string;
-  reason: string | null;
-}
-
-export async function getSyncStatus(): Promise<SyncStatus> {
-  return (await authApi.get("/sync/link/status")).data;
-}
-
-export async function probeServer(target: ServerTarget): Promise<ProbeResult> {
-  return (await authApi.post("/sync/link/probe", target)).data;
-}
-
-export async function getLinkPreview(): Promise<Record<string, number>> {
-  return (await authApi.get("/sync/link/preview")).data?.counts ?? {};
-}
-
-export async function completeLink(
-  input: ServerTarget & {
-    token: string;
-    mode: "merge" | "replace";
-    serverName?: string;
-  },
-): Promise<SyncStatus> {
-  return (await authApi.post("/sync/link/complete", input)).data;
-}
-
-export async function reloginLink(token: string): Promise<SyncStatus> {
-  return (await authApi.post("/sync/link/relogin", { token })).data;
-}
-
-export async function unlinkServer(keepData: boolean): Promise<SyncStatus> {
-  return (await authApi.post("/sync/link/unlink", { keepData })).data;
-}
-
-export async function syncNow(): Promise<SyncStatus> {
-  return (await authApi.post("/sync/link/sync", {}, { timeout: 300_000 })).data;
-}
-
-export async function updateSyncSettings(settings: {
-  disabledTypes?: string[];
-  customHeaders?: SyncProxyHeader[];
-  basicAuth?: SyncBasicAuth | null;
-  allowInvalidCertificate?: boolean;
-}): Promise<SyncStatus> {
-  return (await authApi.put("/sync/link/settings", settings)).data;
-}
-
-export async function getSyncConflicts(): Promise<SyncConflictItem[]> {
-  return (await authApi.get("/sync/link/conflicts")).data?.conflicts ?? [];
-}
-
-export async function settleSyncConflict(
-  id: number,
-  keep: "mine" | "server",
-): Promise<void> {
-  await authApi.post(`/sync/link/conflicts/${id}`, { keep });
-}
-
-export async function getSyncErrors(): Promise<SyncErrorItem[]> {
-  return (await authApi.get("/sync/link/errors")).data?.errors ?? [];
-}
-
-export async function retrySyncErrors(): Promise<SyncStatus> {
-  return (
-    await authApi.post("/sync/link/errors/retry", {}, { timeout: 300_000 })
-  ).data;
-}

src/ui/auth/Auth.tsx

@@ -138,7 +138,7 @@ function hasDesktopManualLogout() {
   return localStorage.getItem(DESKTOP_MANUAL_LOGOUT_KEY) === "true";
 }
 
-function storeAuth(username: string) {
+export function storeAuth(username: string) {
   localStorage.setItem(
     STORAGE_KEY,
     JSON.stringify({ loggedIn: true, username }),

src/ui/auth/ElectronLoginForm.tsx

@@ -1,319 +0,0 @@
-import { getErrorMessage } from "../lib/error-message.js";
-import React, { useState, useEffect, useRef, useCallback } from "react";
-import { Alert, AlertDescription, AlertTitle } from "@/components/alert.tsx";
-import { useTranslation } from "react-i18next";
-import { AlertCircle, Loader2, ArrowLeft, RefreshCw } from "lucide-react";
-
-interface ElectronLoginFormProps {
-  serverUrl: string;
-  onAuthSuccess: (token: string | null) => void | Promise<void>;
-  onChangeServer: () => void;
-  // "local" (default): the app's own login, the token goes to localStorage
-  // like every other client. "link": signing in to a server to link this
-  // desktop to it; the token is only handed to onAuthSuccess, which trades
-  // it for the desktop's own session.
-  targetPurpose?: "local" | "link";
-}
-
-const AUTH_MESSAGE_SOURCES = new Set([
-  "auth_component",
-  "second_factor_auth_component",
-  "method_auth_component",
-  "oidc_callback",
-]);
-
-export function ElectronLoginForm({
-  serverUrl,
-  onAuthSuccess,
-  onChangeServer,
-  targetPurpose = "local",
-}: ElectronLoginFormProps) {
-  const { t } = useTranslation();
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const [isAuthenticating, setIsAuthenticating] = useState(false);
-  const isAuthenticatingRef = useRef(false);
-  const iframeRef = useRef<HTMLIFrameElement>(null);
-  const hasAuthenticatedRef = useRef(false);
-  const [currentUrl, setCurrentUrl] = useState(serverUrl);
-  const hasLoadedOnce = useRef(false);
-  const onAuthSuccessRef = useRef(onAuthSuccess);
-  useEffect(() => {
-    onAuthSuccessRef.current = onAuthSuccess;
-  }, [onAuthSuccess]);
-
-  const handleAuthSuccess = useCallback(
-    async (token: string | null) => {
-      if (hasAuthenticatedRef.current || isAuthenticatingRef.current) return;
-      hasAuthenticatedRef.current = true;
-      isAuthenticatingRef.current = true;
-      setIsAuthenticating(true);
-
-      try {
-        if (targetPurpose === "link") {
-          if (!token) {
-            throw new Error(t("errors.authTokenMissing"));
-          }
-        } else if (token) {
-          localStorage.setItem("jwt", token);
-        }
-        await onAuthSuccessRef.current(token);
-      } catch (err) {
-        setError(
-          err instanceof Error && err.message
-            ? err.message
-            : t("errors.authTokenSaveFailed"),
-        );
-        isAuthenticatingRef.current = false;
-        setIsAuthenticating(false);
-        hasAuthenticatedRef.current = false;
-      }
-    },
-    [t, targetPurpose],
-  );
-
-  // postMessage from server Auth.tsx after the backend has set the HttpOnly cookie.
-  // Only the server's own origin is trusted: the iframe can navigate away
-  // (identity provider, redirects), and those pages must not hand us a token,
-  // start a system browser login, or receive the replies.
-  useEffect(() => {
-    let serverOrigin: string;
-    try {
-      serverOrigin = new URL(serverUrl).origin;
-    } catch {
-      return;
-    }
-
-    const handleMessage = async (event: MessageEvent) => {
-      try {
-        if (event.source !== iframeRef.current?.contentWindow) return;
-        if (event.origin !== serverOrigin) return;
-        if (!event.data || typeof event.data !== "object") return;
-        const {
-          type,
-          platform,
-          source,
-          token,
-          authUrl,
-          callbackPort,
-          providerId,
-        } = event.data;
-
-        if (
-          type === "AUTH_SUCCESS" &&
-          platform === "desktop" &&
-          AUTH_MESSAGE_SOURCES.has(source)
-        ) {
-          await handleAuthSuccess(token ?? null);
-          return;
-        }
-
-        // OIDC login requested from inside the iframe, open the system browser
-        // so captcha stages (e.g. Cloudflare Turnstile) render correctly.
-        if (type === "OIDC_SYSTEM_BROWSER_AUTH" && authUrl && callbackPort) {
-          const sendResultToIframe = (result: {
-            success: boolean;
-            error?: string;
-            secondFactor?: boolean;
-            tempToken?: string;
-            factors?: string;
-          }) => {
-            iframeRef.current?.contentWindow?.postMessage(
-              {
-                type: "OIDC_SYSTEM_BROWSER_AUTH_RESULT",
-                source: "oidc_system_browser_auth",
-                providerId,
-                ...result,
-              },
-              serverOrigin,
-            );
-          };
-          const electronAPI = (
-            window as unknown as {
-              electronAPI?: {
-                externalBrowserLogin?: (
-                  url: string,
-                  port: number,
-                ) => Promise<{
-                  success: boolean;
-                  token?: string;
-                  error?: string;
-                  secondFactor?: boolean;
-                  tempToken?: string;
-                  factors?: string;
-                }>;
-              };
-            }
-          ).electronAPI;
-          if (!electronAPI?.externalBrowserLogin) {
-            sendResultToIframe({
-              success: false,
-              error: t("errors.failedExternalLogin"),
-            });
-            return;
-          }
-          const result = await electronAPI.externalBrowserLogin(
-            authUrl,
-            callbackPort,
-          );
-          if (result.success && result.token) {
-            await handleAuthSuccess(result.token);
-            return;
-          }
-          // The login stopped for a second factor; the iframe asks for it.
-          if (result.secondFactor) {
-            sendResultToIframe({
-              success: false,
-              secondFactor: true,
-              tempToken: result.tempToken,
-              factors: result.factors,
-            });
-            return;
-          }
-          sendResultToIframe({
-            success: false,
-            error: result.error || t("errors.failedExternalLogin"),
-          });
-        }
-      } catch (err) {
-        const providerId =
-          event.data &&
-          typeof event.data === "object" &&
-          typeof event.data.providerId === "number"
-            ? event.data.providerId
-            : undefined;
-        const error = getErrorMessage(err, t("errors.failedExternalLogin"));
-        iframeRef.current?.contentWindow?.postMessage(
-          {
-            type: "OIDC_SYSTEM_BROWSER_AUTH_RESULT",
-            source: "oidc_system_browser_auth",
-            providerId,
-            success: false,
-            error,
-          },
-          serverOrigin,
-        );
-      }
-    };
-
-    window.addEventListener("message", handleMessage);
-    return () => window.removeEventListener("message", handleMessage);
-  }, [handleAuthSuccess, serverUrl, t]);
-
-  useEffect(() => {
-    const iframe = iframeRef.current;
-    if (!iframe) return;
-
-    const handleLoad = () => {
-      setLoading(false);
-      hasLoadedOnce.current = true;
-      setError(null);
-
-      try {
-        if (iframe.contentWindow) {
-          setCurrentUrl(iframe.contentWindow.location.href);
-        }
-      } catch {
-        setCurrentUrl(serverUrl);
-      }
-    };
-
-    const handleError = () => {
-      setLoading(false);
-      if (hasLoadedOnce.current) {
-        setError(t("errors.failedToLoadServer"));
-      }
-    };
-
-    iframe.addEventListener("load", handleLoad);
-    iframe.addEventListener("error", handleError);
-    return () => {
-      iframe.removeEventListener("load", handleLoad);
-      iframe.removeEventListener("error", handleError);
-    };
-  }, [serverUrl, t]);
-
-  const handleRefresh = () => {
-    if (iframeRef.current) {
-      iframeRef.current.src = serverUrl;
-      setLoading(true);
-      setError(null);
-    }
-  };
-
-  const displayUrl = currentUrl.replace(/^https?:\/\//, "");
-
-  return (
-    <div className="relative w-full h-full bg-background flex flex-col">
-      {isAuthenticating && (
-        <div className="absolute inset-0 flex items-center justify-center bg-background z-50">
-          <Loader2 className="h-8 w-8 animate-spin text-primary" />
-        </div>
-      )}
-
-      {!isAuthenticating && (
-        <div className="flex items-center justify-between p-4 pr-12 bg-background border-b border-border">
-          <button
-            onClick={onChangeServer}
-            className="flex items-center gap-2 text-foreground hover:text-primary transition-colors"
-          >
-            <ArrowLeft className="h-5 w-5" />
-            <span className="text-base font-medium">
-              {t("sync.wizard.back")}
-            </span>
-          </button>
-          <div className="flex-1 mx-4 text-center">
-            <span className="text-muted-foreground text-sm truncate block">
-              {displayUrl}
-            </span>
-          </div>
-          <button
-            onClick={handleRefresh}
-            className="p-2 text-foreground hover:text-primary transition-colors"
-            disabled={loading}
-          >
-            <RefreshCw className={`h-5 w-5 ${loading ? "animate-spin" : ""}`} />
-          </button>
-        </div>
-      )}
-
-      {error && !isAuthenticating && (
-        <div className="absolute top-20 left-1/2 transform -translate-x-1/2 z-50 w-full max-w-md px-4">
-          <Alert variant="destructive">
-            <AlertCircle className="h-4 w-4" />
-            <AlertTitle>{t("common.error")}</AlertTitle>
-            <AlertDescription>{error}</AlertDescription>
-          </Alert>
-        </div>
-      )}
-
-      {loading && !isAuthenticating && (
-        <div
-          className="absolute inset-0 flex items-center justify-center bg-background z-40"
-          style={{ marginTop: "60px" }}
-        >
-          <div className="flex items-center">
-            <Loader2 className="h-8 w-8 animate-spin text-primary" />
-            <span className="ml-3 text-muted-foreground">
-              {t("auth.loadingServer")}
-            </span>
-          </div>
-        </div>
-      )}
-
-      <div
-        className="flex-1 overflow-hidden"
-        style={{ visibility: isAuthenticating ? "hidden" : "visible" }}
-      >
-        <iframe
-          ref={iframeRef}
-          src={serverUrl}
-          className="w-full h-full border-0"
-          title={t("auth.serverAuthentication")}
-          sandbox="allow-same-origin allow-scripts allow-forms allow-popups allow-popups-to-escape-sandbox allow-storage-access-by-user-activation allow-top-navigation allow-top-navigation-by-user-activation allow-modals allow-downloads"
-          allow="clipboard-read; clipboard-write; publickey-credentials-get; publickey-credentials-create"
-        />
-      </div>
-    </div>
-  );
-}

src/ui/hooks/use-sync-status.ts

@@ -1,22 +0,0 @@
-import { useSyncExternalStore } from "react";
-import { getSyncStatusSnapshot, subscribeSyncStatus } from "@/lib/sync-status";
-
-/** The desktop's sync status, kept current while the component is mounted. */
-export function useSyncStatus() {
-  return useSyncExternalStore(
-    subscribeSyncStatus,
-    getSyncStatusSnapshot,
-    () => null,
-  );
-}
-
-/** What needs the user's attention in Sync, for the rail badge. */
-export function useSyncAttentionCount(): number | null {
-  const status = useSyncStatus();
-  if (!status?.linked) return null;
-  const count =
-    (status.conflicts ?? 0) +
-    (status.errors ?? 0) +
-    (status.status === "signed_out" ? 1 : 0);
-  return count || null;
-}

src/ui/lib/embedded-frame.ts

@@ -16,14 +16,20 @@ export function isInMobileWebView(): boolean {
   );
 }
 
+// The desktop app's own user agent. The link window frames the server
+// cross-origin, and Electron does not carry webContents.setUserAgent into
+// such a frame, so there navigator.userAgent is Electron's default, which
+// still names the app: "... termix/26.10.2 Chrome/... Electron/43.7.7 ...".
+const DESKTOP_USER_AGENT = /Termix-Desktop\/|\btermix\/[\w.-]+ .*\bElectron\//i;
+
 // Being framed alone is not enough: any site could frame this page and
-// receive the token posted to window.parent. The desktop app tags every
-// request and frame with its own user agent, which a web page cannot fake
-// in someone else's browser.
+// receive the token posted to window.parent. The desktop app's user agent,
+// in either form above, is something a web page cannot fake in someone
+// else's browser.
 export function isInElectronWebView(): boolean {
   if (isInMobileWebView()) return false;
   if ((window as EmbeddedFrameWindow).IS_ELECTRON_WEBVIEW) return true;
-  if (!/Termix-Desktop\//.test(navigator.userAgent)) return false;
+  if (!DESKTOP_USER_AGENT.test(navigator.userAgent)) return false;
   try {
     if (window.self !== window.top) return true;
   } catch {

src/ui/lib/linked-server.ts

@@ -1,3 +1,4 @@
+import { useEffect, useState } from "react";
 import { isElectron } from "@/lib/electron";
 import { authApi } from "@/main-axios";
 import { SYNC_CHANGED_EVENT } from "@/lib/sync-events";
@@ -48,3 +49,22 @@ export function notifySyncChanged(): void {
   cached = null;
   window.dispatchEvent(new CustomEvent(SYNC_CHANGED_EVENT));
 }
+
+/** Whether this desktop is linked to a server, kept current as it changes. */
+export function useDesktopLinked(): boolean {
+  const [linked, setLinked] = useState(false);
+  useEffect(() => {
+    let live = true;
+    const read = () =>
+      void getLinkedSession().then((session) => {
+        if (live) setLinked(!!session);
+      });
+    read();
+    window.addEventListener(SYNC_CHANGED_EVENT, read);
+    return () => {
+      live = false;
+      window.removeEventListener(SYNC_CHANGED_EVENT, read);
+    };
+  }, []);
+  return linked;
+}

src/ui/lib/sync-status.ts

@@ -1,86 +0,0 @@
-import { isElectron } from "@/lib/electron";
-import { getSyncStatus, type SyncStatus } from "@/api/sync-api";
-import { notifySyncChanged } from "@/lib/linked-server";
-
-/**
- * The desktop's sync status, polled from the embedded backend while anything
- * shows it. When a pass finishes, the views that show synced data are told
- * to reload.
- */
-
-const IDLE_MS = 15_000;
-const BUSY_MS = 2_000;
-
-let snapshot: SyncStatus | null = null;
-let timer: ReturnType<typeof setTimeout> | null = null;
-let lastSyncAt: string | null | undefined;
-const listeners = new Set<() => void>();
-
-function emit(): void {
-  for (const listener of listeners) listener();
-}
-
-function announce(): void {
-  notifySyncChanged();
-  window.dispatchEvent(new CustomEvent("hosts:refresh"));
-  window.dispatchEvent(new CustomEvent("termix:hosts-changed"));
-  window.dispatchEvent(new CustomEvent("termix:credentials-changed"));
-  window.dispatchEvent(new CustomEvent("termix:plugins-changed"));
-}
-
-async function poll(): Promise<void> {
-  timer = null;
-  try {
-    const next = await getSyncStatus();
-    const syncedAt = next.lastSyncAt ?? null;
-    if (lastSyncAt !== undefined && syncedAt !== lastSyncAt) announce();
-    if (snapshot && snapshot.linked !== next.linked) notifySyncChanged();
-    lastSyncAt = syncedAt;
-    snapshot = next;
-    emit();
-  } catch {
-    // The backend may still be starting; the next poll tries again.
-  }
-  schedule();
-}
-
-function schedule(delay?: number): void {
-  if (listeners.size === 0 || timer) return;
-  const busy = snapshot?.status === "syncing" || !!snapshot?.pending;
-  timer = setTimeout(() => void poll(), delay ?? (busy ? BUSY_MS : IDLE_MS));
-}
-
-export function subscribeSyncStatus(listener: () => void): () => void {
-  listeners.add(listener);
-  if (isElectron() && listeners.size === 1 && !timer) void poll();
-  return () => {
-    listeners.delete(listener);
-    if (listeners.size === 0 && timer) {
-      clearTimeout(timer);
-      timer = null;
-    }
-  };
-}
-
-export function getSyncStatusSnapshot(): SyncStatus | null {
-  return snapshot;
-}
-
-/** Takes a status a request already returned, and checks again soon. */
-export function setSyncStatus(next: SyncStatus): void {
-  snapshot = next;
-  if (lastSyncAt !== undefined && (next.lastSyncAt ?? null) !== lastSyncAt) {
-    announce();
-  }
-  lastSyncAt = next.lastSyncAt ?? null;
-  emit();
-  if (timer) clearTimeout(timer);
-  timer = null;
-  schedule(BUSY_MS);
-}
-
-export function refreshSyncStatus(): void {
-  if (timer) clearTimeout(timer);
-  timer = null;
-  void poll();
-}

src/ui/locales/en.json

@@ -215,13 +215,6 @@
     "pluginsLoadFailed": "The plugin list could not be loaded. You can choose plugins later from the Plugins tab.",
     "securityTitle": "Secure your account",
     "securityIntro": "Add a passkey or an authenticator app to your account. You can also do this later in Settings, under Security.",
-    "desktopTitle": "How do you want to use Termix?",
-    "desktopBody": "You can change this any time from Sync in the sidebar.",
-    "desktopLocalTitle": "On this device only",
-    "desktopLocalBody": "Everything is stored here. Nothing to set up.",
-    "desktopLinkTitle": "With my Termix server",
-    "desktopLinkBody": "Sign in to your server to use the same hosts and settings on every device.",
-    "desktopLinked": "Linked to {{server}}",
     "pluginsDocsLink": "Read about each one"
   },
   "desktopUpdates": {
@@ -242,6 +235,11 @@
     "ready": "Termix {{version}} is ready to install",
     "readyHint": "It installs the next time Termix restarts."
   },
+  "companion": {
+    "close": "Close panel",
+    "moveSide": "Move panel",
+    "resize": "Resize panel"
+  },
   "nav": {
     "home": "Home",
     "terminal": "Terminal",
@@ -252,7 +250,6 @@
     "hosts": "Hosts",
     "credentials": "Credentials",
     "connections": "Connections",
-    "sync": "Sync",
     "reconnectDisconnectedTerminals": "Reconnect all disconnected terminals",
     "reconnectingTerminals_one": "Reconnecting {{count}} terminal",
     "reconnectingTerminals_other": "Reconnecting {{count}} terminals",
@@ -1151,6 +1148,14 @@
         "title": "Set sign in rules",
         "consequence": "It can sign people out when idle, limit session length, turn off remember me and require a second factor."
       },
+      "ssh:transport": {
+        "title": "Choose how hosts are reached",
+        "consequence": "It can carry the SSH connection to a host over its own route, so it sees everything sent to and from those hosts, passwords included."
+      },
+      "sync:provide": {
+        "title": "Run sync",
+        "consequence": "It can answer all sync requests, so it sees the data that devices and servers sync."
+      },
       "system:tls": {
         "title": "Manage certificates",
         "consequence": "It can replace the certificate Termix serves over HTTPS and answer domain checks from certificate authorities."
@@ -1619,87 +1624,6 @@
     "noData": "No data",
     "filter": "Filter..."
   },
-  "sync": {
-    "minutesAgo_one": "{{count}} minute ago",
-    "minutesAgo_other": "{{count}} minutes ago",
-    "hoursAgo_one": "{{count}} hour ago",
-    "hoursAgo_other": "{{count}} hours ago",
-    "pending_one": "{{count}} change waiting to sync",
-    "pending_other": "{{count}} changes waiting to sync",
-    "proxy": {
-      "headersTitle": "Extra headers",
-      "headersHint": "Sent with every request to the server, for example a Cloudflare Access service token.",
-      "headerName": "Header name",
-      "headerValue": "Value",
-      "savedValue": "Saved, type to change",
-      "addHeader": "Add header",
-      "removeHeader": "Remove header",
-      "basicAuthTitle": "Username and password",
-      "basicAuthHint": "For a proxy that asks for a username and password before Termix.",
-      "username": "Username",
-      "password": "Password",
-      "allowInvalidCertificate": "Trust a self-signed certificate",
-      "allowInvalidCertificateHint": "Only for your own server, when its certificate is not from a known authority."
-    },
-    "problems": {
-      "invalidUrl": "That does not look like a web address.",
-      "unreachable": "Could not reach the server. Check the address and that the server is running.",
-      "unreachableWithReason": "Could not reach the server: {{reason}}",
-      "tlsUntrusted": "The server certificate is not trusted. If this is your own server with a self-signed certificate, turn on the option below.",
-      "basicAuthRequired": "Something in front of the server asks for a username and password. Enter them below.",
-      "proxyLogin": "A login page or proxy answered instead of Termix. Add the headers it needs below, or check the address.",
-      "notTermix": "There is no Termix server at that address. If it runs under a path, include it, like https://example.com/termix.",
-      "versionMismatch": "That server runs an older Termix. Update it to 2.9 or newer to link.",
-      "differentAccount": "You signed in to a different account. Sign in to the account this device is linked to, or unlink first."
-    },
-    "wizard": {
-      "title": "Link to a Termix server",
-      "reloginTitle": "Sign in again",
-      "savedServers": "Recent servers",
-      "removeServer": "Remove from the list",
-      "serverDescription": "Enter the address you use to open Termix in your browser.",
-      "signinDescription": "Sign in to {{url}}",
-      "chooseDescription": "This device already has data. What should happen to it?",
-      "finishingDescription": "Linking this device.",
-      "serverUrl": "Server address",
-      "serverUrlHint": "For example https://termix.example.com",
-      "showProxySettings": "Reverse proxy settings",
-      "hideProxySettings": "Hide reverse proxy settings",
-      "continue": "Continue",
-      "back": "Back",
-      "mergeTitle": "Add it to my account",
-      "mergeBody_one": "The item on this device is added to your account. Items your account already has stay as they are on the server.",
-      "mergeBody_other": "The {{count}} items on this device are added to your account. Items your account already has stay as they are on the server.",
-      "replaceTitle": "Replace it with my account",
-      "replaceBody_one": "The item on this device is removed, and this device takes everything from your account. Hosts kept on this device only stay.",
-      "replaceBody_other": "The {{count}} items on this device are removed, and this device takes everything from your account. Hosts kept on this device only stay.",
-      "link": "Link",
-      "linking": "Linking and running the first sync...",
-      "linked": "Linked. Your data is syncing now.",
-      "signedInAgain": "Signed in. Sync is running again."
-    },
-    "entities": {
-      "hosts": "Hosts",
-      "sshCredentials": "Credentials",
-      "sshFolders": "Folders",
-      "userPreferences": "Preferences",
-      "pluginUserSettings": "Plugin settings",
-      "sharedHosts": "Hosts shared with you",
-      "sharedCredentials": "Credentials shared with you",
-      "vaultProfiles": "Vault profiles",
-      "snippetFolders": "Snippet folders",
-      "snippets": "Snippets",
-      "dashboardServiceLinks": "Service links",
-      "homepageItems": "Homepage items",
-      "networkTopology": "Network map",
-      "workspaces": "Workspaces",
-      "hostDefaults": "Host defaults",
-      "hostDefaultsAdmin": "Server host defaults",
-      "aiProviders": "AI providers",
-      "homepageLayouts": "Homepage layouts",
-      "accountProfile": "Account profile"
-    }
-  },
   "hostDefaults": {
     "source": {
       "folder": "Folder {{name}}",

src/ui/onboarding/onboarding-steps.ts

@@ -1,8 +1,7 @@
-import { Monitor, MonitorDown, Puzzle, Shield } from "lucide-react";
+import { MonitorDown, Puzzle, Shield } from "lucide-react";
 import { CORE_ONBOARDING_STEPS } from "@/types/onboarding";
 import { PluginsStep } from "./steps/PluginsStep";
 import { SecurityStep } from "./steps/SecurityStep";
-import { DesktopSyncStep } from "./steps/DesktopSyncStep";
 import { DesktopUpdatesStep } from "./steps/DesktopUpdatesStep";
 import { desktopUpdates } from "@/lib/desktop-updates";
 import type { OnboardingStepDef } from "./onboarding-registry";
@@ -28,16 +27,6 @@ export const CORE_STEPS: OnboardingStepDef[] = [
     isRelevant: (ctx) => !ctx.pluginsManagedElsewhere && ctx.pluginSetupPending,
     forcePending: (ctx) => ctx.pluginSetupPending,
   },
-  {
-    id: "desktop-sync",
-    version: CORE_ONBOARDING_STEPS["desktop-sync"],
-    titleKey: "onboarding.desktopTitle",
-    icon: Monitor,
-    Component: DesktopSyncStep,
-    audience: "all",
-    position: 20,
-    isRelevant: (ctx) => ctx.isDesktop,
-  },
   {
     id: "desktop-updates",
     version: CORE_ONBOARDING_STEPS["desktop-updates"],

src/ui/onboarding/steps/DesktopSyncStep.tsx

@@ -1,79 +0,0 @@
-import { useState } from "react";
-import { useTranslation } from "react-i18next";
-import { Cloud, Laptop } from "lucide-react";
-import { LinkServerDialog } from "@/settings/sync/LinkServerDialog";
-import { useSyncStatus } from "@/hooks/use-sync-status";
-import { setSyncStatus } from "@/lib/sync-status";
-import { notifySyncChanged } from "@/lib/linked-server";
-
-/**
- * Desktop only: use Termix on this device alone, or link it to a server.
- * Either choice can be changed later from Sync.
- */
-export function DesktopSyncStep() {
-  const { t } = useTranslation();
-  const status = useSyncStatus();
-  const [linkOpen, setLinkOpen] = useState(false);
-  const linked = !!status?.linked;
-
-  const options = [
-    {
-      id: "local",
-      icon: Laptop,
-      title: t("onboarding.desktopLocalTitle"),
-      body: t("onboarding.desktopLocalBody"),
-      selected: !linked,
-      onClick: () => {},
-    },
-    {
-      id: "link",
-      icon: Cloud,
-      title: t("onboarding.desktopLinkTitle"),
-      body: linked
-        ? t("onboarding.desktopLinked", {
-            server: status?.serverName || status?.serverUrl,
-          })
-        : t("onboarding.desktopLinkBody"),
-      selected: linked,
-      onClick: () => !linked && setLinkOpen(true),
-    },
-  ];
-
-  return (
-    <div className="flex flex-col gap-3">
-      <p className="text-xs text-muted-foreground">
-        {t("onboarding.desktopBody")}
-      </p>
-      <div className="flex flex-col gap-1.5">
-        {options.map(({ id, icon: Icon, title, body, selected, onClick }) => (
-          <button
-            key={id}
-            type="button"
-            onClick={onClick}
-            className={`flex items-start gap-2.5 border p-2.5 text-left transition-colors ${
-              selected
-                ? "border-accent-brand bg-accent-brand/10"
-                : "border-border bg-card hover:bg-muted/40"
-            }`}
-          >
-            <Icon size={14} className="mt-0.5 shrink-0 text-accent-brand" />
-            <span className="flex flex-col gap-1">
-              <span className="text-xs font-medium">{title}</span>
-              <span className="text-[10px] leading-snug text-muted-foreground">
-                {body}
-              </span>
-            </span>
-          </button>
-        ))}
-      </div>
-      <LinkServerDialog
-        open={linkOpen}
-        onOpenChange={setLinkOpen}
-        onLinked={(next) => {
-          setSyncStatus(next);
-          notifySyncChanged();
-        }}
-      />
-    </div>
-  );
-}

src/ui/plugin-host/NativeView.tsx

@@ -0,0 +1,158 @@
+import { useEffect, useRef, type CSSProperties, type ReactNode } from "react";
+
+interface Bounds {
+  x: number;
+  y: number;
+  width: number;
+  height: number;
+}
+
+interface EmbeddedViewApi {
+  open: (options: {
+    id: string;
+    url: string;
+    ignoreCert?: boolean;
+    bounds: Bounds;
+    visible: boolean;
+  }) => Promise<unknown>;
+  setBounds: (id: string, bounds: Bounds) => Promise<unknown>;
+  setVisible: (id: string, visible: boolean) => Promise<unknown>;
+  close: (id: string) => Promise<unknown>;
+}
+
+function embeddedViewApi(): EmbeddedViewApi | null {
+  if (typeof window === "undefined") return null;
+  const api = (
+    window as unknown as { electronAPI?: { embeddedView?: unknown } }
+  ).electronAPI?.embeddedView;
+  return (api as EmbeddedViewApi | undefined) ?? null;
+}
+
+const OVERLAY = [
+  '[role="dialog"]',
+  '[role="alertdialog"]',
+  '[role="menu"]',
+  '[role="listbox"]',
+  "[data-radix-popper-content-wrapper]",
+].join(",");
+
+// A native view is drawn above the page, so anything the page opens over it
+// has to hide it first.
+function overlayOpen(host: HTMLElement): boolean {
+  return Array.from(document.querySelectorAll(OVERLAY)).some(
+    (node) => !host.contains(node),
+  );
+}
+
+export interface NativeViewProps {
+  url: string;
+  /** Accept an invalid TLS certificate from this URL's origin. */
+  ignoreCert?: boolean;
+  /** Hide the view, for example while the tab is not shown. */
+  hidden?: boolean;
+  /** Shown where the desktop app's native view is not available. */
+  fallback?: ReactNode;
+  className?: string;
+  style?: CSSProperties;
+}
+
+/**
+ * A page shown in a native view (desktop app only), for sites that do not
+ * work in a sandboxed iframe. It fills this element, hides itself when the
+ * element is not visible or a dialog or menu is open, and is closed on
+ * unmount. In a browser it renders `fallback`.
+ */
+export function NativeView({
+  url,
+  ignoreCert,
+  hidden,
+  fallback,
+  className,
+  style,
+}: NativeViewProps) {
+  const host = useRef<HTMLDivElement>(null);
+  const api = embeddedViewApi();
+  const hiddenRef = useRef(!!hidden);
+  hiddenRef.current = !!hidden;
+  const sync = useRef<() => void>(() => {});
+
+  useEffect(() => {
+    const element = host.current;
+    const view = embeddedViewApi();
+    if (!element || !view) return;
+    const id = crypto.randomUUID();
+    let opened = false;
+    let lastBounds = "";
+    let lastVisible: boolean | null = null;
+    let frame = 0;
+
+    const update = () => {
+      frame = 0;
+      const rect = element.getBoundingClientRect();
+      const bounds = {
+        x: rect.left,
+        y: rect.top,
+        width: rect.width,
+        height: rect.height,
+      };
+      const visible =
+        !hiddenRef.current &&
+        rect.width > 0 &&
+        rect.height > 0 &&
+        element.offsetParent !== null &&
+        !overlayOpen(element);
+      if (!opened) {
+        opened = true;
+        lastBounds = JSON.stringify(bounds);
+        lastVisible = visible;
+        void view.open({ id, url, ignoreCert, bounds, visible });
+        return;
+      }
+      const key = JSON.stringify(bounds);
+      if (key !== lastBounds) {
+        lastBounds = key;
+        void view.setBounds(id, bounds);
+      }
+      if (visible !== lastVisible) {
+        lastVisible = visible;
+        void view.setVisible(id, visible);
+      }
+    };
+    const schedule = () => {
+      if (!frame) frame = requestAnimationFrame(update);
+    };
+    sync.current = schedule;
+
+    const resize = new ResizeObserver(schedule);
+    resize.observe(element);
+    const mutations = new MutationObserver(schedule);
+    mutations.observe(document.body, {
+      childList: true,
+      subtree: true,
+      attributes: true,
+      attributeFilter: ["class", "style", "hidden", "data-state"],
+    });
+    window.addEventListener("resize", schedule);
+    window.addEventListener("scroll", schedule, true);
+    const timer = window.setInterval(schedule, 500);
+    schedule();
+
+    return () => {
+      sync.current = () => {};
+      resize.disconnect();
+      mutations.disconnect();
+      window.removeEventListener("resize", schedule);
+      window.removeEventListener("scroll", schedule, true);
+      window.clearInterval(timer);
+      if (frame) cancelAnimationFrame(frame);
+      void view.close(id);
+    };
+  }, [url, ignoreCert]);
+
+  useEffect(() => {
+    sync.current();
+  }, [hidden]);
+
+  if (!api) return <>{fallback ?? null}</>;
+  return <div ref={host} className={className} style={style} />;
+}

src/ui/plugin-host/app.ts

@@ -1,4 +1,5 @@
-import type { ComponentType } from "react";
+import { useEffect, type ComponentType } from "react";
+import type { Tab } from "@/types/ui-types";
 import type {
   Disposer,
   PluginManifest,
@@ -10,6 +11,12 @@ import {
 } from "@/api/plugins-api";
 import { registerRailItem } from "@/sidebar/rail-items";
 import { registerTabType, type TabRenderProps } from "@/shell/tab-registry";
+import {
+  registerCompanionDef,
+  toggleCompanion,
+  type CompanionDefaults,
+  type CompanionRenderProps,
+} from "@/shell/companions";
 import { registerPanel, type PanelRenderProps } from "@/shell/panel-registry";
 import {
   registerHostEditorSection,
@@ -225,6 +232,46 @@ export function createPluginApp(
       );
     },
 
+    registerCompanion(id, component, options = {}) {
+      const useDefaults = options.useDefaults;
+      const Defaults = useDefaults
+        ? scoped(function CompanionDefaultsReader({
+            onValue,
+          }: {
+            onValue: (value: CompanionDefaults) => void;
+          }) {
+            const value = useDefaults();
+            const { open, side, size, edgeButton } = value;
+            useEffect(() => {
+              onValue({ open, side, size, edgeButton });
+            }, [onValue, open, side, size, edgeButton]);
+            return null;
+          })
+        : undefined;
+      return track(
+        registerCompanionDef({
+          id: `${pluginId}.${id}`,
+          pluginId,
+          component: scoped(
+            component as unknown as ComponentType<CompanionRenderProps>,
+          ),
+          icon: withIconBoundary(pluginId, options.icon as never) as never,
+          titleKey: options.titleKey ? key(options.titleKey) : undefined,
+          order: options.order,
+          tabTypes: options.tabTypes,
+          when: options.when as never,
+          Defaults,
+        }),
+      );
+    },
+
+    toggleCompanion(tab, id) {
+      toggleCompanion(
+        tab as unknown as Tab,
+        id ? `${pluginId}.${id}` : undefined,
+      );
+    },
+
     registerTab(type, component, options = {}) {
       requireDeclared("tab", type, "tab type");
       return track(

src/ui/plugin-host/sdk-ui.ts

@@ -491,21 +491,6 @@ export {
   type ShareTarget,
 } from "@/api/rbac-api";
 export { type BrandingSettings, getBranding } from "@/api/settings-api";
-export {
-  getSyncConflicts,
-  getSyncErrors,
-  retrySyncErrors,
-  settleSyncConflict,
-  type SyncBasicAuth,
-  type SyncConflictItem,
-  type SyncEntityInfo,
-  type SyncErrorItem,
-  syncNow,
-  type SyncProxyHeader,
-  type SyncStatus,
-  unlinkServer,
-  updateSyncSettings,
-} from "@/api/sync-api";
 export {
   getChannelReleases,
   getUpdateChannel,
@@ -553,7 +538,6 @@ export {
   getStatusClasses,
   useStatusColorScheme,
 } from "@/hooks/use-status-color-scheme";
-export { useSyncStatus } from "@/hooks/use-sync-status";
 export { useSshAuthProviders } from "@/hooks/useSshAuthProviders";
 export { changeAppLanguage, normalizeLanguageCode } from "@/i18n/i18n";
 export { LANGUAGES } from "@/i18n/languages";
@@ -590,7 +574,7 @@ export {
   invalidateServerStatusCache,
 } from "@/lib/hosts-request-cache";
 export { reportBetaFeedbackUrl, reportCoreIssueUrl } from "@/lib/issue-url";
-export { notifySyncChanged } from "@/lib/linked-server";
+export { notifySyncChanged, useDesktopLinked } from "@/lib/linked-server";
 export {
   clearLocalAdaptivePreferences,
   getPreferredHostAction,
@@ -603,7 +587,6 @@ export { getConnectedRemoteApi } from "@/lib/remote-server-api";
 export { roleLabel } from "@/lib/role-label";
 export type { StatusValue } from "@/lib/server-status-store";
 export { parseServerTime } from "@/lib/server-time";
-export { refreshSyncStatus, setSyncStatus } from "@/lib/sync-status";
 export { tabJumpHotkeyKeys } from "@/lib/tab-jump-hotkey";
 export {
   ACCENT_PRESET_COLORS,
@@ -740,8 +723,7 @@ export {
   hasVisibleFields,
   isFieldShown,
 } from "@/settings/settings-fields-util";
-export { LinkServerDialog } from "@/settings/sync/LinkServerDialog";
-export { ProxySettingsFields } from "@/settings/sync/ProxySettingsFields";
+export { NativeView, type NativeViewProps } from "./NativeView";
 export { useShellController } from "@/shell/controller/ShellControllerProvider";
 export {
   type KeybindingActionDef,

src/ui/settings/sync/LinkServerDialog.tsx

@@ -1,455 +0,0 @@
-import { useEffect, useState } from "react";
-import { useTranslation } from "react-i18next";
-import { InlineView } from "@/components/surface/surface-scope";
-import { toast } from "sonner";
-import { AlertCircle, Loader2, X } from "lucide-react";
-import { Button } from "@/components/button";
-import { Input } from "@/components/input";
-import { Switch } from "@/components/switch";
-import { ElectronLoginForm } from "@/auth/ElectronLoginForm";
-import {
-  completeLink,
-  getLinkPreview,
-  probeServer,
-  reloginLink,
-  type ProbeProblem,
-  type ServerTarget,
-  type SyncStatus,
-} from "@/api/sync-api";
-import { ProxySettingsFields } from "./ProxySettingsFields";
-import {
-  forgetServerUrl,
-  getSavedServerUrls,
-  rememberServerUrl,
-} from "./saved-servers";
-import { DocsLink } from "@/components/docs-link";
-
-type Step = "server" | "signin" | "choose" | "finishing";
-
-interface LinkServerDialogProps {
-  open: boolean;
-  onOpenChange: (open: boolean) => void;
-  onLinked: (status: SyncStatus) => void;
-  /** Sign back in to the server this desktop is already linked to. */
-  relogin?: { serverUrl: string };
-}
-
-function problemText(
-  t: (key: string, options?: Record<string, unknown>) => string,
-  problem: ProbeProblem | undefined,
-  message: string | undefined,
-): string {
-  switch (problem) {
-    case "invalid_url":
-      return t("sync.problems.invalidUrl");
-    case "tls_untrusted":
-      return t("sync.problems.tlsUntrusted");
-    case "basic_auth_required":
-      return t("sync.problems.basicAuthRequired");
-    case "proxy_login":
-      return t("sync.problems.proxyLogin");
-    case "not_termix":
-      return t("sync.problems.notTermix");
-    case "version_mismatch":
-      return t("sync.problems.versionMismatch");
-    case "different_account":
-      return t("sync.problems.differentAccount");
-    default:
-      return message
-        ? t("sync.problems.unreachableWithReason", { reason: message })
-        : t("sync.problems.unreachable");
-  }
-}
-
-export function LinkServerDialog({
-  open,
-  onOpenChange,
-  onLinked,
-  relogin,
-}: LinkServerDialogProps) {
-  const { t } = useTranslation();
-  const [step, setStep] = useState<Step>(relogin ? "signin" : "server");
-  const [savedUrls, setSavedUrls] = useState<string[]>(getSavedServerUrls);
-  const [target, setTarget] = useState<ServerTarget>({
-    serverUrl: relogin?.serverUrl ?? "",
-    customHeaders: [],
-    basicAuth: null,
-    allowInvalidCertificate: false,
-  });
-  const [showAdvanced, setShowAdvanced] = useState(false);
-  const [checking, setChecking] = useState(false);
-  const [problem, setProblem] = useState<string | null>(null);
-  const [problemKind, setProblemKind] = useState<ProbeProblem | null>(null);
-  const [serverName, setServerName] = useState<string | undefined>();
-  const [token, setToken] = useState<string | null>(null);
-  const [counts, setCounts] = useState<Record<string, number>>({});
-  const [mode, setMode] = useState<"merge" | "replace">("merge");
-  const [finishError, setFinishError] = useState<string | null>(null);
-
-  useEffect(() => {
-    if (!open) return;
-    setStep(relogin ? "signin" : "server");
-    setProblem(null);
-    setProblemKind(null);
-    setToken(null);
-    setFinishError(null);
-    setMode("merge");
-    if (relogin) {
-      setTarget((current) => ({ ...current, serverUrl: relogin.serverUrl }));
-      return;
-    }
-    // An older version of the app may have saved a server address.
-    window.electronAPI
-      ?.invoke?.("get-previous-server-url")
-      .then((result) => {
-        const url = (result as { serverUrl?: string | null } | null)?.serverUrl;
-        if (url) {
-          setTarget((current) =>
-            current.serverUrl ? current : { ...current, serverUrl: url },
-          );
-        }
-      })
-      .catch(() => {});
-  }, [open, relogin]);
-
-  const handleCheck = async () => {
-    setChecking(true);
-    setProblem(null);
-    setProblemKind(null);
-    try {
-      const result = await probeServer(target);
-      if (!result.ok) {
-        setProblemKind(result.problem ?? null);
-        setProblem(problemText(t, result.problem, result.message));
-        if (
-          result.problem === "basic_auth_required" ||
-          result.problem === "proxy_login"
-        ) {
-          setShowAdvanced(true);
-        }
-        if (result.problem === "basic_auth_required" && !target.basicAuth) {
-          setTarget((current) => ({
-            ...current,
-            basicAuth: { username: "", password: "" },
-          }));
-        }
-        return;
-      }
-      setTarget((current) => ({
-        ...current,
-        serverUrl: result.serverUrl ?? current.serverUrl,
-      }));
-      setServerName(result.name);
-      setStep("signin");
-    } catch {
-      setProblem(problemText(t, "unreachable", undefined));
-    } finally {
-      setChecking(false);
-    }
-  };
-
-  const finish = async (sessionToken: string, chosen: "merge" | "replace") => {
-    setStep("finishing");
-    setFinishError(null);
-    try {
-      const status = await completeLink({
-        ...target,
-        token: sessionToken,
-        mode: chosen,
-        serverName,
-      });
-      rememberServerUrl(target.serverUrl);
-      toast.success(t("sync.wizard.linked"));
-      onLinked(status);
-      onOpenChange(false);
-    } catch (error) {
-      const data = (
-        error as {
-          response?: { data?: { problem?: ProbeProblem; message?: string } };
-        }
-      )?.response?.data;
-      setFinishError(problemText(t, data?.problem, data?.message));
-      setStep("choose");
-    }
-  };
-
-  const handleSignedIn = async (sessionToken: string | null) => {
-    if (!sessionToken) return;
-    if (relogin) {
-      try {
-        const status = await reloginLink(sessionToken);
-        toast.success(t("sync.wizard.signedInAgain"));
-        onLinked(status);
-        onOpenChange(false);
-      } catch (error) {
-        const data = (
-          error as {
-            response?: {
-              data?: {
-                error?: string;
-                problem?: ProbeProblem;
-                message?: string;
-              };
-            };
-          }
-        )?.response?.data;
-        throw new Error(
-          data?.error === "different_account"
-            ? t("sync.problems.differentAccount")
-            : problemText(t, data?.problem, data?.message),
-        );
-      }
-      return;
-    }
-    setToken(sessionToken);
-    const preview = await getLinkPreview().catch(() => ({}));
-    setCounts(preview);
-    const total = Object.values(preview).reduce((sum, count) => sum + count, 0);
-    if (total === 0) {
-      await finish(sessionToken, "merge");
-      return;
-    }
-    setStep("choose");
-  };
-
-  const localTotal = Object.values(counts).reduce(
-    (sum, count) => sum + count,
-    0,
-  );
-  const wide = step === "signin";
-
-  const title = relogin
-    ? t("sync.wizard.reloginTitle")
-    : t("sync.wizard.title");
-  const description =
-    step === "server"
-      ? t("sync.wizard.serverDescription")
-      : step === "signin"
-        ? t("sync.wizard.signinDescription", { url: target.serverUrl })
-        : step === "choose"
-          ? t("sync.wizard.chooseDescription")
-          : t("sync.wizard.finishingDescription");
-  const content = (
-    <>
-      {step === "server" && (
-        <form
-          className="flex flex-col gap-4"
-          onSubmit={(event) => {
-            event.preventDefault();
-            void handleCheck();
-          }}
-        >
-          <div className="flex flex-col gap-1.5">
-            <label className="text-xs font-semibold" htmlFor="sync-server-url">
-              {t("sync.wizard.serverUrl")}
-            </label>
-            <Input
-              id="sync-server-url"
-              autoFocus
-              className="rounded-none"
-              placeholder="https://termix.example.com"
-              value={target.serverUrl}
-              onChange={(event) =>
-                setTarget({ ...target, serverUrl: event.target.value })
-              }
-            />
-            <p className="text-[10px] text-muted-foreground">
-              {t("sync.wizard.serverUrlHint")}
-            </p>
-            {!relogin && savedUrls.length > 0 && (
-              <div className="flex flex-col gap-1 pt-1">
-                <span className="text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">
-                  {t("sync.wizard.savedServers")}
-                </span>
-                {savedUrls.map((url) => (
-                  <div
-                    key={url}
-                    className="flex items-center border border-border hover:bg-muted"
-                  >
-                    <button
-                      type="button"
-                      className="flex-1 min-w-0 truncate px-2 py-1.5 text-left font-mono text-xs"
-                      onClick={() => setTarget({ ...target, serverUrl: url })}
-                    >
-                      {url}
-                    </button>
-                    <button
-                      type="button"
-                      title={t("sync.wizard.removeServer")}
-                      className="px-2 py-1.5 text-muted-foreground hover:text-destructive"
-                      onClick={() => setSavedUrls(forgetServerUrl(url))}
-                    >
-                      <X className="size-3" />
-                    </button>
-                  </div>
-                ))}
-              </div>
-            )}
-          </div>
-
-          {problem && (
-            <div className="flex gap-2 border border-destructive/40 bg-destructive/10 p-2.5 text-xs">
-              <AlertCircle className="size-4 shrink-0 text-destructive" />
-              <span>{problem}</span>
-            </div>
-          )}
-
-          {(problemKind === "tls_untrusted" ||
-            target.allowInvalidCertificate) && (
-            <div className="flex items-center justify-between gap-3 border border-border p-2.5">
-              <div className="flex flex-col gap-0.5">
-                <span className="text-xs font-medium">
-                  {t("sync.proxy.allowInvalidCertificate")}
-                </span>
-                <span className="text-[10px] text-muted-foreground">
-                  {t("sync.proxy.allowInvalidCertificateHint")}
-                </span>
-              </div>
-              <Switch
-                checked={!!target.allowInvalidCertificate}
-                onCheckedChange={(checked) =>
-                  setTarget({ ...target, allowInvalidCertificate: checked })
-                }
-              />
-            </div>
-          )}
-
-          <button
-            type="button"
-            className="self-start text-[10px] font-bold uppercase tracking-widest text-muted-foreground hover:text-foreground"
-            onClick={() => setShowAdvanced((value) => !value)}
-          >
-            {showAdvanced
-              ? t("sync.wizard.hideProxySettings")
-              : t("sync.wizard.showProxySettings")}
-          </button>
-          {showAdvanced && (
-            <ProxySettingsFields
-              customHeaders={target.customHeaders ?? []}
-              basicAuth={target.basicAuth ?? null}
-              onChange={(next) => setTarget({ ...target, ...next })}
-            />
-          )}
-
-          <div className="flex justify-end gap-2">
-            <Button
-              type="button"
-              variant="outline"
-              className="rounded-none"
-              onClick={() => onOpenChange(false)}
-            >
-              {t("common.cancel")}
-            </Button>
-            <Button
-              variant="outline"
-              type="submit"
-              className="rounded-none border-accent-brand/40 text-accent-brand hover:bg-accent-brand/10 hover:text-accent-brand dark:border-accent-brand/40 dark:bg-transparent dark:hover:bg-accent-brand/10"
-              disabled={checking || !target.serverUrl.trim()}
-            >
-              {checking && <Loader2 className="size-4 animate-spin" />}
-              {t("sync.wizard.continue")}
-            </Button>
-          </div>
-        </form>
-      )}
-
-      {step === "signin" && (
-        <div className="flex-1 min-h-0">
-          <ElectronLoginForm
-            serverUrl={target.serverUrl}
-            targetPurpose="link"
-            onAuthSuccess={handleSignedIn}
-            onChangeServer={() =>
-              relogin ? onOpenChange(false) : setStep("server")
-            }
-          />
-        </div>
-      )}
-
-      {step === "choose" && (
-        <div className="flex flex-col gap-3">
-          {finishError && (
-            <div className="flex gap-2 border border-destructive/40 bg-destructive/10 p-2.5 text-xs">
-              <AlertCircle className="size-4 shrink-0 text-destructive" />
-              <span>{finishError}</span>
-            </div>
-          )}
-          {(
-            [
-              {
-                value: "merge",
-                title: t("sync.wizard.mergeTitle"),
-                body: t("sync.wizard.mergeBody", { count: localTotal }),
-              },
-              {
-                value: "replace",
-                title: t("sync.wizard.replaceTitle"),
-                body: t("sync.wizard.replaceBody", { count: localTotal }),
-              },
-            ] as const
-          ).map((option) => (
-            <button
-              key={option.value}
-              type="button"
-              onClick={() => setMode(option.value)}
-              className={`text-left border p-3 flex flex-col gap-1 transition-colors ${
-                mode === option.value
-                  ? "border-accent-brand bg-accent-brand/10"
-                  : "border-border hover:bg-muted/40"
-              }`}
-            >
-              <span className="text-sm font-semibold">{option.title}</span>
-              <span className="text-xs text-muted-foreground">
-                {option.body}
-              </span>
-            </button>
-          ))}
-          <div className="flex justify-end gap-2">
-            <Button
-              type="button"
-              variant="outline"
-              className="rounded-none"
-              onClick={() => onOpenChange(false)}
-            >
-              {t("common.cancel")}
-            </Button>
-            <Button
-              variant="outline"
-              type="button"
-              className="rounded-none border-accent-brand/40 text-accent-brand hover:bg-accent-brand/10 hover:text-accent-brand dark:border-accent-brand/40 dark:bg-transparent dark:hover:bg-accent-brand/10"
-              disabled={!token}
-              onClick={() => token && void finish(token, mode)}
-            >
-              {t("sync.wizard.link")}
-            </Button>
-          </div>
-        </div>
-      )}
-
-      {step === "finishing" && (
-        <div className="flex items-center gap-3 py-6 text-sm text-muted-foreground">
-          <Loader2 className="size-5 animate-spin text-accent-brand" />
-          {t("sync.wizard.linking")}
-        </div>
-      )}
-    </>
-  );
-
-  // The wizard takes over the panel, tab or onboarding step it opens from.
-  return (
-    <InlineView
-      open={open}
-      onOpenChange={onOpenChange}
-      title={title}
-      width="wide"
-      scroll={!wide}
-    >
-      {!wide && (
-        <p className="text-xs text-muted-foreground">
-          {description} {step === "server" && <DocsLink core="desktopSync" />}
-        </p>
-      )}
-      {content}
-    </InlineView>
-  );
-}

src/ui/settings/sync/ProxySettingsFields.tsx

@@ -1,147 +0,0 @@
-import { useTranslation } from "react-i18next";
-import { Plus, Trash2 } from "lucide-react";
-import { Input } from "@/components/input";
-import { PasswordInput } from "@/components/password-input";
-import { Switch } from "@/components/switch";
-import type { SyncBasicAuth, SyncProxyHeader } from "@/api/sync-api";
-
-interface ProxySettingsFieldsProps {
-  customHeaders: SyncProxyHeader[];
-  basicAuth: SyncBasicAuth | null;
-  onChange: (next: {
-    customHeaders?: SyncProxyHeader[];
-    basicAuth?: SyncBasicAuth | null;
-  }) => void;
-}
-
-/**
- * What a reverse proxy in front of the server wants: extra headers (a
- * Cloudflare Access service token, a gateway key) and basic auth.
- */
-export function ProxySettingsFields({
-  customHeaders,
-  basicAuth,
-  onChange,
-}: ProxySettingsFieldsProps) {
-  const { t } = useTranslation();
-
-  const setHeader = (index: number, patch: Partial<SyncProxyHeader>) => {
-    onChange({
-      customHeaders: customHeaders.map((header, i) =>
-        i === index ? { ...header, ...patch } : header,
-      ),
-    });
-  };
-
-  return (
-    <div className="flex flex-col gap-4 border border-border p-3">
-      <div className="flex flex-col gap-2">
-        <div className="flex flex-col gap-0.5">
-          <span className="text-xs font-semibold">
-            {t("sync.proxy.headersTitle")}
-          </span>
-          <span className="text-[10px] text-muted-foreground">
-            {t("sync.proxy.headersHint")}
-          </span>
-        </div>
-        {customHeaders.map((header, index) => (
-          <div key={index} className="flex items-center gap-2">
-            <Input
-              className="rounded-none h-8 text-xs"
-              placeholder={t("sync.proxy.headerName")}
-              value={header.name}
-              onChange={(event) =>
-                setHeader(index, { name: event.target.value })
-              }
-            />
-            <PasswordInput
-              className="rounded-none h-8 text-xs"
-              placeholder={
-                header.set
-                  ? t("sync.proxy.savedValue")
-                  : t("sync.proxy.headerValue")
-              }
-              value={header.value}
-              onChange={(event) =>
-                setHeader(index, { value: event.target.value })
-              }
-            />
-            <button
-              type="button"
-              aria-label={t("sync.proxy.removeHeader")}
-              className="p-1.5 text-muted-foreground hover:text-destructive"
-              onClick={() =>
-                onChange({
-                  customHeaders: customHeaders.filter((_, i) => i !== index),
-                })
-              }
-            >
-              <Trash2 className="size-3.5" />
-            </button>
-          </div>
-        ))}
-        <button
-          type="button"
-          className="self-start flex items-center gap-1 text-[10px] font-bold uppercase tracking-widest text-muted-foreground hover:text-foreground"
-          onClick={() =>
-            onChange({
-              customHeaders: [...customHeaders, { name: "", value: "" }],
-            })
-          }
-        >
-          <Plus className="size-3" />
-          {t("sync.proxy.addHeader")}
-        </button>
-      </div>
-
-      <div className="flex flex-col gap-2 border-t border-border pt-3">
-        <div className="flex items-center justify-between gap-3">
-          <div className="flex flex-col gap-0.5">
-            <span className="text-xs font-semibold">
-              {t("sync.proxy.basicAuthTitle")}
-            </span>
-            <span className="text-[10px] text-muted-foreground">
-              {t("sync.proxy.basicAuthHint")}
-            </span>
-          </div>
-          <Switch
-            checked={!!basicAuth}
-            onCheckedChange={(checked) =>
-              onChange({
-                basicAuth: checked ? { username: "", password: "" } : null,
-              })
-            }
-          />
-        </div>
-        {basicAuth && (
-          <div className="flex items-center gap-2">
-            <Input
-              className="rounded-none h-8 text-xs"
-              placeholder={t("sync.proxy.username")}
-              value={basicAuth.username}
-              onChange={(event) =>
-                onChange({
-                  basicAuth: { ...basicAuth, username: event.target.value },
-                })
-              }
-            />
-            <PasswordInput
-              className="rounded-none h-8 text-xs"
-              placeholder={
-                basicAuth.set
-                  ? t("sync.proxy.savedValue")
-                  : t("sync.proxy.password")
-              }
-              value={basicAuth.password}
-              onChange={(event) =>
-                onChange({
-                  basicAuth: { ...basicAuth, password: event.target.value },
-                })
-              }
-            />
-          </div>
-        )}
-      </div>
-    </div>
-  );
-}

src/ui/settings/sync/saved-servers.ts

@@ -1,39 +0,0 @@
-// Same key as 2.8, so a desktop keeps the servers it already used.
-const SAVED_URLS_KEY = "termix_saved_server_urls";
-const MAX_SAVED_URLS = 5;
-
-export function getSavedServerUrls(): string[] {
-  try {
-    const parsed = JSON.parse(localStorage.getItem(SAVED_URLS_KEY) ?? "[]");
-    return Array.isArray(parsed)
-      ? parsed.filter((url): url is string => typeof url === "string")
-      : [];
-  } catch {
-    return [];
-  }
-}
-
-function write(urls: string[]): void {
-  try {
-    localStorage.setItem(SAVED_URLS_KEY, JSON.stringify(urls));
-  } catch {
-    // Storage can be unavailable.
-  }
-}
-
-export function rememberServerUrl(url: string): string[] {
-  const trimmed = url.trim().replace(/\/+$/, "");
-  if (!trimmed) return getSavedServerUrls();
-  const urls = [
-    trimmed,
-    ...getSavedServerUrls().filter((saved) => saved !== trimmed),
-  ].slice(0, MAX_SAVED_URLS);
-  write(urls);
-  return urls;
-}
-
-export function forgetServerUrl(url: string): string[] {
-  const urls = getSavedServerUrls().filter((saved) => saved !== url);
-  write(urls);
-  return urls;
-}

src/ui/shell/CompanionFrame.tsx

@@ -0,0 +1,345 @@
+import {
+  memo,
+  useCallback,
+  useEffect,
+  useMemo,
+  useRef,
+  useState,
+  type ReactNode,
+} from "react";
+import { useTranslation } from "react-i18next";
+import {
+  ArrowDownToLine,
+  ArrowLeftToLine,
+  ArrowRightToLine,
+  PanelRight,
+  X,
+} from "lucide-react";
+import { cn } from "@/lib/utils";
+import { useIsMobile } from "@/hooks/use-mobile";
+import { hostToSSHHost } from "@/lib/host-to-ssh-host";
+import type { Tab } from "@/types/ui-types";
+import {
+  companionApplies,
+  companionKey,
+  patchCompanionState,
+  useCompanionDefs,
+  useCompanionState,
+  type CompanionDef,
+  type CompanionDefaults,
+  type CompanionSide,
+} from "./companions";
+
+const DEFAULT_SIDE_SIZE = 360;
+const DEFAULT_BOTTOM_SIZE = 280;
+const MIN_SIZE = 200;
+
+function DefaultsReader({
+  def,
+  onValue,
+}: {
+  def: CompanionDef;
+  onValue: (id: string, value: CompanionDefaults) => void;
+}) {
+  const Reader = def.Defaults;
+  const report = useCallback(
+    (value: CompanionDefaults) => onValue(def.id, value),
+    [def.id, onValue],
+  );
+  return Reader ? <Reader onValue={report} /> : null;
+}
+
+function sideIcon(side: CompanionSide) {
+  if (side === "left") return ArrowLeftToLine;
+  if (side === "bottom") return ArrowDownToLine;
+  return ArrowRightToLine;
+}
+
+/**
+ * Puts a pane beside a tab for the companions that apply to it. The tab keeps
+ * its place in the tree, so opening or closing a companion never remounts it.
+ */
+export const CompanionFrame = memo(function CompanionFrame({
+  tab,
+  isVisible,
+  children,
+}: {
+  tab: Tab;
+  isVisible: boolean;
+  children: ReactNode;
+}) {
+  const defs = useCompanionDefs();
+  const applicable = useMemo(
+    () => defs.filter((def) => companionApplies(def, tab)),
+    // tab.host and tab.type decide it
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    [defs, tab.type, tab.host],
+  );
+  if (applicable.length === 0) return <>{children}</>;
+  return (
+    <CompanionLayout tab={tab} defs={applicable} isVisible={isVisible}>
+      {children}
+    </CompanionLayout>
+  );
+});
+
+function CompanionLayout({
+  tab,
+  defs,
+  isVisible,
+  children,
+}: {
+  tab: Tab;
+  defs: CompanionDef[];
+  isVisible: boolean;
+  children: ReactNode;
+}) {
+  const { t } = useTranslation();
+  const isMobile = useIsMobile();
+  const key = companionKey(tab);
+  const state = useCompanionState(key);
+  const [defaults, setDefaults] = useState<Record<string, CompanionDefaults>>(
+    {},
+  );
+  const [dragging, setDragging] = useState(false);
+  // A companion stays mounted once opened, so it keeps its place and session.
+  const [mounted, setMounted] = useState<Set<string>>(new Set());
+  const rootRef = useRef<HTMLDivElement>(null);
+
+  const onDefaults = useCallback((id: string, value: CompanionDefaults) => {
+    setDefaults((prev) => {
+      const old = prev[id];
+      if (
+        old &&
+        old.open === value.open &&
+        old.side === value.side &&
+        old.size === value.size &&
+        old.edgeButton === value.edgeButton
+      ) {
+        return prev;
+      }
+      return { ...prev, [id]: value };
+    });
+  }, []);
+
+  // The first time a tab shows, a companion can open itself.
+  useEffect(() => {
+    if (state.seen || !isVisible) return;
+    const ready = defs.every(
+      (def) => !def.Defaults || defaults[def.id] !== undefined,
+    );
+    if (!ready) return;
+    const auto = defs.find((def) => defaults[def.id]?.open);
+    patchCompanionState(key, { seen: true, openId: auto?.id ?? null });
+  }, [state.seen, isVisible, defs, defaults, key]);
+
+  const active = defs.find((def) => def.id === state.openId) ?? null;
+  useEffect(() => {
+    if (!active) return;
+    setMounted((prev) =>
+      prev.has(active.id) ? prev : new Set(prev).add(active.id),
+    );
+  }, [active]);
+
+  const activeDefaults = active ? defaults[active.id] : undefined;
+  const side: CompanionSide = isMobile
+    ? "bottom"
+    : (state.side ?? activeDefaults?.side ?? "right");
+  const baseSize =
+    state.size ??
+    activeDefaults?.size ??
+    (side === "bottom" ? DEFAULT_BOTTOM_SIZE : DEFAULT_SIDE_SIZE);
+
+  const setSide = useCallback(
+    (next: CompanionSide) => patchCompanionState(key, { side: next }),
+    [key],
+  );
+  const close = useCallback(
+    () => patchCompanionState(key, { openId: null }),
+    [key],
+  );
+
+  const startResize = (event: React.MouseEvent) => {
+    event.preventDefault();
+    const root = rootRef.current;
+    if (!root) return;
+    const rect = root.getBoundingClientRect();
+    const total = side === "bottom" ? rect.height : rect.width;
+    const max = Math.max(MIN_SIZE, total - MIN_SIZE);
+    setDragging(true);
+    const move = (e: MouseEvent) => {
+      const raw =
+        side === "right"
+          ? rect.right - e.clientX
+          : side === "left"
+            ? e.clientX - rect.left
+            : rect.bottom - e.clientY;
+      patchCompanionState(key, {
+        size: Math.round(Math.min(max, Math.max(MIN_SIZE, raw))),
+      });
+    };
+    const up = () => {
+      setDragging(false);
+      window.removeEventListener("mousemove", move);
+      window.removeEventListener("mouseup", up);
+    };
+    window.addEventListener("mousemove", move);
+    window.addEventListener("mouseup", up);
+  };
+
+  const getHandle = useCallback(
+    () => (tab.terminalRef?.current as Record<string, unknown> | null) ?? null,
+    [tab.terminalRef],
+  );
+  const sshHost = useMemo(
+    () =>
+      tab.host
+        ? (hostToSSHHost(tab.host) as unknown as Record<string, unknown>)
+        : undefined,
+    [tab.host],
+  );
+
+  const showEdge = defs.filter((def) => defaults[def.id]?.edgeButton !== false);
+  const vertical = side === "bottom";
+  const clamped = vertical ? Math.min(baseSize, 2000) : baseSize;
+  const paneStyle = isMobile
+    ? { height: "55%" }
+    : vertical
+      ? { height: clamped }
+      : { width: clamped };
+  const SideIcon = sideIcon(side);
+
+  return (
+    <div className="flex h-full w-full min-h-0 min-w-0">
+      {defs.map((def) =>
+        def.Defaults ? (
+          <DefaultsReader key={def.id} def={def} onValue={onDefaults} />
+        ) : null,
+      )}
+      <div
+        ref={rootRef}
+        className={cn(
+          "relative flex flex-1 min-h-0 min-w-0",
+          vertical
+            ? "flex-col"
+            : side === "left"
+              ? "flex-row-reverse"
+              : "flex-row",
+        )}
+      >
+        <div className="relative flex-1 min-h-0 min-w-0">{children}</div>
+        {defs.map((def) => {
+          if (!mounted.has(def.id)) return null;
+          const open = active?.id === def.id;
+          const Component = def.component;
+          const Icon = def.icon;
+          return (
+            <div
+              key={def.id}
+              className={cn(
+                "relative flex-shrink-0 flex-col min-h-0 min-w-0 bg-background border-border",
+                open ? "flex" : "hidden",
+                vertical
+                  ? "border-t"
+                  : side === "left"
+                    ? "border-r"
+                    : "border-l",
+                isMobile && "absolute inset-x-0 bottom-0 z-20 shadow-lg",
+              )}
+              style={paneStyle}
+            >
+              {!isMobile && (
+                <div
+                  role="separator"
+                  aria-label={t("companion.resize")}
+                  onMouseDown={startResize}
+                  className={cn(
+                    "absolute z-10",
+                    vertical
+                      ? "inset-x-0 -top-1 h-2 cursor-row-resize"
+                      : side === "left"
+                        ? "inset-y-0 -right-1 w-2 cursor-col-resize"
+                        : "inset-y-0 -left-1 w-2 cursor-col-resize",
+                    dragging && "bg-primary/30",
+                  )}
+                />
+              )}
+              <div className="flex items-center gap-1.5 h-8 px-2 border-b border-border flex-shrink-0">
+                {Icon && <Icon className="size-3.5 text-muted-foreground" />}
+                <span className="text-xs font-medium truncate flex-1">
+                  {def.titleKey ? t(def.titleKey) : def.id}
+                </span>
+                {!isMobile && (
+                  <button
+                    type="button"
+                    className="p-1 text-muted-foreground hover:text-foreground"
+                    title={t("companion.moveSide")}
+                    onClick={() =>
+                      setSide(
+                        side === "right"
+                          ? "bottom"
+                          : side === "bottom"
+                            ? "left"
+                            : "right",
+                      )
+                    }
+                  >
+                    <SideIcon className="size-3.5" />
+                  </button>
+                )}
+                <button
+                  type="button"
+                  className="p-1 text-muted-foreground hover:text-foreground"
+                  title={t("companion.close")}
+                  onClick={close}
+                >
+                  <X className="size-3.5" />
+                </button>
+              </div>
+              <div className="flex-1 min-h-0 min-w-0 overflow-hidden">
+                <Component
+                  tab={tab}
+                  host={tab.host}
+                  sshHost={sshHost}
+                  getHandle={getHandle}
+                  side={side}
+                  isVisible={isVisible && open}
+                  close={close}
+                  setSide={setSide}
+                />
+              </div>
+            </div>
+          );
+        })}
+      </div>
+      {showEdge.length > 0 && !isMobile && (
+        <div className="flex flex-col flex-shrink-0 w-6 items-center gap-1 pt-1 border-l border-border bg-background">
+          {showEdge.map((def) => {
+            const Icon = def.icon ?? PanelRight;
+            const open = active?.id === def.id;
+            return (
+              <button
+                key={def.id}
+                type="button"
+                title={def.titleKey ? t(def.titleKey) : def.id}
+                aria-pressed={open}
+                onClick={() =>
+                  patchCompanionState(key, {
+                    seen: true,
+                    openId: open ? null : def.id,
+                  })
+                }
+                className={cn(
+                  "p-1 text-muted-foreground hover:text-foreground",
+                  open && "text-foreground bg-accent",
+                )}
+              >
+                <Icon className="size-3.5" />
+              </button>
+            );
+          })}
+        </div>
+      )}
+    </div>
+  );
+}

src/ui/shell/companions.ts

@@ -0,0 +1,163 @@
+import { useSyncExternalStore, type ComponentType } from "react";
+import type { Host, Tab } from "@/types/ui-types";
+import { byOrderThenId, createRegistry } from "@/lib/registry";
+
+export type CompanionSide = "left" | "right" | "bottom";
+
+export interface CompanionDefaults {
+  /** Open by itself the first time a matching tab shows. */
+  open?: boolean;
+  side?: CompanionSide;
+  /** Pixels of width, or height at the bottom. */
+  size?: number;
+  /** Show the edge button that opens and closes it. */
+  edgeButton?: boolean;
+}
+
+export interface CompanionRenderProps {
+  tab: Tab;
+  host?: Host;
+  sshHost?: Record<string, unknown>;
+  /** The tab's surface handle, read at call time. */
+  getHandle: () => Record<string, unknown> | null;
+  side: CompanionSide;
+  isVisible: boolean;
+  close: () => void;
+  setSide: (side: CompanionSide) => void;
+}
+
+export interface CompanionDef {
+  id: string;
+  pluginId?: string;
+  titleKey?: string;
+  icon?: ComponentType<{ className?: string }>;
+  component: ComponentType<CompanionRenderProps>;
+  order?: number;
+  /** Tab types it applies to. Any tab with a host when empty. */
+  tabTypes?: string[];
+  when?: (tab: Tab, host?: Host) => boolean;
+  /** Renders nothing and reports the defaults, inside the plugin's scope. */
+  Defaults?: ComponentType<{ onValue: (value: CompanionDefaults) => void }>;
+}
+
+const registry = createRegistry<CompanionDef>(byOrderThenId);
+
+export const registerCompanionDef = registry.register;
+export const getCompanionDef = registry.get;
+export const listCompanionDefs = registry.list;
+export const useCompanionDefs = registry.useList;
+export const resetCompanions = registry.reset;
+
+export function companionApplies(def: CompanionDef, tab: Tab): boolean {
+  if (!tab.host) return false;
+  if (def.tabTypes?.length && !def.tabTypes.includes(tab.type)) return false;
+  return def.when ? def.when(tab, tab.host) : true;
+}
+
+export interface CompanionTabState {
+  /** The companion shown, or null when closed. */
+  openId: string | null;
+  /** Set once the defaults ran, so closing it is not undone. */
+  seen: boolean;
+  side?: CompanionSide;
+  size?: number;
+}
+
+const STORAGE_KEY = "termix:companions";
+const EMPTY: CompanionTabState = { openId: null, seen: false };
+
+let states = new Map<string, CompanionTabState>();
+const listeners = new Set<() => void>();
+let version = 0;
+
+function load(): void {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (!raw) return;
+    const parsed = JSON.parse(raw) as Record<string, CompanionTabState>;
+    states = new Map(Object.entries(parsed));
+  } catch {
+    // storage unavailable or corrupt
+  }
+}
+
+function save(): void {
+  try {
+    const entries = [...states.entries()].slice(-200);
+    localStorage.setItem(
+      STORAGE_KEY,
+      JSON.stringify(Object.fromEntries(entries)),
+    );
+  } catch {
+    // storage unavailable
+  }
+}
+
+load();
+
+/** Open state follows the tab through a restore. */
+export function companionKey(tab: Tab): string {
+  return tab.instanceId ?? tab.id;
+}
+
+export function getCompanionState(key: string): CompanionTabState {
+  return states.get(key) ?? EMPTY;
+}
+
+export function patchCompanionState(
+  key: string,
+  patch: Partial<CompanionTabState>,
+): void {
+  const next = { ...getCompanionState(key), ...patch };
+  states = new Map(states);
+  states.delete(key);
+  states.set(key, next);
+  version += 1;
+  save();
+  for (const listener of listeners) listener();
+}
+
+export function forgetCompanionState(key: string): void {
+  if (!states.has(key)) return;
+  states = new Map(states);
+  states.delete(key);
+  version += 1;
+  save();
+  for (const listener of listeners) listener();
+}
+
+function subscribe(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+export function useCompanionState(key: string): CompanionTabState {
+  useSyncExternalStore(
+    subscribe,
+    () => version,
+    () => version,
+  );
+  return getCompanionState(key);
+}
+
+/** Opens a companion, or closes it when it is the one showing. */
+export function toggleCompanion(tab: Tab, id?: string): void {
+  const key = companionKey(tab);
+  const current = getCompanionState(key);
+  const target =
+    id ??
+    current.openId ??
+    listCompanionDefs().find((def) => companionApplies(def, tab))?.id ??
+    null;
+  if (!target) return;
+  patchCompanionState(key, {
+    seen: true,
+    openId: current.openId === target ? null : target,
+  });
+}
+
+export function resetCompanionStates(): void {
+  states = new Map();
+  version += 1;
+  for (const listener of listeners) listener();
+}

src/ui/shell/controller/ShellControllerProvider.tsx

@@ -11,7 +11,6 @@ import {
   useState,
 } from "react";
 import { useIsMobile } from "@/hooks/use-mobile";
-import { useSyncStatus } from "@/hooks/use-sync-status";
 import { isElectron } from "@/lib/electron";
 import {
   useConfirm,
@@ -128,10 +127,6 @@ export function ShellControllerProvider({
   openSingletonRef.current = tabsState.openSingletonTab;
   const { tabs, activeTabId } = tabsState;
 
-  // Keeps the desktop's sync status polled while the app is open; a pass
-  // that changed data tells the panels to reload.
-  useSyncStatus();
-
   const palette: ShellPalette = {
     isOpen: paletteOpen,
     open: () => setPaletteOpen(true),

src/ui/shell/tabUtils.tsx

@@ -12,6 +12,7 @@ import {
   type TabTypeDef,
 } from "./tab-registry";
 import { getPanel, type PanelDef } from "./panel-registry";
+import { CompanionFrame } from "./CompanionFrame";
 import {
   markAdaptiveResourceUsed,
   runAdaptiveBackgroundTask,
@@ -144,7 +145,9 @@ const RegisteredTab = memo(function RegisteredTab({
     />
   );
   return withTabSuspense(
-    def.panelFrame ? <PanelTabFrame>{content}</PanelTabFrame> : content,
+    <CompanionFrame tab={tab} isVisible={isVisible}>
+      {def.panelFrame ? <PanelTabFrame>{content}</PanelTabFrame> : content}
+    </CompanionFrame>,
   );
 });
 

src/ui/sidebar/rail-items.ts

@@ -1,5 +1,4 @@
 import {
-  Cloud,
   KeyRound,
   Plug,
   Server,
@@ -12,7 +11,6 @@ import {
 import { useMemo, useSyncExternalStore } from "react";
 import { usePermissions } from "@/hooks/use-permissions";
 import { useAreaPreferences } from "@/contexts/UiPreferencesContext";
-import { useSyncAttentionCount } from "@/hooks/use-sync-status";
 import { isElectron } from "@/lib/electron";
 import { createRegistry } from "@/lib/registry";
 import { getPanel } from "@/shell/panel-registry";
@@ -111,15 +109,6 @@ export const RAIL_ITEMS: RailItemDef[] = [
     mobilePrimary: true,
     group: "tools",
   },
-  {
-    id: "sync",
-    icon: Cloud,
-    labelKey: "nav.sync",
-    electronOnly: true,
-    placement: "footer",
-    group: "system",
-    useBadge: useSyncAttentionCount,
-  },
   {
     id: "plugins",
     icon: Puzzle,

src/ui/tests/auth/ElectronLoginForm.test.tsx

@@ -1,140 +0,0 @@
-import { render, screen, waitFor } from "@testing-library/react";
-import { describe, expect, it, vi } from "vitest";
-import { ElectronLoginForm } from "../../auth/ElectronLoginForm";
-
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({ t: (key: string) => key }),
-}));
-
-describe("ElectronLoginForm", () => {
-  it("delegates WebAuthn permissions to the embedded login page", () => {
-    render(
-      <ElectronLoginForm
-        serverUrl="https://termix.example.com"
-        onAuthSuccess={vi.fn()}
-        onChangeServer={vi.fn()}
-      />,
-    );
-
-    const permissions = screen
-      .getByTitle("auth.serverAuthentication")
-      .getAttribute("allow");
-
-    expect(permissions).toContain("publickey-credentials-get");
-    expect(permissions).toContain("publickey-credentials-create");
-  });
-
-  it.each([
-    "auth_component",
-    "second_factor_auth_component",
-    "method_auth_component",
-  ])("accepts a login hand-off from %s", async (source) => {
-    const onAuthSuccess = vi.fn();
-    render(
-      <ElectronLoginForm
-        serverUrl="https://termix.example.com"
-        onAuthSuccess={onAuthSuccess}
-        onChangeServer={vi.fn()}
-      />,
-    );
-    const frame = screen.getByTitle(
-      "auth.serverAuthentication",
-    ) as HTMLIFrameElement;
-    window.dispatchEvent(
-      new MessageEvent("message", {
-        source: frame.contentWindow,
-        origin: "https://termix.example.com",
-        data: {
-          type: "AUTH_SUCCESS",
-          platform: "desktop",
-          source,
-          token: "jwt-1",
-        },
-      }),
-    );
-    await waitFor(() => expect(onAuthSuccess).toHaveBeenCalledWith("jwt-1"));
-  });
-
-  it("ignores messages once the frame has left the server's origin", async () => {
-    const onAuthSuccess = vi.fn();
-    const externalBrowserLogin = vi.fn();
-    (window as unknown as { electronAPI?: unknown }).electronAPI = {
-      externalBrowserLogin,
-    };
-    render(
-      <ElectronLoginForm
-        serverUrl="https://termix.example.com/"
-        onAuthSuccess={onAuthSuccess}
-        onChangeServer={vi.fn()}
-      />,
-    );
-    const frame = screen.getByTitle(
-      "auth.serverAuthentication",
-    ) as HTMLIFrameElement;
-    for (const data of [
-      {
-        type: "AUTH_SUCCESS",
-        platform: "desktop",
-        source: "auth_component",
-        token: "attacker-jwt",
-      },
-      {
-        type: "OIDC_SYSTEM_BROWSER_AUTH",
-        authUrl: "https://evil.example/",
-        callbackPort: 17832,
-      },
-    ]) {
-      window.dispatchEvent(
-        new MessageEvent("message", {
-          source: frame.contentWindow,
-          origin: "https://evil.example",
-          data,
-        }),
-      );
-    }
-    await new Promise((resolve) => setTimeout(resolve, 0));
-    expect(onAuthSuccess).not.toHaveBeenCalled();
-    expect(externalBrowserLogin).not.toHaveBeenCalled();
-    delete (window as unknown as { electronAPI?: unknown }).electronAPI;
-  });
-
-  it("replies to the server's origin only", async () => {
-    (window as unknown as { electronAPI?: unknown }).electronAPI = {
-      externalBrowserLogin: vi.fn().mockResolvedValue({
-        success: false,
-        secondFactor: true,
-        tempToken: "temp-1",
-      }),
-    };
-    render(
-      <ElectronLoginForm
-        serverUrl="https://termix.example.com/"
-        onAuthSuccess={vi.fn()}
-        onChangeServer={vi.fn()}
-      />,
-    );
-    const frame = screen.getByTitle(
-      "auth.serverAuthentication",
-    ) as HTMLIFrameElement;
-    const postMessage = vi.spyOn(frame.contentWindow!, "postMessage");
-    window.dispatchEvent(
-      new MessageEvent("message", {
-        source: frame.contentWindow,
-        origin: "https://termix.example.com",
-        data: {
-          type: "OIDC_SYSTEM_BROWSER_AUTH",
-          authUrl: "https://idp.example.com/authorize",
-          callbackPort: 17832,
-          providerId: -1,
-        },
-      }),
-    );
-    await waitFor(() =>
-      expect(postMessage).toHaveBeenCalledWith(
-        expect.objectContaining({ tempToken: "temp-1" }),
-        "https://termix.example.com",
-      ),
-    );
-    delete (window as unknown as { electronAPI?: unknown }).electronAPI;
-  });
-});

src/ui/tests/lib/embedded-frame.test.ts

@@ -49,4 +49,26 @@ describe("embedded frame detection", () => {
     );
     expect(isInElectronWebView()).toBe(true);
   });
+
+  it("spots the desktop link window by Electron's default user agent", () => {
+    // What a cross-origin frame inside the desktop app reports (#1675).
+    vi.spyOn(window, "top", "get").mockReturnValue({} as Window);
+    vi.spyOn(navigator, "userAgent", "get").mockReturnValue(
+      "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) termix/26.10.2 Chrome/150.0.7871.250 Electron/43.7.7 Safari/537.36",
+    );
+    expect(isInElectronWebView()).toBe(true);
+  });
+
+  it("does not trust another Electron app or a plain browser frame", () => {
+    vi.spyOn(window, "top", "get").mockReturnValue({} as Window);
+    const ua = vi.spyOn(navigator, "userAgent", "get");
+    ua.mockReturnValue(
+      "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/150.0 Safari/537.36",
+    );
+    expect(isInElectronWebView()).toBe(false);
+    ua.mockReturnValue(
+      "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) other-app/1.0.0 Chrome/150.0 Electron/43.7.7 Safari/537.36",
+    );
+    expect(isInElectronWebView()).toBe(false);
+  });
 });