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# Termix plugin architecture
This is the contract between Termix core and a plugin. It is the reference for
anyone writing a plugin and the specification the runtime in
`src/backend/plugins/` implements.
Status: the redesign lands across several steps. Everything marked **A1** is
built today. Later markers name the step that delivers the rest.
---
## The shape of it
### 1. One tier
Every plugin, official or community, runs in-process in the Termix server and
in the browser. There is no first-party allowlist, no worker tier, and no
special case keyed on a plugin id anywhere in core.
This is not a sandbox. See [What this protects](#what-this-protects-and-what-it-does-not).
### 2. SDK only
A plugin imports `@termix/plugin-sdk`, its own files and its own npm
dependencies. Entry points:
| Entry | Contents |
| --------------------------------- | ---------------------------------------------------------- |
| `@termix/plugin-sdk/backend` | `PluginContext`, `definePlugin()`, `PluginCapabilityError` |
| `@termix/plugin-sdk/db` | `defineTable()`, the column builders, the legacy-table map |
| `@termix/plugin-sdk/ddl` | The per-dialect DDL emitter, shared with the CLI |
| `@termix/plugin-sdk/frontend` | The `app` object types (stubs until A7) |
| `@termix/plugin-sdk/manifest` | Manifest types, validation, the JSON schema |
| `@termix/plugin-sdk/capabilities` | The capability catalog |
| `@termix/plugin-sdk/settings` | Settings field types and the shared value validator |
| `@termix/plugin-sdk/testing` | Test helpers, incl. `createFakeContext()` |
Plugins never import from `src/` or `@/`, and core never imports from
`plugins/`. Anything a plugin needs from core becomes a typed, documented SDK
API. Enforced by lint, with the exceptions recorded under
[legacy core imports](#legacy-core-imports-the-debt-d1-removes).
The SDK holds the contract: types, the catalog, and pure helpers. The ctx
implementation lives in core (`src/backend/plugins/ctx.ts`) and is injected at
activation, so a plugin cannot reach around it.
### 3. Capabilities are what a plugin's code may do
Declared in the manifest's `capabilities` array using `domain:action` names
from one catalog in the SDK. Every privileged SDK call checks the capability
and writes an audit line naming the plugin and the acting user.
Two things must both be true, and a grant for something the manifest never
declared is ignored rather than honoured:
1. the manifest declares it, and
2. it is granted in `plugin_permission_grants`.
That means widening a plugin's reach always requires a new manifest the user
can see. In 2.9.0 bundled plugins are granted everything they declare
automatically, with `source: "bundled"`.
Adding a capability is one catalog entry (id, risk, i18n title and consequence
text) plus the SDK method that checks it.
### 4. User permissions are what a user may do
These stay in core RBAC and keep their dotted spelling (`hosts.view`), so they
can never be confused with colon-separated capabilities.
**A5 delivered this.** A plugin declares short names in
`contributes.permissions`, and core registers each as `<pluginId>.<name>`. The
plugin never writes the prefix, so it cannot claim a core group or another
plugin's namespace: `parseManifest` refuses a name starting with `hosts`,
`snippets`, `credentials`, `admin` or the plugin's own id, and the runtime
re-checks against every namespace already in the catalog, because the validator
cannot know which other plugins exist.
The ids are unchanged by the move. `ai` + `use` is `ai.use`, which is exactly
what the core catalog held before, so no role had to be migrated when `ai.*` and
`automations.*` left `PERMISSION_CATALOG` and `SYSTEM_ROLE_DEFAULTS`.
**A permission outlives its plugin.** Core records every id it has ever
registered in `rbac_known_permissions`, loaded at boot before any request is
served and backfilled from what roles already hold. Disabling a plugin now only
marks its group `enabled: false`: the group stays in the catalog so the role
editor can grey it, and `PUT /rbac/roles/:id` keeps accepting it. Previously the
group was unregistered outright, so an admin could not save _any_ change to a
role that still held one of these while the plugin was off. A permission nobody
has ever registered is still rejected.
**Defaults apply once.** `defaultRoles` names the seeded system roles (`admin`,
`user`) and nothing else. Each application is recorded in
`rbac_applied_defaults`, a core table with no foreign key to `plugins`, so an
admin who revokes a default does not get it handed back on the next boot or by
reinstalling the plugin. That ledger used to live in `plugin_storage`, which
cascades with the plugin row.
Both tables are deliberately unlinked from `plugins`: the whole point is
surviving the plugin being gone.
`ctx.rbac` is the plugin-side view: `has(permission)` for the current actor,
`hasFor(userId, permission)`, and `require(permission)` as route middleware. All
three resolve a bare short name against this plugin's prefix and take a full id
belonging to a core group or another plugin as given, which is what makes a
cross-plugin check expressible. `require` additionally refuses anything the
plugin does not declare itself, at registration time, and denies with the same
`401`/`403` bodies `requirePermission()` sends.
### 5. Data
Plugins own their tables. A plugin declares them with `defineTable()` from
`@termix/plugin-sdk/db` and ships migrations for `sqlite`, `postgres` and
`mysql` under `migrations/<dialect>/NNNN_name.sql`. Table names are prefixed
`p_<id with - as _>_`, which `defineTable` adds. `ctx.kv` is for small
key/value state. Core `schema.ts` ends up holding only core tables.
**One table object, three DDL emitters.** The sqlite-core definitions already
encode correctly on every engine at query time, which is why core's own 44
repositories use `schema.ts` on all three. Only DDL genuinely differs, and
that mapping lives in `@termix/plugin-sdk/ddl` so `termix-plugin migrations`
and the server's runner cannot drift into disagreeing.
**MySQL cannot index TEXT.** Any column carrying a key becomes
`varchar(255)`, and `defineTable` refuses an index on `text()` or `json()`
outright rather than silently truncating it.
**Migrations are applied at activation**, before `activate()` runs, so a
plugin's first query never meets a missing table. Applied migrations are
recorded in `plugin_migrations` with a checksum, which makes them immutable:
editing one that already ran blocks that plugin rather than leaving two
installs with quietly different schemas. A migration that throws marks its
plugin failed and core keeps booting.
**Adoption** is how a feature keeps its rows when it moves out of core. The
legacy table is renamed into the plugin's namespace
(`fleets` -> `p_fleets_fleets`) rather than copied, so nothing is duplicated
and no row is migrated one at a time. `LEGACY_TABLE_OWNERS` maps each legacy
table to the one plugin allowed to adopt it, enforced by the CLI at build time
and by the runner at activation, because a plugin installed from a tarball
never ran the CLI.
**Anything DDL-only in `db/index.ts` is SQLite-only.** `alert_rules`,
`alert_rule_channels` and `alert_firings` were created only there and never
declared in `schema.ts`, so they never existed on Postgres or MySQL at all.
Automations replaced them and A3 drops them. A core table needs all three
artifacts in lockstep: the `schema.ts` declaration, the `index.ts` DDL, and the
regenerated `schema.pg.ts`/`schema.mysql.ts` plus drizzle migrations.
**Sync entities are registered, not hardcoded.** `ctx.sync.registerEntity`
adds an entity to remote sync; core registers its own ten the same way in
`database/routes/sync-entities.ts`. The wire names are unchanged, because
existing tombstones and rows on the far side match on those strings. The
Electron client asks the server for the ordered list and falls back to its
frozen array for a server that predates the endpoint.
### 6. HTTP and WebSockets
Plugin routes live under `/plugin-api/<id>/` and sockets under
`/plugin-ws/<id>/<path>`, served by the main backend with core auth. No plugin
gets its own port or nginx block.
**A4 delivered this.** A plugin calls `ctx.http.router(options)` and gets an
Express Router core mounts at `/plugin-api/<id>/`, or `ctx.ws.route(path,
handler)` for a socket. Core runs the same middleware in front of every plugin:
1. **Auth**, unless the path is listed in `options.public`. A public path is
audited when the router is registered and logged on every request, because
"this plugin opened a hole in auth" should be findable later. It matches the
full path, with `:param` segments allowed, so declaring `/webhook/:token`
public cannot open `/webhook/:token/anything`.
2. **The actor**, from the user core authenticated, never from the request body.
3. **An enabled check** returning 503 while the plugin is disabled. That is a
different fact from 404 ("no such plugin") and a caller can act on it.
4. **Body limits**, defaulting to the 2mb core itself accepts. `database.ts`
skips its own global parser for `/plugin-api` so a plugin's `bodyLimit`
actually applies; `rawBody` turns the parsers off for a router that parses
its own (multer, a raw body for signature checks).
5. **An error wrapper** that logs against the plugin, never leaks a stack, and
feeds the error budget.
`ctx.rbac.require(permission)` adds a per-route RBAC gate, and a plugin may only
require a permission it declares itself.
Both surfaces need `network:serve`. The declaration is checked when the router
or route is created; the **grant** is checked per request and per upgrade,
because it lives in the database and `router()` has to be synchronous. A revoked
grant therefore takes effect on the next request without a restart: HTTP answers
403, an upgrade is refused 403.
Sockets are served from the main server's `upgrade` event, on both the HTTP
server and the direct HTTPS one. Auth is the same `utils/ws-auth.ts` path every
other Termix socket uses, and a token still awaiting TOTP is refused exactly as
it is for HTTP. Binary frames and backpressure are untouched. Everything a
plugin registered is disposed on deactivate, and live sockets are **closed**,
not merely unrouted: a terminal session must not outlive the plugin that owns it.
`ctx.ws.upgrade(path, handler)` hands over the raw upgrade, after core has
authenticated it, for a library that insists on owning its own WebSocketServer.
guacamole-lite is why it exists. Three routes are public because they
authenticate themselves in a way core cannot: the terminal (a share-link guest
arrives with a share token), the Docker console (per-message auth), and the
Guacamole display (a single-use encrypted connection token in the query, minted
by an authenticated route).
### 7. Settings
Plugins declare settings fields in the manifest with scope `admin`, `user` or
`host`. Core renders them from the schema, stores values in `plugin_settings`,
and encrypts secret fields.
**A6 delivered this.** A field is `{ key, type, labelKey, ... }`, with types
`boolean`, `string`, `number`, `select`, `multiselect`, `secret`, `textarea`,
`json` and `custom`. `requires` names a boolean in the same scope that gates
it, `group` is a section heading, and `permission` is who may write it: admin
fields fall back to `admin.plugins.manage`, and a short name resolves against
the plugin's own permissions exactly as `ctx.rbac` does.
`type: "custom"` names a component the frontend registered, for the few things
a schema cannot express (a device browser, a provider list). It is deliberately
narrow: a plugin supplies data everywhere else, so it cannot ship its own form
styling and drift from the rest of the app, and a page disappears cleanly when
its plugin does.
**One service, two callers.** `src/backend/plugins/settings.ts` is behind both
`ctx.settings` and the HTTP routes, so validation, encryption and redaction are
decided once. Two implementations would drift, and the one that drifted would
be the one writing to the database.
**The manifest is the schema.** A read is driven by the declared fields, not by
the stored rows: an unwritten field comes back with its `default`, and a row
for a field the plugin has since dropped is ignored rather than handed to the
UI. A write to a key the manifest never declared is refused, which is what
stops a PUT from filling a plugin's namespace with arbitrary keys.
**Secrets never leave the server.** A `secret` field is encrypted with
`encryptSystemSecret` (the installation key, not a user DEK: these have to be
readable before any user is unlocked) and every HTTP read replaces it with
`{ set: boolean }`. Sending that marker back is a no-op, so saving a form
cannot clear a key it was never shown. Clearing one writes null rather than an
encrypted empty string, so it reads back as unset.
**Storage.** `plugin_settings(plugin_id, scope, scope_id, key, value,
encrypted, updated_at)`, unique on the first four. `scope_id` is null for
admin, a user id for user and a host id as text for host. It is polymorphic, so
it carries no foreign key and the engine cannot cascade it: `UserRepository`
and `HostRepository` delete these rows explicitly, with tests that fail if
those calls ever go. The foreign key to `plugins` is real, so uninstalling
leaves nothing.
**Routes**, all with core auth: `GET|PUT /plugins/:id/settings/admin`
(`admin.plugins.manage`, or the field's own permission), `/settings/user`
(always the caller, never a user id from the body) and
`/settings/host/:hostId` (needs edit access to that host). A rejected PUT
returns `400 { errors: { <key>: message } }` per field, so a form shows every
problem at once.
**Host payloads carry them.** Host list and get responses include a
`pluginSettings` map, enabled plugins only and secrets redacted, built in one
query for the whole list rather than one request per plugin per host. It is
attached after the sanitizers, because the connect-level projection of a shared
host reduces it to an allowlist.
`ctx.settings` is `get/set`, `getUser/setUser`, `getHost/setHost`, `getAll`,
`onChange` (disposed with the plugin) and `readCore`. **Reading and writing a
plugin's own settings needs no capability**: the manifest already declares
every field, and a plugin that had to ask permission to read its own
configuration would be useless. Only `readCore`, which reaches outside the
plugin's namespace, is gated on `settings:read-core`, and it serves a short
allowlist (`CORE_SETTINGS_ALLOWLIST`) rather than the whole settings table.
### 8. UI
A plugin frontend is a built ESM bundle loaded at runtime by the core loader.
It registers everything through the `app` object: rail items, panels, tabs,
host editor sections, host actions and badges, context menu items, palette
entries, dashboard cards, homepage widgets, settings components, action slots,
login/2FA UI, SSH auth editors. The shell contains no plugin ids. **A7.**
### 9. Cross-plugin use
Through `ctx.services` (typed, versioned, RBAC-checked per call), `ctx.events`,
and frontend actions and slots. Dependencies are declared in the manifest:
`dependencies` are hard, `optionalDependencies` are soft. The loader activates
in dependency order. A plugin must keep working when an optional dependency is
missing.
### 10. Lifecycle
`activate(ctx)` creates all state. Everything registered through `ctx` or `app`
is disposed automatically on deactivate. See [Lifecycle rules](#lifecycle-rules).
### 11. Tests
Each plugin has `plugins/<id>/tests/backend` (node) and
`plugins/<id>/tests/frontend` (jsdom), run by its own vitest config:
```ts
// plugins/<id>/vitest.config.ts
import { pluginVitestConfig } from "@termix/plugin-sdk/vitest-preset";
export default pluginVitestConfig(import.meta.url);
```
The preset supplies both projects, the shared setup file
(`@termix/plugin-sdk/testing/setup`, which core's `vitest.setup.ts` re-exports
so there is one copy) and the `@/` alias the frontends still use.
`npm run test` runs core only, `npm run test:plugins` runs every plugin and
`npm run test:all` runs both. Core tests (`src/backend/tests`, `src/ui/tests`)
never test plugin code; they may test the plugin runtime with fixture plugins,
which is why `src/backend/tests/plugins/` still holds the loader, manifest,
capability, registry, service, secret and shutdown suites.
`@termix/plugin-sdk/testing` provides `createMockCtx()`, which enforces
capabilities the way the runtime does, `createFakeContext()` for tests that do
not care about the gates, and `renderWithApp()` for frontend tests (**A7**
finishes it).
### 12. Auth
Core keeps password login, sessions, API keys, trusted proxy login, Electron
auto-session and trusted devices, plus the base SSH auth types password, key,
stored credential, agent and none. Every other login method, second factor and
SSH auth method is a plugin through `ctx.auth`. **A8.**
### 13. Where plugins live
Official plugins live in `plugins/<id>/` as npm workspace packages in this
monorepo for all of 2.9.0, and get split into their own repos later. Every
plugin is enabled by default in 2.9.0; there is no install UI until 3.0.0.
The layout is fixed, and the directory name must equal the manifest `id`:
```
plugins/<id>/
manifest.json id, capabilities, contributions
package.json @termix-plugin/<id>, private, scripts call the CLI
tsconfig.json extends @termix/plugin-sdk/tsconfig.plugin.json
vitest.config.ts one line, the SDK preset
src/backend/index.ts exports activate(ctx) and deactivate()
src/frontend/index.tsx exports activate(app) and deactivate() (A7)
locales/en.json English strings; Crowdin translates the rest
migrations/{sqlite,postgres,mysql}/ owned tables, one .sql per dialect
migrations/snapshot.json diff basis for the generator
src/backend/tables.ts defineTable() definitions
tests/backend/ vitest, node
tests/frontend/ vitest, jsdom
README.md CHANGELOG.md
dist/ build output, gitignored
```
### 14. Upgrades must be lossless
Every move of data, settings or host columns into a plugin comes with a
migration for all three dialects and a test proving existing data survives.
#### Moving a host column into a plugin
A6 built the host-scope settings path but moved no columns; each Phase B step
moves its own. `ssh_data` still holds `enable_docker`, `stats_config`,
`web_ui_config`, `enable_proxmox`, `enable_rdp`, `mac_address` and the rest,
and the hardcoded host editor tabs still read them. The order matters, because
dropping a column before its data has moved loses it:
1. Declare the fields in the plugin's `contributes.settings.host`, keeping the
key names the form already uses so the editor tab can be deleted rather than
rewritten.
2. Write a boot migration that copies each row's column into host-scope
`plugin_settings` for that plugin, keyed by the host id as text. Make it
idempotent by checking for an existing row first, the way
`tailscale-settings-migration.ts` does, and cover it with a test that runs
it twice.
3. Switch the plugin's backend to `ctx.settings.getHost` and delete the
hardcoded editor tab; the schema-driven Plugins group replaces it.
4. Only then drop the column, in lockstep across all four artifacts: the
`schema.ts` declaration, the `db/index.ts` bootstrap DDL, a drizzle
migration per dialect, and `npm run schema:generate` for the pg and mysql
variants. The two bootstrap guard tests fail if these disagree.
A column that is still read anywhere in core is not ready to be dropped. Ship
the copy and the switch first, and drop it in a later step if that is safer.
---
## Manifest v2 reference
`plugins/<id>/manifest.json`. The directory name must equal `id`. Unknown
fields are rejected at every level: a typo'd `contribute` used to validate
clean and be silently dropped, which made a manifest describe something it did
not do.
```jsonc
{
"id": "example", // ^[a-z][a-z0-9-]{1,39}$, equals the directory name
"name": "Example",
"version": "1.0.0", // semver
"description": "What it does.",
"author": { "name": "You", "url": "https://..." },
"license": "MIT",
"repository": "https://...", // optional
"category": "Productivity", // see the enum below
"icon": "Sparkles", // optional: Lucide name or a bundled icon.svg
"engine": {
"termix": ">=2.9.0", // display only, never enforced
"api": "1", // the real compatibility gate
},
"capabilities": ["kv:own", "ui:surface"],
"dependencies": { "other-plugin": "^1.0.0" }, // missing one blocks activation
"optionalDependencies": { "maybe": "^1.0.0" }, // missing one is normal
"provides": [
{
"service": "example.thing",
"version": "1.0.0",
"permission": "example.use",
},
],
"requires": [
{ "service": "other.thing", "versionRange": "^1.0.0", "optional": true },
],
"providesSecret": [
{ "key": "api-key", "permission": "example.secrets.share" },
],
"requiresSecret": [
{ "plugin": "other-plugin", "key": "api-key", "optional": true },
],
"contributes": {
"tabs": [
{
"id": "example",
"titleKey": "nav.example",
"icon": "Sparkles",
"openFrom": ["rail"],
},
],
"actions": [
{
"id": "example.open",
"titleKey": "k",
"handler": "open",
"permission": "example.use",
},
],
"actionSlots": [{ "id": "example.toolbar", "accepts": ["button"] }],
"permissions": [
{
"name": "use", // registered as "example.use"
"titleKey": "permissions.use.title", // plugin-relative
"descriptionKey": "permissions.use.description",
"defaultRoles": ["user"], // system roles only, applied once
},
],
"settings": {
"admin": [
{
"key": "apiKey",
"type": "secret", // encrypted at rest, never sent to a browser
"labelKey": "settings.apiKey.label",
"descriptionKey": "settings.apiKey.description",
"placeholderKey": "settings.apiKey.placeholder",
"group": "settings.group.api", // section heading
},
{
"key": "retries",
"type": "number",
"labelKey": "k",
"min": 0,
"max": 5,
"default": 3,
},
{
"key": "browser",
"type": "custom", // a registered component, for what a schema cannot express
"component": "devices",
},
],
"user": [
{
"key": "advanced",
"type": "boolean",
"labelKey": "k",
"permission": "tweak", // one of this plugin's own permissions
},
],
"host": {
"enableKey": "enableExample", // boolean rendered first, gating the rest
"enableLabelKey": "k",
"fields": [
{
"key": "port",
"type": "number",
"labelKey": "k",
"requires": "enableExample",
},
],
},
},
"hostCapability": {
"key": "enableExample",
"labelKey": "k",
"editorTab": "general",
},
},
"backend": "dist/backend.js", // default
"frontend": "dist/frontend.js", // default
"locales": "locales", // default
"platforms": ["linux", "win32", "darwin"], // optional
}
```
`category` is one of: Terminal, Files & Transfer, Infrastructure, Monitoring,
Networking, Access & Security, Productivity.
`openFrom` is one of: rail, host-context-menu, palette.
Field types are `boolean`, `string`, `number`, `select`, `multiselect`,
`secret`, `textarea`, `json` and `custom`. `labelKey` is required for every
type but `custom`, which needs `component` instead; `options` is required and
non-empty for `select` and `multiselect` and rejected elsewhere; `min`/`max`
belong to `number` alone; and `requires` must name a boolean field in the same
scope, which includes the host section's `enableKey`.
Cross-field rules the JSON schema cannot express, checked by `parseManifest`:
- `engine.api` must match the SDK major version this build implements.
- Every `provides[].permission`, `providesSecret[].permission` and
`contributes.actions[].permission` must appear in the plugin's own
`contributes.permissions`, compared against the qualified `<pluginId>.<name>`
form. A permission the catalog never sees is one no admin can grant, so the
surface would be invisible rather than denied.
- `requiresSecret[].plugin` and both dependency maps must not name the plugin
itself, and a plugin cannot be in both `dependencies` and
`optionalDependencies`.
- Every `contributes.permissions[].name` must be unique, must not start with a
core group (`hosts`, `snippets`, `credentials`, `admin`) or with the plugin's
own id, and every `defaultRoles` entry must be `admin` or `user`.
- A `contributes.settings` field `permission` written as a bare short name must
appear in the plugin's own `contributes.permissions`. A dotted id is taken as
given, because the validator cannot know which other plugins exist.
`contributes.hostCapability`, `provides`, `requires`, `providesSecret` and
`requiresSecret` are carried forward from v1 unchanged because the service and
secret registries read them at activation. A6 and A7 reshape them.
Removed in A5: `contributes.permissionGroup` and its `defaultForRole`, replaced
by `contributes.permissions`. A plugin no longer picks its own group name.
Removed in v2: `permissions` (replaced by `capabilities`), `sidecars`, the
`capabilities.{backend,frontend,electron,platforms}` object (replaced by the
`backend`/`frontend`/`platforms` fields), `contributes.dashboardCards`,
`contributes.settingsPanel`, `contributes.apiPrefix`, and
`process:transport-owner` (the marker for the tier that no longer exists).
---
## Capability catalog
Colon-separated, ordered worst first. The i18n keys resolve under
`plugins.capabilities.<id>.title` and `.consequence` in
`src/ui/locales/en.json`, and the copy describes the consequence to the person
deciding, not the mechanism.
| Capability | Risk | Meaning |
| -------------------- | -------- | -------------------------------------------------------------- |
| `credentials:read` | critical | See plaintext secrets for any reachable host |
| `ssh:connect` | high | Run commands on hosts it is connected to |
| `process:spawn` | high | Run programs on the Termix server |
| `users:write` | high | Create and change user accounts |
| `auth:provide` | high | Add a login method or second factor |
| `system:tls` | high | Request and replace the server certificate |
| `hosts:write` | medium | Create and change hosts |
| `credentials:use` | medium | Connect using a host's stored credentials, without seeing them |
| `network:outbound` | medium | Make outbound requests |
| `network:serve` | medium | Open a listening port |
| `users:read` | medium | See usernames and roles, never hashes or 2FA state |
| `events:core` | medium | Subscribe to and emit core events carrying other users' data |
| `notify:send` | medium | Send notifications through configured channels |
| `audit:read` | medium | Read the audit log |
| `desktop:window` | medium | Open desktop windows (Electron only) |
| `hosts:read` | low | See the host list it can already see |
| `db:own` | low | Own tables |
| `kv:own` | low | Small key/value state |
| `secrets:own` | low | Its own encrypted secrets |
| `settings:read-core` | low | Read core server settings |
| `ui:surface` | low | Contribute tabs, panels and settings |
### Rules
- One catalog, in `packages/plugin-sdk/src/capabilities.ts`. Nothing else
defines a capability.
- Adding one is an entry here plus the SDK method that checks it. A capability
nothing checks is decoration, and v1 shipped nineteen of those.
- A capability is checked where the privileged thing happens, not at
activation. Activation-time checks say what a plugin might do; call-time
checks say what it did.
- `events:core` is the exception that proves the shape: without it a plugin may
only emit under `plugin.<its id>.`, because otherwise it could publish
`host.status` and drive the automations engine as though core had.
---
## The ctx surface
Built per plugin in `src/backend/plugins/ctx.ts` and passed to `activate`.
| Member | Capability | Status |
| ------------------------------------------------ | ------------------------------------ | ------ |
| `ctx.pluginId`, `ctx.manifest` | none | **A1** |
| `ctx.log.*` | none | **A1** |
| `ctx.events.emit` / `.on` | `events:core` for core topics | **A1** |
| `ctx.kv.get/set/delete/list` | `kv:own` | **A1** |
| `ctx.registry.*` | none | **A1** |
| `ctx.services.provide` / `.get` | per-service RBAC | **A1** |
| `ctx.secrets.offer` / `.withdraw` / `.getShared` | per-secret RBAC | **A1** |
| `ctx.disposables.add` | none | **A1** |
| `ctx.asUser(userId, fn)` | none, always audited | **A1** |
| `ctx.currentActor()` | none | **A1** |
| `ctx.db.define` / `.client` / `.refs` | `db:own` | **A3** |
| `ctx.sync.registerEntity` | none | **A3** |
| `ctx.http.router` / `ctx.ws.route` / `.upgrade` | `network:serve` | **A4** |
| `ctx.rbac.has` / `.hasFor` / `.require` | own permissions only | **A5** |
| `ctx.hosts.*` | `hosts:read` / `hosts:write` | B |
| `ctx.ssh.*` | `ssh:connect`, `credentials:use` | B |
| `ctx.settings.*` | `settings:read-core` (readCore only) | **A6** |
| `ctx.notify.*` | `notify:send` | A6 |
| `ctx.auth.*` | `auth:provide` | A8 |
| `ctx.fetch` | `network:outbound` | B |
### The actor
Never comes from plugin code. It is held in `AsyncLocalStorage` and set two
ways, with no third:
- **A request.** A4's HTTP and WebSocket middleware runs the handler as the
user core already authenticated.
- **`ctx.asUser(userId, fn)`** for background work with no request behind it.
Always audited, and every core API inside still applies that user's RBAC.
A plugin cannot pass a user id to a guarded method and have it believed. This
is what closes the forged-caller bug the old worker broker had, where a worker
could set `callerUserId` on its own messages.
---
## Lifecycle rules
1. **Everything is created inside `activate`.** No servers, timers, listeners
or connections at module scope. ESM caches modules, so disable-then-enable
re-runs `activate` against the same module object: anything created at
module scope is already torn down by the second call and never comes back.
2. **Everything is released on deactivate.** Registrations made through `ctx`
are tracked automatically. Anything the plugin creates itself goes in
`ctx.disposables.add(fn)`. A plugin that keeps a port after deactivate makes
"disabled" a lie and makes re-enabling fail on a port it still holds.
3. **Disposal does not depend on the plugin behaving.** The runtime empties the
disposable bag even when the plugin's `deactivate()` throws or does not
exist, in reverse registration order, isolating each disposer.
4. **A failed `activate` is still cleaned up**, and the plugin's own
`deactivate()` is _not_ called: it never finished starting, so it has no
state to tear down.
5. **Plugins never touch process signals or `process.exit`.** Core calls
`deactivate` on shutdown: `gracefulShutdown` in `src/backend/starter.ts`
calls `shutdownPlugins()`, which stops every plugin in reverse activation
order. A plugin that installs its own `SIGTERM` handler and exits skips the
rest of that sequence, including other plugins and the database flush.
6. **Enable, disable, enable must work without a restart.**
### States
`enabled`, `disabled`, `blocked` (a hard dependency is missing, recoverable),
`failed` (activation threw, a dependency cycle, or the error budget tripped).
`lastError` carries the reason.
### Error budget
Core wraps plugin callbacks it invokes. Five failures inside 60 seconds (both
configurable) marks the plugin `failed` and deactivates it, because a plugin
throwing on every call is worse than one that is off.
`POST /plugins/:id/retry` clears the budget and starts it again.
---
## What this protects, and what it does not
Be precise about this, because it is easy to overclaim and the previous
architecture did.
**What the capability system gives you**
- Every privileged thing a plugin can do through `ctx` is declared in a
manifest you can read before installing it.
- Every privileged call is checked against what was granted, and refused if it
was not.
- Every privileged call, allowed or refused, leaves an audit line naming the
plugin and the acting user. You can answer "what did this plugin do, and on
whose behalf".
- A plugin cannot name a user and be believed, so it cannot act as someone it
was not invoked by.
- Removing a capability from a manifest revokes the grant on the next boot.
**What it does not give you**
- **Containment.** A plugin runs in the server process. It can
`import("node:fs")` and read whatever the server user can read, open its own
sockets, spawn processes, and reach core modules directly. Guarding `ctx`
does not change any of that.
- **Protection from malicious code.** A plugin that wants to bypass the gate
can. Nothing here stops it.
`ctx.db` is a clear example. It hands back a handle scoped to the plugin's own
tables, and the `p_<id>_` prefix, the CLI check and the runner's check all say
a plugin may only touch its own. None of that is enforced by the engine: a
plugin holding that handle can write any table in the database, and `ctx.db.refs`
hands it `users` and `ssh_data` outright. The prefix, the capability, the audit
line, lint and review are the contract. The engine is not.
So the honest boundary is: capabilities stop accidental and casual overreach,
and make every privileged call auditable. What stops malicious code is
**signing, review and the kill list** - the same trust model as any other
software you choose to install on a server.
The old worker tier claimed more than this, and the claim was not true either:
`worker_threads` shares the process, so a worker plugin could already reach
anything core could. The honest options for real containment are a child
process with `--permission`, or a WASM isolate. Neither is on the roadmap, and
until one is, this document does not pretend otherwise.
---
## Building a plugin
`termix-plugin`, the CLI the SDK ships, is the only build a plugin needs. It
runs from the plugin's own directory, so a plugin that moves to its own repo
keeps working unchanged.
| Command | What it does |
| -------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `termix-plugin build` | esbuild bundles `src/backend/index.ts` to `dist/backend.js` (ESM, node22) and `src/frontend/index.tsx` to `dist/frontend.js` (ESM, browser), then copies `locales/` and `migrations/` into `dist/`. Imported CSS lands in `dist/frontend.css`. |
| `termix-plugin validate` | Runs the SDK's `parseManifest`, checks the files the manifest names exist, and checks that migrations only touch this plugin's tables and exist for every dialect. |
| `termix-plugin migrations` | Diffs `src/backend/tables.ts` against `migrations/snapshot.json` and writes one `.sql` per dialect. `--check` fails when a definition changed without a migration. A rename or a type change is refused rather than guessed at, because that is a data decision. |
| `termix-plugin test` | Runs the plugin's vitest suite. |
| `termix-plugin pack` | Writes a `.tgz` of the manifest, `dist/`, locales, migrations and README. **D3** adds signing. |
`npm run build:plugins` builds every plugin and stages the result in
`dist/plugins/<id>/`, which is what `getBundledPluginsDir()` resolves to and
what Docker and electron-builder package. `npm run build`, `build:backend` and
`dev:backend` all call it.
TypeScript only type-checks (`tsconfig.plugins.json`, `noEmit`); esbuild does
every emit. Nothing is written next to a source file.
### Host-provided packages
These ship with the Termix server and are never bundled into a plugin, because
a second copy of express or React is a bug, and a second `ssh2` means a second
set of native bindings. A plugin may depend on anything outside these lists,
and that is bundled into its output.
**Backend** (plus every node builtin): `@termix/plugin-sdk`, `express`, `ssh2`,
`ws`, `multer`, `cookie-parser`, `axios`, `jszip`, `guacamole-lite`,
`@anthropic-ai/sdk`, `drizzle-orm`.
**Frontend**: `react`, `react-dom`, `react/jsx-runtime`, `@termix/plugin-sdk`,
`i18next`, `react-i18next`, and the UI libraries core provides today
(`lucide-react`, `sonner`, `axios`, `cytoscape`, `react-cytoscapejs`,
`guacamole-common-js`, `react-xtermjs`, `@xterm/*`). **A7** serves these
through the SDK `ui` entry.
The lists live in `packages/plugin-sdk/cli/lib/externals.mjs`.
---
## Legacy core imports: the debt D1 removes
The twelve bundled plugins predate the SDK. They still reach core by relative
path (`../../../../src/backend/...`), which an esbuild plugin,
`packages/plugin-sdk/cli/lib/legacy-core-imports.mjs`, keeps out of the bundle
and rewrites to the compiled output path (`../../../backend/backend/...`, or
`../../../backend/types/...` for shared types). The rewrite is output-relative,
so a source file at any nesting collapses to the same prefix. D1 deletes that
file.
This is expected and temporary. The SDK does not yet expose what they need:
the SSH connection pool, host resolution, the repository layer, the shared
component library. D1 removes the debt once A3 through A8 have given them
supported APIs to move onto.
What the lint fence enforces today, in `eslint.config.mjs`:
| Direction | Severity | Offenders | Emptied by |
| ------------------------------------------------ | --------- | --------- | ---------- |
| Core importing a plugin backend | **Error** | 0 | - |
| A plugin backend importing frontend code or `@/` | **Error** | 0 | - |
| The shell importing plugin components | Warning | 16 files | A7 |
| A plugin importing core by relative path | Warning | 70 files | D1 |
| A plugin importing another plugin's source | Warning | 3 files | B18 |
A warning does not fail a build, so the counts are held by
`scripts/check-plugin-boundaries.cjs`, run by `npm run lint`. Every offender is
listed in `scripts/plugin-boundary-allowlist.json`: a new one fails, and so
does an entry that stopped being an offender, so the list shrinks as each step
lands rather than rotting. `--write` regenerates it. D1 empties it and the two
plugin-side warnings become errors.
The two plugin-backend directions use different rule names
(`no-restricted-imports` and `@typescript-eslint/no-restricted-imports`)
because flat config replaces a rule's options rather than merging them, so one
rule cannot carry both severities on the same files.
Known specifics:
- **TODO(B18):** `plugins/ai/src/backend/tools/executor.ts` imports
`automations`' `routes.js` directly. It is declared as a hard `dependencies`
entry so the loader starts automations first and marks `ai` blocked if
automations is disabled. In B18 `ai` calls automations through an
`automations` service as an `optionalDependency` and the direct import goes
away.
- **TODO(B18):** `plugins/host-metrics/src/backend/` reaches `automations`
twice, for a `MetricsSnapshot` type and a fire-and-forget
`import("...headless-viewer.js")` that registers a viewer bridge. Both
degrade silently when automations is absent, so host-metrics declares it as
an `optionalDependency` (added in A2; it previously declared nothing, and
the loader had no reason to order the two).
- Core feature servers that are not plugins yet still own ports: tunnel 30003,
file-manager 30004, dashboard 30006, tmux 30010, serial 30011 and homepage 30012. Each keeps its nginx block until its own Phase B step. No plugin owns
a port any more (A4).
- `src/ui/shell/pluginLoader.ts` still hardcodes plugin ids in
`BUILT_IN_TABS_BY_PLUGIN` and `applyFirstPartyActions`. A7 removes both.
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