diff --git a/packages/plugin-sdk/CHANGELOG.md b/packages/plugin-sdk/CHANGELOG.md
index 5479f4c5c..c85e0b687 100644
--- a/packages/plugin-sdk/CHANGELOG.md
+++ b/packages/plugin-sdk/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 1.0.21
+
+Plugin API 1.12.0.
+
+### Added
+
+- `@termix-ssh/plugin-sdk/host-scripts`: Docker, Linux metrics, systemd, journal and OpenRC command builders and parsers, plus `scriptShell()` and `passwordSudoScript()` to send scripts to `bash -s` on stdin. It has no Node or ssh2 imports, so the Termix mobile app runs the same code
+
 ## 1.0.20
 
 Plugin API 1.12.0.
diff --git a/packages/plugin-sdk/PLUGIN-GUIDE.md b/packages/plugin-sdk/PLUGIN-GUIDE.md
index 59ab078fe..5777831cb 100644
--- a/packages/plugin-sdk/PLUGIN-GUIDE.md
+++ b/packages/plugin-sdk/PLUGIN-GUIDE.md
@@ -1,6 +1,6 @@
 # Termix plugin guide
 
-SDK 1.0.20 | Plugin API 1.12.0
+SDK 1.0.21 | Plugin API 1.12.0
 
 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.
@@ -335,7 +335,9 @@ try {
 
 `ctx.ssh.withConnection(hostId, { pool, purpose }, fn)` borrows a pooled connection for frequent short
 commands. `@termix-ssh/plugin-sdk/host-commands` has helpers to detect the OS and run package manager and
-sudo commands. Hosts from `ctx.hosts` never carry secrets. Pass the host or its id to `ctx.ssh`.
+sudo commands. `@termix-ssh/plugin-sdk/host-scripts` builds Docker, metrics, systemd and journal
+commands and parses their output; send a script on stdin to the command `scriptShell()` returns. Hosts from
+`ctx.hosts` never carry secrets. Pass the host or its id to `ctx.ssh`.
 
 ### The desktop app
 
@@ -905,6 +907,7 @@ To run your own registry instead, see https://docs.termix.site/develop/registrie
 | `@termix-ssh/plugin-sdk/testing`                                     | `createMockCtx`, `createTestDb`, `renderWithApp`, `createFakeContext`                          |
 | `@termix-ssh/plugin-sdk/vitest-preset`                               | `pluginVitestConfig`                                                                           |
 | `@termix-ssh/plugin-sdk/host-commands`                               | OS detection, package manager and sudo helpers over ssh2                                       |
+| `@termix-ssh/plugin-sdk/host-scripts`                                | Docker, metrics, systemd and journal command builders and parsers, scripts sent to `bash -s`   |
 | `@termix-ssh/plugin-sdk/ssh-certs`                                   | `applyCertificateAuth()` for certificate based SSH auth                                        |
 | `@termix-ssh/plugin-sdk/ssh-keys`                                    | `generateSshKeyPair()`, `detectSshKeyType()`, `publicKeyFromPrivate()`, `validateSshKeyPair()` |
 | `@termix-ssh/plugin-sdk/desktop`                                     | The desktop app bridge, typed. Check it exists before use                                      |
diff --git a/packages/plugin-sdk/package.json b/packages/plugin-sdk/package.json
index 684db9831..5a9ee7651 100644
--- a/packages/plugin-sdk/package.json
+++ b/packages/plugin-sdk/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@termix-ssh/plugin-sdk",
-  "version": "1.0.20",
+  "version": "1.0.21",
   "description": "The contract between Termix core and a plugin: types, the capability catalog and the manifest schema.",
   "license": "Apache-2.0",
   "repository": {
@@ -81,6 +81,10 @@
       "types": "./dist/host-commands.d.ts",
       "default": "./dist/host-commands.js"
     },
+    "./host-scripts": {
+      "types": "./dist/host-scripts/index.d.ts",
+      "default": "./dist/host-scripts/index.js"
+    },
     "./ssh-certs": {
       "types": "./dist/ssh-certs.d.ts",
       "default": "./dist/ssh-certs.js"
diff --git a/packages/plugin-sdk/src/host-commands.ts b/packages/plugin-sdk/src/host-commands.ts
index b526cf945..c131faa57 100644
--- a/packages/plugin-sdk/src/host-commands.ts
+++ b/packages/plugin-sdk/src/host-commands.ts
@@ -11,6 +11,9 @@
 
 export type { Client, ClientChannel } from "ssh2";
 import type { Client, ClientChannel } from "ssh2";
+// Homebrew and OrbStack paths a non-interactive shell misses.
+import { EXTRA_PATH_DIRS } from "./host-scripts/docker.js";
+export { EXTRA_PATH_DIRS };
 
 export interface ExecResult {
   stdout: string;
@@ -114,14 +117,6 @@ export interface PlatformInfo {
   osPrettyName: string | null;
 }
 
-/**
- * Non-interactive SSH shells don't source ~/.zprofile or ~/.bash_profile,
- * so PATH additions from installers like Homebrew or OrbStack are missing.
- * Extend PATH with their common install locations before probing.
- */
-export const EXTRA_PATH_DIRS =
-  '/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:"$HOME/.orbstack/bin"';
-
 const DOCKER_PROBE =
   `command -v docker >/dev/null 2>&1` +
   ` || [ -S /var/run/docker.sock ]` +
diff --git a/packages/plugin-sdk/src/host-scripts/docker.ts b/packages/plugin-sdk/src/host-scripts/docker.ts
new file mode 100644
index 000000000..efb80eabc
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/docker.ts
@@ -0,0 +1,468 @@
+/**
+ * Docker and Podman command builders and output parsers.
+ *
+ * Container ids and names are checked with CONTAINER_ID_RE before they go on
+ * a command line, so they need no quoting. Anything free form is quoted.
+ */
+import { HostScriptError } from "./text.js";
+
+export type ContainerRuntime = "docker" | "podman";
+
+export function normalizeContainerRuntime(value: unknown): ContainerRuntime {
+  return value === "podman" ? "podman" : "docker";
+}
+
+export function getRuntimeLabel(runtime: ContainerRuntime): string {
+  return runtime === "podman" ? "Podman" : "Docker";
+}
+
+/**
+ * Non-interactive SSH shells don't source ~/.zprofile or ~/.bash_profile,
+ * so PATH additions from installers like Homebrew or OrbStack are missing.
+ */
+export const EXTRA_PATH_DIRS =
+  '/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:"$HOME/.orbstack/bin"';
+
+export function containerCommand(
+  runtime: ContainerRuntime | undefined,
+  args: string,
+  isWindows = false,
+): string {
+  const cli = `${normalizeContainerRuntime(runtime)} ${args}`;
+  // cmd and PowerShell don't understand the POSIX env prefix.
+  return isWindows ? cli : `PATH="${EXTRA_PATH_DIRS}:$PATH" ${cli}`;
+}
+
+export const CONTAINER_ID_RE = /^[a-zA-Z0-9][a-zA-Z0-9_.-]*$/;
+export const DOCKER_TIMESTAMP_RE = /^[0-9T:.Z+-]+$/;
+
+export function isContainerId(value: unknown): value is string {
+  return (
+    typeof value === "string" &&
+    value.length <= 256 &&
+    CONTAINER_ID_RE.test(value)
+  );
+}
+
+function requireContainer(id: string): string {
+  if (!isContainerId(id))
+    throw new HostScriptError("That is not a valid container id");
+  return id;
+}
+
+export const CONTAINER_ACTIONS = [
+  "start",
+  "stop",
+  "restart",
+  "pause",
+  "unpause",
+] as const;
+export type ContainerAction = (typeof CONTAINER_ACTIONS)[number];
+
+const LIST_FORMAT_UNIX = `'{"id":"{{.ID}}","name":"{{.Names}}","image":"{{.Image}}","status":"{{.Status}}","state":"{{.State}}","ports":"{{.Ports}}","created":"{{.CreatedAt}}"}' `;
+const LIST_FORMAT_WINDOWS = `"{\\"id\\":\\"{{.ID}}\\",\\"name\\":\\"{{.Names}}\\",\\"image\\":\\"{{.Image}}\\",\\"status\\":\\"{{.Status}}\\",\\"state\\":\\"{{.State}}\\",\\"ports\\":\\"{{.Ports}}\\",\\"created\\":\\"{{.CreatedAt}}\\"}"`;
+const STATS_FORMAT_UNIX = `'{"cpu":"{{.CPUPerc}}","memory":"{{.MemUsage}}","memoryPercent":"{{.MemPerc}}","netIO":"{{.NetIO}}","blockIO":"{{.BlockIO}}","pids":"{{.PIDs}}"}' `;
+const STATS_FORMAT_WINDOWS = `"{\\"cpu\\":\\"{{.CPUPerc}}\\",\\"memory\\":\\"{{.MemUsage}}\\",\\"memoryPercent\\":\\"{{.MemPerc}}\\",\\"netIO\\":\\"{{.NetIO}}\\",\\"blockIO\\":\\"{{.BlockIO}}\\",\\"pids\\":\\"{{.PIDs}}\\"}"`;
+
+export function listFormat(isWindows: boolean): string {
+  return isWindows ? LIST_FORMAT_WINDOWS : LIST_FORMAT_UNIX;
+}
+
+export function statsFormat(isWindows: boolean): string {
+  return isWindows ? STATS_FORMAT_WINDOWS : STATS_FORMAT_UNIX;
+}
+
+/** One row of `ps --format listFormat()`. */
+export interface ContainerRow {
+  id: string;
+  name: string;
+  image: string;
+  status: string;
+  state: string;
+  ports: string;
+  created: string;
+}
+
+/** CLI arguments, without the runtime, for each container command. */
+export const dockerArgs = {
+  version: () => "--version",
+  ping: () => "ps",
+  list: (all: boolean, isWindows = false) =>
+    `ps ${all ? "-a " : ""}--format ${listFormat(isWindows)}`,
+  inspect: (id: string) => `inspect ${requireContainer(id)}`,
+  stats: (id: string, isWindows = false) =>
+    `stats ${requireContainer(id)} --no-stream --format ${statsFormat(isWindows)}`,
+  action: (action: ContainerAction, id: string) => {
+    if (!CONTAINER_ACTIONS.includes(action))
+      throw new HostScriptError("Unknown action");
+    return `${action} ${requireContainer(id)}`;
+  },
+  remove: (id: string, force: boolean) =>
+    `rm ${force ? "-f " : ""}${requireContainer(id)}`,
+  logs: (
+    id: string,
+    options: {
+      tail?: number;
+      timestamps?: boolean;
+      since?: string;
+      until?: string;
+    } = {},
+  ) => {
+    let args = `logs ${requireContainer(id)}`;
+    if (options.tail && options.tail > 0)
+      args += ` --tail ${Math.floor(options.tail)}`;
+    if (options.timestamps) args += " --timestamps";
+    if (options.since && DOCKER_TIMESTAMP_RE.test(options.since)) {
+      args += ` --since ${options.since}`;
+    }
+    if (options.until && DOCKER_TIMESTAMP_RE.test(options.until)) {
+      args += ` --until ${options.until}`;
+    }
+    return `${args} 2>&1`;
+  },
+  states: () => `ps -a --format ${PS_STATE_FORMAT}`,
+  composeProjects: () => "compose ls -a --format json",
+};
+
+/** The version from `docker --version` or `podman --version`. */
+export function parseRuntimeVersion(output: string): string {
+  return output.match(/(?:Docker|podman) version ([^\s,]+)/i)?.[1] ?? "unknown";
+}
+
+export type RuntimeProblem =
+  "NOT_INSTALLED" | "DAEMON_NOT_RUNNING" | "PERMISSION_DENIED" | "DOCKER_ERROR";
+
+/** Sorts a failed `docker ps` into a reason the UI can explain. */
+export function classifyRuntimeError(message: string): RuntimeProblem {
+  if (
+    /command not found|not found: (docker|podman)|No such file or directory/i.test(
+      message,
+    )
+  ) {
+    return "NOT_INSTALLED";
+  }
+  if (message.includes("Cannot connect to the Docker daemon"))
+    return "DAEMON_NOT_RUNNING";
+  if (/permission denied/i.test(message)) return "PERMISSION_DENIED";
+  return "DOCKER_ERROR";
+}
+
+/** Parses `ps --format listFormat()` output, skipping lines that are not JSON. */
+export function parseContainerList(output: string): Record<string, unknown>[] {
+  return output
+    .split("\n")
+    .filter((line) => line.trim())
+    .flatMap((line) => {
+      try {
+        return [JSON.parse(line) as Record<string, unknown>];
+      } catch {
+        return [];
+      }
+    });
+}
+
+export interface ContainerStats {
+  cpu: string;
+  memoryUsed: string;
+  memoryLimit: string;
+  memoryPercent: string;
+  netInput: string;
+  netOutput: string;
+  blockRead: string;
+  blockWrite: string;
+  pids: string;
+}
+
+/** Parses one `stats --no-stream --format statsFormat()` line. Throws on bad JSON. */
+export function parseContainerStats(output: string): ContainerStats {
+  const raw = JSON.parse(output.trim()) as Record<string, string>;
+  const split = (value: string | undefined) => {
+    const [first, second] = (value ?? "").split(" / ");
+    return [first?.trim() || "0B", second?.trim() || "0B"];
+  };
+  const [memoryUsed, memoryLimit] = split(raw.memory);
+  const [netInput, netOutput] = split(raw.netIO);
+  const [blockRead, blockWrite] = split(raw.blockIO);
+  return {
+    cpu: raw.cpu,
+    memoryUsed,
+    memoryLimit,
+    memoryPercent: raw.memoryPercent,
+    netInput,
+    netOutput,
+    blockRead,
+    blockWrite,
+    pids: raw.pids,
+  };
+}
+
+export interface ContainerState {
+  /** Docker's own state word: running, exited, restarting, ... */
+  state: string;
+  /** Health from the status text, when the image declares a healthcheck. */
+  unhealthy: boolean;
+}
+
+export type DockerEventName = "exited" | "started" | "unhealthy" | "restarting";
+
+export const PS_STATE_FORMAT = `'{"name":"{{.Names}}","state":"{{.State}}","status":"{{.Status}}"}'`;
+
+/** Parses `ps -a --format PS_STATE_FORMAT` output, one JSON object per line. */
+export function parseContainerStates(
+  output: string,
+): Map<string, ContainerState> {
+  const states = new Map<string, ContainerState>();
+  for (const line of output.split("\n")) {
+    const trimmed = line.trim();
+    if (!trimmed) continue;
+    try {
+      const parsed = JSON.parse(trimmed) as {
+        name?: string;
+        state?: string;
+        status?: string;
+      };
+      if (!parsed.name) continue;
+      states.set(parsed.name, {
+        state: (parsed.state ?? "").toLowerCase(),
+        unhealthy: /\(unhealthy\)/i.test(parsed.status ?? ""),
+      });
+    } catch {
+      // A partial line is not worth failing the whole poll over.
+    }
+  }
+  return states;
+}
+
+/**
+ * The events a pair of snapshots implies. A container missing from the
+ * previous snapshot counts as newly seen rather than started, so the first
+ * poll after a restart does not replay every running container.
+ */
+export function diffContainerStates(
+  previous: Map<string, ContainerState>,
+  current: Map<string, ContainerState>,
+): Array<{ container: string; event: DockerEventName }> {
+  const events: Array<{ container: string; event: DockerEventName }> = [];
+  for (const [name, now] of current) {
+    const before = previous.get(name);
+    if (!before) continue;
+    if (before.state !== now.state) {
+      if (now.state === "exited")
+        events.push({ container: name, event: "exited" });
+      else if (now.state === "running")
+        events.push({ container: name, event: "started" });
+      else if (now.state === "restarting") {
+        events.push({ container: name, event: "restarting" });
+      }
+    }
+    // A container can go unhealthy while it stays up.
+    if (!before.unhealthy && now.unhealthy) {
+      events.push({ container: name, event: "unhealthy" });
+    }
+  }
+  return events;
+}
+
+export interface ContainerCounts {
+  running: number;
+  stopped: number;
+  unhealthy: number;
+  total: number;
+}
+
+/** Counts from `ps -a --format PS_STATE_FORMAT` output. */
+export function countContainers(output: string): ContainerCounts {
+  const states = [...parseContainerStates(output).values()];
+  const running = states.filter((s) => s.state === "running").length;
+  return {
+    running,
+    stopped: states.length - running,
+    unhealthy: states.filter((s) => s.unhealthy).length,
+    total: states.length,
+  };
+}
+
+// Compose stacks
+
+export const STACK_NAME_RE = /^[a-z0-9][a-z0-9_-]{0,62}$/;
+export const STACK_SERVICE_RE = /^[a-zA-Z0-9][a-zA-Z0-9_.-]{0,126}$/;
+export const COMPOSE_FILES = [
+  "compose.yaml",
+  "compose.yml",
+  "docker-compose.yaml",
+  "docker-compose.yml",
+];
+
+export const STACK_ACTIONS = [
+  "deploy",
+  "redeploy",
+  "pull",
+  "start",
+  "stop",
+  "restart",
+  "pause",
+  "unpause",
+  "down",
+  "destroy",
+] as const;
+export type StackAction = (typeof STACK_ACTIONS)[number];
+
+/** Actions that can target one service of a stack. */
+export const STACK_SERVICE_ACTIONS: StackAction[] = [
+  "deploy",
+  "pull",
+  "start",
+  "stop",
+  "restart",
+  "pause",
+  "unpause",
+];
+
+export type StackState =
+  "running" | "partial" | "stopped" | "paused" | "not-deployed";
+
+export interface StackSummary {
+  name: string;
+  managed: boolean;
+  state: StackState;
+  running: number;
+  total: number;
+  composeFile: string | null;
+}
+
+export interface StackService {
+  service: string;
+  name: string;
+  id: string;
+  image: string;
+  state: string;
+  status: string;
+  health: string;
+  ports: string;
+}
+
+/** `compose ls` and `compose ps --format json` print one object per line or one array. */
+export function parseJsonLines(output: string): Record<string, unknown>[] {
+  const text = output.trim();
+  if (!text) return [];
+  if (text.startsWith("[")) {
+    try {
+      return JSON.parse(text) as Record<string, unknown>[];
+    } catch {
+      return [];
+    }
+  }
+  return text.split("\n").flatMap((line) => {
+    try {
+      return [JSON.parse(line) as Record<string, unknown>];
+    } catch {
+      return [];
+    }
+  });
+}
+
+const str = (value: unknown): string =>
+  typeof value === "string" ? value : "";
+
+export function parseServices(output: string): StackService[] {
+  return parseJsonLines(output).map((row) => {
+    const publishers = Array.isArray(row.Publishers)
+      ? (row.Publishers as Record<string, unknown>[])
+      : [];
+    const ports = publishers
+      .filter((p) => Number(p.PublishedPort) > 0)
+      .map((p) => `${p.PublishedPort}:${p.TargetPort}`)
+      .filter((value, index, all) => all.indexOf(value) === index)
+      .join(", ");
+    return {
+      service: str(row.Service),
+      name: str(row.Name),
+      id: str(row.ID),
+      image: str(row.Image),
+      state: str(row.State),
+      status: str(row.Status),
+      health: str(row.Health),
+      ports,
+    };
+  });
+}
+
+function stateOf(running: number, paused: number, total: number): StackState {
+  if (total === 0) return "not-deployed";
+  if (paused === total) return "paused";
+  if (running === total) return "running";
+  if (running > 0) return "partial";
+  return "stopped";
+}
+
+/** Turns the `compose ls` status text ("running(2), exited(1)") into a state. */
+export function parseStackStatus(status: string): {
+  state: StackState;
+  running: number;
+  total: number;
+} {
+  let running = 0;
+  let paused = 0;
+  let total = 0;
+  for (const part of status.split(",")) {
+    const match = part.trim().match(/^([a-z]+)\((\d+)\)$/i);
+    if (!match) continue;
+    const count = Number(match[2]);
+    total += count;
+    if (match[1] === "running") running += count;
+    if (match[1] === "paused") paused += count;
+  }
+  return { state: stateOf(running, paused, total), running, total };
+}
+
+export function stackStateFromServices(services: StackService[]) {
+  const total = services.length;
+  const running = services.filter((s) => s.state === "running").length;
+  const paused = services.filter((s) => s.state === "paused").length;
+  return { state: stateOf(running, paused, total), running, total };
+}
+
+/** Stacks from `compose ls -a --format json`, for hosts with no stacks folder. */
+export function parseComposeProjects(output: string): StackSummary[] {
+  return parseJsonLines(output)
+    .flatMap((project) => {
+      const name = str(project.Name);
+      if (!STACK_NAME_RE.test(name)) return [];
+      return [
+        {
+          name,
+          managed: false,
+          ...parseStackStatus(str(project.Status)),
+          composeFile: str(project.ConfigFiles).split(",")[0] || null,
+        },
+      ];
+    })
+    .sort((a, b) => a.name.localeCompare(b.name));
+}
+
+/** The compose commands one action runs, in order. */
+export function composeArgsFor(
+  action: StackAction,
+  service: string | undefined,
+  options: { removeVolumes?: boolean },
+): string[] {
+  const target = service ? ` ${service}` : "";
+  switch (action) {
+    case "deploy":
+      return [`up -d --remove-orphans${target}`];
+    case "redeploy":
+      return [`pull${target}`, `up -d --remove-orphans${target}`];
+    case "pull":
+      return [`pull${target}`];
+    case "start":
+    case "stop":
+    case "restart":
+    case "pause":
+    case "unpause":
+      return [`${action}${target}`];
+    case "down":
+      return ["down --remove-orphans"];
+    case "destroy":
+      return [`down --remove-orphans${options.removeVolumes ? " -v" : ""}`];
+  }
+}
diff --git a/packages/plugin-sdk/src/host-scripts/index.ts b/packages/plugin-sdk/src/host-scripts/index.ts
new file mode 100644
index 000000000..548e55ef3
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/index.ts
@@ -0,0 +1,15 @@
+/**
+ * Host scripts: command builders and output parsers for Docker, Linux
+ * metrics, systemd, the journal and OpenRC.
+ *
+ * Pure TypeScript with no Node or ssh2 imports, so the same code runs in a
+ * plugin backend and in the mobile app. Run a script by sending it on stdin
+ * to the command from `scriptShell()`.
+ */
+export * from "./text.js";
+export * from "./shell.js";
+export * from "./docker.js";
+export * from "./metrics.js";
+export * from "./systemd.js";
+export * from "./journal.js";
+export * from "./openrc.js";
diff --git a/packages/plugin-sdk/src/host-scripts/journal.ts b/packages/plugin-sdk/src/host-scripts/journal.ts
new file mode 100644
index 000000000..86fe5faff
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/journal.ts
@@ -0,0 +1,242 @@
+/** journalctl scripts and parsers. */
+import { isUnit } from "./systemd.js";
+import { HostScriptError, shellQuote as q, utf8Decode } from "./text.js";
+
+export const MAX_JOURNAL_LINES = 5000;
+const FIELDS = "MESSAGE,PRIORITY,_SYSTEMD_UNIT,SYSLOG_IDENTIFIER,_PID,_COMM";
+
+export interface JournalQuery {
+  units: string[];
+  priority?: number;
+  since?: string;
+  until?: string;
+  boot?: string;
+  grep?: string;
+  lines: number;
+  kernel: boolean;
+}
+
+export interface JournalEntry {
+  /** Unix ms. */
+  time: number;
+  priority: number;
+  unit: string;
+  ident: string;
+  pid: string;
+  message: string;
+}
+
+export interface BootView {
+  offset: number;
+  id: string;
+  first: string;
+  last: string;
+}
+
+const RELATIVE_RE = /^-\d{1,5}(s|m|min|h|d|w)$/;
+const DATE_RE = /^\d{4}-\d{2}-\d{2}( \d{2}:\d{2}(:\d{2})?)?$/;
+const WORDS = ["today", "yesterday", "now"];
+
+export function isJournalTime(value: string): boolean {
+  return (
+    RELATIVE_RE.test(value) || DATE_RE.test(value) || WORDS.includes(value)
+  );
+}
+
+function str(value: unknown): string {
+  return typeof value === "string" ? value.trim() : "";
+}
+
+/** Reads journal filters from a query string. Anything odd throws a HostScriptError. */
+export function parseJournalQuery(
+  input: Record<string, unknown>,
+): JournalQuery {
+  const rawUnits = Array.isArray(input.unit) ? input.unit : [input.unit];
+  const units = rawUnits.map(str).filter(Boolean);
+  for (const unit of units) {
+    if (!isUnit(unit))
+      throw new HostScriptError("That is not a valid unit name");
+  }
+  if (units.length > 20) throw new HostScriptError("Too many units");
+
+  const query: JournalQuery = {
+    units,
+    lines: 300,
+    kernel: input.kernel === "true" || input.kernel === true,
+  };
+  const priority = str(input.priority);
+  if (priority) {
+    const value = Number(priority);
+    if (!Number.isInteger(value) || value < 0 || value > 7) {
+      throw new HostScriptError("priority must be 0 to 7");
+    }
+    query.priority = value;
+  }
+  for (const key of ["since", "until"] as const) {
+    const value = str(input[key]);
+    if (!value) continue;
+    if (!isJournalTime(value))
+      throw new HostScriptError(`${key} is not a valid time`);
+    query[key] = value;
+  }
+  const boot = str(input.boot);
+  if (boot) {
+    if (!/^(-?\d{1,4}|[0-9a-f]{32})$/.test(boot))
+      throw new HostScriptError("boot is not valid");
+    query.boot = boot;
+  }
+  const grep = typeof input.grep === "string" ? input.grep : "";
+  if (grep) {
+    if (grep.length > 200 || /[\r\n\0]/.test(grep)) {
+      throw new HostScriptError("The search is too long");
+    }
+    query.grep = grep;
+  }
+  const lines = Number(str(input.lines) || 300);
+  if (Number.isFinite(lines) && lines > 0) {
+    query.lines = Math.min(MAX_JOURNAL_LINES, Math.round(lines));
+  }
+  return query;
+}
+
+/** journalctl arguments for a query, each one quoted. */
+export function journalArgs(
+  query: Omit<JournalQuery, "lines"> & { lines?: number },
+  options: { follow?: boolean; useGrep?: boolean } = {},
+): string {
+  const args = ["journalctl", "--no-pager", "-q", "-o", "json"];
+  args.push(`--output-fields=${FIELDS}`);
+  if (options.follow) args.push("-f");
+  if (query.lines) args.push("-n", String(Math.floor(query.lines)));
+  for (const unit of query.units) {
+    if (!isUnit(unit))
+      throw new HostScriptError("That is not a valid unit name");
+    args.push("-u", q(unit));
+  }
+  if (query.kernel) args.push("-k");
+  if (query.priority !== undefined)
+    args.push("-p", String(Math.floor(query.priority)));
+  if (query.since) args.push("--since", q(query.since));
+  if (query.until) args.push("--until", q(query.until));
+  if (query.boot) args.push("-b", q(query.boot));
+  if (query.grep && options.useGrep !== false) {
+    args.push("--case-sensitive=false", "-g", q(query.grep));
+  }
+  return args.join(" ");
+}
+
+export function journalScript(query: JournalQuery): string {
+  // Older journalctl builds have no -g. Then the search runs on our side instead.
+  const noGrep = journalArgs(
+    { ...query, lines: query.grep ? MAX_JOURNAL_LINES : query.lines },
+    { useGrep: false },
+  );
+  return `
+command -v journalctl >/dev/null 2>&1 || { echo "SCRIPT_ERR:This host has no journal"; exit 1; }
+${journalArgs(query)} 2>/tmp/termix-journal.$$
+RC=$?
+if [ $RC -ne 0 ] && grep -qi "pattern" /tmp/termix-journal.$$; then
+  rm -f /tmp/termix-journal.$$
+  echo "@@TERMIX_NOGREP@@"
+  ${noGrep}
+  exit 0
+fi
+cat /tmp/termix-journal.$$ >&2; rm -f /tmp/termix-journal.$$
+exit $RC
+`;
+}
+
+function messageOf(value: unknown): string {
+  if (typeof value === "string") return value;
+  if (Array.isArray(value)) {
+    return utf8Decode(value.filter((n): n is number => typeof n === "number"));
+  }
+  return value == null ? "" : String(value);
+}
+
+/** One `journalctl -o json` line, or null when it is not an entry. */
+export function parseEntry(line: string): JournalEntry | null {
+  const text = line.trim();
+  if (!text.startsWith("{")) return null;
+  let raw: Record<string, unknown>;
+  try {
+    raw = JSON.parse(text) as Record<string, unknown>;
+  } catch {
+    return null;
+  }
+  const micros = Number(raw.__REALTIME_TIMESTAMP);
+  const priority = Number(raw.PRIORITY);
+  return {
+    time: Number.isFinite(micros) ? Math.floor(micros / 1000) : 0,
+    priority: Number.isInteger(priority) ? priority : 6,
+    unit: messageOf(raw._SYSTEMD_UNIT),
+    ident: messageOf(raw.SYSLOG_IDENTIFIER ?? raw._COMM),
+    pid: messageOf(raw._PID),
+    message: messageOf(raw.MESSAGE),
+  };
+}
+
+export function parseJournal(
+  output: string,
+  query: JournalQuery,
+): JournalEntry[] {
+  const fallback = output.includes("@@TERMIX_NOGREP@@");
+  const body = fallback ? output.split("@@TERMIX_NOGREP@@")[1] : output;
+  let entries = body
+    .split("\n")
+    .map(parseEntry)
+    .filter((entry): entry is JournalEntry => entry !== null);
+  if (fallback && query.grep) {
+    const needle = query.grep.toLowerCase();
+    entries = entries
+      .filter((entry) => entry.message.toLowerCase().includes(needle))
+      .slice(-query.lines);
+  }
+  return entries;
+}
+
+export const BOOTS_SCRIPT = `journalctl --list-boots --no-pager 2>/dev/null | tail -n 50; exit 0\n`;
+
+export function parseBoots(output: string): BootView[] {
+  const boots: BootView[] = [];
+  for (const line of output.split("\n")) {
+    const match =
+      /^\s*(-?\d+)\s+([0-9a-f]{32})\s+(\w{3} \S+ \S+ \S+)\s*.?\s*(\w{3} \S+ \S+ \S+)?/.exec(
+        line,
+      );
+    if (!match) continue;
+    boots.push({
+      offset: Number(match[1]),
+      id: match[2],
+      first: match[3],
+      last: match[4] ?? "",
+    });
+  }
+  return boots.reverse();
+}
+
+export const USAGE_SCRIPT = `journalctl --disk-usage 2>&1; exit 0\n`;
+
+export function parseUsage(output: string): string {
+  return /take up (\S+)/.exec(output)?.[1] ?? "";
+}
+
+const SIZE_RE = /^\d{1,6}(K|M|G)$/;
+const AGE_RE = /^\d{1,4}(d|w|month|months|year|years)$/;
+
+export function vacuumScript(body: Record<string, unknown>): string {
+  const size = str(body.size);
+  const time = str(body.time);
+  if (!size && !time) throw new HostScriptError("Give a size or an age");
+  if (size && !SIZE_RE.test(size))
+    throw new HostScriptError("Size looks like 500M or 2G");
+  if (time && !AGE_RE.test(time))
+    throw new HostScriptError("Age looks like 7d or 4w");
+  const flags = [
+    size ? `--vacuum-size=${size}` : "",
+    time ? `--vacuum-time=${time}` : "",
+  ]
+    .filter(Boolean)
+    .join(" ");
+  return `journalctl ${flags} 2>&1 || { echo "SCRIPT_ERR:journalctl vacuum failed"; exit 1; }\n`;
+}
diff --git a/packages/plugin-sdk/src/host-scripts/metrics.ts b/packages/plugin-sdk/src/host-scripts/metrics.ts
new file mode 100644
index 000000000..a130670f5
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/metrics.ts
@@ -0,0 +1,433 @@
+/**
+ * Linux metrics: one awk sample of /proc for CPU, memory, load, network and
+ * processes, plus df parsing for disks.
+ */
+
+// One awk reads every /proc file itself, so a sample is one exec of awk instead
+// of a shell plus six tools. Output sections are split by @@; each process line
+// is pid, utime+stime ticks, rss pages, starttime, state, ppid, comm.
+const AWK = String.raw`BEGIN{f="/proc/stat";while((getline l<f)>0)if(l~/^cpu/)print l;close(f);print "@@";f="/proc/meminfo";while((getline l<f)>0)if(l~/^(MemTotal|MemFree|MemAvailable|Buffers|Cached|SwapTotal|SwapFree):/)print l;close(f);print "@@";f="/proc/loadavg";getline l<f;print l;close(f);f="/proc/uptime";getline l<f;print l;close(f);print "@@";f="/proc/net/dev";while((getline l<f)>0)print l;close(f);print "@@";print pg;print "@@";for(i=1;i<ARGC;i++){f=ARGV[i];if((getline s<f)>0){a=index(s,"(");if(a&&match(s,/\)[^)]*$/)){split(substr(s,RSTART+2),x," ");print substr(s,1,a-2)"	"(x[12]+x[13])"	"x[22]"\t"x[20]"\t"x[1]"	"x[2]"	"substr(s,a+1,RSTART-a-1)}}close(f)}}`;
+
+/** The live sample command. The page size never changes on a host, so pass it back once known. */
+export const liveCmd = (pageBytes?: number) =>
+  "awk -v pg=" +
+  (pageBytes ?? '"$(getconf PAGESIZE)"') +
+  " '" +
+  AWK +
+  "' /proc/[0-9]*/stat";
+
+export interface LiveSample {
+  /** The admin minimum between samples; the client never polls faster. */
+  minIntervalS?: number;
+  cpu: number | null;
+  cpuMix?: { user: number; system: number; iowait: number; steal: number };
+  cores: Array<number | null>;
+  coreIds: string[];
+  memTotalKb: number;
+  memCachedKb: number;
+  memFreeKb: number;
+  memUsedKb: number;
+  swapTotalKb: number;
+  swapUsedKb: number;
+  load: [number, number, number];
+  net: Array<{ name: string; rxBps: number | null; txBps: number | null }>;
+  count: number;
+  running: number;
+  procs: Array<{
+    pid: number;
+    name: string;
+    cpu: number;
+    memKb: number;
+    state: string;
+    ppid: number;
+  }>;
+  /** Seconds since boot. */
+  uptime?: number;
+  /** Total bytes received and sent on every interface but lo, since boot. */
+  netTotals?: { rx: number; tx: number };
+}
+
+/** What the next call needs from this one. */
+export interface LivePrev {
+  at: number;
+  uptime: number;
+  pageBytes: number;
+  cpu: Map<string, { total: number; idle: number }>;
+  /** Aggregate user nice system idle iowait irq softirq steal ticks, for the breakdown. */
+  cpuRaw?: number[];
+  /** Keyed by pid:starttime so a reused pid never inherits another process's ticks. */
+  ticks: Map<string, number>;
+  net: Map<string, { rx: number; tx: number }>;
+}
+
+/** Total and idle ticks from a /proc/stat `cpu` line. */
+export function parseCpuLine(
+  cpuLine: string,
+): { total: number; idle: number } | undefined {
+  const parts = cpuLine.trim().split(/\s+/);
+  if (parts[0] !== "cpu") return undefined;
+  const nums = parts
+    .slice(1)
+    .map((n) => Number(n))
+    .filter((n) => Number.isFinite(n));
+  if (nums.length < 4) return undefined;
+  const idle = (nums[3] ?? 0) + (nums[4] ?? 0);
+  const total = nums.reduce((a, b) => a + b, 0);
+  return { total, idle };
+}
+
+const TOP_N = 60;
+
+/** Parses `liveCmd()` output. Rates need the `next` of the previous call. */
+export function parseLive(
+  output: string,
+  prev: LivePrev | undefined,
+  at = Date.now(),
+): { sample: LiveSample; next: LivePrev } {
+  const [cpuS = "", memS = "", loadS = "", netS = "", pageS = "", procS = ""] =
+    output.split("@@\n");
+
+  // Only the first 8 fields: guest and guest_nice are already inside user and nice.
+  const cpu = new Map<string, { total: number; idle: number }>();
+  let cpuRaw: number[] | undefined;
+  for (const l of cpuS.split("\n")) {
+    const name = l.split(/\s+/)[0];
+    if (!name.startsWith("cpu")) continue;
+    if (name === "cpu") cpuRaw = l.split(/\s+/).slice(1, 9).map(Number);
+    const c = parseCpuLine(
+      l
+        .replace(/^cpu\d*/, "cpu")
+        .split(/\s+/)
+        .slice(0, 9)
+        .join(" "),
+    );
+    if (c) cpu.set(name, c);
+  }
+  // Matched by name, so an offline core does not shift the ones after it.
+  const pct = (name: string) => {
+    const p = prev?.cpu.get(name);
+    const c = cpu.get(name);
+    if (!p || !c || c.total <= p.total) return null;
+    const used = c.total - p.total - (c.idle - p.idle);
+    return Math.max(0, Math.min(100, (used / (c.total - p.total)) * 100));
+  };
+
+  // Where the busy time went since the last sample, as percent of all ticks.
+  let cpuMix: LiveSample["cpuMix"];
+  if (prev?.cpuRaw && cpuRaw && cpuRaw.length === 8) {
+    const d = cpuRaw.map((v, i) => v - (prev.cpuRaw?.[i] ?? 0));
+    const total = d.reduce((a, b) => a + b, 0);
+    if (total > 0 && d.every((v) => v >= 0)) {
+      const p = (n: number) => (n / total) * 100;
+      cpuMix = {
+        user: p(d[0] + d[1]),
+        system: p(d[2] + d[5] + d[6]),
+        iowait: p(d[4]),
+        steal: p(d[7]),
+      };
+    }
+  }
+
+  const mem: Record<string, number> = {};
+  for (const l of memS.split("\n")) {
+    const m = l.match(/^(\w+):\s+(\d+)/);
+    if (m) mem[m[1]] = Number(m[2]);
+  }
+
+  const [la = "", up = ""] = loadS.trim().split("\n");
+  const laParts = la.split(/\s+/).map(Number);
+  const uptime = Number(up.split(/\s+/)[0]) || 0;
+
+  const nets = new Map<string, { rx: number; tx: number }>();
+  for (const l of netS.split("\n")) {
+    const [name, rest] = l.split(":");
+    if (!rest || name.trim() === "lo") continue;
+    const f = rest.trim().split(/\s+/);
+    nets.set(name.trim(), { rx: Number(f[0]) || 0, tx: Number(f[8]) || 0 });
+  }
+  // A reboot makes uptime go backwards, so rates start again.
+  const dt = prev && uptime > prev.uptime ? uptime - prev.uptime : 0;
+  const rate = (now: number, before: number | undefined) =>
+    dt > 0 && before !== undefined && now >= before
+      ? (now - before) / dt
+      : null;
+
+  const pageBytes = Number(pageS.trim()) || prev?.pageBytes || 4096;
+  const pageKb = pageBytes / 1024;
+  const aggDelta =
+    prev && cpu.has("cpu") && prev.cpu.has("cpu")
+      ? cpu.get("cpu")!.total - prev.cpu.get("cpu")!.total
+      : 0;
+  const cores = [...cpu.keys()].filter((k) => k !== "cpu");
+  const ncpu = Math.max(1, cores.length);
+  const ticks = new Map<string, number>();
+  const procs: LiveSample["procs"] = [];
+  for (const l of procS.split("\n")) {
+    const [pid, t, rss, start, state, ppid, ...rest] = l.split("\t");
+    const name = rest.join("\t");
+    if (!name) continue;
+    const key = pid + ":" + start;
+    const tk = Number(t) || 0;
+    ticks.set(key, tk);
+    const before = prev?.ticks.get(key);
+    procs.push({
+      pid: Number(pid),
+      name,
+      cpu:
+        before !== undefined && aggDelta > 0 && tk >= before
+          ? ((tk - before) / aggDelta) * ncpu * 100
+          : 0,
+      memKb: (Number(rss) || 0) * pageKb,
+      state: state || "?",
+      ppid: Number(ppid) || 0,
+    });
+  }
+  procs.sort((a, b) => b.cpu - a.cpu || b.memKb - a.memKb);
+
+  // Awk exits 0 when /proc is missing (macOS, restricted containers); that is not a sample.
+  if (!cpu.has("cpu") || !mem.MemTotal || !uptime) {
+    throw new Error("live sample unavailable: /proc data missing");
+  }
+  const memTotalKb = mem.MemTotal;
+  const swapTotalKb = mem.SwapTotal ?? 0;
+  let rxTotal = 0;
+  let txTotal = 0;
+  for (const c of nets.values()) {
+    rxTotal += c.rx;
+    txTotal += c.tx;
+  }
+  return {
+    sample: {
+      cpu: pct("cpu"),
+      cores: cores.map(pct),
+      coreIds: cores.map((k) => k.slice(3)),
+      cpuMix,
+      memTotalKb,
+      memCachedKb: (mem.Buffers ?? 0) + (mem.Cached ?? 0),
+      memFreeKb: mem.MemFree ?? 0,
+      memUsedKb: memTotalKb - (mem.MemAvailable ?? 0),
+      swapTotalKb,
+      swapUsedKb: swapTotalKb - (mem.SwapFree ?? 0),
+      load: [laParts[0] || 0, laParts[1] || 0, laParts[2] || 0],
+      net: [...nets].map(([name, c]) => ({
+        name,
+        rxBps: rate(c.rx, prev?.net.get(name)?.rx),
+        txBps: rate(c.tx, prev?.net.get(name)?.tx),
+      })),
+      count: procs.length,
+      running: procs.filter((p) => p.state === "R").length,
+      procs: procs.slice(0, TOP_N),
+      uptime,
+      netTotals: { rx: rxTotal, tx: txTotal },
+    },
+    next: { at, uptime, pageBytes, cpu, cpuRaw, ticks, net: nets },
+  };
+}
+
+// Disks
+
+const DARWIN_DATA_MOUNT = "/System/Volumes/Data";
+const PSEUDO_FS_RE =
+  /^(tmpfs|devtmpfs|overlay|udev|none|shm|squashfs|efivarfs)$/;
+
+/** GNU df sizes in KiB, without the header. */
+export const DF_BYTES_COMMAND = "df -TkP | tail -n +2";
+/** GNU df sizes as short human text, without the header. */
+export const DF_HUMAN_COMMAND = "df -hT -P | tail -n +2";
+
+export interface DfRow {
+  filesystem: string;
+  type: string;
+  mount: string;
+  parts: string[];
+}
+
+export interface DiskFilesystem {
+  filesystem: string;
+  type: string;
+  mount: string;
+  percent: number | null;
+  usedHuman: string | null;
+  totalHuman: string | null;
+  availableHuman: string | null;
+  usedBytes: number | null;
+  totalBytes: number | null;
+  availableBytes: number | null;
+  label?: string;
+}
+
+export interface MonitoredMount {
+  path: string;
+  label?: string;
+}
+
+function toFixedNum(n: number | null | undefined, digits = 2): number | null {
+  if (typeof n !== "number" || !Number.isFinite(n)) return null;
+  return Number(n.toFixed(digits));
+}
+
+/**
+ * Parses `df -T -P` style output: Filesystem, Type, then the size columns,
+ * with Mounted-on last. Pseudo filesystems are left out.
+ */
+export function parseDfLines(output: string): DfRow[] {
+  return output
+    .split("\n")
+    .map((l) => l.trim())
+    .filter(Boolean)
+    .map((line) => {
+      const parts = line.split(/\s+/);
+      return {
+        filesystem: parts[0] || "",
+        type: parts[1] || "",
+        mount: parts[6] || "",
+        parts,
+      };
+    })
+    .filter((row) => row.parts.length >= 7 && !PSEUDO_FS_RE.test(row.type));
+}
+
+/** The most used real filesystem in a `df -TkP` row set. */
+export function findWorstMountIndex(bytesRows: DfRow[]): {
+  index: number;
+  usedBytes: number;
+  totalBytes: number;
+} {
+  let worstIndex = -1;
+  let worstUsedBytes = -1;
+  let worstTotalBytes = 0;
+  bytesRows.forEach((row, index) => {
+    const totalBytes = Number(row.parts[2]);
+    const usedBytes = Number(row.parts[3]);
+    if (
+      !Number.isFinite(totalBytes) ||
+      !Number.isFinite(usedBytes) ||
+      totalBytes <= 0
+    ) {
+      return;
+    }
+    const usedRatio = usedBytes / totalBytes;
+    const worstRatio =
+      worstTotalBytes > 0 ? worstUsedBytes / worstTotalBytes : -1;
+    if (usedRatio > worstRatio) {
+      worstIndex = index;
+      worstUsedBytes = usedBytes;
+      worstTotalBytes = totalBytes;
+    }
+  });
+  return {
+    index: worstIndex,
+    usedBytes: worstUsedBytes,
+    totalBytes: worstTotalBytes,
+  };
+}
+
+/**
+ * Merges `df -TkP` size rows (parts[2..4] in `blockSizeBytes` units) and
+ * `df -hT -P` human rows into one list. Human rows only supply the display
+ * text, matched by mount point so a mismatched row count can't shift them.
+ */
+export function buildFilesystemList(
+  bytesRows: DfRow[],
+  humanRows: DfRow[],
+  blockSizeBytes = 1,
+): DiskFilesystem[] {
+  const aligned = humanRows.length === bytesRows.length;
+  return bytesRows
+    .map((row, index) => {
+      const totalBytes = Number(row.parts[2]) * blockSizeBytes;
+      const usedBytes = Number(row.parts[3]) * blockSizeBytes;
+      const availableBytes = Number(row.parts[4]) * blockSizeBytes;
+      if (!Number.isFinite(totalBytes) || totalBytes <= 0) return null;
+      const humanRow = aligned
+        ? humanRows[index]
+        : humanRows.find((h) => h.mount === row.mount);
+      const percent = Number.isFinite(usedBytes)
+        ? Math.max(0, Math.min(100, (usedBytes / totalBytes) * 100))
+        : null;
+      return {
+        filesystem: row.filesystem,
+        type: row.type,
+        mount: row.mount,
+        percent: toFixedNum(percent, 0),
+        usedHuman: humanRow?.parts[3] || null,
+        totalHuman: humanRow?.parts[2] || null,
+        availableHuman: humanRow?.parts[4] || null,
+        usedBytes: Number.isFinite(usedBytes) ? usedBytes : null,
+        totalBytes,
+        availableBytes: Number.isFinite(availableBytes) ? availableBytes : null,
+      };
+    })
+    .filter((fs): fs is DiskFilesystem => fs !== null);
+}
+
+/**
+ * The headline disk is the root filesystem. On macOS "/" is the small sealed
+ * system volume, so the data volume wins there. With no root mount the most
+ * used one is shown.
+ */
+export function selectPrimaryFilesystem(
+  filesystems: DiskFilesystem[],
+): DiskFilesystem | null {
+  if (filesystems.length === 0) return null;
+  const root =
+    filesystems.find((fs) => fs.mount === DARWIN_DATA_MOUNT) ??
+    filesystems.find((fs) => fs.mount === "/");
+  if (root) return root;
+  let best = filesystems[0];
+  for (const fs of filesystems) {
+    const ratio = (fs.usedBytes ?? 0) / (fs.totalBytes || 1);
+    const bestRatio = (best.usedBytes ?? 0) / (best.totalBytes || 1);
+    if (ratio > bestRatio) best = fs;
+  }
+  return best;
+}
+
+/**
+ * Drops mounts by exact path ("/mnt/nas") or by filesystem type substring
+ * ("nfs" matches nfs and nfs4), so network shares can be hidden.
+ */
+export function filterExcludedFilesystems(
+  filesystems: DiskFilesystem[],
+  excludedMounts?: string[] | null,
+): DiskFilesystem[] {
+  if (!excludedMounts || excludedMounts.length === 0) return filesystems;
+  const normalized = excludedMounts
+    .map((entry) => entry.trim().toLowerCase())
+    .filter(Boolean);
+  if (normalized.length === 0) return filesystems;
+  return filesystems.filter((fs) => {
+    const mount = fs.mount.toLowerCase();
+    const type = fs.type.toLowerCase();
+    return !normalized.some(
+      (entry) => mount === entry || (type && type.includes(entry)),
+    );
+  });
+}
+
+export function mergeMonitoredFilesystems(
+  filesystems: DiskFilesystem[],
+  monitored: MonitoredMount[],
+  customFilesystems: Array<DiskFilesystem | null>,
+): DiskFilesystem[] {
+  const result = [...filesystems];
+  monitored.forEach((entry, index) => {
+    const path = entry.path.trim();
+    const custom = customFilesystems[index];
+    if (!path || !custom) return;
+    const existing = result.find((fs) => fs.mount === path);
+    if (existing) {
+      existing.label = entry.label?.trim() || undefined;
+      return;
+    }
+    result.push({
+      ...custom,
+      mount: path,
+      label: entry.label?.trim() || undefined,
+    });
+  });
+  return result;
+}
+
+/** Host name, OS, kernel and arch in one exec, as key=value lines. */
+export const SYSTEM_INFO_COMMAND = `echo "hostname=$(hostname 2>/dev/null || cat /etc/hostname 2>/dev/null)"; echo "os=$( . /etc/os-release 2>/dev/null; echo "$PRETTY_NAME")"; echo "kernel=$(uname -r 2>/dev/null)"; echo "arch=$(uname -m 2>/dev/null)"`;
diff --git a/packages/plugin-sdk/src/host-scripts/openrc.ts b/packages/plugin-sdk/src/host-scripts/openrc.ts
new file mode 100644
index 000000000..287da98ff
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/openrc.ts
@@ -0,0 +1,94 @@
+/** OpenRC scripts, with states mapped onto the words systemd uses. */
+import { isOpenRcName, type UnitAction, type UnitSummary } from "./systemd.js";
+import { HostScriptError, shellQuote as q } from "./text.js";
+
+export const OPENRC_LIST_SCRIPT = `
+rc-status --servicelist 2>/dev/null
+echo "@@TERMIX_RUNLEVELS@@"
+rc-update show -v 2>/dev/null
+exit 0
+`;
+
+function activeOf(state: string): { active: string; sub: string } {
+  switch (state) {
+    case "started":
+      return { active: "active", sub: "running" };
+    case "crashed":
+      return { active: "failed", sub: "crashed" };
+    case "starting":
+      return { active: "activating", sub: "starting" };
+    case "stopping":
+      return { active: "deactivating", sub: "stopping" };
+    case "inactive":
+    case "hotplugged":
+      return { active: "inactive", sub: state };
+    default:
+      return { active: "inactive", sub: state || "stopped" };
+  }
+}
+
+export function parseOpenRcList(output: string): UnitSummary[] {
+  const [list = "", levels = ""] = output.split("@@TERMIX_RUNLEVELS@@");
+  const units = new Map<string, UnitSummary>();
+  for (const line of list.split("\n")) {
+    const match = /^\s*(\S+)\s+\[\s*([a-z ]+?)\s*\]/.exec(line);
+    if (!match) continue;
+    const { active, sub } = activeOf(match[2]);
+    units.set(match[1], {
+      name: match[1],
+      type: "service",
+      load: "loaded",
+      active,
+      sub,
+      description: "",
+      fileState: "disabled",
+      preset: "",
+    });
+  }
+  for (const line of levels.split("\n")) {
+    const match = /^\s*(\S+)\s*\|\s*(.*)$/.exec(line);
+    if (!match) continue;
+    const runlevels = match[2].trim();
+    const known = units.get(match[1]) ?? {
+      name: match[1],
+      type: "service",
+      load: "loaded",
+      active: "inactive",
+      sub: "stopped",
+      description: "",
+      fileState: "disabled",
+      preset: "",
+    };
+    known.fileState = runlevels ? "enabled" : "disabled";
+    known.description = runlevels ? `Runlevels: ${runlevels}` : "";
+    units.set(match[1], known);
+  }
+  return [...units.values()].sort((a, b) => a.name.localeCompare(b.name));
+}
+
+function requireName(name: string): string {
+  if (!isOpenRcName(name))
+    throw new HostScriptError("That is not a valid service name");
+  return name;
+}
+
+export function openRcActionScript(name: string, action: UnitAction): string {
+  const s = q(requireName(name));
+  switch (action) {
+    case "start":
+    case "stop":
+    case "restart":
+      return `rc-service ${s} ${action} 2>&1 || { echo "SCRIPT_ERR:rc-service ${action} failed"; exit 1; }\n`;
+    case "enable":
+      return `rc-update add ${s} default 2>&1 || { echo "SCRIPT_ERR:rc-update add failed"; exit 1; }\n`;
+    case "disable":
+      return `rc-update del ${s} 2>&1 || { echo "SCRIPT_ERR:rc-update del failed"; exit 1; }\n`;
+    default:
+      throw new HostScriptError("OpenRC can't do that", 400);
+  }
+}
+
+export function openRcStatusScript(name: string): string {
+  const s = q(requireName(name));
+  return `rc-service ${s} status 2>&1; rc-update show -v 2>/dev/null | grep -E '^ *'${s}' *\\|'; exit 0\n`;
+}
diff --git a/packages/plugin-sdk/src/host-scripts/shell.ts b/packages/plugin-sdk/src/host-scripts/shell.ts
new file mode 100644
index 000000000..5b4f27f20
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/shell.ts
@@ -0,0 +1,117 @@
+/**
+ * How a script reaches the host: the command line runs a shell that reads
+ * the script from stdin (`bash -s`), so names and values in a script are
+ * never parsed out of argv.
+ */
+import { shellQuote, toBase64 } from "./text.js";
+
+// systemctl and friends often live in sbin, which a normal login skips.
+// TZ=UTC so tools print every time in UTC, which parses the same anywhere.
+const ENV = "SYSTEMD_COLORS=0 SYSTEMD_PAGER=cat LC_ALL=C TZ=UTC";
+
+/** Puts sbin on PATH and sets a plain, UTC environment. */
+export const SCRIPT_PRELUDE = `export PATH="$PATH:/usr/sbin:/sbin:/usr/local/sbin"; export ${ENV}; `;
+const SUDO = `sudo -n env PATH="$PATH" ${ENV}`;
+
+/**
+ * - `plain`: the login user.
+ * - `auto`: root when it can be had without a password, else the login user.
+ * - `root`: root or passwordless sudo, fails on anything else.
+ * - `root-only`: root logins only, for hosts where sudo is turned off.
+ */
+export type ScriptShellMode = "plain" | "auto" | "root" | "root-only";
+
+const ERR = "SCRIPT_ERR:";
+
+/** The command line that runs a script sent on stdin. */
+export function scriptShell(mode: ScriptShellMode): string {
+  switch (mode) {
+    case "plain":
+      return `${SCRIPT_PRELUDE}exec bash -s`;
+    case "auto":
+      return `${SCRIPT_PRELUDE}if [ "$(id -u)" = "0" ]; then exec bash -s; elif sudo -n true 2>/dev/null; then exec ${SUDO} bash -s; else exec bash -s; fi`;
+    case "root":
+      return `${SCRIPT_PRELUDE}if [ "$(id -u)" = "0" ]; then exec bash -s; else exec ${SUDO} bash -s; fi`;
+    case "root-only":
+      return `${SCRIPT_PRELUDE}if [ "$(id -u)" = "0" ]; then exec bash -s; else echo "${ERR}This needs root, or turn on Use sudo for this host"; exit 1; fi`;
+  }
+}
+
+/**
+ * Runs a script as root with a sudo password. The command is `plain`; all of
+ * the returned stdin goes to the host. The password is read by the first
+ * line into a shell variable and piped to `sudo -S`, so it is never in argv,
+ * never in the environment and never run as a command. Root logins and
+ * passwordless sudo skip the password. The script itself travels as base64.
+ */
+export function passwordSudoScript(
+  script: string,
+  password: string,
+): { command: string; stdin: string } {
+  if (/[\r\n\0]/.test(password)) {
+    throw new Error("A sudo password can't contain a line break");
+  }
+  const run = `bash -c "$TERMIX_S"`;
+  const stdin = `IFS= read -r TERMIX_PW
+${password}
+TERMIX_S=$(printf '%s' ${shellQuote(toBase64(script))} | base64 -d)
+if [ "$(id -u)" = "0" ]; then unset TERMIX_PW; exec ${run}
+elif sudo -n true 2>/dev/null; then unset TERMIX_PW; exec ${SUDO} ${run}
+else P=$TERMIX_PW; unset TERMIX_PW; printf '%s\\n' "$P" | sudo -k -S -p '' env PATH="$PATH" ${ENV} ${run}; exit $?
+fi
+`;
+  return { command: scriptShell("plain"), stdin };
+}
+
+/** sudo asked for a password or a terminal it did not get. */
+export const SUDO_REFUSED_RE =
+  /password is required|a terminal is required|no tty present/i;
+/** sudo got a password and it was wrong. */
+export const SUDO_WRONG_RE =
+  /incorrect password|sorry, try again|no password was provided/i;
+/** The user may not use sudo at all. */
+export const NOT_SUDOER_RE =
+  /is not in the sudoers file|not allowed to run sudo/i;
+
+/**
+ * Scripts print `SCRIPT_ERR:` lines (or the older `SERVICES_ERR:`) before a
+ * non zero exit to explain a failure.
+ */
+export function scriptError(stdout: string): string {
+  return stdout
+    .split("\n")
+    .map((line) => {
+      if (line.startsWith(ERR)) return line.slice(ERR.length);
+      if (line.startsWith("SERVICES_ERR:")) return line.slice(13);
+      return null;
+    })
+    .filter((line): line is string => line !== null)
+    .join("\n")
+    .trim();
+}
+
+/** A line a script prints to explain why it stops. */
+export function errLine(message: string): string {
+  return `echo ${shellQuote(ERR + message)}`;
+}
+
+/**
+ * Runs a long command in the background and stops it once stdin closes,
+ * which happens when the SSH channel ends. A pty can't be trusted for this:
+ * sudo keeps its own and the command would outlive the viewer.
+ */
+export function watchdog(command: string): string {
+  return `${command} &
+P=$!
+trap 'kill $P 2>/dev/null' EXIT
+cat >/dev/null
+`;
+}
+
+/** The wrapper a streamed command runs in, as one shell command line. */
+export function streamCommand(script: string, sudo: boolean): string {
+  const quoted = shellQuote(`${SCRIPT_PRELUDE}${script}`);
+  return sudo
+    ? `if [ "$(id -u)" = "0" ]; then exec bash -c ${quoted}; elif sudo -n true 2>/dev/null; then exec ${SUDO} bash -c ${quoted}; else exec bash -c ${quoted}; fi`
+    : `exec bash -c ${quoted}`;
+}
diff --git a/packages/plugin-sdk/src/host-scripts/systemd.ts b/packages/plugin-sdk/src/host-scripts/systemd.ts
new file mode 100644
index 000000000..9d3481b90
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/systemd.ts
@@ -0,0 +1,389 @@
+/**
+ * systemd unit scripts and parsers, plus init system detection.
+ * Every script is meant for `scriptShell()`, sent on stdin.
+ */
+import { HostScriptError, parseKeys, shellQuote as q } from "./text.js";
+
+export const UNIT_TYPES = [
+  "service",
+  "socket",
+  "timer",
+  "target",
+  "mount",
+  "automount",
+  "path",
+  "swap",
+  "slice",
+  "scope",
+  "device",
+] as const;
+export type UnitType = (typeof UNIT_TYPES)[number];
+
+// Backslash is allowed for escaped names like dev-disk-by\x2duuid.
+const UNIT_RE = new RegExp(
+  `^[A-Za-z0-9_][A-Za-z0-9:_.@\\\\-]{0,250}\\.(${UNIT_TYPES.join("|")})$`,
+);
+const OPENRC_RE = /^[A-Za-z0-9_][A-Za-z0-9_.@-]{0,127}$/;
+
+export function isUnit(name: unknown): name is string {
+  return typeof name === "string" && UNIT_RE.test(name);
+}
+
+export function unitType(name: string): UnitType {
+  return name.slice(name.lastIndexOf(".") + 1) as UnitType;
+}
+
+/** Units a file may be written for. Templates and device style names are out. */
+export function isWritableUnitName(name: string): boolean {
+  return (
+    isUnit(name) &&
+    !name.includes("\\") &&
+    ["service", "socket", "timer", "target", "path", "mount"].includes(
+      unitType(name),
+    )
+  );
+}
+
+export function isOpenRcName(name: unknown): name is string {
+  return typeof name === "string" && OPENRC_RE.test(name);
+}
+
+export function requireUnit(name: unknown): string {
+  if (!isUnit(name)) throw new HostScriptError("That is not a valid unit name");
+  return name;
+}
+
+export type InitSystem = "systemd" | "openrc" | "none";
+
+/** A unit name or, on OpenRC, a service name. */
+export function requireService(name: unknown, init: string): string {
+  if (init === "openrc") {
+    if (!isOpenRcName(name))
+      throw new HostScriptError("That is not a valid service name");
+    return name;
+  }
+  return requireUnit(name);
+}
+
+export interface UnitSummary {
+  name: string;
+  type: string;
+  load: string;
+  active: string;
+  sub: string;
+  description: string;
+  /** enabled, disabled, static, masked and so on. Empty when unknown. */
+  fileState: string;
+  preset: string;
+}
+
+export interface UnitDetail {
+  name: string;
+  props: Record<string, string>;
+  status: string;
+}
+
+export interface TimerView {
+  name: string;
+  description: string;
+  active: string;
+  fileState: string;
+  /** Unix ms, or null when not set. */
+  next: number | null;
+  last: number | null;
+  activates: string;
+  schedule: string[];
+}
+
+export const UNIT_ACTIONS = [
+  "start",
+  "stop",
+  "restart",
+  "reload",
+  "enable",
+  "disable",
+  "enable-now",
+  "disable-now",
+  "mask",
+  "unmask",
+  "reset-failed",
+  "revert",
+] as const;
+export type UnitAction = (typeof UNIT_ACTIONS)[number];
+
+/** Actions OpenRC can do. */
+export const OPENRC_ACTIONS: readonly UnitAction[] = [
+  "start",
+  "stop",
+  "restart",
+  "enable",
+  "disable",
+];
+
+export const DETECT_SCRIPT = `
+INIT=none
+if command -v systemctl >/dev/null 2>&1 && [ -d /run/systemd/system ]; then INIT=systemd
+elif command -v rc-service >/dev/null 2>&1; then INIT=openrc; fi
+echo "init=$INIT"
+if [ "$INIT" = systemd ]; then echo "version=$(systemctl --version 2>/dev/null | head -n1 | awk '{print $2}')"; fi
+if [ "$INIT" = openrc ]; then echo "version=$(openrc --version 2>/dev/null | head -n1 | awk '{print $NF}')"; fi
+echo "os=$( . /etc/os-release 2>/dev/null; echo "$PRETTY_NAME")"
+echo "hostname=$(hostname 2>/dev/null || cat /etc/hostname 2>/dev/null)"
+echo "uid=$(id -u)"
+if command -v journalctl >/dev/null 2>&1; then echo "journal=1"; fi
+if [ "$INIT" = systemd ]; then echo "failed=$(systemctl list-units --state=failed --plain --no-legend --no-pager 2>/dev/null | wc -l)"; fi
+if [ "$INIT" = openrc ]; then echo "failed=$(rc-status --crashed 2>/dev/null | wc -l)"; fi
+exit 0
+`;
+
+export interface Detected {
+  init: InitSystem;
+  version: string;
+  os: string;
+  hostname: string;
+  root: boolean;
+  journal: boolean;
+  failed: number;
+}
+
+export function parseDetect(output: string): Detected {
+  const keys = parseKeys(output);
+  const init =
+    keys.init === "systemd" || keys.init === "openrc" ? keys.init : "none";
+  return {
+    init,
+    version: keys.version ?? "",
+    os: keys.os ?? "",
+    hostname: keys.hostname ?? "",
+    root: keys.uid === "0",
+    journal: keys.journal === "1",
+    failed: Number(keys.failed) || 0,
+  };
+}
+
+/** Types the list can show. */
+export const LIST_TYPES = [
+  "service",
+  "socket",
+  "timer",
+  "target",
+  "path",
+  "mount",
+] as const;
+export type ListType = (typeof LIST_TYPES)[number] | "all";
+
+export function listUnitsScript(type: ListType): string {
+  const types = type === "all" ? LIST_TYPES.join(",") : type;
+  if (type !== "all" && !LIST_TYPES.includes(type))
+    throw new HostScriptError("Unknown unit type");
+  return `
+systemctl list-units --all --plain --no-legend --no-pager --full --type=${types} 2>/dev/null
+echo "@@TERMIX_FILES@@"
+systemctl list-unit-files --plain --no-legend --no-pager --full --type=${types} 2>/dev/null
+exit 0
+`;
+}
+
+/** Merges list-units and list-unit-files. Template units are left out. */
+export function parseUnitList(output: string): UnitSummary[] {
+  const [loaded = "", files = ""] = output.split("@@TERMIX_FILES@@");
+  const units = new Map<string, UnitSummary>();
+  for (const raw of loaded.split("\n")) {
+    const line = raw.replace(/^[●*\s]+/, "").trimEnd();
+    if (!line) continue;
+    const match = /^(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s*(.*)$/.exec(line);
+    if (!match) continue;
+    const [, name, load, active, sub, description] = match;
+    if (!name.includes(".") || name.includes("@.")) continue;
+    units.set(name, {
+      name,
+      type: unitType(name),
+      load,
+      active,
+      sub,
+      description: description.trim(),
+      fileState: "",
+      preset: "",
+    });
+  }
+  for (const raw of files.split("\n")) {
+    const line = raw.trim();
+    if (!line) continue;
+    const [name, state = "", preset = ""] = line.split(/\s+/);
+    if (!name || !name.includes(".") || name.includes("@.")) continue;
+    const known = units.get(name);
+    const cleanPreset = preset === "-" ? "" : preset;
+    if (known) {
+      known.fileState = state;
+      known.preset = cleanPreset;
+    } else {
+      units.set(name, {
+        name,
+        type: unitType(name),
+        load: state === "masked" ? "masked" : "unloaded",
+        active: "inactive",
+        sub: "dead",
+        description: "",
+        fileState: state,
+        preset: cleanPreset,
+      });
+    }
+  }
+  return [...units.values()].sort((a, b) => a.name.localeCompare(b.name));
+}
+
+export const DETAIL_PROPS = [
+  "Id",
+  "Description",
+  "LoadState",
+  "ActiveState",
+  "SubState",
+  "UnitFileState",
+  "UnitFilePreset",
+  "Result",
+  "MainPID",
+  "ExecMainStartTimestamp",
+  "ActiveEnterTimestamp",
+  "InactiveEnterTimestamp",
+  "MemoryCurrent",
+  "MemoryPeak",
+  "CPUUsageNSec",
+  "TasksCurrent",
+  "NRestarts",
+  "FragmentPath",
+  "DropInPaths",
+  "Requires",
+  "Wants",
+  "After",
+  "WantedBy",
+  "TriggeredBy",
+  "Triggers",
+  "User",
+  "Group",
+  "Restart",
+  "Type",
+  "ExecStart",
+  "CanStart",
+  "CanStop",
+  "CanReload",
+] as const;
+
+export function detailScript(unit: string): string {
+  const props = DETAIL_PROPS.map((p) => `-p ${p}`).join(" ");
+  return `
+systemctl show --no-pager ${props} -- ${q(requireUnit(unit))}
+echo "@@TERMIX_STATUS@@"
+systemctl status --no-pager --full -n 0 -- ${q(unit)} 2>&1
+exit 0
+`;
+}
+
+export function parseDetail(unit: string, output: string): UnitDetail {
+  const [props = "", status = ""] = output.split("@@TERMIX_STATUS@@");
+  return { name: unit, props: parseKeys(props), status: status.trim() };
+}
+
+const VERBS: Record<UnitAction, string> = {
+  start: "start",
+  stop: "stop",
+  restart: "restart",
+  reload: "reload",
+  enable: "enable",
+  disable: "disable",
+  "enable-now": "enable --now",
+  "disable-now": "disable --now",
+  mask: "mask",
+  unmask: "unmask",
+  "reset-failed": "reset-failed",
+  revert: "revert",
+};
+
+/** The systemctl call for an action. Prints `state=` after it. */
+export function actionScript(unit: string, action: UnitAction): string {
+  const verb = VERBS[action];
+  if (!verb) throw new HostScriptError("Unknown action");
+  const u = q(requireUnit(unit));
+  return `
+systemctl ${verb} -- ${u} 2>&1 || { echo "SCRIPT_ERR:systemctl ${verb} failed"; exit 1; }
+echo "state=$(systemctl is-active -- ${u} 2>/dev/null)"
+`;
+}
+
+/** Times systemctl prints under TZ=UTC, like "Thu 2026-10-22 02:03:51 UTC". */
+export function parseSystemdTime(value: string | undefined): number | null {
+  if (!value) return null;
+  const match = /(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})/.exec(value);
+  if (!match) return null;
+  const [, y, mo, d, h, mi, s] = match.map(Number);
+  return Date.UTC(y, mo - 1, d, h, mi, s);
+}
+
+export const TIMERS_SCRIPT = `
+UNITS=$( { systemctl list-units --all --type=timer --plain --no-legend --no-pager --full 2>/dev/null | awk '{print $1}'; systemctl list-unit-files --type=timer --plain --no-legend --no-pager --full 2>/dev/null | awk '{print $1}'; } | grep '\\.timer$' | grep -v '@\\.timer$' | sort -u)
+[ -n "$UNITS" ] || exit 0
+systemctl show --no-pager -p Id -p Description -p ActiveState -p UnitFileState -p NextElapseUSecRealtime -p LastTriggerUSec -p Triggers -p TimersCalendar -p TimersMonotonic -- $UNITS
+exit 0
+`;
+
+/** Reads systemctl show output for many units, split by blank lines. */
+export function parseShowBlocks(output: string): Array<Record<string, string>> {
+  const blocks: Array<Record<string, string>> = [];
+  for (const block of output.split(/\n\s*\n/)) {
+    const lines = block.split("\n").filter((line) => line.includes("="));
+    if (!lines.length) continue;
+    // A unit can have several TimersCalendar lines; keep all of them.
+    const keys: Record<string, string> = {};
+    for (const line of lines) {
+      const eq = line.indexOf("=");
+      const key = line.slice(0, eq).trim();
+      const value = line.slice(eq + 1).trim();
+      keys[key] = key in keys ? `${keys[key]}\n${value}` : value;
+    }
+    blocks.push(keys);
+  }
+  return blocks;
+}
+
+function schedules(value: string | undefined): string[] {
+  if (!value) return [];
+  const out: string[] = [];
+  for (const line of value.split("\n")) {
+    const match = /\{\s*(\w+)=(.+?)\s*;/.exec(line);
+    if (match) out.push(`${match[1]}=${match[2]}`);
+  }
+  return out;
+}
+
+export function parseTimers(output: string): TimerView[] {
+  return parseShowBlocks(output)
+    .filter((keys) => keys.Id?.endsWith(".timer"))
+    .map((keys) => ({
+      name: keys.Id,
+      description: keys.Description ?? "",
+      active: keys.ActiveState ?? "",
+      fileState: keys.UnitFileState ?? "",
+      next: parseSystemdTime(keys.NextElapseUSecRealtime),
+      last: parseSystemdTime(keys.LastTriggerUSec),
+      activates: (keys.Triggers ?? "").split(/\s+/)[0] ?? "",
+      schedule: [
+        ...schedules(keys.TimersCalendar),
+        ...schedules(keys.TimersMonotonic),
+      ],
+    }))
+    .sort((a, b) => (a.next ?? Infinity) - (b.next ?? Infinity));
+}
+
+/** One line per unit from systemctl is-active, in the order asked. */
+export function isActiveScript(units: string[]): string {
+  return `systemctl is-active -- ${units.map((u) => q(requireUnit(u))).join(" ")} 2>/dev/null; exit 0\n`;
+}
+
+export function parseIsActive(
+  units: string[],
+  output: string,
+): Map<string, string> {
+  const lines = output.split("\n").map((line) => line.trim());
+  const out = new Map<string, string>();
+  units.forEach((unit, i) => out.set(unit, lines[i] || "unknown"));
+  return out;
+}
diff --git a/packages/plugin-sdk/src/host-scripts/text.ts b/packages/plugin-sdk/src/host-scripts/text.ts
new file mode 100644
index 000000000..3f1217edd
--- /dev/null
+++ b/packages/plugin-sdk/src/host-scripts/text.ts
@@ -0,0 +1,118 @@
+/**
+ * Quoting, encoding and the error type the host scripts share.
+ *
+ * No Node APIs here: this entry also runs in the mobile app.
+ */
+
+/** A bad input to a host script builder. `status` is the HTTP status to answer with. */
+export class HostScriptError extends Error {
+  constructor(
+    message: string,
+    readonly status = 400,
+    readonly extra: Record<string, unknown> = {},
+  ) {
+    super(message);
+    this.name = "HostScriptError";
+  }
+}
+
+/** Wraps a value in single quotes for a POSIX shell. */
+export function shellQuote(value: string): string {
+  return `'${value.replace(/'/g, `'\\''`)}'`;
+}
+
+// Written by hand because some JS engines (Hermes) have no TextDecoder.
+
+/** UTF-8 bytes of a string. */
+export function utf8Encode(text: string): Uint8Array {
+  const out: number[] = [];
+  for (const char of text) {
+    const cp = char.codePointAt(0) ?? 0xfffd;
+    if (cp < 0x80) out.push(cp);
+    else if (cp < 0x800) out.push(0xc0 | (cp >> 6), 0x80 | (cp & 63));
+    else if (cp < 0x10000) {
+      out.push(0xe0 | (cp >> 12), 0x80 | ((cp >> 6) & 63), 0x80 | (cp & 63));
+    } else {
+      out.push(
+        0xf0 | (cp >> 18),
+        0x80 | ((cp >> 12) & 63),
+        0x80 | ((cp >> 6) & 63),
+        0x80 | (cp & 63),
+      );
+    }
+  }
+  return Uint8Array.from(out);
+}
+
+/** A string from UTF-8 bytes. Bad sequences become U+FFFD. */
+export function utf8Decode(bytes: ArrayLike<number>): string {
+  let out = "";
+  let i = 0;
+  while (i < bytes.length) {
+    const b = bytes[i];
+    let need = 0;
+    let cp = 0;
+    if (b < 0x80) cp = b;
+    else if (b >= 0xc2 && b < 0xe0) [need, cp] = [1, b & 31];
+    else if (b >= 0xe0 && b < 0xf0) [need, cp] = [2, b & 15];
+    else if (b >= 0xf0 && b < 0xf5) [need, cp] = [3, b & 7];
+    else {
+      out += "\ufffd";
+      i++;
+      continue;
+    }
+    let j = 1;
+    for (; j <= need; j++) {
+      const next = bytes[i + j];
+      if (next === undefined || (next & 0xc0) !== 0x80) break;
+      cp = (cp << 6) | (next & 63);
+    }
+    const tooSmall = [0, 0x80, 0x800, 0x10000][need];
+    if (
+      j <= need ||
+      cp < tooSmall ||
+      cp > 0x10ffff ||
+      (cp >= 0xd800 && cp < 0xe000)
+    ) {
+      out += "\ufffd";
+      i += Math.max(1, j);
+      continue;
+    }
+    out += String.fromCodePoint(cp);
+    i += need + 1;
+  }
+  return out;
+}
+
+const B64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/** Base64 of the UTF-8 bytes of a string, for `base64 -d` on the host. */
+export function toBase64(text: string): string {
+  const bytes = utf8Encode(text);
+  let out = "";
+  for (let i = 0; i < bytes.length; i += 3) {
+    const a = bytes[i];
+    const b = i + 1 < bytes.length ? bytes[i + 1] : 0;
+    const c = i + 2 < bytes.length ? bytes[i + 2] : 0;
+    const n = (a << 16) | (b << 8) | c;
+    out += B64[(n >> 18) & 63] + B64[(n >> 12) & 63];
+    out += i + 1 < bytes.length ? B64[(n >> 6) & 63] : "=";
+    out += i + 2 < bytes.length ? B64[n & 63] : "=";
+  }
+  return out;
+}
+
+/** Reads key=value lines. Only the first = splits a line. */
+export function parseKeys(output: string): Record<string, string> {
+  const out: Record<string, string> = {};
+  for (const line of output.split("\n")) {
+    const eq = line.indexOf("=");
+    if (eq > 0) out[line.slice(0, eq).trim()] = line.slice(eq + 1).trim();
+  }
+  return out;
+}
+
+/** Trims output and keeps it short enough to show. */
+export function scrub(text: string, max = 600): string {
+  return text.trim().slice(0, max);
+}
diff --git a/src/backend/tests/plugins/host-scripts/docker.test.ts b/src/backend/tests/plugins/host-scripts/docker.test.ts
new file mode 100644
index 000000000..2e6b1ba40
--- /dev/null
+++ b/src/backend/tests/plugins/host-scripts/docker.test.ts
@@ -0,0 +1,211 @@
+import { describe, expect, it } from "vitest";
+import {
+  classifyRuntimeError,
+  composeArgsFor,
+  containerCommand,
+  countContainers,
+  diffContainerStates,
+  dockerArgs,
+  parseComposeProjects,
+  parseContainerList,
+  parseContainerStates,
+  parseContainerStats,
+  parseRuntimeVersion,
+  parseServices,
+  parseStackStatus,
+  stackStateFromServices,
+} from "@termix-ssh/plugin-sdk/host-scripts";
+
+describe("containerCommand", () => {
+  it("extends PATH on POSIX hosts", () => {
+    const command = containerCommand("podman", "ps");
+    expect(command.startsWith('PATH="')).toBe(true);
+    expect(command.endsWith(" podman ps")).toBe(true);
+  });
+
+  it("runs the plain CLI on Windows hosts", () => {
+    expect(containerCommand("docker", "ps -a", true)).toBe("docker ps -a");
+  });
+
+  it("falls back to docker for an unknown runtime", () => {
+    expect(containerCommand(undefined, "ps", true)).toBe("docker ps");
+  });
+});
+
+describe("dockerArgs", () => {
+  it("builds the container commands", () => {
+    expect(dockerArgs.inspect("web")).toBe("inspect web");
+    expect(dockerArgs.action("restart", "web")).toBe("restart web");
+    expect(dockerArgs.remove("web", true)).toBe("rm -f web");
+    expect(dockerArgs.list(true)).toContain("ps -a --format '{");
+    expect(dockerArgs.stats("web")).toContain("stats web --no-stream");
+  });
+
+  it("refuses container ids that could break the command line", () => {
+    expect(() => dockerArgs.inspect("web; rm -rf /")).toThrow();
+    expect(() => dockerArgs.logs("$(id)")).toThrow();
+    expect(() => dockerArgs.action("restart", "-rf")).toThrow();
+    expect(() => dockerArgs.action("kill" as never, "web")).toThrow();
+  });
+
+  it("only passes sane log filters", () => {
+    expect(
+      dockerArgs.logs("web", {
+        tail: 50.7,
+        timestamps: true,
+        since: "2026-10-01T00:00:00Z",
+      }),
+    ).toBe("logs web --tail 50 --timestamps --since 2026-10-01T00:00:00Z 2>&1");
+    expect(dockerArgs.logs("web", { since: "1h; id" })).toBe("logs web 2>&1");
+  });
+});
+
+describe("docker parsing", () => {
+  it("reads the version and sorts errors", () => {
+    expect(parseRuntimeVersion("Docker version 27.3.1, build ce12230")).toBe(
+      "27.3.1",
+    );
+    expect(parseRuntimeVersion("podman version 5.2.0")).toBe("5.2.0");
+    expect(parseRuntimeVersion("nope")).toBe("unknown");
+    expect(classifyRuntimeError("bash: docker: command not found")).toBe(
+      "NOT_INSTALLED",
+    );
+    expect(
+      classifyRuntimeError(
+        "Cannot connect to the Docker daemon at unix:///var/run/docker.sock",
+      ),
+    ).toBe("DAEMON_NOT_RUNNING");
+    expect(
+      classifyRuntimeError("permission denied while trying to connect"),
+    ).toBe("PERMISSION_DENIED");
+    expect(classifyRuntimeError("something else")).toBe("DOCKER_ERROR");
+  });
+
+  it("skips lines that are not JSON in the list", () => {
+    const rows = parseContainerList(
+      '{"id":"a","name":"web"}\nWARNING: x\n{"id":"b","name":"db"}\n',
+    );
+    expect(rows.map((r) => r.name)).toEqual(["web", "db"]);
+  });
+
+  it("splits the stats columns", () => {
+    const stats = parseContainerStats(
+      '{"cpu":"1.5%","memory":"10MiB / 1GiB","memoryPercent":"1%","netIO":"1kB / 2kB","blockIO":"0B / 0B","pids":"3"}',
+    );
+    expect(stats).toMatchObject({
+      cpu: "1.5%",
+      memoryUsed: "10MiB",
+      memoryLimit: "1GiB",
+      netInput: "1kB",
+      netOutput: "2kB",
+      pids: "3",
+    });
+  });
+
+  const ps = [
+    `{"name":"web","state":"running","status":"Up 2 hours"}`,
+    `{"name":"db","state":"running","status":"Up 2 hours (unhealthy)"}`,
+    `{"name":"old","state":"exited","status":"Exited (0)"}`,
+  ].join("\n");
+
+  it("counts running, stopped and unhealthy containers", () => {
+    expect(countContainers(ps)).toEqual({
+      running: 2,
+      stopped: 1,
+      unhealthy: 1,
+      total: 3,
+    });
+  });
+
+  it("turns two snapshots into events", () => {
+    const before = parseContainerStates(ps);
+    const after = parseContainerStates(
+      [
+        `{"name":"web","state":"exited","status":"Exited (1)"}`,
+        `{"name":"db","state":"running","status":"Up (unhealthy)"}`,
+        `{"name":"old","state":"running","status":"Up 1 second"}`,
+        `{"name":"new","state":"running","status":"Up"}`,
+      ].join("\n"),
+    );
+    expect(diffContainerStates(before, after)).toEqual([
+      { container: "web", event: "exited" },
+      { container: "old", event: "started" },
+    ]);
+  });
+});
+
+describe("compose", () => {
+  it("reads stack status text", () => {
+    expect(parseStackStatus("running(2), exited(1)")).toEqual({
+      state: "partial",
+      running: 2,
+      total: 3,
+    });
+    expect(parseStackStatus("paused(2)")).toMatchObject({ state: "paused" });
+    expect(parseStackStatus("")).toMatchObject({ state: "not-deployed" });
+  });
+
+  it("reads projects from compose ls", () => {
+    const stacks = parseComposeProjects(
+      JSON.stringify([
+        {
+          Name: "web",
+          Status: "running(2)",
+          ConfigFiles: "/opt/stacks/web/compose.yaml",
+        },
+        { Name: "Bad Name", Status: "running(1)", ConfigFiles: "" },
+      ]),
+    );
+    expect(stacks).toEqual([
+      {
+        name: "web",
+        managed: false,
+        state: "running",
+        running: 2,
+        total: 2,
+        composeFile: "/opt/stacks/web/compose.yaml",
+      },
+    ]);
+  });
+
+  it("reads services from compose ps, one line or one array", () => {
+    const row = {
+      Service: "app",
+      Name: "web-app-1",
+      ID: "abc",
+      Image: "nginx",
+      State: "running",
+      Status: "Up",
+      Health: "",
+      Publishers: [
+        { PublishedPort: 8080, TargetPort: 80 },
+        { PublishedPort: 8080, TargetPort: 80 },
+        { PublishedPort: 0, TargetPort: 443 },
+      ],
+    };
+    const lines = parseServices(JSON.stringify(row));
+    expect(lines[0]).toMatchObject({ service: "app", ports: "8080:80" });
+    expect(
+      parseServices(JSON.stringify([row, { ...row, State: "exited" }])),
+    ).toHaveLength(2);
+    expect(
+      stackStateFromServices(
+        parseServices(JSON.stringify([row, { ...row, State: "exited" }])),
+      ),
+    ).toEqual({
+      state: "partial",
+      running: 1,
+      total: 2,
+    });
+  });
+
+  it("maps actions to compose commands", () => {
+    expect(composeArgsFor("redeploy", "app", {})).toEqual([
+      "pull app",
+      "up -d --remove-orphans app",
+    ]);
+    expect(
+      composeArgsFor("destroy", undefined, { removeVolumes: true }),
+    ).toEqual(["down --remove-orphans -v"]);
+  });
+});
diff --git a/src/backend/tests/plugins/host-scripts/metrics.test.ts b/src/backend/tests/plugins/host-scripts/metrics.test.ts
new file mode 100644
index 000000000..d83d65d23
--- /dev/null
+++ b/src/backend/tests/plugins/host-scripts/metrics.test.ts
@@ -0,0 +1,400 @@
+import { describe, it, expect } from "vitest";
+import {
+  buildFilesystemList,
+  filterExcludedFilesystems,
+  findWorstMountIndex,
+  liveCmd,
+  mergeMonitoredFilesystems,
+  parseCpuLine,
+  parseDfLines,
+  parseLive,
+  selectPrimaryFilesystem,
+} from "@termix-ssh/plugin-sdk/host-scripts";
+
+describe("parseCpuLine", () => {
+  it("parses a standard /proc/stat cpu line", () => {
+    // user nice system idle iowait irq softirq
+    const result = parseCpuLine("cpu  100 0 50 800 30 0 20");
+    expect(result).toBeDefined();
+    // idle = idle(800) + iowait(30)
+    expect(result?.idle).toBe(830);
+    // total = sum of all fields
+    expect(result?.total).toBe(100 + 0 + 50 + 800 + 30 + 0 + 20);
+  });
+
+  it("tolerates leading/trailing whitespace", () => {
+    const result = parseCpuLine("  cpu 1 2 3 4  ");
+    expect(result?.total).toBe(10);
+    expect(result?.idle).toBe(4);
+  });
+
+  it("returns undefined for non-cpu lines", () => {
+    expect(parseCpuLine("cpu0 1 2 3 4")).toBeUndefined();
+    expect(parseCpuLine("intr 12345")).toBeUndefined();
+  });
+
+  it("returns undefined when there are fewer than 4 numeric fields", () => {
+    expect(parseCpuLine("cpu 1 2 3")).toBeUndefined();
+  });
+});
+
+describe("parseDfLines", () => {
+  it("parses df -T -P output into rows", () => {
+    const output =
+      "/dev/nvme0n1p2 ext4 3848290697216 1046898851840 2606516101120  29% /\n" +
+      "/dev/nvme1n1p1 ext4 15393162788864 15239230844928 153931922841  99% /data\n";
+    const rows = parseDfLines(output);
+    expect(rows).toHaveLength(2);
+    expect(rows[0].mount).toBe("/");
+    expect(rows[0].type).toBe("ext4");
+    expect(rows[1].mount).toBe("/data");
+  });
+
+  it("filters out pseudo filesystems", () => {
+    const output =
+      "tmpfs tmpfs 8000 0 8000 0% /dev/shm\n" +
+      "overlay overlay 100 50 50 50% /\n" +
+      "/dev/sda1 ext4 100 50 50 50% /mnt/data\n";
+    const rows = parseDfLines(output);
+    expect(rows).toHaveLength(1);
+    expect(rows[0].mount).toBe("/mnt/data");
+  });
+
+  it("captures the filesystem type for network shares", () => {
+    const output =
+      "nas.local:/export nfs4 2000 1900 100 95% /mnt/nas\n" +
+      "//server/share cifs 2000 1000 1000 50% /mnt/smb\n";
+    const rows = parseDfLines(output);
+    expect(rows[0].type).toBe("nfs4");
+    expect(rows[1].type).toBe("cifs");
+  });
+
+  it("keeps full image and firmware mounts out of disk usage", () => {
+    const rows = parseDfLines(
+      "/dev/loop0 squashfs 100 100 0 100% /snap/core/1\n" +
+        "efivarfs efivarfs 100 89 11 89% /sys/firmware/efi/efivars\n" +
+        "/dev/sda1 ext4 1000 400 600 40% /\n",
+    );
+    expect(rows.map((row) => row.mount)).toEqual(["/"]);
+    expect(findWorstMountIndex(rows)).toEqual({
+      index: 0,
+      usedBytes: 400,
+      totalBytes: 1000,
+    });
+  });
+
+  it("retains real storage without requiring a /dev source", () => {
+    const rows = parseDfLines(
+      "/dev/sda1 btrfs 1000 400 600 40% /\n" +
+        "tank/data zfs 2000 1000 1000 50% /data\n" +
+        "nas:/export nfs4 2000 1900 100 95% /mnt/nas\n" +
+        "//server/share cifs 2000 1000 1000 50% /mnt/smb\n",
+    );
+    expect(rows.map((row) => row.type)).toEqual([
+      "btrfs",
+      "zfs",
+      "nfs4",
+      "cifs",
+    ]);
+  });
+});
+
+describe("findWorstMountIndex", () => {
+  it("picks the most-utilized mount, not just the first row", () => {
+    const rows = parseDfLines(
+      "/dev/nvme0n1p2 ext4 3848290697216 1046898851840 2606516101120  29% /\n" +
+        "/dev/nvme1n1p1 ext4 15393162788864 15239230844928 153931922841  99% /data\n",
+    );
+    const worst = findWorstMountIndex(rows);
+    expect(worst.index).toBe(1);
+    expect(worst.totalBytes).toBe(15393162788864);
+    expect(worst.usedBytes).toBe(15239230844928);
+  });
+
+  it("falls back to the only mount available", () => {
+    const rows = parseDfLines("/dev/sda1 ext4 100 30 70 30% /\n");
+    const worst = findWorstMountIndex(rows);
+    expect(worst.index).toBe(0);
+  });
+
+  it("skips rows with invalid or zero totals", () => {
+    const rows = parseDfLines(
+      "/dev/sda1 ext4 0 0 0 0% /broken\n" +
+        "/dev/sda2 ext4 100 40 60 40% /ok\n",
+    );
+    const worst = findWorstMountIndex(rows);
+    expect(worst.index).toBe(1);
+  });
+
+  it("returns index -1 when there are no usable rows", () => {
+    const worst = findWorstMountIndex([]);
+    expect(worst.index).toBe(-1);
+    expect(worst.totalBytes).toBe(0);
+  });
+});
+
+const BYTES_OUTPUT =
+  "/dev/nvme0n1p2 ext4 1000 400 600 40% /\n" +
+  "/dev/nvme1n1p1 ext4 2000 1900 100 95% /data\n";
+const HUMAN_OUTPUT =
+  "/dev/nvme0n1p2 ext4 1.0K 400 600 40% /\n" +
+  "/dev/nvme1n1p1 ext4 2.0K 1.9K 100 95% /data\n";
+
+describe("buildFilesystemList", () => {
+  it("returns every real filesystem with byte maths and human strings", () => {
+    const list = buildFilesystemList(
+      parseDfLines(BYTES_OUTPUT),
+      parseDfLines(HUMAN_OUTPUT),
+    );
+    expect(list).toHaveLength(2);
+    expect(list[0]).toMatchObject({
+      mount: "/",
+      type: "ext4",
+      percent: 40,
+      usedHuman: "400",
+      totalHuman: "1.0K",
+      availableHuman: "600",
+      usedBytes: 400,
+      totalBytes: 1000,
+    });
+    expect(list[1]).toMatchObject({ mount: "/data", percent: 95 });
+  });
+
+  it("matches human rows by mount when the row counts differ", () => {
+    const list = buildFilesystemList(
+      parseDfLines(BYTES_OUTPUT),
+      parseDfLines("/dev/nvme1n1p1 ext4 2.0K 1.9K 100 95% /data\n"),
+    );
+    expect(list[0].totalHuman).toBeNull();
+    expect(list[1].totalHuman).toBe("2.0K");
+  });
+
+  it("drops filesystems with a zero or invalid total", () => {
+    const list = buildFilesystemList(
+      parseDfLines(
+        "/dev/sda1 ext4 0 0 0 0% /broken\n/dev/sda2 ext4 100 40 60 40% /ok\n",
+      ),
+      [],
+    );
+    expect(list).toHaveLength(1);
+    expect(list[0].mount).toBe("/ok");
+  });
+});
+
+describe("selectPrimaryFilesystem", () => {
+  it("prefers root over a fuller secondary mount", () => {
+    const list = buildFilesystemList(
+      parseDfLines(BYTES_OUTPUT),
+      parseDfLines(HUMAN_OUTPUT),
+    );
+    expect(selectPrimaryFilesystem(list)?.mount).toBe("/");
+  });
+
+  it("falls back to the most-utilized mount when there is no root", () => {
+    const list = buildFilesystemList(
+      parseDfLines(
+        "/dev/sda1 ext4 1000 100 900 10% /mnt/a\n" +
+          "/dev/sda2 ext4 1000 800 200 80% /mnt/b\n",
+      ),
+      [],
+    );
+    expect(selectPrimaryFilesystem(list)?.mount).toBe("/mnt/b");
+  });
+
+  it("returns null for an empty list", () => {
+    expect(selectPrimaryFilesystem([])).toBeNull();
+  });
+});
+
+describe("filterExcludedFilesystems", () => {
+  const list = buildFilesystemList(
+    parseDfLines(
+      "/dev/sda1 ext4 1000 400 600 40% /\n" +
+        "nas.local:/export nfs4 2000 1900 100 95% /mnt/nas\n" +
+        "//server/share cifs 2000 1000 1000 50% /mnt/smb\n",
+    ),
+    [],
+  );
+
+  it("returns the same list when no mounts are excluded", () => {
+    expect(filterExcludedFilesystems(list)).toHaveLength(3);
+    expect(filterExcludedFilesystems(list, [])).toHaveLength(3);
+  });
+
+  it("excludes an exact mount path match", () => {
+    const filtered = filterExcludedFilesystems(list, ["/mnt/nas"]);
+    expect(filtered.map((fs) => fs.mount)).toEqual(["/", "/mnt/smb"]);
+  });
+
+  it("excludes by filesystem type substring, case-insensitively", () => {
+    const filtered = filterExcludedFilesystems(list, ["NFS"]);
+    expect(filtered.map((fs) => fs.mount)).toEqual(["/", "/mnt/smb"]);
+  });
+
+  it("supports excluding multiple network filesystem types at once", () => {
+    const filtered = filterExcludedFilesystems(list, ["nfs", "cifs"]);
+    expect(filtered.map((fs) => fs.mount)).toEqual(["/"]);
+  });
+
+  it("ignores blank/whitespace-only entries", () => {
+    const filtered = filterExcludedFilesystems(list, ["  ", ""]);
+    expect(filtered).toHaveLength(3);
+  });
+});
+
+describe("mergeMonitoredFilesystems", () => {
+  it("adds an arbitrary path with a user label", () => {
+    const detected = buildFilesystemList(
+      parseDfLines("/dev/sda1 ext4 1000 400 600 40% /\n"),
+      [],
+    );
+    const custom = buildFilesystemList(
+      parseDfLines("/dev/sda1 ext4 1000 400 600 40% /\n"),
+      [],
+    );
+    const result = mergeMonitoredFilesystems(
+      detected,
+      [{ path: "/config", label: "Home Assistant" }],
+      custom,
+    );
+
+    expect(result).toHaveLength(2);
+    expect(result[1]).toMatchObject({
+      mount: "/config",
+      label: "Home Assistant",
+      totalBytes: 1000,
+    });
+  });
+
+  it("labels a path that is already a detected mount", () => {
+    const detected = buildFilesystemList(
+      parseDfLines("/dev/sda1 ext4 1000 400 600 40% /data\n"),
+      [],
+    );
+    const result = mergeMonitoredFilesystems(
+      detected,
+      [{ path: "/data", label: "Media" }],
+      detected,
+    );
+
+    expect(result).toHaveLength(1);
+    expect(result[0].label).toBe("Media");
+  });
+});
+
+const out = (
+  agg: [number, number],
+  core: [number, number],
+  rx: number,
+  up: number,
+  procs: string,
+  page = "4096",
+) =>
+  [
+    `cpu  ${agg[0]} 0 0 ${agg[1]} 0 0 0 0 0 0\ncpu0 ${core[0]} 0 0 ${core[1]} 0 0 0 0 0 0`,
+    "MemTotal: 1000 kB\nMemAvailable: 400 kB\nSwapTotal: 0 kB\nSwapFree: 0 kB",
+    `0.1 0.2 0.3 1/2 3\n${up} 5`,
+    `Inter-|\n eth0: ${rx} 0 0 0 0 0 0 0 ${rx * 2} 0\n lo: 9 0 0 0 0 0 0 0 9 0`,
+    page,
+    procs,
+  ].join("\n@@\n");
+
+const proc = (pid: number, ticks: number, start: number, name = "java") =>
+  `${pid}\t${ticks}\t10\t${start}\tR\t1\t${name}\n`;
+
+describe("parseLive extras", () => {
+  it("reports state, parent, CPU mix, cache and the running count", () => {
+    const mk = (user: number, sys: number, wait: number, idle: number) =>
+      out([user, idle], [user, idle], 1, 10, procs).replace(
+        /cpu {2}\d+ 0 0 \d+ 0 0 0 0/,
+        `cpu  ${user} 0 ${sys} ${idle} ${wait} 0 0 0`,
+      );
+    const procs = "5\t1\t10\t7\tR\t2\tjava\n6\t1\t10\t8\tS\t5\tsh\n";
+    const a = parseLive(mk(0, 0, 0, 0), undefined, 0);
+    const b = parseLive(mk(30, 10, 10, 50), a.next, 1000);
+    expect(b.sample.cpuMix).toMatchObject({ user: 30, system: 10, iowait: 10 });
+    expect(b.sample.running).toBe(1);
+    expect(b.sample.procs.find((p) => p.pid === 6)).toMatchObject({
+      state: "S",
+      ppid: 5,
+    });
+    expect(b.sample.memCachedKb).toBe(0);
+  });
+});
+
+describe("liveCmd", () => {
+  it("asks for the page size once, then passes the cached number", () => {
+    expect(liveCmd()).toContain('pg="$(getconf PAGESIZE)"');
+    expect(liveCmd(16384)).toContain("pg=16384 ");
+    expect(liveCmd(16384)).not.toContain("getconf");
+  });
+});
+
+describe("parseLive", () => {
+  it("has no rates on the first sample", () => {
+    const { sample } = parseLive(
+      out([100, 100], [100, 100], 1000, 10, proc(7, 0, 1)),
+      undefined,
+    );
+    expect(sample.cpu).toBeNull();
+    expect(sample.net[0].rxBps).toBeNull();
+    expect(sample.memUsedKb).toBe(600);
+  });
+
+  it("derives cpu, per-core, net and process rates from the delta", () => {
+    const a = parseLive(
+      out([100, 100], [100, 100], 1000, 10, proc(7, 0, 1)),
+      undefined,
+    );
+    // aggregate: +50 busy, +50 idle; core 0: +25 busy, +75 idle
+    const { sample } = parseLive(
+      out([150, 150], [125, 175], 3000, 11, proc(7, 50, 1)),
+      a.next,
+    );
+    expect(sample.cpu).toBeCloseTo(50, 0);
+    expect(sample.cores[0]).toBeCloseTo(25, 0);
+    expect(sample.net).toEqual([{ name: "eth0", rxBps: 2000, txBps: 4000 }]);
+    expect(sample.procs[0]).toMatchObject({ pid: 7, name: "java", memKb: 40 });
+    expect(sample.procs[0].cpu).toBeCloseTo(50, 0);
+  });
+
+  it("does not charge a reused pid with the old process's ticks", () => {
+    const a = parseLive(
+      out([100, 100], [100, 100], 1000, 10, proc(7, 5, 1)),
+      undefined,
+    );
+    // same pid, new start time, lower ticks must not look like a huge delta
+    const { sample } = parseLive(
+      out([150, 150], [125, 175], 3000, 11, proc(7, 9000, 2)),
+      a.next,
+    );
+    expect(sample.procs[0].cpu).toBe(0);
+  });
+
+  it("keeps the cached page size when a run omits it, and keeps names with tabs", () => {
+    const a = parseLive(
+      out([1, 1], [1, 1], 1, 10, proc(1, 0, 1), "16384"),
+      undefined,
+    );
+    expect(a.next.pageBytes).toBe(16384);
+    const b = parseLive(
+      out([2, 2], [2, 2], 2, 11, proc(1, 0, 1, "a	b"), ""),
+      a.next,
+    );
+    expect(b.next.pageBytes).toBe(16384);
+    expect(b.sample.procs[0]).toMatchObject({ name: "a\tb", memKb: 160 });
+  });
+
+  it("starts rates again after a reboot", () => {
+    const a = parseLive(
+      out([100, 100], [100, 100], 5000, 900, proc(7, 0, 1)),
+      undefined,
+    );
+    const { sample } = parseLive(
+      out([10, 10], [10, 10], 20, 5, proc(7, 0, 1)),
+      a.next,
+    );
+    expect(sample.cpu).toBeNull();
+    expect(sample.net[0].rxBps).toBeNull();
+  });
+});
diff --git a/src/backend/tests/plugins/host-scripts/services.test.ts b/src/backend/tests/plugins/host-scripts/services.test.ts
new file mode 100644
index 000000000..75e1bf866
--- /dev/null
+++ b/src/backend/tests/plugins/host-scripts/services.test.ts
@@ -0,0 +1,244 @@
+import { describe, expect, it } from "vitest";
+import {
+  isUnit,
+  journalArgs,
+  parseBoots,
+  parseDetect,
+  parseEntry,
+  parseIsActive,
+  parseJournal,
+  parseJournalQuery,
+  parseOpenRcList,
+  parseSystemdTime,
+  parseTimers,
+  parseUnitList,
+  parseUsage,
+  shellQuote as q,
+  vacuumScript,
+} from "@termix-ssh/plugin-sdk/host-scripts";
+
+describe("names", () => {
+  it("quotes for bash", () => {
+    expect(q("a'b")).toBe(`'a'\\''b'`);
+  });
+
+  it("takes unit names and refuses anything else", () => {
+    expect(isUnit("nginx.service")).toBe(true);
+    expect(isUnit("getty@tty1.service")).toBe(true);
+    expect(isUnit("dev-disk-by\\x2duuid-1.device")).toBe(true);
+    expect(isUnit("-rf.service")).toBe(false);
+    expect(isUnit("a;b.service")).toBe(false);
+    expect(isUnit("a b.service")).toBe(false);
+    expect(isUnit("nginx")).toBe(false);
+    expect(isUnit("$(id).service")).toBe(false);
+  });
+});
+
+describe("systemd parsing", () => {
+  const list = [
+    "cron.service           loaded    active   running Regular background program",
+    "● bad.service      loaded    failed   failed  Broken thing",
+    "getty@tty1.service     loaded    active   running Getty on tty1",
+    "@@TERMIX_FILES@@",
+    "cron.service           enabled   enabled",
+    "bad.service            disabled  enabled",
+    "getty@.service         enabled   enabled",
+    "old.service            masked    -",
+    "",
+  ].join("\n");
+
+  it("merges loaded units with unit files and skips templates", () => {
+    const units = parseUnitList(list);
+    expect(units.map((u) => u.name)).toEqual([
+      "bad.service",
+      "cron.service",
+      "getty@tty1.service",
+      "old.service",
+    ]);
+    const cron = units.find((u) => u.name === "cron.service")!;
+    expect(cron).toMatchObject({
+      active: "active",
+      sub: "running",
+      description: "Regular background program",
+      fileState: "enabled",
+      preset: "enabled",
+    });
+    expect(units.find((u) => u.name === "bad.service")!.active).toBe("failed");
+    expect(units.find((u) => u.name === "old.service")).toMatchObject({
+      load: "masked",
+      active: "inactive",
+      preset: "",
+    });
+  });
+
+  it("reads UTC times", () => {
+    expect(parseSystemdTime("Thu 2026-10-22 02:03:51 UTC")).toBe(
+      Date.UTC(2026, 9, 22, 2, 3, 51),
+    );
+    expect(parseSystemdTime("")).toBeNull();
+    expect(parseSystemdTime("n/a")).toBeNull();
+  });
+
+  it("reads timers from systemctl show blocks", () => {
+    const out = [
+      "TimersCalendar={ OnCalendar=*-*-* 06,18:00:00 ; next_elapse=@1792605600 }",
+      "NextElapseUSecRealtime=Thu 2026-10-22 02:03:51 UTC",
+      "LastTriggerUSec=Wed 2026-10-21 17:02:58 UTC",
+      "Id=apt-daily.timer",
+      "Triggers=apt-daily.service",
+      "ActiveState=active",
+      "",
+      "TimersMonotonic={ OnUnitActiveUSec=1d ; next_elapse=1d }",
+      "TimersMonotonic={ OnBootUSec=15min ; next_elapse=15min }",
+      "NextElapseUSecRealtime=",
+      "LastTriggerUSec=",
+      "Id=clean.timer",
+      "Triggers=clean.service",
+    ].join("\n");
+    const timers = parseTimers(out);
+    expect(timers[0]).toMatchObject({
+      name: "apt-daily.timer",
+      activates: "apt-daily.service",
+      next: Date.UTC(2026, 9, 22, 2, 3, 51),
+      schedule: ["OnCalendar=*-*-* 06,18:00:00"],
+    });
+    expect(timers[1]).toMatchObject({
+      name: "clean.timer",
+      next: null,
+      last: null,
+      schedule: ["OnUnitActiveUSec=1d", "OnBootUSec=15min"],
+    });
+  });
+
+  it("maps is-active lines to units", () => {
+    const states = parseIsActive(
+      ["a.service", "b.service"],
+      "active\nfailed\n",
+    );
+    expect(states.get("a.service")).toBe("active");
+    expect(states.get("b.service")).toBe("failed");
+  });
+
+  it("reads what detect prints", () => {
+    expect(
+      parseDetect(
+        "init=systemd\nversion=257\nos=Debian GNU/Linux 13 (trixie)\nuid=0\njournal=1\nfailed=2\n",
+      ),
+    ).toMatchObject({
+      init: "systemd",
+      version: "257",
+      root: true,
+      journal: true,
+      failed: 2,
+    });
+    expect(parseDetect("init=weird\nuid=1000\n")).toMatchObject({
+      init: "none",
+      root: false,
+    });
+  });
+});
+
+describe("journal", () => {
+  it("checks filters", () => {
+    const query = parseJournalQuery({
+      unit: ["nginx.service", "ssh.service"],
+      priority: "3",
+      since: "-1h",
+      boot: "-1",
+      grep: "fail'ed",
+      lines: "99999",
+    });
+    expect(query.lines).toBe(5000);
+    const args = journalArgs(query);
+    expect(args).toContain("-u 'nginx.service' -u 'ssh.service'");
+    expect(args).toContain("-p 3");
+    expect(args).toContain("--since '-1h'");
+    expect(args).toContain("-b '-1'");
+    expect(args).toContain(`-g 'fail'\\''ed'`);
+    expect(() => parseJournalQuery({ unit: "x;rm" })).toThrow();
+    expect(() => parseJournalQuery({ priority: "9" })).toThrow();
+    expect(() => parseJournalQuery({ since: "$(id)" })).toThrow();
+    expect(() => parseJournalQuery({ boot: "abc" })).toThrow();
+  });
+
+  it("parses entries, binary messages included", () => {
+    const entry = parseEntry(
+      JSON.stringify({
+        __REALTIME_TIMESTAMP: "1792612429684000",
+        PRIORITY: "3",
+        _SYSTEMD_UNIT: "x.service",
+        SYSLOG_IDENTIFIER: "x",
+        _PID: "12",
+        MESSAGE: [104, 105],
+      }),
+    );
+    expect(entry).toEqual({
+      time: 1792612429684,
+      priority: 3,
+      unit: "x.service",
+      ident: "x",
+      pid: "12",
+      message: "hi",
+    });
+    expect(parseEntry("not json")).toBeNull();
+  });
+
+  it("filters here when journalctl has no -g", () => {
+    const line = (message: string) =>
+      JSON.stringify({ __REALTIME_TIMESTAMP: "1000", MESSAGE: message });
+    const out = `@@TERMIX_NOGREP@@\n${line("Disk Error")}\n${line("ok")}\n`;
+    const query = parseJournalQuery({ grep: "error", lines: "10" });
+    expect(parseJournal(out, query).map((e) => e.message)).toEqual([
+      "Disk Error",
+    ]);
+  });
+
+  it("reads boots and disk use", () => {
+    const boots = parseBoots(
+      [
+        "IDX BOOT ID                          FIRST ENTRY                 LAST ENTRY",
+        "-1 d2785a657f4c4561a1f436db27555b50 Tue 2026-10-20 13:56:45 UTC Wed 2026-10-21 10:37:00 UTC",
+        "  0 61b15588a75b4c0cb8dea321fcc438ab Wed 2026-10-21 10:38:10 UTC Wed 2026-10-21 20:00:00 UTC",
+      ].join("\n"),
+    );
+    expect(boots.map((b) => b.offset)).toEqual([0, -1]);
+    expect(boots[0].first).toBe("Wed 2026-10-21 10:38:10 UTC");
+    expect(
+      parseUsage(
+        "Archived and active journals take up 378.6M in the file system.",
+      ),
+    ).toBe("378.6M");
+  });
+
+  it("only takes sane vacuum values", () => {
+    expect(vacuumScript({ size: "500M" })).toContain("--vacuum-size=500M");
+    expect(vacuumScript({ time: "4w" })).toContain("--vacuum-time=4w");
+    expect(() => vacuumScript({ size: "1; rm -rf /" })).toThrow();
+    expect(() => vacuumScript({})).toThrow();
+  });
+});
+
+describe("openrc", () => {
+  it("maps services and runlevels", () => {
+    const units = parseOpenRcList(
+      [
+        " sshd                 [  started  ]",
+        " crond                [  stopped  ]",
+        " nginx                [  crashed  ]",
+        "@@TERMIX_RUNLEVELS@@",
+        "            sshd | default",
+        "           nginx | ",
+        "",
+      ].join("\n"),
+    );
+    expect(units.find((u) => u.name === "sshd")).toMatchObject({
+      active: "active",
+      fileState: "enabled",
+    });
+    expect(units.find((u) => u.name === "nginx")).toMatchObject({
+      active: "failed",
+      fileState: "disabled",
+    });
+    expect(units.find((u) => u.name === "crond")!.active).toBe("inactive");
+  });
+});
diff --git a/src/backend/tests/plugins/host-scripts/shell.test.ts b/src/backend/tests/plugins/host-scripts/shell.test.ts
new file mode 100644
index 000000000..3d41e7d19
--- /dev/null
+++ b/src/backend/tests/plugins/host-scripts/shell.test.ts
@@ -0,0 +1,130 @@
+import { execFileSync } from "node:child_process";
+import { describe, expect, it } from "vitest";
+import {
+  actionScript,
+  errLine,
+  isActiveScript,
+  listUnitsScript,
+  openRcActionScript,
+  parseKeys,
+  passwordSudoScript,
+  scriptError,
+  scriptShell,
+  SUDO_REFUSED_RE,
+  SUDO_WRONG_RE,
+  toBase64,
+  utf8Decode,
+  utf8Encode,
+  watchdog,
+} from "@termix-ssh/plugin-sdk/host-scripts";
+
+describe("text helpers", () => {
+  it("encodes base64 like Buffer does", () => {
+    for (const text of [
+      "",
+      "a",
+      "ab",
+      "abc",
+      "héllo wörld",
+      "emoji 🙂 here",
+      "line\nbreak",
+    ]) {
+      expect(toBase64(text)).toBe(Buffer.from(text, "utf8").toString("base64"));
+    }
+  });
+
+  it("round trips UTF-8 and replaces bad bytes", () => {
+    const text = "plain, ünïcode, 日本, 🙂";
+    expect(utf8Decode(utf8Encode(text))).toBe(text);
+    expect(Array.from(utf8Encode(text))).toEqual(
+      Array.from(Buffer.from(text, "utf8")),
+    );
+    expect(utf8Decode([0x61, 0xff, 0x62])).toBe("a\ufffdb");
+    expect(utf8Decode([0xe6, 0x97])).toBe("\ufffd");
+  });
+
+  it("reads key=value lines", () => {
+    expect(parseKeys("a=1\nb = two=2\njunk\n")).toEqual({ a: "1", b: "two=2" });
+  });
+});
+
+describe("script shells", () => {
+  it("always reads the script from stdin", () => {
+    for (const mode of ["plain", "auto", "root"] as const) {
+      expect(scriptShell(mode)).toContain("bash -s");
+    }
+    expect(scriptShell("auto")).toContain("sudo -n true");
+    expect(scriptShell("root-only")).toContain("SCRIPT_ERR:");
+  });
+
+  it("collects error lines, old and new markers", () => {
+    expect(scriptError("x\nSCRIPT_ERR:one\nSERVICES_ERR:two\n")).toBe(
+      "one\ntwo",
+    );
+    expect(errLine("it's broken")).toBe(`echo 'SCRIPT_ERR:it'\\''s broken'`);
+  });
+
+  it("matches sudo refusals", () => {
+    expect(SUDO_REFUSED_RE.test("sudo: a password is required")).toBe(true);
+    expect(SUDO_WRONG_RE.test("sudo: 1 incorrect password attempt")).toBe(true);
+  });
+
+  it("keeps the sudo password out of the command line", () => {
+    const { command, stdin } = passwordSudoScript(
+      "systemctl restart 'a.service'\n",
+      "s3cr'et $(id)",
+    );
+    expect(command).not.toContain("s3cr");
+    expect(stdin.split("\n")[0]).toBe("IFS= read -r TERMIX_PW");
+    expect(stdin.split("\n")[1]).toBe("s3cr'et $(id)");
+    expect(stdin).toContain("sudo -k -S -p ''");
+    expect(stdin).not.toContain("systemctl restart");
+    expect(() => passwordSudoScript("x", "a\nb")).toThrow();
+  });
+
+  it.runIf(process.platform !== "win32")(
+    "runs the script and never runs the password",
+    () => {
+      const { stdin } = passwordSudoScript(
+        'echo "ran:$1${TERMIX_PW:-none}"\n',
+        "touch /tmp/should-not-exist",
+      );
+      // No sudo here: swap it for a fake that drops its own stdin line.
+      const fake = stdin.replace(
+        /printf '%s\\n' "\$P" \| sudo -k -S -p '' env PATH="\$PATH" [^\n]* bash -c "\$TERMIX_S"/,
+        'printf "%s\\n" "$P" | { IFS= read -r _; bash -c "$TERMIX_S"; }',
+      );
+      expect(fake).not.toBe(stdin);
+      const out = execFileSync(
+        "bash",
+        ["-c", "sudo() { return 1; }; export -f sudo; exec bash -s"],
+        {
+          input: fake,
+          encoding: "utf8",
+        },
+      );
+      expect(out.trim()).toBe("ran:none");
+    },
+  );
+});
+
+describe("unit scripts", () => {
+  it("quotes units and refuses bad names", () => {
+    expect(actionScript("a.service", "enable-now")).toContain(
+      "systemctl enable --now -- 'a.service'",
+    );
+    expect(() => actionScript("a;b.service", "start")).toThrow();
+    expect(isActiveScript(["a.service", "b.timer"])).toContain(
+      "-- 'a.service' 'b.timer'",
+    );
+    expect(() => listUnitsScript("bogus" as never)).toThrow();
+    expect(openRcActionScript("sshd", "enable")).toContain(
+      "rc-update add 'sshd' default",
+    );
+    expect(() => openRcActionScript("sshd", "mask")).toThrow();
+  });
+
+  it("stops a watched command once stdin closes", () => {
+    expect(watchdog("journalctl -f")).toContain("cat >/dev/null");
+  });
+});