fix(bootstrap): self-heal a systemd unit left on a retired plugin root

The residue an interrupted update leaves behind is invisible: the server
runs, every doctor row reads OK, and the unit quietly still names a cache
directory Claude Code deleted during the update. Nothing surfaces it until
a reboot, when the dashboard does not come back and nothing recorded why.

- fastPathOk now rejects a stale unit, so the next SessionStart repairs it
  instead of short-circuiting. `unitIsStale` is pure fs on purpose: that
  path runs on every session and may not spawn a process.
- Repairing the unit is not restarting the server. A current, healthy
  server keeps running and the corrected unit takes effect at the next
  start (`pendingSystemdRestart = systemdOwned && needsServer`), and the
  detached-spawn fallback is guarded by needsServer so a stale unit alone
  cannot start a second server onto a bound port.
- systemdOwned now also requires the unit to be ACTIVE. Installed-but-
  stopped owns nothing: skipping the stop there and asking systemd to start
  would bind an occupied port and crash-loop under Restart=always.
- /agenthub-doctor gains a systemd row naming the consequence ("will NOT
  come back after a reboot") and the fix. WARN, never FAIL — the dashboard
  in front of you works, and having no unit at all is a normal setup.

The fast-path test pins the regression against an otherwise fully healthy
install, live server included; without a live server it would have passed
against the unfixed code either way.

CLAUDE.md

@@ -43,7 +43,7 @@ A **lane** is a durable unit of parallel agent work — one working directory, m
 See `docs/LANES.md` for full guide: stage reporting, custom templates, lane actions, and the five node states.
 
 ## Non-negotiable engineering rules
-- **When a `agenthub.service` unit of ours owns the server, nothing else may stop it.** The bootstrap that performs a self-update is spawned by the running server, so it lives in that server's systemd cgroup: SIGTERM-ing the server from there exits 0 (which `Restart=on-failure` read as "meant to stop") AND trips `KillMode=control-group`, reaping the bootstrap before it can repoint the unit or write `state.json` — a dashboard dead after every update until some later session bootstrapped again. So `scripts/systemd-service.js` splits the API: `writeUserService` repoints the unit and starts NOTHING, `restartUserService` uses `--no-block`, and `plugin-bootstrap.js` defers that restart past `writeState` and `releaseLock` (`pendingSystemdRestart`). The unit is `Restart=always`. Do not add a path that stops the dashboard from inside its own cgroup, and do not move the restart earlier. `agenthub service install` may keep using `installUserService` — it runs from a user's shell, outside the cgroup.
+- **When a `agenthub.service` unit of ours owns the server, nothing else may stop it.** The bootstrap that performs a self-update is spawned by the running server, so it lives in that server's systemd cgroup: SIGTERM-ing the server from there exits 0 (which `Restart=on-failure` read as "meant to stop") AND trips `KillMode=control-group`, reaping the bootstrap before it can repoint the unit or write `state.json` — a dashboard dead after every update until some later session bootstrapped again. So `scripts/systemd-service.js` splits the API: `writeUserService` repoints the unit and starts NOTHING, `restartUserService` uses `--no-block`, and `plugin-bootstrap.js` defers that restart past `writeState` and `releaseLock` (`pendingSystemdRestart`). The unit is `Restart=always`. Do not add a path that stops the dashboard from inside its own cgroup, and do not move the restart earlier. `agenthub service install` may keep using `installUserService` — it runs from a user's shell, outside the cgroup. `systemdOwned` additionally requires the unit to be ACTIVE (an installed-but-stopped unit owns nothing; treating it as owner skips the stop and then binds an occupied port). A unit naming a RETIRED plugin root is invisible until a reboot, so `fastPathOk` rejects it via `unitIsStale` (pure fs — that path may never spawn a process) and the bootstrap rewrites it; repairing the unit is NOT restarting the server (`pendingSystemdRestart = systemdOwned && needsServer`), and the detached-spawn fallback is guarded by `needsServer` so a stale unit alone never starts a second server onto a bound port.
 - **A session reload is typed into a live pane, never spawned.** `/reload-plugins` and `/reload-skills` are scoped BY CLAUDE CODE to the session that runs them, so nothing can reload a session from the outside. `server/lib/cc-reload.js` therefore types them into the dashboard's existing tmux lane panes and spawns NO `claude` process — a one-shot `claude -p "/reload-plugins"` reloads only its own short-lived session, exits, and leaves a junk session in the dashboard's own history. Do not add a path that starts a session in order to reload one.
 - Preserve existing behavior unless explicitly asked to change it.
 - Prefer minimal, reversible diffs.

docs/PLUGINS.md

@@ -210,11 +210,33 @@ the Settings panel do — still stops it.
 it runs from your own shell, outside the unit's cgroup, so it may block and
 start in one step.
 
+**A unit pointing at a retired plugin root repairs itself on the next session.**
+This is the residue an interrupted update leaves behind, and it is invisible
+while the dashboard is up: the server runs fine, every doctor row reads OK, and
+then a reboot starts a cache directory Claude Code deleted during the update —
+so the dashboard never comes back, for a reason nothing recorded. The fast path
+therefore checks it (`unitIsStale`, pure fs — it may not spawn a process on
+every `SessionStart`) and refuses to short-circuit, and the bootstrap rewrites
+the unit.
+
+Repairing the *unit* is not restarting the *server*: when the running server is
+current and healthy, the corrected unit is simply left to take effect at the
+next start (`pendingSystemdRestart = systemdOwned && needsServer`). Restarting
+a working dashboard to fix a file that only matters at boot would be churn the
+user feels for nothing. For the same reason the detached-spawn fallback is
+guarded by `needsServer` — entering that branch for a stale unit alone would
+start a second server onto a port the live one already holds.
+
+`systemdOwned` requires the unit to be **active**, not merely present: an
+installed-but-stopped unit owns nothing, and treating it as the owner would
+skip the stop and then ask systemd to bind an occupied port — a crash loop,
+courtesy of `Restart=always`.
+
 ### Commands
 
 | Command | Does |
 |---|---|
-| `/agenthub-doctor` | Node version, bootstrap state, runtime deps, server liveness, duplicate hooks, CLI launcher + PATH, **tmux** (`WARN` when absent — only the run console, `agenthub lanes shell` and session reloads need it), **skill plugins** (see below), UI bundle |
+| `/agenthub-doctor` | Node version, bootstrap state, runtime deps, server liveness, duplicate hooks, CLI launcher + PATH, **systemd** (`WARN` when the unit names a retired plugin root — the dashboard will not survive a reboot — or when it is installed but stopped; no unit at all is fine), **tmux** (`WARN` when absent — only the run console, `agenthub lanes shell` and session reloads need it), **skill plugins** (see below), UI bundle |
 | `/agenthub-update` | Pull the latest `agenthub` release via `claude plugin marketplace update` + `claude plugin update agenthub@<marketplace> -y`, then reinstall dependencies and restart the server (`plugin-bootstrap.js --force`). The plugin pull needs a manual `/reload-plugins` afterward to take effect in the current session — not scriptable from a command. |
 | `/agenthub-open` | Rebuild the UI bundle and print the dashboard URL. Re-runs the bootstrap first when the server is down or still executing a plugin root that a mid-session `/plugin` update retired, so a fresh bundle never talks to an older server's routes |
 | `/ship-full <requirement>` | Put the lane on the 16-node `ship-feature` template, then run `/agenthub:ship-feature-lane` **in this session**. The in-session twin of `agenthub ship-full` (which spawns its own `claude` from a terminal) |

plugins/agenthub/commands/agenthub-doctor.md

@@ -1,5 +1,5 @@
 ---
-description: Diagnose a plugin-installed AgentHub — Node, npm, disk, bootstrap, server, hooks, CLI, tmux, UI build
+description: Diagnose a plugin-installed AgentHub — Node, npm, disk, bootstrap, server, hooks, CLI, systemd, tmux, UI build
 ---
 
 Run the diagnostic and report what it found. Do not fix anything unless the user
@@ -31,6 +31,11 @@ Print the output verbatim, then add at most three lines of guidance based on the
   means that attempt has not run or did not succeed — say `/agenthub-update` retries
   it, and print the `claude plugin install …` line from the output as the manual
   route.
+- `WARN systemd` → when it says the unit names a **previous plugin version**,
+  the dashboard is running now but will NOT come back after a reboot. Starting
+  a new Claude Code session repairs it; print the `--force` command from the
+  output as the immediate fix. "installed but not running" just needs
+  `systemctl --user start agenthub`.
 - `WARN tmux` → only the run console, `agenthub lanes shell` and the
   session-reload keystrokes are affected; monitoring, lanes and the CLI are not.
   Print the install command from the output. If the row says `ok` but Start Run

scripts/plugin-bootstrap.js

@@ -107,6 +107,12 @@ function fastPathOk(rt = runtimeDir()) {
   // pipelines drive. Reading one recorded flag keeps this hot path cheap — the
   // actual check (manifest + every user SKILL.md) runs once, in the worker.
   if (!state.skillPluginsSettled) return false;
+  // A live server says nothing about whether it will come back. When our unit
+  // still names a previous plugin cache directory, everything looks healthy
+  // until the next reboot — and then the dashboard is simply gone, from a path
+  // Claude Code deleted long ago. Reading one file is cheap enough for a hot
+  // path; `unitIsStale` deliberately spawns nothing.
+  if (require("./systemd-service").unitIsStale("agenthub", PLUGIN_ROOT)) return false;
   return serverIsLive();
 }
 
@@ -518,7 +524,13 @@ function bootstrap(rt = runtimeDir(), { force = false } = {}) {
     // before it can write state or point the unit at the new cache dir. That
     // is the bug that left a dashboard dead after every self-update until the
     // next Claude Code session happened to bootstrap again.
-    const systemdOwned = svc.systemctlAvailable() && svc.unitIsOurs("agenthub");
+    // ACTIVE matters, not merely present: a unit of ours that is installed but
+    // stopped owns nothing right now. If a detached server is holding the port
+    // in that state, treating systemd as the owner would skip the stop and then
+    // ask systemd to start a second server onto a bound port — a crash loop,
+    // courtesy of Restart=always.
+    const systemdOwned =
+      svc.systemctlAvailable() && svc.unitIsOurs("agenthub") && svc.unitIsActive("agenthub");
 
     // After a plugin update the running server executes code from a cache
     // directory Claude Code has already discarded — retire it first. Only
@@ -530,7 +542,13 @@ function bootstrap(rt = runtimeDir(), { force = false } = {}) {
       waitForPortsFree();
     }
 
-    if (movedRoot || !serverIsLive()) {
+    // Two different needs, deliberately not collapsed. `needsServer` is "the
+    // running process must be replaced"; `unitStale` is "the unit names a cache
+    // directory that is no longer this one", which is invisible until a reboot
+    // and must be repaired even while a perfectly healthy server is up.
+    const needsServer = movedRoot || !serverIsLive();
+    const unitStale = svc.unitIsStale("agenthub", PLUGIN_ROOT);
+    if (needsServer || unitStale) {
       const unit = {
         name: "agenthub",
         description: "AgentHub dashboard server (Claude Code plugin)",
@@ -557,17 +575,25 @@ function bootstrap(rt = runtimeDir(), { force = false } = {}) {
           : "unavailable";
       if (result === "written" || result === "unchanged") {
         if (result === "written") svc.enableLinger();
-        pendingSystemdRestart = systemdOwned;
+        // Only when the RUNNING process has to change. A stale unit beside a
+        // healthy server is now corrected on disk and left to take effect at
+        // the next start — restarting a working dashboard to fix a file that
+        // only matters at boot would be churn the user feels for no reason.
+        pendingSystemdRestart = systemdOwned && needsServer;
         log(
           rt,
-          result === "written"
+          result === "unchanged"
-            ? "installed a systemd --user service — the dashboard now survives reboots without Claude Code"
+            ? "systemd --user service already up to date"
-            : "systemd --user service already up to date"
+            : unitStale && !needsServer
+              ? "repointed the systemd --user service at the current plugin version (it named a retired one)"
+              : "installed a systemd --user service — the dashboard now survives reboots without Claude Code"
         );
-      } else {
+      } else if (needsServer) {
         // No systemd (macOS/Windows/WSL without it), or the unit exists but
         // wasn't ours to touch — same detached-spawn fallback as before,
-        // scoped to this session only.
+        // scoped to this session only. Guarded by `needsServer`: entering this
+        // block for a stale unit alone must never spawn a second server onto
+        // the port the live one already holds.
         const pid = startDashboard(rt);
         log(
           rt,

scripts/plugin-doctor.js

@@ -83,6 +83,7 @@ function diagnose() {
   );
 
   add(...cliStatus());
+  add(...systemdStatus());
   add(...tmuxStatus());
   add(...skillPluginStatus());
 
@@ -220,6 +221,53 @@ function skillPluginStatus() {
   ];
 }
 
+/**
+ * The failure this row exists for is silent by construction: a unit still
+ * naming a retired plugin cache directory keeps a running dashboard looking
+ * perfectly healthy, and only bites at the next reboot — when the server does
+ * not come back, from a path Claude Code deleted weeks earlier. Nothing else
+ * in this report would show it.
+ *
+ * WARN, never FAIL: the dashboard in front of you is working, and on macOS,
+ * Windows or a Linux box without systemd there is no unit to have an opinion
+ * about.
+ */
+function systemdStatus() {
+  const svc = require("./systemd-service");
+  const unit = svc.unitPath("agenthub");
+
+  if (!svc.unitIsOurs("agenthub")) {
+    if (fs.existsSync(unit)) {
+      return ["warn", "systemd", `${unit} exists but was not written by AgentHub — left untouched`];
+    }
+    return [
+      "ok",
+      "systemd",
+      svc.systemctlAvailable()
+        ? "no unit — the server is started per session (install one with `agenthub service install`)"
+        : "not available on this platform — the server is started per session",
+    ];
+  }
+
+  if (svc.unitIsStale("agenthub", PLUGIN_ROOT)) {
+    return [
+      "warn",
+      "systemd",
+      `${unit} still points at a previous plugin version — the dashboard will NOT come back after a reboot. ` +
+        `Starting a new Claude Code session repairs it; or run: node ${path.join(PLUGIN_ROOT, "scripts", "plugin-bootstrap.js")} --force`,
+    ];
+  }
+
+  if (!svc.unitIsActive("agenthub")) {
+    return [
+      "warn",
+      "systemd",
+      "unit is installed and current but not running — start it with `systemctl --user start agenthub`",
+    ];
+  }
+  return ["ok", "systemd", "unit is current and running — the dashboard survives reboots"];
+}
+
 /**
  * WARN (never FAIL) when `tmux` is absent: every run the dashboard starts is a
  * tmux session (`server/lib/tmux.js`), so without the binary the run console,

scripts/systemd-service.js

@@ -63,6 +63,36 @@ function unitIsOurs(name) {
  * later Claude Code session happened to run the bootstrap. An explicit
  * `systemctl stop` (what uninstall does) still stops it for good.
  */
+/**
+ * Does our unit still point at `root`? A plugin update moves the install to a
+ * new cache directory, and a unit left naming the old one is a failure that
+ * shows NOTHING until the next reboot — the dashboard simply does not come
+ * back, from a path Claude Code garbage-collected weeks earlier.
+ *
+ * Pure fs, no `systemctl`: this is called from the bootstrap's fast path, which
+ * runs on every single SessionStart and may not spawn a process.
+ *
+ * A foreign unit is never "stale" — it is not ours to judge or rewrite.
+ */
+function unitIsStale(name, root) {
+  let body;
+  try {
+    body = fs.readFileSync(unitPath(name), "utf8");
+  } catch {
+    return false; // no unit at all: nothing to be stale
+  }
+  if (!body.includes(MARKER)) return false;
+  return !body.includes(`\nWorkingDirectory=${root}\n`);
+}
+
+/** Is the unit currently running? Costs a `systemctl` call — never call it
+ *  from the fast path. */
+function unitIsActive(name) {
+  if (!systemctlAvailable()) return false;
+  const res = execImpl(["is-active", `${name}.service`], { encoding: "utf8", stdio: "pipe" });
+  return String(res.stdout || "").trim() === "active";
+}
+
 function unitContent({ description, workingDir, execStart, env }) {
   const envLines = Object.entries(env)
     .map(([k, v]) => `Environment=${k}=${v}`)
@@ -178,6 +208,8 @@ function enableLinger() {
 module.exports = {
   systemctlAvailable,
   unitIsOurs,
+  unitIsStale,
+  unitIsActive,
   writeUserService,
   restartUserService,
   installUserService,

server/__tests__/plugin-bootstrap.test.js

@@ -129,6 +129,71 @@ describe("fast path", () => {
     );
     assert.equal(boot.fastPathOk(RT), false);
   });
+
+  it("is false when the systemd unit still names a retired plugin root", () => {
+    // The one failure a live server hides completely: everything is healthy
+    // until the next reboot, and then the dashboard never comes back because
+    // its unit points into a cache directory Claude Code has deleted. The fast
+    // path has to reject it, or no SessionStart ever repairs it.
+    //
+    // Everything else here is deliberately HEALTHY — including a live server,
+    // without which `fastPathOk` is false anyway and this test would pass
+    // against the unfixed code.
+    const ROOT = path.resolve(__dirname, "..", "..");
+    const pkg = require("../../package.json");
+    const infoPath = path.join(TMP_HOME, ".agenthub.json");
+    const prevHome = process.env.HOME;
+    // HOME first: `unitPath()` resolves against it, and computing the path
+    // before this line points every write in this test at the REAL
+    // ~/.config/systemd/user/agenthub.service — which the cleanup below then
+    // deletes. (Asked how I know.)
+    process.env.HOME = TMP_HOME;
+    const unit = require("../../scripts/systemd-service").unitPath("agenthub");
+    assert.ok(
+      unit.startsWith(TMP_HOME + path.sep),
+      `refusing to touch a unit outside the temp home: ${unit}`
+    );
+
+    const writeUnit = (workingDir) => {
+      fs.mkdirSync(path.dirname(unit), { recursive: true });
+      fs.writeFileSync(
+        unit,
+        "[Unit]\n# agenthub-managed-unit — regenerated on install, do not edit by hand\n" +
+          `[Service]\nWorkingDirectory=${workingDir}\n`,
+        "utf8"
+      );
+    };
+
+    try {
+      fs.mkdirSync(path.join(RT, "node_modules"), { recursive: true });
+      fs.writeFileSync(
+        infoPath,
+        JSON.stringify({ servers: [{ port: 4820, pid: process.pid, startedAt: "x" }] })
+      );
+      boot.writeState(
+        {
+          pluginVersion: pkg.version,
+          depsHash: boot.depsHash(),
+          pluginRoot: ROOT,
+          skillPluginsSettled: "nothing-missing",
+        },
+        RT
+      );
+
+      // Control: a unit naming THIS root is the steady state — fast path taken.
+      writeUnit(ROOT);
+      assert.equal(boot.fastPathOk(RT), true, "a current unit must not block the fast path");
+
+      // The regression: same healthy install, unit left on a retired root.
+      writeUnit("/plugins/cache/agenthub/deadbeef");
+      assert.equal(boot.fastPathOk(RT), false);
+    } finally {
+      fs.rmSync(infoPath, { force: true });
+      fs.rmSync(unit, { force: true });
+      if (prevHome === undefined) delete process.env.HOME;
+      else process.env.HOME = prevHome;
+    }
+  });
 });
 
 describe("skill-plugin auto-install gate", () => {

server/__tests__/plugin-doctor-systemd.test.js

@@ -0,0 +1,121 @@
+/**
+ * @file Tests the `systemd` row of scripts/plugin-doctor.js.
+ *
+ * The row exists for a failure nothing else in the report can see: a unit still
+ * naming a retired plugin cache directory leaves a running, healthy-looking
+ * dashboard that simply does not come back after the next reboot — it starts a
+ * path Claude Code deleted during the update. Every other row would read OK.
+ *
+ * WARN and never FAIL: the dashboard in front of the user works, and plenty of
+ * machines legitimately have no unit at all.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+const { describe, it, beforeEach, after } = require("node:test");
+const assert = require("node:assert/strict");
+const fs = require("node:fs");
+const os = require("node:os");
+const path = require("node:path");
+
+const TMP_HOME = fs.mkdtempSync(path.join(os.tmpdir(), "agenthub-doctor-systemd-"));
+const prevHome = process.env.HOME;
+// Before anything resolves a unit path: `unitPath()` reads HOME, and a path
+// computed against the real one makes these tests rewrite the developer's own
+// ~/.config/systemd/user/agenthub.service.
+process.env.HOME = TMP_HOME;
+process.env.CLAUDE_HOME = path.join(TMP_HOME, ".claude");
+
+const svc = require("../../scripts/systemd-service");
+const { diagnose } = require("../../scripts/plugin-doctor");
+
+const UNIT = svc.unitPath("agenthub");
+const PLUGIN_ROOT = path.resolve(__dirname, "..", "..");
+
+assert.ok(UNIT.startsWith(TMP_HOME + path.sep), `refusing to touch ${UNIT}`);
+
+beforeEach(() => {
+  fs.rmSync(UNIT, { force: true });
+  // Claim systemd exists and the unit is running, so each test varies exactly
+  // one thing: the unit file on disk.
+  svc.__setExecImpl((args) => ({
+    status: 0,
+    stdout: args[0] === "is-active" ? "active\n" : "",
+  }));
+});
+
+after(() => {
+  svc.__reset();
+  if (prevHome === undefined) delete process.env.HOME;
+  else process.env.HOME = prevHome;
+  delete process.env.CLAUDE_HOME;
+  fs.rmSync(TMP_HOME, { recursive: true, force: true });
+});
+
+function row() {
+  const found = diagnose().find((r) => r.label === "systemd");
+  assert.ok(found, "the doctor must always emit a systemd row");
+  return found;
+}
+
+function writeUnit(workingDir) {
+  fs.mkdirSync(path.dirname(UNIT), { recursive: true });
+  fs.writeFileSync(
+    UNIT,
+    "[Unit]\n# agenthub-managed-unit — regenerated on install, do not edit by hand\n" +
+      `[Service]\nWorkingDirectory=${workingDir}\n`,
+    "utf8"
+  );
+}
+
+const linuxOnly = { skip: process.platform !== "linux" ? "systemd is Linux-only" : false };
+
+describe("plugin-doctor: systemd row", linuxOnly, () => {
+  it("warns, never fails, when the unit names a retired plugin root", () => {
+    writeUnit("/plugins/cache/sg/agenthub/deadbeef");
+    const r = row();
+
+    assert.equal(r.level, "warn", "a working dashboard must not fail the doctor run");
+    assert.match(r.detail, /previous plugin version/i);
+    // The consequence is the whole point — a reader who does not know it will
+    // ignore the row.
+    assert.match(r.detail, /reboot/i);
+    assert.match(r.detail, /plugin-bootstrap\.js --force|new Claude Code session/);
+  });
+
+  it("passes when the unit is current and running", () => {
+    writeUnit(PLUGIN_ROOT);
+    const r = row();
+
+    assert.equal(r.level, "ok", r.detail);
+    assert.match(r.detail, /current and running/i);
+  });
+
+  it("warns when the unit is current but stopped", () => {
+    writeUnit(PLUGIN_ROOT);
+    svc.__setExecImpl((args) => ({
+      status: 3,
+      stdout: args[0] === "is-active" ? "inactive\n" : "",
+    }));
+
+    const r = row();
+    assert.equal(r.level, "warn");
+    assert.match(r.detail, /not running/i);
+  });
+
+  it("reports no unit as fine, not as a problem", () => {
+    // A plugin install without `agenthub service install` is a normal setup:
+    // the server is started per session.
+    const r = row();
+    assert.equal(r.level, "ok", r.detail);
+    assert.match(r.detail, /no unit/i);
+  });
+
+  it("warns about a unit it did not write, and never claims it is stale", () => {
+    fs.mkdirSync(path.dirname(UNIT), { recursive: true });
+    fs.writeFileSync(UNIT, "[Service]\nExecStart=/opt/someone-elses-agenthub\n", "utf8");
+
+    const r = row();
+    assert.equal(r.level, "warn");
+    assert.match(r.detail, /not written by AgentHub|left untouched/i);
+  });
+});

server/__tests__/systemd-service.test.js

@@ -134,6 +134,53 @@ describe("systemd-service — restartUserService", linuxOnly, () => {
   });
 });
 
+describe("systemd-service — unitIsStale", linuxOnly, () => {
+  it("is true when the unit names a plugin root that is no longer the current one", () => {
+    // Invisible while the server runs, fatal at the next reboot: the unit
+    // starts a path Claude Code garbage-collected after the update.
+    svc.writeUserService({ ...UNIT, workingDir: "/plugin/root/old" });
+    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), true);
+  });
+
+  it("is false for a unit already naming the current root", () => {
+    svc.writeUserService(UNIT);
+    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), false);
+  });
+
+  it("is false when there is no unit, and for one we do not own", () => {
+    assert.equal(svc.unitIsStale("agenthub", "/plugin/root/new"), false);
+
+    fs.mkdirSync(path.dirname(svc.unitPath("agenthub")), { recursive: true });
+    fs.writeFileSync(svc.unitPath("agenthub"), "[Service]\nWorkingDirectory=/opt/mine\n", "utf8");
+    assert.equal(
+      svc.unitIsStale("agenthub", "/plugin/root/new"),
+      false,
+      "a foreign unit is not ours to call stale, or to rewrite"
+    );
+  });
+
+  it("spawns nothing — the bootstrap fast path runs it on every SessionStart", () => {
+    svc.writeUserService(UNIT);
+    calls = [];
+
+    svc.unitIsStale("agenthub", "/plugin/root/new");
+    assert.deepEqual(calls, []);
+  });
+});
+
+describe("systemd-service — unitIsActive", linuxOnly, () => {
+  it("is true only for `active`", () => {
+    svc.__setExecImpl((args) => ({ status: 0, stdout: args[0] === "is-active" ? "active\n" : "" }));
+    assert.equal(svc.unitIsActive("agenthub"), true);
+
+    svc.__setExecImpl((args) => ({
+      status: 3,
+      stdout: args[0] === "is-active" ? "inactive\n" : "",
+    }));
+    assert.equal(svc.unitIsActive("agenthub"), false);
+  });
+});
+
 describe("systemd-service — unitIsOurs", linuxOnly, () => {
   it("is false when no unit exists at all", () => {
     fs.rmSync(svc.unitPath("agenthub"), { force: true });