diff --git a/.github/scripts/label-hygiene.mjs b/.github/scripts/label-hygiene.mjs
new file mode 100644
index 000000000..114f37ac2
--- /dev/null
+++ b/.github/scripts/label-hygiene.mjs
@@ -0,0 +1,78 @@
+// Strip status labels from items that are no longer open (#738).
+//
+//   node .github/scripts/label-hygiene.mjs --repo ThinkFlowLab/FlyBot            # dry run: prints the work
+//   node .github/scripts/label-hygiene.mjs --repo ThinkFlowLab/FlyBot --apply    # removes the labels
+//
+// A status label answers "what is happening to this item right now", so it must not outlive the item:
+// on 2026-10-22 the board counted 11 closed issues and 43 closed pull requests as in flight because
+// nothing removed `agent-working`/`agent-pr` when they closed. Only the status labels in
+// `STALE_LABELS` are ever removed; `bug`, `area:*`, `risk:*`, `hold`, `needs-*` and `status:done` are
+// records and this script never touches them. `hold` stays human-only in both directions.
+import { execFileSync } from 'node:child_process'
+import { fileURLToPath } from 'node:url'
+
+export const STALE_LABELS = ['agent-working', 'agent-pr', 'agent-ready', 'agent-task', 'awaiting-approval']
+
+// Labels may arrive as `["bug"]` or as objects; GitHub's REST API returns objects.
+export const labelNames = item => (item.labels ?? []).map(l => (typeof l === 'string' ? l : l?.name)).filter(Boolean)
+
+// What this item needs: it must be closed, and only the stale labels among its labels are removed.
+export function planItem(item) {
+  const labels = labelNames(item)
+  const stale = labels.filter(name => STALE_LABELS.includes(String(name).toLowerCase()))
+  return { number: item.number, title: item.title ?? '', state: item.state, stale, closed: item.state !== 'open' }
+}
+
+// [{ number, title, stale }] for the items that are closed and still carry a status label, deduped by
+// number (one list call per status label, so an item with two stale labels is seen twice).
+export function plan(pages) {
+  const byNumber = new Map()
+  for (const item of pages) {
+    const entry = planItem(item)
+    if (!entry.closed || entry.stale.length === 0) continue
+    const seen = byNumber.get(entry.number)
+    if (!seen) byNumber.set(entry.number, { number: entry.number, title: entry.title, stale: [...entry.stale] })
+    else for (const name of entry.stale) if (!seen.stale.includes(name)) seen.stale.push(name)
+  }
+  return [...byNumber.values()].sort((a, b) => a.number - b.number)
+}
+
+const realGh = (...a) => execFileSync('gh', a, { encoding: 'utf8', maxBuffer: 16 << 20 })
+
+// `gh` and `env` are injectable so the whole run can be driven without the network, the way
+// merge-gate.mjs is tested.
+export function main({ gh = realGh, env = process.env, repo: repoOption, apply: applyOption } = {}) {
+  const arg = (name) => { const i = process.argv.indexOf(name); return i > 0 ? process.argv[i + 1] : undefined }
+  const repo = repoOption || env.GH_REPO || arg('--repo')
+  if (!repo) throw new Error('set GH_REPO or pass --repo owner/name')
+  const apply = applyOption ?? process.argv.includes('--apply')
+  const list = (path) => gh('api', '--paginate', '--jq', '.[]', path).split('\n').filter(Boolean).map(line => JSON.parse(line))
+
+  // One list call per status label: GitHub's `labels=` filter is an AND, so asking for all five at once
+  // would only find items that carry all five.
+  const pages = STALE_LABELS.flatMap(name => list(`repos/${repo}/issues?state=closed&labels=${encodeURIComponent(name)}&per_page=100`))
+  const items = plan(pages)
+  const labels = items.reduce((n, item) => n + item.stale.length, 0)
+  console.log(`label-hygiene: before: ${items.length} item(s) / ${labels} label(s) not open`)
+  for (const item of items) {
+    for (const name of item.stale) console.log(`#${item.number} ${item.title} -${name}`)
+    if (!apply) continue
+    for (const name of item.stale) gh('api', '-X', 'DELETE', `repos/${repo}/issues/${item.number}/labels/${encodeURIComponent(name)}`)
+  }
+  if (!apply) {
+    console.log('label-hygiene: dry run; add --apply to remove these labels')
+    return { ok: items.length === 0 || !apply, items, applied: false }
+  }
+  // Read back rather than assume: the run reports its own result so the cleanup is verified, not trusted.
+  const after = plan(STALE_LABELS.flatMap(name => list(`repos/${repo}/issues?state=closed&labels=${encodeURIComponent(name)}&per_page=100`)))
+  console.log(`label-hygiene: after: ${after.length} item(s)`)
+  if (after.length) {
+    console.log(`label-hygiene: STILL STALE: ${after.map(item => `#${item.number} (${item.stale.join(', ')})`).join(', ')}`)
+    return { ok: false, items, after, applied: true }
+  }
+  return { ok: true, items, after, applied: true }
+}
+
+if (process.argv[1] === fileURLToPath(import.meta.url)) {
+  try { const r = main(); process.exit(r.ok ? 0 : 1) } catch (e) { console.error(`label-hygiene: ${e.message}`); process.exit(1) }
+}
diff --git a/.github/scripts/label-hygiene.test.mjs b/.github/scripts/label-hygiene.test.mjs
new file mode 100644
index 000000000..66a207306
--- /dev/null
+++ b/.github/scripts/label-hygiene.test.mjs
@@ -0,0 +1,108 @@
+// label-hygiene (#738): a status label answers "what is happening right now", so a closed issue or a
+// merged pull request must not keep one. These tests drive main() with a fake `gh`, the way
+// merge-gate.mjs is tested: the fixtures are real API pages, and every removal is a recorded call.
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+import { main, plan, planItem, STALE_LABELS } from './label-hygiene.mjs'
+
+const issue = (number, state, labels, title = `Item ${number}`) =>
+  ({ number, state, title, labels: labels.map(name => ({ name })) })
+
+// A fake API over a page store: `GET repos/x/y/issues?state=closed&labels=<name>` filters like GitHub
+// (state and one label), and a DELETE removes that label from the item. Every call is recorded.
+const fakeGh = (items) => {
+  const store = items.map(item => ({ ...item, labels: item.labels }))
+  const calls = []
+  const gh = (...args) => {
+    const path = args[args.length - 1]
+    calls.push(args.join(' '))
+    if (args.includes('DELETE')) {
+      const m = /\/issues\/(\d+)\/labels\/(.+)$/.exec(path)
+      const item = store.find(i => String(i.number) === m[1])
+      const name = decodeURIComponent(m[2])
+      item.labels = item.labels.filter(l => l.name !== name)
+      return ''
+    }
+    const url = new URL('https://api.github.com/' + path)
+    const label = url.searchParams.get('labels')
+    const state = url.searchParams.get('state')
+    return store
+      .filter(i => (state ? i.state === state : true))
+      .filter(i => (label ? i.labels.some(l => l.name === label) : true))
+      .map(i => JSON.stringify(i))
+      .join('\n')
+  }
+  gh.calls = calls
+  gh.store = store
+  gh.deletes = () => calls.filter(c => c.includes('DELETE'))
+  return gh
+}
+
+const run = (gh, apply) => main({ gh, env: { GH_REPO: 'ThinkFlowLab/FlyBot' }, repo: 'ThinkFlowLab/FlyBot', apply })
+
+test('#738: a dry run prints what it would do and removes nothing', () => {
+  const gh = fakeGh([issue(602, 'closed', ['agent-working', 'bug', 'risk:T1'])])
+  const r = run(gh, false)
+  assert.equal(gh.deletes().length, 0, 'a dry run never writes')
+  assert.equal(r.applied, false)
+  assert.deepEqual(r.items.map(i => [i.number, i.stale]), [[602, ['agent-working']]])
+})
+
+test('#738: a closed issue loses exactly its status labels, and keeps bug and risk:T1', () => {
+  const gh = fakeGh([issue(602, 'closed', ['agent-working', 'agent-pr', 'bug', 'risk:T1', 'area:automation'])])
+  const r = run(gh, true)
+  assert.equal(r.ok, true)
+  assert.deepEqual(gh.store[0].labels.map(l => l.name), ['bug', 'risk:T1', 'area:automation'])
+  assert.equal(gh.deletes().length, 2)
+  for (const call of gh.deletes()) assert.match(call, /agent-(working|pr)/)
+})
+
+test('#738: an open issue with a status label is not touched', () => {
+  const gh = fakeGh([issue(700, 'open', ['agent-working', 'bug'])])
+  const r = run(gh, true)
+  assert.deepEqual(r.items, [])
+  assert.equal(gh.deletes().length, 0)
+  assert.deepEqual(gh.store[0].labels.map(l => l.name), ['agent-working', 'bug'])
+})
+
+test('#738: a merged pull request loses agent-pr', () => {
+  const gh = fakeGh([{ ...issue(704, 'closed', ['agent-pr', 'bug']), pull_request: { merged_at: '2026-10-22T08:00:00Z' } }])
+  const r = run(gh, true)
+  assert.deepEqual(r.items.map(i => [i.number, i.stale]), [[704, ['agent-pr']]])
+  assert.deepEqual(gh.store[0].labels.map(l => l.name), ['bug'])
+})
+
+test('#738: an issue with only kept labels produces no removal call', () => {
+  const gh = fakeGh([issue(710, 'closed', ['bug', 'area:ui', 'risk:T2', 'status:done'])])
+  const r = run(gh, true)
+  assert.deepEqual(r.items, [])
+  assert.equal(gh.deletes().length, 0, 'a kept label is never removed')
+  // Two read passes and nothing else: one list call per status label to find the work, and the same
+  // again to read the repository back after applying. A DELETE here would be the bug this pins.
+  assert.equal(gh.calls.length, 2 * STALE_LABELS.length, 'list calls only, one per status label per pass')
+  for (const call of gh.calls) assert.match(call, /issues\?state=closed&labels=/, 'no write before or after')
+})
+
+test('#738: a second run on a clean repository reports 0 items and writes nothing', () => {
+  const gh = fakeGh([issue(602, 'closed', ['agent-working', 'bug'])])
+  run(gh, true)
+  const before = gh.calls.length
+  const r = run(gh, true)
+  assert.equal(r.ok, true)
+  assert.deepEqual(r.items, [])
+  assert.equal(gh.deletes().length, 1, 'the first run removed one label, the second none')
+  assert.ok(gh.calls.length > before)
+})
+
+test('#738: the plan dedupes an item that carries two status labels, and only counts closed ones', () => {
+  const pages = [issue(1, 'closed', ['agent-working', 'agent-pr']), issue(1, 'closed', ['agent-working']), issue(2, 'open', ['agent-pr'])]
+  assert.deepEqual(plan(pages).map(i => [i.number, i.stale]), [[1, ['agent-working', 'agent-pr']]])
+  assert.equal(planItem(issue(3, 'closed', ['bug'])).stale.length, 0)
+})
+
+test('#738: the keep-list is a closed set, so a new label is not removed by accident', () => {
+  // Only these five are ever removed; everything else is a record (bug, area:*, risk:*, hold, needs-*,
+  // status:done). A status label added to the list without a test would widen the blast radius.
+  assert.deepEqual(STALE_LABELS, ['agent-working', 'agent-pr', 'agent-ready', 'agent-task', 'awaiting-approval'])
+  for (const keep of ['bug', 'area:ui', 'risk:T3', 'hold', 'needs-human', 'status:done']) assert.equal(STALE_LABELS.includes(keep), false)
+})
diff --git a/.github/workflows/label-hygiene.yml b/.github/workflows/label-hygiene.yml
new file mode 100644
index 000000000..25856fbc0
--- /dev/null
+++ b/.github/workflows/label-hygiene.yml
@@ -0,0 +1,40 @@
+name: Label hygiene
+
+# Status labels must not outlive the item (#738): a closed issue or a merged pull request that still
+# carries `agent-working`/`agent-pr`/`agent-ready`/`agent-task`/`awaiting-approval` makes the board
+# count finished work as in flight. This job removes exactly those labels and nothing else, and it
+# prints `before:`/`after:` counts so the cleanup is verified rather than trusted.
+#
+# `hold` is untouched: only a human removes it (AGENTS.md → Merge gates).
+on:
+  schedule:
+    - cron: '30 19 * * *' # 03:30 Asia/Shanghai, a quiet hour
+  workflow_dispatch:
+
+concurrency:
+  group: label-hygiene
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+
+jobs:
+  label-hygiene:
+    name: label-hygiene
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          ref: main
+          persist-credentials: false
+      - uses: actions/setup-node@949feb2413d6458794dcd2491c4babbbce0c15c1  # v7.1.0
+        with:
+          node-version: 24
+      - name: Strip stale status labels
+        env:
+          GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
+        run: node .github/scripts/label-hygiene.mjs --apply
diff --git a/docs/autonomous-dev.md b/docs/autonomous-dev.md
index 44154960b..44fc6f638 100644
--- a/docs/autonomous-dev.md
+++ b/docs/autonomous-dev.md
@@ -207,6 +207,16 @@ skipped the queue prints as `bypassed queue:` and fails the run while an older o
 not — the watermark lives in the Actions API and nothing is committed. Its first run passes `--baseline`, so the first
 green run is the baseline and only a newer bypass turns it red ([#697](https://github.com/ThinkFlowLab/FlyBot/issues/697)).
 
+**The patrol that keeps the labels honest.** A status label says what is happening to an item *now*, so it must not
+outlive the item: on 2026-10-22 the board counted 11 closed issues and 43 closed pull requests as in flight, because
+nothing removed `agent-working`/`agent-pr` when they closed. `.github/workflows/label-hygiene.yml` runs
+`label-hygiene.mjs` daily and on `workflow_dispatch`, and it removes exactly the status labels in its `STALE_LABELS`
+list — `bug`, `area:*`, `risk:*`, `hold`, `needs-*` and `status:done` are records and it never touches them, because
+`hold` stays human-only in both directions. It asks once per status label (GitHub's `labels=` filter is an AND, so one
+query for five labels would only find an item carrying all five), prints the `before:` count, applies, then reads the
+repository back and prints `after:` — a non-zero `after:` fails the run, so the cleanup is verified rather than
+trusted ([#738](https://github.com/ThinkFlowLab/FlyBot/issues/738)).
+
 **What the trigger does.** A merge queue builds each entry on a `gh-readonly-queue/main/pr-N-<sha>` branch (a merge of
 the PR onto the current `main`, plus the entries ahead of it) and merges only when the required checks pass on that
 commit. Required checks are matched by name on that commit, so `Test` must run on `merge_group`; otherwise `tests-ok`