diff --git a/README.md b/README.md
index e194bdc..30ff383 100644
--- a/README.md
+++ b/README.md
@@ -268,6 +268,7 @@ The five questions and actions in the chart:
 | Recall | a tool call failed | shows Claude the lesson that describes the failure |
 | Capture | a call works after one failed | decides whether it is the fix, and if so tells Claude to record the lesson |
 | Stop check | Claude is about to finish | refuses the stop once if a lesson is owed and not yet recorded or declined |
+| In-flight check | Claude is about to finish | refuses the stop once if work is still in flight with nothing watching it: a detached process, a workflow run dispatched by hand, or the user's own pull request with pending checks, and no polling loop alive. Runs `hooks/inflight-stop-check.sh`, which can also be registered directly as a Stop hook |
 
 Two things happen beside the chart. A request that keeps coming back is offered a skill,
 as described above. And each time a session invokes a skill that compound lists, the use
diff --git a/hooks/decisions.test.ts b/hooks/decisions.test.ts
index 451489b..c7d0a6f 100644
--- a/hooks/decisions.test.ts
+++ b/hooks/decisions.test.ts
@@ -220,6 +220,9 @@ type World = {
   // What `check` prints whatever the call, and what `log --json` prints, when the test says.
   check: string | undefined
   logReply: string | undefined
+  // What the in-flight check prints at a stop ('' = nothing in flight), and the stdin it got.
+  inflight: string
+  inflightStdin: string[]
 }
 
 let worlds = 0
@@ -230,7 +233,7 @@ let worlds = 0
 function world(on: On): World {
   worlds += 1
   const n = worlds
-  const w: World = { bare: true, calls: [], logged: [], asked: 0, judge: '{"name":null}', show: '', verdict: { counted: true, ineffective: false }, fails: () => false, owed: [], check: undefined, logReply: undefined }
+  const w: World = { bare: true, calls: [], logged: [], asked: 0, judge: '{"name":null}', show: '', verdict: { counted: true, ineffective: false }, fails: () => false, owed: [], check: undefined, logReply: undefined, inflight: '', inflightStdin: [] }
   mock.env(on, { HOME: '/home/me', COMPOUND_HOME: '/home/me/compound', COMPOUND_PROMPT_MIN_CHARS: '100000' })
   on('session.id', () => ({ value: `decisions-${n}` }))
   on('session.root', () => ({ value: `/work/decisions-${n}` }))
@@ -255,6 +258,10 @@ function world(on: On): World {
       w.logged.push(sent)
       return done(argv.includes('--json') ? (w.logReply ?? JSON.stringify({ ts: '2026-10-05T12:00:00Z', session: `decisions-${n}`, ...event })) : '')
     }
+    if (String(argv[1] ?? '').endsWith('/hooks/inflight-stop-check.sh')) {
+      w.inflightStdin.push(e.init?.stdin ?? '')
+      return done(w.inflight)
+    }
     if (verb === 'list') return done(LESSONS)
     if (verb === 'show') return done(w.show)
     if (verb === 'check') {
@@ -543,3 +550,45 @@ test('the stop refused for two owed lessons carries both ids, as the CLI listed
   expect(stop.block).toContain('- 1: --settles ab12cd34')
   expect(stop.block).toContain('- 2: --settles ef56ab78')
 })
+
+// ---- the in-flight check at the stop ------------------------------------------------------
+
+const UNWATCHED = JSON.stringify({ decision: 'block', reason: 'Work is still in flight and NO waiter is running:\nDETACHED PROCESSES:\npid 6263 (up 17:12) python canary-runner.py' })
+
+test('a stop with work in flight and no waiter is refused with what is in flight', async ($, on) => {
+  const w = world(on)
+  mock.clock(on, { now: 1_800_000_000_000 })
+  w.inflight = UNWATCHED
+  const stop = await $.classic.Stop({ stop_hook_active: false } as never)
+  expect(stop.block).toContain('[compound] Work is still in flight and NO waiter is running')
+  expect(stop.block).toContain('pid 6263')
+  expect(w.inflightStdin).toEqual([JSON.stringify({ stop_hook_active: false })])
+})
+
+test('the check is told when the stop follows a block, so the script can stay silent', async ($, on) => {
+  const w = world(on)
+  mock.clock(on, { now: 1_800_000_000_000 })
+  await $.classic.Stop({ stop_hook_active: true } as never)
+  expect(w.inflightStdin).toEqual([JSON.stringify({ stop_hook_active: true })])
+})
+
+test('nothing in flight, or a check that prints something unreadable, lets the stop through', async ($, on) => {
+  const w = world(on)
+  mock.clock(on, { now: 1_800_000_000_000 })
+  expect((await $.classic.Stop({ stop_hook_active: false } as never)).block).toBeUndefined()
+  w.inflight = 'not json at all'
+  expect((await $.classic.Stop({ stop_hook_active: false } as never)).block).toBeUndefined()
+  w.inflight = JSON.stringify({ decision: 'approve', reason: 'fine' })
+  expect((await $.classic.Stop({ stop_hook_active: false } as never)).block).toBeUndefined()
+})
+
+test('an owed lesson and unwatched work are both in the one refusal', async ($, on) => {
+  const w = world(on)
+  mock.clock(on, { now: 1_800_000_000_000 })
+  w.owed = [{ ts: '2026-10-05T12:00:00Z', type: 'capture', id: 'ab12cd34', call: 'c1', tool: 'Bash', failed: './deploy.sh', error: 'no target', fixed: './deploy.sh --target x' }]
+  w.inflight = UNWATCHED
+  const stop = await $.classic.Stop({ stop_hook_active: false } as never)
+  expect(stop.block).toContain('This session owes a lesson')
+  expect(stop.block).toContain('./deploy.sh --target x')
+  expect(stop.block).toContain('NO waiter is running')
+})
diff --git a/hooks/inflight-stop-check.sh b/hooks/inflight-stop-check.sh
new file mode 100755
index 0000000..8f9a7d9
--- /dev/null
+++ b/hooks/inflight-stop-check.sh
@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Stop hook: refuse to end a turn that leaves work in flight with nothing watching it.
+# Blocks at most once per stop (stop_hook_active), and only for work that is plausibly
+# this user's own: detached processes, runs they dispatched, their PRs with pending checks.
+input=$(cat)
+[ "$(printf '%s' "$input" | jq -r '.stop_hook_active // false' 2>/dev/null)" = "true" ] && exit 0
+
+items=""
+# 1. Detached processes (reparented to init) that look like a test suite or a Claude-launched job.
+procs=$(ps -eo ppid=,pid=,etime=,command= 2>/dev/null \
+  | awk '$1==1' | grep -E 'pytest|/claude-[0-9]+/|nohup' | grep -vE 'grep|inflight-stop-check' \
+  | awk '{printf "pid %s (up %s) %s\n", $2, $3, substr($0, index($0,$4), 110)}' | head -6)
+[ -n "$procs" ] && items="${items}DETACHED PROCESSES:\n${procs}\n"
+
+if command -v gh >/dev/null 2>&1 && git rev-parse --git-dir >/dev/null 2>&1; then
+  # 2. Workflow runs I dispatched by hand that are still going (cron runs are not mine to watch).
+  me=$(gh api user --jq .login 2>/dev/null)   # "@me" is not accepted by `gh run list --user`
+  runs=$(gh run list --user "$me" --event workflow_dispatch --status in_progress --limit 6 \
+         --json databaseId,workflowName --jq '.[]|"run \(.databaseId) \(.workflowName)"' 2>/dev/null)
+  [ -n "$runs" ] && items="${items}DISPATCHED RUNS IN PROGRESS:\n${runs}\n"
+  # 3. My open PRs with checks still pending.
+  for n in $(gh pr list --author @me --state open --limit 10 --json number --jq '.[].number' 2>/dev/null); do
+    p=$(gh pr checks "$n" --json state --jq '[.[]|select(.state=="IN_PROGRESS" or .state=="QUEUED" or .state=="PENDING")]|length' 2>/dev/null)
+    [ "${p:-0}" != "0" ] && items="${items}PR #$n: $p check(s) pending\n"
+  done
+fi
+[ -z "$items" ] && exit 0
+
+# A waiter is a live polling loop: a shell whose command sleeps AND polls gh / a pid / a log.
+waiters=$(ps -eo command= 2>/dev/null | grep -E 'sleep [0-9]+' \
+  | grep -E 'gh (run|pr) |ps -p|pgrep|grep -q' | grep -vE 'inflight-stop-check' | grep -vc '^grep')
+[ "${waiters:-0}" -gt 0 ] && exit 0
+
+reason=$(printf 'Work is still in flight and NO waiter is running:\n%b\nBefore stopping, either start a background waiter (run_in_background) that exits when these finish, with a deadline, or say plainly in the final message that nobody is watching them and when to look.' "$items")
+jq -n --arg r "$reason" '{decision:"block", reason:$r}'
diff --git a/hooks/register.ts b/hooks/register.ts
index 3821da8..36c3ed8 100644
--- a/hooks/register.ts
+++ b/hooks/register.ts
@@ -1423,6 +1423,46 @@ function turnEnded(sid: string): undefined {
   return undefined
 }
 
+// ---- the in-flight check at the stop ------------------------------------------------------
+
+// hooks/inflight-stop-check.sh is the same script a person can register directly as a Stop
+// hook. It answers one question: is work still in flight (a detached process, a workflow
+// run dispatched by hand, the user's own pull request with pending checks) with no polling
+// loop alive to see it finish? When it is, the script prints a Stop-hook JSON decision and
+// its reason is the refusal. The script itself refuses only once per stop: it is told
+// whether this stop follows a block and stays silent when it does.
+//
+// The failure it prevents: a turn starts a three-hour run, dispatches a workflow, opens
+// pull requests, writes a status summary and ends. Nothing fails; the work finishes or
+// stalls unseen. A lesson that says "keep a waiter going" is not enough, because the
+// session that forgets the waiter forgets the lesson too.
+//
+// It never throws and never blocks on its own failure: a script that is missing, times
+// out or prints something unreadable lets the stop through.
+const INFLIGHT_SH = 'hooks/inflight-stop-check.sh'
+const INFLIGHT_BUDGET_MS = 45000
+const BASH = '/bin/bash'
+
+async function inflight($: EngineInterface, followsBlock: boolean): Promise<string | undefined> {
+  if (await off($)) return undefined
+  const script = `${$.plugin.root}/${INFLIGHT_SH}`
+  try {
+    if (!(await $.fs.exists(script))) return undefined
+    const done = await $.process.run([BASH, script], {
+      cwd: await projectRoot($),
+      timeoutMs: INFLIGHT_BUDGET_MS,
+      stdin: JSON.stringify({ stop_hook_active: followsBlock }),
+    })
+    const printed = done.stdout.trim()
+    if (printed === '') return undefined
+    const said = JSON.parse(printed) as { decision?: unknown, reason?: unknown }
+    if (said.decision !== 'block' || typeof said.reason !== 'string' || said.reason === '') return undefined
+    return `[compound] ${said.reason}`
+  } catch {
+    return undefined
+  }
+}
+
 async function onStop($: EngineInterface, followsBlock: boolean): Promise<string | undefined> {
   if (await off($)) return undefined
   const sid = await $.session.id()
@@ -1743,7 +1783,10 @@ export const register: Register = on => {
   on('classic.Stop', async ($, e, next) => {
     const result = await next(e)
     try {
-      const block = await onStop($, e.stop_hook_active === true)
+      const followsBlock = e.stop_hook_active === true
+      const owed = await onStop($, followsBlock)
+      const unwatched = await inflight($, followsBlock)
+      const block = owed === undefined ? unwatched : (unwatched === undefined ? owed : `${owed}\n\n${unwatched}`)
       if (block === undefined) return result
       return { ...result, block: result.block === undefined ? block : `${result.block}\n\n${block}` }
     } catch (err) {