fix(labels): sweep on labeled so the handoff is immediate

A review landing was never a trigger for the labels workflow, so the exact
moment `state:needs-human` became true — the third bot approving — fired
nothing, and the label waited on the `*/15` cron. That cron does not run at
its declared rate: measured across box, rig and cast over a two-hour window
on 2026-07-20, one scheduled run each against the eight `*/15` implies.

The obvious fix does not work. There is no `pull_request_review_target`, and
on fork PRs — all of them here — `pull_request_review` runs with a read-only
token and cannot label anything.

So the handoff wakes the sweep itself:

- `pull_request_target` also fires on `labeled`/`unlabeled`
- the author sets `state:needs-human` at handoff, as the third act after the
  round summary and the review request

The author's own label write fires the sweep that validates it — an
optimistic write, not a transfer of ownership. The reconciler confirms or
corrects it seconds later, and the cron falls back to a last resort. It
cannot loop: the reconciler writes with GITHUB_TOKEN, which does not create
workflow runs; agent writes use a PAT, which does.

`labels-reconcile.sh` is unchanged — it already recomputes every open PR
from scratch on every run, which is what makes the optimistic write safe.
The `scope` job is skipped on label events, where no path can have changed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/labels.yml

@@ -9,15 +9,32 @@ name: labels
 # is ever checked out or executed — labeler reads changed paths via the API,
 # and reconcile checks out the BASE branch only. Keep it that way.
 #
-# Review-submitted transitions (bots finishing a round) ride the cron: there
-# is no pull_request_review_target, so the 15-minute tick is the wake signal —
-# the same cadence the reviewer bots poll at.
+# There is no pull_request_review_target, so a review landing cannot wake this
+# workflow directly — and the */15 cron is advisory: GitHub deprioritises short
+# intervals hard enough that a quiet repo goes hours between ticks. So the
+# handoff wakes the sweep itself: the author sets state:needs-human when handing
+# the PR to the maintainer (CONTRIBUTING step 6), and `labeled` fires this
+# workflow, which confirms or corrects that optimistic write within seconds. The
+# cron stays as the last resort, for the round an agent forgets to hand off.
+#
+# This cannot loop: the reconciler's own label writes use GITHUB_TOKEN, and
+# GitHub does not create workflow runs from GITHUB_TOKEN-triggered events. Agent
+# writes use a PAT and therefore do trigger — exactly the asymmetry wanted.
 on:
   schedule:
     - cron: "*/15 * * * *"
   workflow_dispatch: # also bootstraps missing labels — run once on a fresh repo
   pull_request_target:
-    types: [opened, reopened, ready_for_review, converted_to_draft, synchronize]
+    types:
+      [
+        opened,
+        reopened,
+        ready_for_review,
+        converted_to_draft,
+        synchronize,
+        labeled,
+        unlabeled,
+      ]
 
 permissions:
   contents: read
@@ -26,7 +43,12 @@ permissions:
 
 jobs:
   scope:
-    if: github.event_name == 'pull_request_target'
+    # Not on labeled/unlabeled: those events change no paths, so labeler has
+    # nothing new to derive — and label churn is precisely what they are.
+    if: >-
+      github.event_name == 'pull_request_target' &&
+      github.event.action != 'labeled' &&
+      github.event.action != 'unlabeled'
     runs-on: ubuntu-latest
     concurrency:
       group: labels-scope-${{ github.event.pull_request.number }}

CHANGELOG.md

@@ -188,6 +188,40 @@ on the way to cutting its first release, and this file starts there.
 
 ### Changed
 
+- **`state:needs-human` no longer waits on the cron to become true** (#96)
+  — the labels workflow now also wakes on `pull_request_target: labeled` and
+  `unlabeled`, and the author sets `state:needs-human` themselves when handing
+  a PR to the maintainer.
+
+  A review landing was never a trigger. There is no
+  `pull_request_review_target`, and on fork PRs — which is all of them here —
+  `pull_request_review` runs with a read-only token and cannot label anything.
+  So the exact moment the label became true, the third bot approving, fired
+  nothing at all: the label waited for the `*/15` cron, or for somebody to
+  touch an unrelated PR. And that cron does not run at its declared rate —
+  GitHub deprioritises short intervals hard enough that, measured across the
+  three repos over a two-hour window on 2026-07-20, each got **one** scheduled
+  run against the eight `*/15` implies. heavy-duty/rig#94 took its third
+  approval and sat on `state:bots-reviewing` for hours; box and cast happened
+  to catch a tick and flipped correctly, on byte-identical workflow files. The
+  lag was worst on the quietest repo, which depends on the cron most and
+  receives it least.
+
+  The two halves fix each other: the author's own label write is what fires
+  the sweep that validates it. That makes it an optimistic write rather than a
+  transfer of ownership — seconds later the reconciler either confirms the
+  label or corrects it, and the cron falls back to being a genuine last
+  resort, for the round an agent forgets to hand off. It cannot loop, because
+  the reconciler's own writes use `GITHUB_TOKEN` and GitHub does not create
+  workflow runs from `GITHUB_TOKEN`-triggered events, while agent writes use a
+  PAT and do. `labels-reconcile.sh` is unchanged: it already recomputes every
+  open PR from scratch on every run, which is exactly what makes the
+  optimistic write safe. The `scope` job is skipped on the two new actions,
+  where no path can have changed and labeler has nothing to derive.
+
+  Landed in all three repos together (heavy-duty/box#141, heavy-duty/cast#131) — `labels.yml` and the label
+  taxonomy are shared.
+
 - **PR labels split into two axes: `state:*` (whose ball) and `blocker:*`
   (what is in the way)** (heavy-duty/box#137) — `state:needs-rebase`, added
   here only days ago by #87, is retired in the same breath. In its place:

CONTRIBUTING.md

@@ -31,14 +31,24 @@ labels tell you where everything is without opening anything.
    judgment belongs to the **author** — escalate by requesting the
    maintainer's review (step 6), and the reconciler flips the label on that
    request, because an explicit request is a fact it can trust.
-6. **When the round passes, the author hands the PR to the maintainer** by
-   requesting their review — that request is what flips `state:needs-human`,
+6. **When the round passes, the author hands the PR to the maintainer** in
+   three acts, in this order: post the tagged round summary, request the
+   maintainer's review, then set `state:needs-human` yourself — removing the
+   state label it replaces. The review request is what *earns* the label,
    provided the PR carries **no `blocker:*` label**. A blocker means the work
-   is still yours whatever the round said, so a request on a conflicted or red
-   PR will not flip it. With three formal head-current approvals the labels
+   is still yours whatever the round said, so on a conflicted or red PR
+   neither the request nor your own label write will stick — the sweep takes
+   it straight back off. With three formal head-current approvals the labels
    workflow requests the maintainer automatically; when part of the panel is
    comment-only, reading their agreement is the author's judgment, so the
    author makes the request.
+
+   Writing the label by hand is an **optimistic write, not a transfer of
+   ownership**. The machine stays the authority — but because the workflow
+   wakes on `labeled`, the author's own write fires the sweep that validates
+   it, and a handoff that had not earned the label is corrected seconds later.
+   Forgetting the write is not a failure either; it only means the label waits
+   for the cron, which is the lag this replaced.
 7. **Checks must be green**: `shellcheck`, `bash test/cli.sh` and
    `bash test/release.sh` locally mirror what CI runs; the db dump/restore
    round-trip (`test/db-integration.sh`) executes in CI where Docker is
@@ -97,7 +107,7 @@ machine-owned label just gets corrected on the next pass:
 
 | Labels | Set by |
 |---|---|
-| `state:*` | the labels workflow ([.github/workflows/labels.yml](.github/workflows/labels.yml)) — recomputed from GitHub's own facts every 15 minutes and on PR events. Never by hand. Exactly one per PR: *whose ball is it.* |
+| `state:*` | the labels workflow ([.github/workflows/labels.yml](.github/workflows/labels.yml)) — recomputed from GitHub's own facts on PR events (label changes included) and every 15 minutes. Machine-owned, with one exception: the author sets `state:needs-human` at handoff (step 6) and the workflow reconciles it. Otherwise never by hand. Exactly one per PR: *whose ball is it.* |
 | `blocker:*` | the same workflow, from the same facts — *what is in the way.* Any number per PR, or none. Never by hand: applying one does not stop a merge, and removing one does not unblock anything. Fix the thing and the next sweep drops the label. |
 | `stale` | the same workflow — 48h without commits, comments, or reviews. `blocked` PRs are exempt: they are quiet legitimately. |
 | `scope:*` on PRs | actions/labeler, from the changed paths ([.github/labeler.yml](.github/labeler.yml)). Additive — you may add more, the machine won't remove them. |

LABELS.md

@@ -107,13 +107,30 @@ would just say the same thing twice, drifting apart eventually.
 
 ## Maintenance
 
-State labels are written by automation, never by hand. Every state above is
-derivable from GitHub's own facts — the draft flag, requested reviewers,
+State labels are machine-owned, with exactly one exception. Every state above
+is derivable from GitHub's own facts — the draft flag, requested reviewers,
 review states, push timestamps — so the labels workflow
 ([.github/workflows/labels.yml](.github/workflows/labels.yml)) recomputes the
-state and reconciles labels statelessly, on a 15-minute cron plus PR events.
-A hand-moved label is a lie waiting to happen; the workflow asserts the
-effective state instead. `scope:` labels on PRs are applied from the changed
+state and reconciles labels statelessly, on PR events (label changes included)
+plus a 15-minute cron. A hand-moved label is a lie waiting to happen; the
+workflow asserts the effective state instead.
+
+The exception is `state:needs-human`, which the author sets at handoff
+([CONTRIBUTING.md](CONTRIBUTING.md), step 6). That is an optimistic write, not
+a transfer of ownership: because `pull_request_target: labeled` wakes the
+workflow, the author's own label write fires the sweep that validates it, and
+a handoff that had not earned the label is corrected within seconds.
+
+It exists because the wake signal was missing. There is no
+`pull_request_review_target` — on fork PRs, which is all of them here,
+`pull_request_review` runs read-only and cannot label anything — so the moment
+the label becomes true, the third approval landing, fired nothing at all. What
+was left was the `*/15` cron, and GitHub deprioritises short intervals hard
+enough that the delivered rate is closer to hourly. The label could therefore
+lag the round it described by hours, worst on the quietest repo: every sweep
+reconciles the whole board, so a busy repo stays fresh by piggybacking on
+unrelated PR events, while a quiet one depends on the cron most and receives
+it least. `scope:` labels on PRs are applied from the changed
 paths by actions/labeler ([.github/labeler.yml](.github/labeler.yml));
 [CONTRIBUTING.md](CONTRIBUTING.md) says who sets what.