Babysit Pr

---
name: babysit-pr
description: Watch a single PR on a persistent Monitor and auto-dispatch /fixpr (recoverable blockers) or /wrap (merge-ready). Reads PR state via pr-state.sh + merge-gate.sh each tick, classifies into {merged, merge-ready, conflicting, has-recoverable-blockers, waiting-on-bots, hard-blocked}, tracks in-flight dispatches in session-state for idempotency, applies stable-state backoff, emits a timestamped heartbeat per tick, and hard-terminates on merge/hard-blocked/N blocker ticks/user stop. Stop with /babysit-pr-stop. Invoke as `/babysit-pr <PR> [--cadence Nm] [--max-iter N] [--silent] [--auto-resolve-conflicts] [--max-conflict-rounds N]`.
triggers:
  - babysit pr
  - babysit this pr
  - watch this pr
  - keep an eye on pr
argument-hint: "<PR> [--cadence Nm] [--max-iter N] [--silent] [--auto-resolve-conflicts] [--max-conflict-rounds N]"
---

Watch one PR and drive it toward merge **without looping forever**. Each tick reads the PR's state through the shared scripts, classifies it, and dispatches the right skill — `/fixpr` to fix recoverable blockers, `/wrap` to merge when the gate is met — then re-arms the poll until a terminal condition fires.

`/babysit-pr` is a **thin orchestrator**: it never re-implements PR-state aggregation, the merge gate, fix logic, or the merge flow. It reads `pr-state.sh` + `merge-gate.sh`, and it dispatches `/fixpr` / `/wrap`. All code-verification, thread resolution, CI fixing, and merge-gate enforcement stay inside those skills (`fixpr/SKILL.md`, `wrap/SKILL.md`, `cr-merge-gate.md`). This skill only decides *which* to call and *when to stop*.

This is reused by `/pr-monitor-and-manage` (issue #460): that skill invokes `/babysit-pr` per discovered PR rather than re-implementing the per-PR decision tree.

## Safety boundaries (HARD STOPS — non-negotiable, `safety.md` / #450)

`/babysit-pr` is read-only plus the dispatches below. It MUST NOT:

- **Never babysit a PR you did not author (issue #733, `safety.md`).** Enrolling a PR in a watch loop is a "touch". Before the first tick, gate the target with `"$PR_AUTHORSHIP_SH" <PR>` (exit 0 = yours). Not yours / undetermined → refuse with one line naming the authorship guard, and do NOT enrol — unless the user named this specific PR in chat this session (per-PR override; say you are operating under it). `polling-state-gate.sh --ensure-session` also refuses non-author enrolment as a fail-safe (bypass only with `--allow-nonauthor` under that override).
- **Never modify branch protection** — no calls to `.../branches/.../protection`.
- **Never dismiss human-authored reviews.** Only `/fixpr`'s `dismiss-stale-bot-changes.sh` (bot allowlist, wrong `commit_id`) may dismiss, and only bot reviews.
- **Never resolve a review thread** itself — thread resolution happens only inside `/fixpr` Steps 1–4 after code-verification. `/babysit-pr` does not call `resolveReviewThread`.
- **Never bypass `/fixpr`'s code-verification step** — it dispatches the full `/fixpr` workflow, never a shortcut.
- **Never post `@coderabbitai full review`** without `cr-review-hourly.sh --check` passing first. The **only** sanctioned trigger path in this skill is the T1b pre-flight (`pr-preflight.sh`, issue #493), which gates CR on `cr-review-hourly.sh` (`--check` + atomic `--record-explicit`) automatically, never triggers Greptile, and never flips another user's draft. `/fixpr` owns any further triggers after a push.

A human `CHANGES_REQUESTED` on HEAD is `hard-blocked` → record and exit. Never auto-dismiss it.

- **Auto-resolve mode (`--auto-resolve-conflicts`) performs unattended rebases and force-pushes.** The resolver (`.claude/skills/merge-conflict/resolve_merge_conflicts.py`) only applies mechanically-simple hunks per its "when in doubt, complex" contract; any complex hunk aborts the rebase and reports the specific file + line range + reason instead of applying it. Because unattended force-pushes are a bigger authorization step than the rest of the dispatch table, this mode is **opt-in** — the default on `CONFLICTING` is a conservative stop that recommends `/merge-conflict`.

## Arguments & knobs

| Argument | Default | Meaning |
|----------|---------|---------|
| `<PR>` (required) | — | PR number to watch. Must be an open PR. |
| `--cadence Nm` | `5m` | Base poll cadence. Floor `1m` (60s) — clamp anything lower. |
| `--max-iter N` | `6` | Hard termination after N **consecutive blocker-state ticks** (≈90 min once backoff widens to 15m). |
| `--silent` | off | Suppress the per-tick heartbeat **except** on state change, dispatch, or termination (those always print). |
| `--auto-resolve-conflicts` | off | Opt-in: on `CONFLICTING`, dispatch `/fixpr` in safe-only mode (`BABYSIT_SAFE_CONFLICT_MODE=1`) to rebase and auto-resolve mechanically-simple hunks. Any complex hunk aborts the rebase and terminates with a per-hunk report. Off by default — performs unattended rebases and force-pushes. |
| ~~`--durable`~~ | removed | Accepted and ignored (issue #827). It swapped the session watcher for a `CronCreate` job to buy cross-session continuity that never existed. Issue #914 measured cron producing zero ticks; issue #924 found dynamic `/loop` unreliable too. The watcher is always a persistent `Monitor`. Why this is not re-implemented on the durable scheduler the harness *does* provide: `.claude/reference/cross-session-durability.md`. |
| `--max-conflict-rounds N` | `3` | Hard termination after N consecutive conflict rounds. Each round that enters the auto-resolve path increments `conflict_streak`, which does not reset on SHA change — only on a non-`conflicting` tick. |

Parse from `$ARGUMENTS`. The first bare integer is `<PR>`. Validate `--cadence` matches `^[0-9]+m$`; clamp `< 1m` to `1m`. Validate `--max-iter` is a positive integer. `--auto-resolve-conflicts` is a boolean flag (present = true, absent = false; stored as `AUTO_RESOLVE_CONFLICTS=true|false`). `--max-conflict-rounds N` must be a positive integer; default `3` (stored as `MAX_CONFLICT_ROUNDS`).

`--monitor-generation <token>` is runtime-only. Parse it only for an internal `--tick`; never
accept it as user configuration or copy it across a re-arm. Every Monitor arm generates a fresh
token and embeds it in its emitted command so an event already queued by a stopped Monitor cannot
act as the replacement generation.

Parse the internal fields explicitly before the ordinary argument parser consumes the remaining
flags. A direct invocation carrying `--monitor-generation` is invalid; only a Monitor-emitted tick
may present it:

```bash
BABYSIT_INTERNAL_TICK=false
[[ " $ARGUMENTS " == *" --tick "* ]] && BABYSIT_INTERNAL_TICK=true
TICK_GENERATION=""
_BABYSIT_EXPECT_GENERATION=false
for _BABYSIT_ARG in $ARGUMENTS; do
  if [[ "$_BABYSIT_EXPECT_GENERATION" == true ]]; then
    TICK_GENERATION="$_BABYSIT_ARG"
    _BABYSIT_EXPECT_GENERATION=false
    continue
  fi
  [[ "$_BABYSIT_ARG" == "--monitor-generation" ]] && _BABYSIT_EXPECT_GENERATION=true
done
if [[ "$_BABYSIT_EXPECT_GENERATION" == true ]]; then
  echo "ERROR: --monitor-generation requires a token." >&2
  exit 2
fi
if [[ "$BABYSIT_INTERNAL_TICK" != true && -n "$TICK_GENERATION" ]]; then
  echo "ERROR: --monitor-generation is runtime-only and requires --tick." >&2
  exit 2
fi
```

The ordinary parser must ignore `--tick`, `--monitor-generation`, and the generation token already
captured above. It must never reinterpret the token as the PR number or persist it as watcher
configuration.

`--durable` is still **accepted** so a saved chip payload or muscle memory does not hard-error; print one line and carry on with `Monitor`:

```text
[babysit] --durable was removed (issue #827) — it never provided cross-session continuity. Watching on Monitor.
```

## Two modes: arm vs tick

This skill runs in one of two modes, disambiguated by the internal `--tick` flag:

- **Arm mode** (`/babysit-pr <PR> …`, no `--tick`): validate, initialize `session-state.json`, arm the recurring poll, run **one** tick immediately, then end the turn.
- **Tick mode** (`/babysit-pr <PR> --tick`): the body the poll re-invokes each cycle. Runs exactly one tick of classification + dispatch + bookkeeping. **Never re-arms the monitor** except to change cadence on a backoff threshold crossing.

The persistent `Monitor` command armed in arm mode emits `/babysit-pr <PR> --tick` (plus the resolved cadence flags) once per cadence, so every emitted event enters tick mode — see A3.

---

## Resolve the shared scripts (once, both modes)

Use the standard three-candidate lookup (same pattern as `fixpr/SKILL.md`). Prefer the global install; fall back to the in-repo copy when developing the skill itself.

```bash
resolve_script() {
  # $1 = script basename; echoes the first executable path or empty
  local name="$1" candidate
  for candidate in \
    "$HOME/.claude/skills-worktree/.claude/scripts/$name" \
    "$HOME/.claude/scripts/$name" \
    ".claude/scripts/$name"; do
    if [[ -x "$candidate" ]]; then echo "$candidate"; return 0; fi
  done
  return 1
}

PR_STATE_SH=$(resolve_script pr-state.sh)        || { echo "ERROR: pr-state.sh not found" >&2; exit 1; }
MERGE_GATE_SH=$(resolve_script merge-gate.sh)     || { echo "ERROR: merge-gate.sh not found" >&2; exit 1; }
SESSION_STATE_SH=$(resolve_script session-state.sh) || { echo "ERROR: session-state.sh not found" >&2; exit 1; }
CR_HOURLY_SH=$(resolve_script cr-review-hourly.sh)   || true   # optional; degrade gracefully
GREPTILE_SH=$(resolve_script greptile-budget.sh)     || true   # optional; degrade gracefully
PREFLIGHT_SH=$(resolve_script pr-preflight.sh)       || true   # optional; degrade gracefully (#493)
PR_AUTHORSHIP_SH=$(resolve_script pr-authorship.sh) || { echo "ERROR: pr-authorship.sh not found (checked all three paths) — babysit authorship gate unavailable" >&2; exit 1; }
ADMIN_MERGE_SH=$(resolve_script admin-merge.sh)     || { echo "ERROR: admin-merge.sh not found (checked all three paths) — clean-BEHIND recovery unavailable" >&2; exit 1; }

to_epoch() {
  # Portable ISO-8601 UTC (e.g. 2026-07-21T17:13:05Z) -> epoch seconds.
  # Tries GNU date, then BSD/macOS date. Returns non-zero (no stdout) if both
  # fail -- callers MUST check the exit code, never assume a numeric result
  # (a silently fabricated epoch previously corrupted TTL/age math -- #634).
  local iso="$1"
  date -u -d "$iso" +%s 2>/dev/null && return 0
  date -u -j -f "%Y-%m-%dT%H:%M:%SZ" "$iso" +%s 2>/dev/null && return 0
  return 1
}

bump_parse_failure_counter() {
  # $1 = field name under .prs["<PR>"].babysit, $2 = limit. Echoes the new
  # count on stdout (always -- callers can log it regardless of outcome).
  # Returns 0 while still under the limit (caller keeps its safe default).
  # Returns 1 once the count reaches the limit, OR if persisting the
  # increment itself fails -- an untrackable counter can never be trusted to
  # self-heal, so a write failure is treated the same as "limit reached"
  # (#634: a bounded counter that can silently fail to persist is really an
  # unbounded one).
  local field="$1" limit="$2" raw count
  raw=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.$field" 2>/dev/null)
  [[ "$raw" =~ ^[0-9]+$ ]] || raw=0   # missing/null/corrupt -> 0, never feed raw jq output to arithmetic
  count=$(( raw + 1 ))
  echo "$count"
  "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.$field=$count" >/dev/null 2>&1 || return 1
  (( count < limit ))
}
```

**Always read/write `session-state.json` via `session-state.sh --get`/`--set`** (atomic, sibling-preserving) — never raw `jq` writes (`handoff-files.md`). State for this skill lives under `.prs["<N>"]`:

- Backoff fields reuse the **shared schema fields** `.prs["<N>"].digest` and `.prs["<N>"].digest_streak` (per `scheduling-reliability.md` / `session-state-schema.json`) so the backoff watchdog sees a consistent streak.
- Babysit-specific fields live under a nested `.prs["<N>"].babysit` object so they don't collide with phase/reviewer fields other skills write.

```jsonc
// .prs["<N>"].babysit
{
  "active": true,
  "started_at": "2026-06-25T19:00:00Z",
  "last_tick_at": "2026-06-25T19:00:00Z",   // refreshed every tick — freshness signal for A2
  "last_tick_parse_failures": 0, // consecutive A2 to_epoch() failures on last_tick_at; treated as stale (reclaimed) at BABYSIT_PARSE_FAIL_LIMIT (default 3)
  "cadence_base_minutes": 5,
  "cadence_effective_minutes": 5,
  "tick_count": 0,
  "blocker_streak": 0,          // consecutive blocker-state ticks (drives --max-iter)
  "max_blocker_ticks": 6,
  "silent": false,
  "stop_requested": false,      // set true by /babysit-pr-stop
  "dispatch_in_flight": null,   // {"skill":"fixpr"|"wrap","started_at":"…"} while a dispatch runs
  "dispatch_parse_failures": 0, // consecutive T0 to_epoch() failures on dispatch_in_flight.started_at; force-reclaimed at BABYSIT_PARSE_FAIL_LIMIT (default 3)
  "last_dispatch": null,        // {"skill":"…","started_at":"…","completed_at":"…","status":"…"}
  "auto_resolve_conflicts": false, // from --auto-resolve-conflicts; enables unattended rebase+force-push on simple conflicts
  "max_conflict_rounds": 3,        // from --max-conflict-rounds; hard cap on consecutive conflict rounds
  "conflict_streak": 0             // consecutive conflict rounds entered this watcher run; does not reset on SHA change — only on a non-conflicting tick
}
```

---

## ARM MODE

Run only when invoked **without** `--tick`.

### A1. Validate the PR

```bash
PR_JSON=$(gh pr view "$PR" --json number,state,headRefOid 2>&1) || {
  echo "ERROR: PR #$PR not found or gh failed: $PR_JSON" >&2; exit 1; }
PR_PR_STATE=$(jq -r '.state' <<<"$PR_JSON")     # OPEN | MERGED | CLOSED
if [[ "$PR_PR_STATE" != "OPEN" ]]; then
  echo "PR #$PR is $PR_PR_STATE — nothing to babysit."; exit 0
fi
```

### A2. Refuse duplicate watchers (idempotent setup)

A live watcher writes `babysit.last_tick_at` every tick (T5). Treat `active == true` as a duplicate **only when the watcher is actually fresh** — otherwise a crashed/aborted session would leave `active=true` forever and brick re-arm. The freshness window is generous: `3 ×` the effective cadence, floored at the dispatch TTL (`BABYSIT_DISPATCH_TTL_MIN`, default 30m) so a long in-flight `/fixpr` never looks dead.

```bash
ALREADY=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.active"); RC=$?
if [[ "$RC" -eq 3 ]]; then ALREADY="null"; elif [[ "$RC" -ne 0 ]]; then
  echo "ERROR: session-state.sh --get failed (exit $RC) — aborting arm to avoid double-watch." >&2; exit "$RC"
fi
if [[ "$ALREADY" == "true" ]]; then
  RETAINED_TASK_ID=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.monitor_task_id" 2>/dev/null || echo "null")
  RETAINED_GENERATION=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.monitor_generation" 2>/dev/null || echo "null")
  STOP_PENDING=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.stop_requested" 2>/dev/null || echo "false")
  if [[ "$STOP_PENDING" == "true" ]]; then
    echo "ERROR: babysit-pr teardown incomplete for PR #$PR (retained Monitor task ID: $RETAINED_TASK_ID) — retry /babysit-pr-stop $PR or repair the runtime task before re-arming." >&2
    exit 1
  fi
  if [[ -z "$RETAINED_TASK_ID" || "$RETAINED_TASK_ID" == "null" ||
        -z "$RETAINED_GENERATION" || "$RETAINED_GENERATION" == "null" ]]; then
    "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.stop_requested=true" >/dev/null 2>&1 || true
    echo "ERROR: active babysit-pr watcher for PR #$PR lacks a complete Monitor identity (task ID + generation) — refusing blind stale reclaim; inspect the runtime task and repair teardown before re-arming." >&2
    exit 1
  fi
  LAST_TICK=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.last_tick_at" 2>/dev/null || echo "")
  EFF_MIN=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.cadence_effective_minutes" 2>/dev/null || echo 5)
  [[ "$EFF_MIN" =~ ^[0-9]+$ ]] || EFF_MIN=5
  FRESH_MIN=$(( EFF_MIN * 3 )); (( FRESH_MIN < ${BABYSIT_DISPATCH_TTL_MIN:-30} )) && FRESH_MIN=${BABYSIT_DISPATCH_TTL_MIN:-30}
  PARSE_FAIL_LIMIT="${BABYSIT_PARSE_FAIL_LIMIT:-3}"
  AGE_MIN=999999
  if [[ -n "$LAST_TICK" && "$LAST_TICK" != "null" ]]; then
    if LAST_TICK_EPOCH=$(to_epoch "$LAST_TICK"); then
      AGE_MIN=$(( ( $(date -u +%s) - LAST_TICK_EPOCH ) / 60 ))
      "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.last_tick_parse_failures=0" >/dev/null 2>&1 || true
    else
      if A2_FAIL_COUNT=$(bump_parse_failure_counter last_tick_parse_failures "$PARSE_FAIL_LIMIT"); then
        echo "WARNING: could not parse babysit.last_tick_at ('$LAST_TICK') as epoch on this platform's date (failure ${A2_FAIL_COUNT}/${PARSE_FAIL_LIMIT}) — treating watcher as fresh (safe default) instead of reclaiming it blind. If this persists, run /babysit-pr-stop $PR." >&2
        AGE_MIN=0
      else
        echo "WARNING: babysit.last_tick_at ('$LAST_TICK') failed to parse ${A2_FAIL_COUNT} arm attempts in a row, or the failure counter itself could not be persisted — treating watcher slot as corrupted and reclaiming it rather than blocking re-arm forever." >&2
        # AGE_MIN stays at its 999999 default above -> falls through to the stale/reclaim path below.
      fi
    fi
  fi
  if (( AGE_MIN < FRESH_MIN )); then
    echo "Already babysitting PR #$PR (last tick ${AGE_MIN}m ago) — not arming a second watcher. Use /babysit-pr-stop $PR to stop."
    exit 0
  fi
  echo "[babysit] stale watcher for PR #$PR (last tick ${AGE_MIN}m ago ≥ ${FRESH_MIN}m) — reclaiming and re-arming."
  "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.stop_requested=true" || {
    echo "ERROR: could not publish the stale-watch teardown guard — leaving the recorded Monitor untouched." >&2; exit 1; }
fi
```

Before A3, a stale reclaim **must stop the exact `$RETAINED_TASK_ID` with `TaskStop`**. If that
stop fails, retain `active=true`, the exact task ID+generation pair, and `stop_requested=true`;
report incomplete teardown and abort. Only after exact `TaskStop` succeeds may A3 replace the
babysit object and arm one new Monitor. Never infer that a silent Monitor died, and never arm beside
it.

Execute that teardown before the A3 initialization block. Call `TaskStop` with
`task_id="$RETAINED_TASK_ID"`, then bind its tool result to `TASK_STOP_SUCCEEDED`; do not simulate a
successful stop from silence or age:

```bash
if [[ "$ALREADY" == "true" ]]; then
  # TaskStop tool call: task_id="$RETAINED_TASK_ID"
  # Set TASK_STOP_SUCCEEDED=true only when that exact tool call succeeds.
  if [[ "${TASK_STOP_SUCCEEDED:-false}" != "true" ]]; then
    echo "ERROR: stale babysit watcher teardown failed for PR #$PR (Monitor task $RETAINED_TASK_ID, generation $RETAINED_GENERATION) — retaining the complete identity and stop_requested=true; not re-arming." >&2
    exit 1
  fi
fi
```

After success, leave `stop_requested=true` and the old identity pair recorded until A3 replaces the
whole babysit object atomically. That keeps any already-queued old-generation event inert during
the stop-to-publication gap.

### A3. Initialize state and arm the poll

Write the babysit object (one atomic `--set` batch), seeding backoff fields to a neutral start:

```bash
NOW=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
"$SESSION_STATE_SH" \
  --set ".prs[\"$PR\"].babysit={\"active\":true,\"started_at\":\"$NOW\",\"last_tick_at\":\"$NOW\",\"last_tick_parse_failures\":0,\"cadence_base_minutes\":$BASE_MIN,\"cadence_effective_minutes\":$BASE_MIN,\"tick_count\":0,\"blocker_streak\":0,\"max_blocker_ticks\":$MAX_ITER,\"silent\":$SILENT,\"stop_requested\":false,\"monitor_task_id\":null,\"monitor_generation\":null,\"dispatch_in_flight\":null,\"dispatch_parse_failures\":0,\"last_dispatch\":null,\"auto_resolve_conflicts\":$AUTO_RESOLVE_CONFLICTS,\"max_conflict_rounds\":$MAX_CONFLICT_ROUNDS,\"conflict_streak\":0}" \
  --set ".prs[\"$PR\"].digest_streak=0"
```

Generate a fresh non-secret generation token, then arm a persistent `Monitor` with description
`babysit PR #<PR>` and this command:

```bash
MONITOR_GENERATION="$(date -u +%Y%m%dT%H%M%SZ)-$$-${RANDOM:-0}"
while sleep "$(( BASE_MIN * 60 ))"; do
  printf '%s\n' "/babysit-pr $PR --tick --monitor-generation $MONITOR_GENERATION --cadence ${BASE_MIN}m"
done
```

Each stdout line becomes an out-of-turn chat event. `sleep` comes first because arm mode runs one
tick immediately. Pass `persistent: true`, capture the returned task ID, and persist it as
`.prs["$PR"].babysit.monitor_task_id`. The watcher stays session-scoped by design — one that
outlived its session would be auto-dispatching `/wrap` merges into an empty room.

**Never substitute either `/loop` mode or `CronCreate`.** Issue #914 measured listed cron jobs
producing zero ticks across an 11-minute idle window; issue #924 recorded two dynamic `/loop`
watchers stopping until a manual turn. `Monitor` is the only recurring primitive with positive
out-of-turn liveness evidence.

**Arming is not ticking.** A watcher can be `active` in state, listed by the runtime, and silent — that is Pattern 7 in `.claude/reference/scheduling-failure-modes.md`, first observed on this very skill (PR #908, where all six ticks were driven by hand). Two things now catch it: `babysit-tick-watchdog.sh` warns once `last_tick_at` exceeds 2 × the effective cadence, and the pre-exit checklist asks for liveness rather than presence.

**The silence ceiling is a backstop, not this watcher's cadence.** `bgwork-ceiling.sh` trips on a silence budget far wider than any poll interval, so a run where the ceiling is producing the only ticks is a **broken poll**, not a working watch — in #908 it surfaced each stall roughly 18 minutes late, after the branch had gone `BEHIND` twice. If ticks are only appearing alongside ceiling breaches, stop and re-arm rather than riding the backstop.

**Roll back if arming fails.** The `--set` above already published `active=true` with a fresh `last_tick_at`, so a failed arm leaves a watcher that A2 reads as *live* for the whole freshness window (30m by default) while nothing is ticking — re-arm is blocked precisely when it is needed. A Monitor call that errors or returns no task ID is a failed arm. Treat init+arm as one transaction:

```bash
if [[ -z "${MONITOR_TASK_ID:-}" || "$MONITOR_TASK_ID" == "null" ]]; then
  "$SESSION_STATE_SH" \
    --set ".prs[\"$PR\"].babysit.active=false" \
    --set ".prs[\"$PR\"].babysit.last_tick_at=null" \
    --set ".prs[\"$PR\"].babysit.monitor_task_id=null" \
    --set ".prs[\"$PR\"].babysit.monitor_generation=null"
  echo "ERROR: could not arm the Monitor for PR #$PR — watcher state rolled back, re-run /babysit-pr $PR." >&2
  exit 1
fi
"$SESSION_STATE_SH" \
  --set ".prs[\"$PR\"].babysit.monitor_task_id=$MONITOR_TASK_ID" \
  --set ".prs[\"$PR\"].babysit.monitor_generation=\"$MONITOR_GENERATION\""
```

If that task-ID publication fails, do not continue to the immediate tick: the Monitor is live but
not discoverable from durable state. Call `TaskStop` for the exact returned `$MONITOR_TASK_ID`. If
that rollback stop succeeds, reopen A2 with this atomic rollback:

```bash
"$SESSION_STATE_SH" \
  --set ".prs[\"$PR\"].babysit.active=false" \
  --set ".prs[\"$PR\"].babysit.last_tick_at=null" \
  --set ".prs[\"$PR\"].babysit.monitor_task_id=null" \
  --set ".prs[\"$PR\"].babysit.monitor_generation=null"
```

If rollback `TaskStop` fails, retain `active=true`, best-effort set `stop_requested=true` and publish
the exact task ID plus generation so A2 refuses a later re-arm independent of tick age. Report both
identifiers and exit non-zero. Do not claim that the watcher was cleaned up.

Then **run one tick immediately** (fall through to TICK MODE below) so the user gets instant feedback, and emit the initial heartbeat. Per the `scheduling-reliability.md` **pre-exit checklist**, before ending the arm turn confirm: (1) the Monitor task is active, (2) a timestamped heartbeat was sent, (3) state was recorded.

---

## TICK MODE

Run on every poll cycle (and once at the end of arm mode). One tick = classify → maybe dispatch → bookkeep → maybe re-arm cadence → heartbeat.

### T0. Stop / terminal short-circuit (check FIRST)

```bash
if [[ "$BABYSIT_INTERNAL_TICK" == true ]]; then
  RECORDED_GENERATION=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.monitor_generation" 2>/dev/null || echo "null")
  if [[ -z "$TICK_GENERATION" || "$TICK_GENERATION" == "null" ||
        "$TICK_GENERATION" != "$RECORDED_GENERATION" ]]; then
    echo "[babysit] Ignoring a stale or unidentified Monitor tick for PR #$PR."
    exit 0
  fi
fi
STOP=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.stop_requested" 2>/dev/null || echo "false")
ACTIVE=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.active" 2>/dev/null || echo "false")
if [[ "$STOP" == "true" || "$ACTIVE" != "true" ]]; then
  # user ran /babysit-pr-stop, or state was cleared — terminate cleanly
  goto TERMINATE with reason="user-stop"
fi
```

If `dispatch_in_flight` is set, decide whether it is **still running** or **stale** using an explicit TTL (`BABYSIT_DISPATCH_TTL_MIN`, default `30` — comfortably longer than `/fixpr`'s 20-min wait cap plus `/wrap` recovery, so a live dispatch is never mistaken for stale).

A `started_at` that fails to parse on **both** GNU and BSD `date` (see `to_epoch()` above) is treated as still-running for that tick — the safe direction, since this check runs every tick unattended and wrongly reclaiming a live dispatch causes a duplicate `/fixpr`/`/wrap` run. But "safe for one tick" must not mean "stuck forever" if the value is genuinely corrupted (not just a transient hiccup): `dispatch_parse_failures` counts consecutive parse failures for the current `dispatch_in_flight`, and once it reaches `BABYSIT_PARSE_FAIL_LIMIT` (default `3`) the entry is force-reclaimed as corrupted rather than left blocking indefinitely:

```bash
TTL_MIN="${BABYSIT_DISPATCH_TTL_MIN:-30}"
PARSE_FAIL_LIMIT="${BABYSIT_PARSE_FAIL_LIMIT:-3}"
IN_FLIGHT=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.dispatch_in_flight" 2>/dev/null || echo "null")
DISPATCH_BLOCKING=0
if [[ "$IN_FLIGHT" != "null" && -n "$IN_FLIGHT" ]]; then
  STARTED=$(jq -r '.started_at // empty' <<<"$IN_FLIGHT")
  RECLAIM_REASON=""
  if STARTED_EPOCH=$(to_epoch "$STARTED"); then
    AGE_MIN=$(( ( $(date -u +%s) - STARTED_EPOCH ) / 60 ))
    "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.dispatch_parse_failures=0" >/dev/null 2>&1 || true
    (( AGE_MIN >= TTL_MIN )) && RECLAIM_REASON="stale (age ${AGE_MIN}m >= ${TTL_MIN}m TTL)"
  else
    if FAIL_COUNT=$(bump_parse_failure_counter dispatch_parse_failures "$PARSE_FAIL_LIMIT"); then
      echo "WARNING: could not parse dispatch_in_flight.started_at ('$STARTED') as epoch on this platform's date (failure ${FAIL_COUNT}/${PARSE_FAIL_LIMIT}) — treating dispatch as still in-flight this tick. If this persists, run /babysit-pr-stop $PR." >&2
    else
      echo "WARNING: dispatch_in_flight.started_at ('$STARTED') failed to parse ${FAIL_COUNT} ticks in a row, or the failure counter itself could not be persisted — treating as corrupted and force-reclaiming rather than blocking forever." >&2
      RECLAIM_REASON="corrupted (unparseable started_at, parse-failure counter reached ${PARSE_FAIL_LIMIT} or could not be persisted)"
    fi
  fi
  if [[ -n "$RECLAIM_REASON" ]]; then
    # Stale (TTL exceeded) or corrupted (parse-fail limit exceeded): reclaim so it never blocks forever.
    "$SESSION_STATE_SH" \
      --set ".prs[\"$PR\"].babysit.last_dispatch=$(jq -c '. + {completed_at: (now|todate), status: "stale-reclaimed"}' <<<"$IN_FLIGHT")" \
      --set ".prs[\"$PR\"].babysit.dispatch_in_flight=null" \
      --set ".prs[\"$PR\"].babysit.dispatch_parse_failures=0"
    echo "[babysit] reclaimed $RECLAIM_REASON dispatch — proceeding"
  else
    DISPATCH_BLOCKING=1            # a prior tick's /fixpr or /wrap is genuinely still running (or unparseable, within grace)
  fi
fi
```

If `DISPATCH_BLOCKING == 1`, **skip this tick's dispatch** (idempotency — see T4): emit a "dispatch in progress" heartbeat and finish the tick without classifying-and-dispatching on top of the running dispatch. Otherwise continue normally (a stale or corrupted in-flight has been reclaimed above).

### T1. Read PR state (the two shared scripts — never re-implement)

```bash
# Authoritative merge-readiness + blocker breakdown.
GATE_JSON=$("$MERGE_GATE_SH" "$PR"); GATE_EXIT=$?
```

**Fail closed before classifying** — `merge-gate.sh` exit codes are: `0` met (valid JSON), `1` not-met (valid JSON), `2` usage error, `3` PR not found/closed/merged, `4` gh/jq error. Only `0`/`1` produce real gate JSON. Do **not** let a transient tooling failure (`2`/`4`) or a bad `gh pr view` fall through into the jq parsing below — that would manufacture a bogus classification or dispatch:

```bash
case "$GATE_EXIT" in
  0|1) ;;                                  # valid gate JSON — proceed to classify
  3)  # PR not found / closed / merged — let T3's terminal handling decide (merged vs closed)
      PR_NOW=$(gh pr view "$PR" --json state --jq '{state}' 2>/dev/null || echo '{}')
      # fall through to T3 with GATE_JSON unused; T3 row 1/2 classify merged/closed
      SKIP_STATE_READ=1 ;;
  *)  # exit 2/4/other — tooling/transient error. Heartbeat + skip this tick (no classify, no dispatch).
      TS=$(TZ='America/New_York' date +'%a %b %-d %I:%M %p ET')
      echo "[$TS] #$PR tick: merge-gate.sh failed (exit $GATE_EXIT) — skipping classification this tick, retrying next cadence."
      # update last_tick_at so A2 freshness still reflects a live watcher, then end the tick
      "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.last_tick_at=$(date -u +'%Y-%m-%dT%H:%M:%SZ')" 2>/dev/null || true
      return 0 2>/dev/null || exit 0 ;;
esac
```

When `SKIP_STATE_READ` is unset, fetch the full state bundle (findings/threads/CI/SHA). Guard `gh pr view` and `pr-state.sh` the same way — a non-zero exit means skip the tick, never classify on empty data:

```bash
if [[ -z "${SKIP_STATE_READ:-}" ]]; then
  PR_CREATED=$(gh pr view "$PR" --json createdAt --jq '.createdAt') || {
    echo "[babysit] gh pr view failed — skipping tick, retry next cadence." >&2; exit 0; }
  BUNDLE=$("$PR_STATE_SH" --pr "$PR" --since "$PR_CREATED") || {
    echo "[babysit] pr-state.sh failed — skipping tick, retry next cadence." >&2; exit 0; }
fi
```

### T1b. Pre-flight — draft→ready + four-reviewer trigger (issue #493)

**Run after the gate-exit check (which sets `SKIP_STATE_READ`), then re-fetch `GATE_JSON` and `BUNDLE` so that T1c field extraction and T3 classification operate on post-trigger snapshots.** A reviewer just engaged by pre-flight is not misclassified as "missing" and does not cause a spurious `/fixpr` dispatch on the same tick.

Run the shared `pr-preflight.sh` so a draft PR you own is flipped ready and all four conditionally-triggered reviewers (CodeAnt, CodeRabbit, Cursor, Graphite) are engaged on the current SHA before T2/T3 decide anything. This is the **same** script `/fixpr` Step 0c and `/pr-monitor-and-manage` use — `/babysit-pr` never re-implements the draft flip or trigger logic. Since #576 "engaged on the current SHA" is enforced rather than assumed: a reviewer whose only artifact is on a superseded commit is re-triggered, so a PR does not sit in `waiting-on-bots` relying on each bot's own auto-review-on-push. It is idempotent (a PR whose reviewers are all fresh on HEAD is a no-op), rate-cap safe (skips only `@coderabbitai full review` when `cr-review-hourly.sh` reports the cap hit, posting the other three), never flips another user's draft, and never triggers Greptile.

Run **only** on a valid state read (skip when `SKIP_STATE_READ=1` — a gone/merged/closed PR needs no pre-flight):

```bash
PREFLIGHT_SUMMARY_JSON=""
if [[ -z "${SKIP_STATE_READ:-}" && -n "$PREFLIGHT_SH" ]]; then
  PREFLIGHT_OUT=$("$PREFLIGHT_SH" "$PR") || echo "[babysit] pr-preflight.sh exited non-zero (exit $?) — continuing tick" >&2
  echo "$PREFLIGHT_OUT"   # its timestamped action lines double as part of this tick's heartbeat
  PREFLIGHT_SUMMARY_JSON=$(sed -n 's/^PREFLIGHT_SUMMARY: //p' <<<"$PREFLIGHT_OUT")
elif [[ -z "$PREFLIGHT_SH" && -z "${SKIP_STATE_READ:-}" ]]; then
  echo "[babysit] pr-preflight.sh not found — skipping draft/reviewer pre-flight this tick"
fi
```

Re-fetch `GATE_JSON` and `BUNDLE` after pre-flight so that any reviewer or draft-state change made by pre-flight is captured before T3 classifies. Guard the same way as T1 — skip the tick on tooling error:

```bash
if [[ -z "${SKIP_STATE_READ:-}" ]]; then
  GATE_JSON=$("$MERGE_GATE_SH" "$PR"); GATE_EXIT=$?
  if [[ "$GATE_EXIT" != "0" && "$GATE_EXIT" != "1" ]]; then
    TS=$(TZ='America/New_York' date +'%a %b %-d %I:%M %p ET')
    echo "[$TS] #$PR tick: merge-gate.sh post-preflight re-fetch failed (exit $GATE_EXIT) — skipping classification this tick."
    "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.last_tick_at=$(date -u +'%Y-%m-%dT%H:%M:%SZ')" 2>/dev/null || true
    return 0 2>/dev/null || exit 0
  fi
  PR_CREATED=$(gh pr view "$PR" --json createdAt --jq '.createdAt') || {
    echo "[babysit] gh pr view failed (post-preflight re-fetch) — skipping tick, retry next cadence." >&2; exit 0; }
  BUNDLE=$("$PR_STATE_SH" --pr "$PR" --since "$PR_CREATED") || {
    echo "[babysit] pr-state.sh failed (post-preflight re-fetch) — skipping tick, retry next cadence." >&2; exit 0; }
fi
```

### T1c. Extract fields from post-preflight snapshots

Pull the fields the classifier needs (only when `GATE_EXIT` was `0`/`1` and the bundle was read). These snapshots were taken after pre-flight ran, so they reflect the post-trigger bot state:

```bash
HEAD_SHA=$(jq -r '.head_sha // ""'                 <<<"$GATE_JSON")
GATE_MET=$(jq -r '.met'                            <<<"$GATE_JSON")
HUMAN_CR=$(jq -r '.human_changes_requested | length' <<<"$GATE_JSON")
MERGE_STATE=$(jq -r '.merge_state // ""'           <<<"$GATE_JSON")
MERGEABLE=$(jq -r '.mergeable // ""'               <<<"$GATE_JSON")
CI_FAILING=$(jq -r '.ci_status.failing // 0'       <<<"$GATE_JSON")
CI_INCOMPLETE=$(jq -r '.ci_status.in_progress // 0' <<<"$GATE_JSON")
STALE_BOT_CR=$(jq -r '.stale_bot_changes_requested_count // 0' <<<"$GATE_JSON")
MISSING=$(jq -r '.missing | join(" | ")'           <<<"$GATE_JSON")
# Sorted blocking CI conclusions — the `ci_blocking_conclusions_sorted` field of
# the T5 digest tuple. merge-gate.sh exposes blocking runs as .ci_status.blocking[].
CI_BLOCKING_SORTED=$(jq -r '[.ci_status.blocking[].conclusion] | sort | join(",")' <<<"$GATE_JSON")

UNRESOLVED=$(jq -r '.threads.unresolved_count'      < "$BUNDLE")
NEW_FINDINGS=$(jq -r '.new_since_baseline.finding_count // 0' < "$BUNDLE")
CR_STATE=$(jq -r '.bot_statuses.CodeRabbit.state // "none"'   < "$BUNDLE")
GREP_STATE=$(jq -r '.bot_statuses.Greptile.state // "none"'   < "$BUNDLE")
# BugBot reports via check-run, not commit status; derive a coarse state.
BUGBOT_STATE=$(jq -r '[.check_runs.all[] | select((.name//""|ascii_downcase)|contains("cursor") or contains("bugbot"))] | (if length==0 then "none" elif any(.[]; .status!="completed") then "pending" else "done" end)' < "$BUNDLE" 2>/dev/null || echo "none")
```

(When `SKIP_STATE_READ=1` was set above — gate exit `3` — skip straight to T3's terminal handling, which classifies `merged` vs `closed-unmerged` from `PR_NOW`.)

Record the draft→ready action and any triggered reviewers in the T7 heartbeat / final summary from `$PREFLIGHT_SUMMARY_JSON`.

### T2. Rate-cap snapshot (MUST run before classification)

`/babysit-pr` never posts review triggers itself — `/fixpr` owns triggers and their caps. But the **classifier (T3) must already know** the budget state, so this snapshot runs **first**: it decides whether "missing fresh bot review" is a recoverable gap (a reviewer can still be triggered) or a `hard-blocked` budget-exhaustion (no path to the gate this window).

```bash
CR_BUDGET_OK=1; GREP_BUDGET_OK=1
if [[ -n "$CR_HOURLY_SH" ]]; then "$CR_HOURLY_SH" --check >/dev/null 2>&1 || CR_BUDGET_OK=0; fi
if [[ -n "$GREPTILE_SH" ]]; then "$GREPTILE_SH" --check >/dev/null 2>&1 || GREP_BUDGET_OK=0; fi
```

- **CodeRabbit:** `cr-review-hourly.sh --check` exit `1` ⇒ `CR_BUDGET_OK=0` (hourly budget exhausted). `/babysit-pr` only consults `--check`, never consumes — `/fixpr`'s own `--record-explicit` enforces the ≤2/PR/hour cap atomically when it actually posts `@coderabbitai full review`.
- **Greptile:** `greptile-budget.sh --check` exit `1` ⇒ `GREP_BUDGET_OK=0` (daily budget exhausted).
- **BugBot (`@cursor review`):** per-seat and **spend-metered** (#1199), but with no budget helper to consult — so never gate the classifier on it. Its own refusal comment is the signal: do not re-nudge a HEAD BugBot already refused (`bugbot.md`).

The classifier (T3) consumes `CR_BUDGET_OK` / `GREP_BUDGET_OK`: a PR whose only gap is a fresh review becomes `hard-blocked` (budget exhaustion) **only** when CR **and** Greptile are both exhausted and there is no other recoverable work; otherwise it stays `waiting-on-bots` (a trigger path still exists). Re-running `/babysit-pr` after the window resets resumes cleanly.

### T3. Classify (first match wins, in this order)

Re-fetch the authoritative open/merged state once:

```bash
PR_NOW=$(gh pr view "$PR" --json state --jq '{state}')
PR_STATE_NOW=$(jq -r '.state' <<<"$PR_NOW")
PR_MERGED=$(jq -r '(.state == "MERGED")' <<<"$PR_NOW")
```

| # | Class | Condition | Action |
|---|-------|-----------|--------|
| 1 | `merged` | `PR_MERGED == true` (or gate exit 3 because merged) | **Exit** — terminal success. |
| 2 | `hard-blocked` | `HUMAN_CR > 0` (human `CHANGES_REQUESTED` on HEAD), **or** PR `CLOSED` unmerged, **or** the only gap is a fresh review and both budgets are exhausted (`CR_BUDGET_OK == 0 && GREP_BUDGET_OK == 0`, from T2), **or** a Greptile P0 needing design input persists | **Record blocker, exit.** Never auto-dismiss. |
| 3 | `merge-ready` | `GATE_MET == true` (gate exit 0) | **Dispatch `/wrap`** (T4). |
| 4 | `conflicting` | `MERGEABLE == CONFLICTING` (checked before other recoverable signals; first-match priority) | See T4 `conflicting` dispatch — branches on `--auto-resolve-conflicts` flag and `conflict_streak` cap. |
| 5 | `has-recoverable-blockers` | gate exit 1 **and** any of: `UNRESOLVED > 0`, `NEW_FINDINGS > 0`, `CI_FAILING > 0`, `STALE_BOT_CR > 0`, `MERGE_STATE` ∈ {`BEHIND`,`DIRTY`} | When `MERGE_STATE == BEHIND` is the **only** blocker, first complete `cr-merge-gate.md` Step 2 (per-criterion Test Plan verification at this SHA — ticked boxes alone are a proxy), then run `"$ADMIN_MERGE_SH" <PR> --auto-plain --ac-verified` (issue #754): exit 0 → merged, relay its evidence block and **exit** (terminal, as class 1); exit 8 → record the printed bypass as a blocker and exit; exit 1 → fall through. Otherwise **dispatch `/fixpr`** (T4). |
| 6 | `waiting-on-bots` | gate exit 1 and the only gaps are pending review/CI: `CI_INCOMPLETE > 0`, or a missing-but-pending bot approval / `REVIEW_REQUIRED` with no findings/threads/failing-CI (and at least one review budget remains per T2) | **Heartbeat only, no dispatch.** Bots are still working on the current SHA. |

`waiting-on-bots` is the "do nothing, just wait" state — the gate isn't met but there is nothing actionable yet (no findings to fix, no threads to resolve, CI still running, a bot hasn't posted its verdict). Do **not** dispatch `/fixpr` here — that would burn CR/CI cycles on a PR that just needs time. `/fixpr` owns its own bounded post-push wait (#454); `/babysit-pr` simply tolerates the gap across ticks.

### T4. Dispatch with idempotency (`session-state.json` is the source of truth)

Only classes `merge-ready` (→ `/wrap`), `conflicting` (→ `/fixpr` in safe-only mode **or** terminate), and `has-recoverable-blockers` (→ `/fixpr`) dispatch.

#### T4: `conflicting` dispatch

Read the watcher's config from session-state:

```bash
AUTO_RESOLVE=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.auto_resolve_conflicts" 2>/dev/null || echo "false")
MAX_ROUNDS=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.max_conflict_rounds" 2>/dev/null || echo 3)
[[ "$MAX_ROUNDS" =~ ^[0-9]+$ ]] || MAX_ROUNDS=3
CONFLICT_STREAK=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.conflict_streak" 2>/dev/null || echo 0)
[[ "$CONFLICT_STREAK" =~ ^[0-9]+$ ]] || CONFLICT_STREAK=0
```

Branch:

- **If `AUTO_RESOLVE != "true"`** (flag not set — default): **terminate**. Record blocker `merge-conflict` and emit:
  ```
  [babysit] PR #$PR is CONFLICTING — stopping (default). Run /merge-conflict to classify hunks, then re-arm babysit. Use --auto-resolve-conflicts to enable unattended rebase.
  ```
  → go to T-END with reason `hard-blocked`, blocker `merge-conflict`.

- **If `AUTO_RESOLVE == "true"` and `CONFLICT_STREAK >= MAX_ROUNDS`**: **terminate** (churn cap hit). Emit:
  ```
  [babysit] conflict-round-cap: $CONFLICT_STREAK consecutive conflict rounds on PR #$PR (cap=$MAX_ROUNDS). Surfacing to a human.
  ```
  → go to T-END with reason `conflict-round-cap`.

- **Otherwise** (`AUTO_RESOLVE == "true"` and `CONFLICT_STREAK < MAX_ROUNDS`): increment `conflict_streak`, then dispatch `/fixpr` in safe-only mode:

  ```bash
  NEW_STREAK=$((CONFLICT_STREAK + 1))
  "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.conflict_streak=$NEW_STREAK" >/dev/null
  # Mark in-flight (standard idempotency guard — step 2 of the shared dispatch protocol below)
  # Pass BABYSIT_SAFE_CONFLICT_MODE=1 so /fixpr Step 6 invokes the resolver directly
  TARGET="fixpr"
  EXTRA_ENV="BABYSIT_SAFE_CONFLICT_MODE=1"
  ```

  After dispatch completes, branch on `DISPATCH_STATUS`:
  - `CONFLICTS` (complex hunk found, rebase aborted): **terminate**. Parse `CONFLICT_COMPLEX_REPORT_JSON` from the fixpr output (the `CONFLICT_COMPLEX_REPORT_JSON:` line) and store into `.babysit.last_dispatch`:
    ```bash
    "$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.last_dispatch=$(
      jq -c --argjson report "$COMPLEX_REPORT_JSON" \
        '. + {complex_report: $report}' <<<"$LAST_DISPATCH_JSON"
    )" >/dev/null 2>&1 || true
    ```
    → go to T-END with reason `hard-blocked`, blocker `merge-conflict-complex`.
  - Any other status (`CLEAN`, `REVIEW_PENDING`, `BEHIND`, etc.): rebase+push succeeded (all hunks were simple). **Reset `blocker_streak` to 0** (forward progress); let `conflict_streak` persist for the next tick. Resume normal polling — the next tick re-reads the new HEAD SHA from the gate.

1. **Idempotency guard (already evaluated in T0).** `DISPATCH_BLOCKING` from T0 is authoritative: it is `1` only when a prior `dispatch_in_flight` is **within** the `BABYSIT_DISPATCH_TTL_MIN` window (genuinely still running) — a stale entry was already reclaimed to `null` there. If `DISPATCH_BLOCKING == 1`, **refuse to re-dispatch**: emit "dispatch in progress (<skill>), skipping" and finish the tick. This prevents two overlapping `/fixpr` (or `/wrap`) runs racing on the same PR when a dispatch outlives the cadence, while the TTL guarantees a crashed dispatch cannot wedge the watcher forever.
2. **Mark in-flight before invoking:**

   ```bash
   START=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
   "$SESSION_STATE_SH" \
     --set ".prs[\"$PR\"].babysit.dispatch_in_flight={\"skill\":\"$TARGET\",\"started_at\":\"$START\"}" \
     --set ".prs[\"$PR\"].babysit.dispatch_parse_failures=0"
   ```

3. **Invoke the full skill.** Execute the complete `.claude/skills/$TARGET/SKILL.md` workflow inline (or via a Phase A subagent in `bypassPermissions` mode with the `safety.md` block when the parent is in monitor mode — `subagent-orchestration.md`). `/fixpr` runs Steps 0–7 including its Step 4d post-push wait; `/wrap` runs its merge-gate recovery + AC + squash-merge + main-sync. **Do not shortcut either.**
4. **Clear in-flight after it returns:**

   ```bash
   DONE=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
   "$SESSION_STATE_SH" \
     --set ".prs[\"$PR\"].babysit.last_dispatch={\"skill\":\"$TARGET\",\"started_at\":\"$START\",\"completed_at\":\"$DONE\",\"status\":\"$DISPATCH_STATUS\"}" \
     --set ".prs[\"$PR\"].babysit.dispatch_in_flight=null"
   ```

   `DISPATCH_STATUS` = the parsed `Status:` / `FIXPR_WRAP_STATUS:` from `/fixpr`, or `merged`/`blocked`/`stopped` from `/wrap`.
5. **On dispatch error:** record `status: "error"`, clear `dispatch_in_flight`, do **not** retry within this tick — the next tick re-classifies from scratch.

After a `/wrap` dispatch that reports the PR merged, the next tick (T3 #1) sees `merged` and terminates. After a `/fixpr` dispatch, the next tick re-reads state on the new SHA.

### T5. Backoff + bookkeeping (`scheduling-reliability.md` stable-state backoff)

Compute the per-tick **digest** over the canonical tuple (free-text blockers excluded):

```
digest = sha256( head_sha | cr_state | bugbot_state | greptile_state | ci_blocking_conclusions_sorted | blocker_kind )
```

where `blocker_kind` is the classification name (`merge-ready` / `has-recoverable-blockers` / `waiting-on-bots` / `hard-blocked`) and `ci_blocking_conclusions_sorted` is the sorted list of blocking CI conclusions from the gate JSON.

```bash
DIGEST=$(printf '%s|%s|%s|%s|%s|%s' "$HEAD_SHA" "$CR_STATE" "$BUGBOT_STATE" "$GREP_STATE" "$CI_BLOCKING_SORTED" "$CLASS" | sha256sum | awk '{print "sha256:"$1}')
PREV_DIGEST=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].digest" 2>/dev/null || echo "null")
PREV_STREAK=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].digest_streak" 2>/dev/null || echo 0)
[[ "$PREV_STREAK" =~ ^[0-9]+$ ]] || PREV_STREAK=0
if [[ "$DIGEST" == "$PREV_DIGEST" ]]; then STREAK=$((PREV_STREAK + 1)); else STREAK=1; fi
```

**Cadence tiers** (`scheduling-reliability.md` widens a stable state and stops a frozen one). The widened cadence is **derived from the configured base**, never hard-coded, so it is **always slower than the base** regardless of `--cadence`:

```bash
# Widened cadence: at least 15m, and at least 3× the base — whichever is larger.
# base 5m → 15m (satisfies the AC); base 1m → 15m; base 20m → 60m (still slower).
WIDE_MIN=$(( BASE_MIN * 3 )); (( WIDE_MIN < 15 )) && WIDE_MIN=15
(( WIDE_MIN < BASE_MIN )) && WIDE_MIN=$BASE_MIN     # guard: never faster than base
PREV_EFFECTIVE_MIN=$("$SESSION_STATE_SH" --get ".prs[\"$PR\"].babysit.cadence_effective_minutes" 2>/dev/null || echo "$BASE_MIN")
[[ "$PREV_EFFECTIVE_MIN" =~ ^[0-9]+$ ]] || PREV_EFFECTIVE_MIN=$BASE_MIN
if (( STREAK >= 3 )); then EFFECTIVE_MIN=$WIDE_MIN; else EFFECTIVE_MIN=$BASE_MIN; fi
```

| `digest_streak` | Effective cadence |
|-----------------|-------------------|
| `< 3` | base (`--cadence`, default 5m) |
| `>= 3` | `WIDE_MIN` = `max(15m, 3 × base)` — for the default 5m base this is **15m** (satisfies the AC) |
| `>= 9` | **terminate** (truly frozen — stop the `Monitor`) |

**Revert to base cadence on any state change** (digest differs → `STREAK` reset to 1 → `cadence_effective_minutes` returns to `BASE_MIN`).

**Blocker-streak** (drives `--max-iter` termination): a tick is a *blocker-state tick* when `CLASS` ∈ {`has-recoverable-blockers`, `waiting-on-bots`} **and** the digest did not change (no forward progress). Increment `blocker_streak` on such ticks; reset to `0` on `merge-ready`/`merged` or on any digest change. A `conflicting` tick that successfully auto-resolved and pushed counts as forward progress — reset `blocker_streak` to `0` (the new SHA will change the digest on the next tick); `conflict_streak` is NOT reset by a SHA change, only by a non-`conflicting` tick (any class other than `conflicting`).

**Conflict-streak** bookkeeping per tick:
- `CLASS == conflicting` and dispatch status was `CONFLICTS` (complex hunk, aborted): `conflict_streak` was already incremented in T4 dispatch; tick terminates via T-END (no T5 persist needed).
- `CLASS == conflicting` and dispatch succeeded (rebase+push): `conflict_streak` was already incremented in T4; `blocker_streak` reset to `0`; do NOT reset `conflict_streak`.
- `CLASS != conflicting` (any other class, including after a successful rebase): reset `conflict_streak` to `0`.

Compute `CONFLICT_STREAK_NEW` for the persist block:

```bash
# If T4 incremented conflict_streak (conflicting dispatch), it already wrote the new value
# and stored it in $NEW_STREAK. Otherwise (non-conflicting tick), reset to 0.
if [[ "$CLASS" == "conflicting" ]]; then
  CONFLICT_STREAK_NEW="${NEW_STREAK:-$CONFLICT_STREAK}"  # T4 set NEW_STREAK on a conflicting dispatch
else
  CONFLICT_STREAK_NEW=0
fi
```

Persist all non-cadence counters atomically, then increment the tick count. `$DIGEST` (the `sha256:…` string computed above) is not valid JSON, so `session-state.sh --set` stores it as a string literal. Cadence and task identity are committed together below; publishing the desired cadence here would make a failed `TaskStop` look like a successful tier crossing:

```bash
NOW=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
"$SESSION_STATE_SH" \
  --set ".prs[\"$PR\"].digest=$DIGEST" \
  --set ".prs[\"$PR\"].digest_streak=$STREAK" \
  --set ".prs[\"$PR\"].babysit.blocker_streak=$BLOCKER_STREAK" \
  --set ".prs[\"$PR\"].babysit.conflict_streak=$CONFLICT_STREAK_NEW" \
  --set ".prs[\"$PR\"].babysit.tick_count=$NEW_TICK_COUNT" \
  --set ".prs[\"$PR\"].babysit.last_tick_at=$NOW"
```

**Re-arm cadence only when it crosses a tier boundary.** Before comparing cadences, read the exact
current `babysit.monitor_task_id` on every tick. A missing ID while active is degraded teardown: set
`stop_requested=true`, report it, and terminate without retaining or arming a task. Then compare the
computed `$EFFECTIVE_MIN` to the captured `$PREV_EFFECTIVE_MIN`; this comparison is mandatory on
every tick. When they are equal, retain the identified Monitor and cadence. When they differ, stop
the exact current Monitor. Before that stop, atomically set `stop_requested=true`; this makes every
already-emitted old-generation event exit at T0 throughout the stop-to-publication gap. In other
words, cadence changes must **guard, then stop the exact current Monitor** and complete this transaction:

1. Publish `stop_requested=true`, then stop the exact current Monitor task with `TaskStop`. A failed
   old-task stop retains its complete ID+generation pair, `$PREV_EFFECTIVE_MIN`, and the stop guard
   in state and aborts the re-arm as incomplete teardown.
2. Generate a fresh `$NEW_MONITOR_GENERATION`, then arm a replacement whose sleep and emitted
   `--cadence` use `$EFFECTIVE_MIN` and whose event includes
   `--monitor-generation $NEW_MONITOR_GENERATION`.
3. Publish the replacement ID, generation, cadence, and cleared stop guard in one atomic state write:

   ```bash
   "$SESSION_STATE_SH" \
     --set ".prs[\"$PR\"].babysit.monitor_task_id=$NEW_MONITOR_TASK_ID" \
     --set ".prs[\"$PR\"].babysit.monitor_generation=\"$NEW_MONITOR_GENERATION\"" \
     --set ".prs[\"$PR\"].babysit.cadence_effective_minutes=$EFFECTIVE_MIN" \
     --set ".prs[\"$PR\"].babysit.stop_requested=false"
   ```

If replacement arming fails, the old task is already stopped: atomically set `active=false`,
`stop_requested=false`, `monitor_task_id=null`, `monitor_generation=null`, and restore
`cadence_effective_minutes=$PREV_EFFECTIVE_MIN`, then report that the watcher terminated. If the
publication write fails, stop the exact replacement task. After a successful rollback stop, clear
the known-stopped old identity and set `active=false`, `stop_requested=false`; after a failed rollback stop, best-effort
publish `stop_requested=true`, `active=true`, and the exact `$NEW_MONITOR_TASK_ID` plus
`$NEW_MONITOR_GENERATION` so a later `/babysit-pr-stop` can retry the potentially-live task. Never
retain the already-stopped old identity as if it were the replacement, and never claim the cadence
changed until the ID+generation+cadence publication succeeds. A queued event from the stopped old
generation is rejected at T0 before it can classify, dispatch, terminate, or re-arm the replacement.

On an actual widen, record it so `polling-backoff-warn.sh` stops re-emitting its widen advisory (it dedupes on `type == "update"` at the new interval):

```bash
"$SESSION_STATE_SH" --set ".prs[\"$PR\"].last_cron_action={\"type\":\"update\",\"interval\":\"${WIDE_MIN}m\",\"at\":\"$(date -u +%Y-%m-%dT%H:%M:%SZ)\"}"
```

### T6. Termination check

Terminate (→ T-END) when **any** hold:

- `CLASS == merged` → reason `merged`.
- `CLASS == hard-blocked` → reason `hard-blocked` (record the specific blocker: human reviewer login(s), conflict, budget exhaustion, persistent P0).
- `CLASS == conflicting` and `AUTO_RESOLVE != "true"` → reason `hard-blocked`, blocker `merge-conflict` (terminated from T4; see T-END for recommended command).
- `CLASS == conflicting` and `conflict_streak >= max_conflict_rounds` → reason `conflict-round-cap` (churn cap hit; see T-END for round count and blocker report).
- `CLASS == conflicting` and dispatch returned `CONFLICTS` (complex hunk) → reason `hard-blocked`, blocker `merge-conflict-complex` (see T-END for per-hunk report).
- PR `CLOSED` unmerged → reason `closed-unmerged`.
- `blocker_streak >= max_blocker_ticks` (default 6) → reason `blocker-tick-cap` (≈90 min once backed off to 15m).
- `digest_streak >= 9` → reason `stable-frozen` (`scheduling-reliability.md` ≥9 stop).
- `stop_requested == true` / `active != true` → reason `user-stop`.

Otherwise the Monitor continues — its next stdout event re-enters tick mode.

### T7. Heartbeat (per tick — never silent by default)

Always run a `date` for the timestamp (never estimate — `monitor-mode.md`):

```bash
TS=$(TZ='America/New_York' date +'%a %b %-d %I:%M %p ET')
```

One-liner format:

```
[<TS>] #<PR> tick <n>: state=<class>, action=<dispatch /fixpr | dispatch /wrap | no-op | waiting | dispatch-in-progress>, next in <effective-cadence>
```

Append context: blocker reason on `hard-blocked`/`waiting-on-bots`; dispatch target on a dispatch; `(backoff: stable ×<streak>, widened to <WIDE_MIN>m)` when cadence widened; the final summary on termination.

**`--silent`:** suppress the line on plain `waiting-on-bots`/no-change ticks, but **always** print on state change, any dispatch, backoff transitions, and termination. (Default — no `--silent` — prints every tick, satisfying the per-tick heartbeat AC.)

### T-END. Terminate cleanly

Set the stop flag first so any already-emitted tick's T0 short-circuit exits cleanly. Do **not**
clear `active` until the recorded Monitor task has stopped; otherwise A2 can admit a duplicate
watcher while the old task is still emitting:

```bash
"$SESSION_STATE_SH" --set ".prs[\"$PR\"].babysit.stop_requested=true"
```

**Cancelling the poll is a required terminal action — a persistent Monitor does not lapse on its own.** Read `babysit.monitor_task_id`, stop that exact task with `TaskStop`, and do not re-arm it. If the ID is missing or `TaskStop` fails, keep both `active=true` and the ID for diagnosis, report degraded teardown, and do not claim completion; `stop_requested=true` still makes an already-emitted tick exit at T0. A2 treats that stop-requested active state as an incomplete teardown and refuses re-arm regardless of tick age, so the ordinary stale-watcher reclaim can never revive an old Monitor alongside a replacement.

One idempotent exception: when T0 observed `active != true` **and** the task ID is already null,
another teardown path (normally `/babysit-pr-stop`) completed the exact stop before this queued tick
ran. Treat that pair as already stopped, not degraded, and do not call `TaskStop` without an ID.

**Record the stop.** `polling-backoff-warn.sh` suppresses a repeated STOP advisory by reading `.prs["<N>"].last_cron_action.type == "delete"`. The field name is historical — it records the poll-lifecycle action, whatever primitive backs the poll:

```bash
"$SESSION_STATE_SH" \
  --set ".prs[\"$PR\"].babysit.active=false" \
  --set ".prs[\"$PR\"].babysit.monitor_task_id=null" \
  --set ".prs[\"$PR\"].babysit.monitor_generation=null" \
  --set ".prs[\"$PR\"].last_cron_action={\"type\":\"delete\",\"interval\":\"paused\",\"at\":\"$(date -u +%Y-%m-%dT%H:%M:%SZ)\"}"
```

Run that atomic cleanup only after `TaskStop` succeeds. Clear `dispatch_in_flight` in the same
call only when it is null; if a user stop raced an existing `/fixpr` or `/wrap`, retain the marker
until that dispatch completes or T0's TTL reclaim owns it.

Belt-and-suspenders: even if cancellation is delayed, the T0 short-circuit (`stop_requested` /
`active != true`) makes every subsequent tick an immediate no-op terminate — but cancellation is
still mandatory so the runtime stops invoking the watcher.

If exact teardown failed, emit a `babysit-pr teardown incomplete` report with the retained task ID
and generation instead of the successful `babysit-pr complete` summary below.

Emit the final summary:

```
=== babysit-pr complete ===
PR:           #<PR>
Pre-flight:   <last tick's draft→ready + reviewers triggered, from $PREFLIGHT_SUMMARY_JSON; "clean" when no-op across ticks>
Final state:  <class>
Reason:       merged | hard-blocked | conflict-round-cap | closed-unmerged | blocker-tick-cap | stable-frozen | user-stop
Ticks:        <tick_count>
Dispatches:   <count> (/fixpr ×N, /wrap ×M)
Last dispatch: <skill> → <status>
Blocker:      <named blocker when hard-blocked / blocker-tick-cap / conflict-round-cap, else "none">
Conflict rounds: <conflict_streak> of <max_conflict_rounds> (omit when conflict_streak == 0)
```

**Conflict-specific terminal output:**

- **`conflict-round-cap`** (churn cap hit): after the standard summary, print:
  ```
  Conflict rounds attempted: <conflict_streak> (cap=<max_conflict_rounds>)
  Branch kept re-conflicting — resolve manually, then re-arm babysit.
  ```

- **`hard-blocked` with blocker `merge-conflict`** (default behavior, flag not set): after the standard summary, print:
  ```
  PR is CONFLICTING. Run /merge-conflict to classify hunks and resolve manually,
  or re-arm with --auto-resolve-conflicts to enable unattended simple-hunk resolution.
  ```

- **`hard-blocked` with blocker `merge-conflict-complex`** (auto-resolve mode, complex hunk found): after the standard summary, print the per-hunk report from the resolver verbatim — one entry per line:
  ```
  Complex conflict hunks (require human resolution):
    <file>: <location> — <reason>
    <file>: <location> — <reason>
    ...
  Rebase was aborted. Resolve the above hunks manually, then re-arm babysit.
  ```
  The per-hunk entries come from `complex_report` stored in `.babysit.last_dispatch.complex_report` (set in T4 on `CONFLICTS` return). Parse via `jq -r '.complex_report[] | "  \(.file): \(.location) — \(.reason)"'`.

---

## Notes

- **Stop anytime:** `/babysit-pr-stop <PR>` sets `stop_requested=true`; the next tick's T0 terminates cleanly. See `.claude/skills/babysit-pr-stop/SKILL.md`.
- **One watcher per PR** — arm mode refuses a duplicate (A2).
- **Session-scoped by design.** The watcher dies with the session. A watcher left `active` by a session that ended is cleared at the next session start by `session-scheduling-reconcile.sh`, so `/status` never reports a watcher that is not running.
- **One persistent Monitor per PR** — arm mode refuses a duplicate and stores the task ID for stop/re-arm.
- **Monitor mode:** while a dispatch subagent is in flight, the parent follows `monitor-mode.md` (orchestration only, ≤5-min heartbeat). The per-tick heartbeat satisfies the heartbeat requirement.
- **Post-merge install:** after this skill lands on `main`, symlink it globally via the skills worktree per `skill-symlinks.md`.