/watch-pr

name: watch-pr
description: Watch an Elixir/Phoenix PR for new review comments (bot + human) and CI results via a background watcher that wakes Claude only on real events. Use after opening a PR or pushing, while waiting on CI or reviewers.
effort: medium
argument-hint: <PR number or URL> [--checks-only] [--fix]

Watch PR (Token-Conscious)

Watch a PR's reviews, comments, and CI with a background watcher that wakes Claude ONLY on real events — no foreground sleep loops, no context bloat. The watcher polls quietly in its own process; nothing enters context until something genuinely changed.

Usage

/phx:watch-pr 42                 # watch reviews + comments + checks
/phx:watch-pr 42 --checks-only   # CI only (delegates to gh pr checks --watch)
/phx:watch-pr 42 --fix           # on actionable review, draft fixes too
/phx:watch-pr 42 --codex         # + request Codex cloud review, loop until clean
/phx:watch-pr 42 --codex --codex-rounds 2   # cap re-review rounds (default 3)

Iron Laws

1. **NEVER foreground-poll with `sleep` in the session** — use the background watcher (Monitor / run_in_background). Foreground polling bloats context and straddles the 5-min cache TTL 2. **Deltas ONLY enter context** — never dump full `gh` JSON. The watcher emits one-line events; read `.claude/watch/pr-{n}.jsonl` on demand 3. **Silence is not success** — the watcher MUST emit on PR closed/merged, CI failure, repeated gh errors, and watchdog timeout — not just "new comment". A silent watcher looks identical to a hung one 4. **NEVER auto-post replies or auto-push** — hand off to `/phx:pr-review` for responses; show drafts and get approval. ONE exception: passing `--codex` IS the consent to post the `@codex review` trigger comment (and its per-round re-requests) — nothing else is ever auto-posted 5. **Bound every watch** — default MAX_DURATION 3600s (7200s with `--codex`); always stop on terminal state. Codex rounds are bounded by `--codex-rounds` (default 3) — each round costs cloud quota

Workflow

Step 1: Parse Arguments

Extract PR number (from number or URL — URL also yields the repo). Detect `--checks-only` / `--fix` / `--codex` / `--codex-rounds N`. Baseline timestamp = now; events are "new since baseline", so old reviews don't re-fire.

With `--codex`, the **default is to POST `@codex review`** — the flag IS that consent (Iron Law 4). Skip the trigger ONLY when the connector bot (`chatgpt-codex-connector[bot]`) has itself reacted to / reviewed the current head SHA. The repo's CI "Codex" check and any local `codex exec` / `/phx:review --codex` / `/phx:codex-loop` run are DIFFERENT mechanisms from the GitHub connector — they NEVER satisfy the skip. When unsure, post. The connector auto-registers PRs on ready (its absence surfaces later as `codex_timeout`), so check ITS reactions before posting a redundant trigger:

HEAD_AT=$(gh api "repos/{owner}/{repo}/commits/$(gh pr view {n} --json headRefOid -q .headRefOid)" --jq .commit.committer.date)
BOT=$(gh api "repos/{owner}/{repo}/issues/{n}/reactions" | jq -r --arg t "$HEAD_AT" \
  '[.[] | select(.user.login == "chatgpt-codex-connector[bot]" and .created_at >= $t) | .content] | unique | join(",")')

(`gh api --jq` accepts no `--arg` — pipe through standalone `jq`.)

**Definitive check first**: a **connector-bot** comment or review containing `Reviewed commit: {sha}` that matches the current head sha means that state IS reviewed (clean if it says "Didn't find any major issues") — trust it over timestamps, which are client-set and can skew. Then:

| Connector-bot signal on current head | Action | |-------------------------------|--------| | `+1` reaction | Connector already reviewed this head clean — no trigger, no codex round; watch CI/humans only | | `eyes` + a codex review already submitted since `$HEAD_AT` | Findings already posted — skip the watch; run the `codex_review` action (Step 3) now | | `eyes` only | Review in flight — do NOT post; export `WATCH_CODEX=1 WATCH_CODEX_SINCE=$HEAD_AT` (no trigger id) and watch | | none (or reactions predate head) | Post the trigger and capture its id: |

TRIGGER_ID=$(gh api --method POST "repos/{owner}/{repo}/issues/${PR}/comments" \
  -f body="@codex review" --jq '.id')

Export `WATCH_CODEX=1 WATCH_CODEX_TRIGGER_ID=$TRIGGER_ID` to the watcher env and set MAX_DURATION 7200. Round counter starts at 1.

Step 2a: `--checks-only` Path

No custom poller needed — `gh pr checks --watch` blocks until all checks finish, then exits. Run via Bash with `run_in_background: true`:

gh pr checks {n} --watch --fail-fast --interval 10

Exit code is the signal: `0` = pass, `1` = fail, `8` = pending. On exit, report the conclusion; on failure, offer `/phx:investigate` with the failing job log (`gh run view {run-id} --log-failed`).

Step 2b: Full Watch Path

Start the **Monitor tool** (preferred — streams each event line back) on:

${CLAUDE_SKILL_DIR}/scripts/watch-pr.sh {n} reviews,comments,checks

Monitor is a deferred tool — load its schema FIRST via ToolSearch (`select:Monitor`); calling it blind fails with InputValidationError (params are `command`, `description`, `timeout_ms`, `persistent` — do not invent others). Set `timeout_ms` = MAX_DURATION × 1000. Where Monitor is unavailable (Bedrock/Vertex/Foundry), run the same script via Bash `run_in_background: true` — it exits on the first terminal event instead. Stay idle or keep working until an event lands.

Step 3: React Per Event

| Event | Action | |-------|--------| | `review` / `comment` (actionable) | Summarize the delta; with `--fix` draft fixes + `mix compile && mix test`; route reply drafting to `/phx:pr-review {n}` | | `check` conclusion `failure` | Offer `/phx:investigate` on the failing job | | `codex_ack` | Note "codex is reviewing (~15–20 min on large PRs)"; keep waiting | | `codex_review` | Stop the watcher. Run `/phx:pr-review {n} --bots-only` (fix → rep