# t3257: Reconstruct PR #21876 worker-loop timeline

## Session origin

Child of #21901. Dispatched as headless worker to reconstruct the exact chronological lifecycle of PR #21876 by correlating GitHub timeline events with local pulse logs.

## What

Detailed timestamped timeline of the PR #21876 cascade: 9 worker dispatches, 5 force-pushes, 3 pulse approvals (2 dismissed), and ultimate closure without merge — all for a single-file documentation PR on issue #21860.

## Why

Parent #21901 documented the root cause (stale PR-existence detection via GitHub Search) but lacked a second-by-second chronological correlation across all data sources. This timeline provides the forensic reference for validating future dispatch-loop guards.

## How

Data sources correlated:

- `gh api /repos/marcusquinn/aidevops/issues/21876/events` — 12 lifecycle events
- `gh api /repos/marcusquinn/aidevops/issues/21876/timeline` — 40+ timeline entries
- `~/.aidevops/logs/pulse-merge.log` lines 17559-18067 — 9 merge-pass approval cycles + 9 post-closure "mergeable=" skips
- `~/.aidevops/logs/pulse.log` lines 2662-22656 — 9 dispatch stages, CLAIM_WON entries, HARD STOP at count=5
- `~/.aidevops/logs/headless-runtime-metrics.jsonl` — 9 worker outcome records (7 success, 2 local_error)
- Issue #21860 comments — 4 WORKER_BRANCH_ORPHAN markers, 1 worker_failed marker

## Acceptance

- [x] Chronological timeline posted as comment on parent #21901
- [x] Timeline includes timestamps, actors, events, and source evidence
- [x] Investigation corroborates parent's root-cause finding (stale PR-existence detection)

## Tier

tier:standard — data correlation across known sources, no novel design.
