[FEATURE] Closed-PR postmortem miner

[acipat]

Feature Description

Problem Statement

Many agent-generated PRs are rejected for predictable reasons: wrong premise, effort underestimated, change-detector tests, or conflicts with upstream design intent. The pipeline creates issues and PRs but does not systematically mine closed/rejected PRs for patterns that would prevent future failures — the same failure modes recur across cycles because the historical signal is never turned into durable rules.

Proposed Solution

Add a closed-PR postmortem miner that:

1. Periodically scans closed/merged/rejected PRs in the fork (gh pr list --state closed).
2. Classifies the close reason by reading the closing comment and labels (e.g., rejected, needs-work, implemented-on-main, duplicate).
3. Emits durable rules or checklists for the research/analysis stages — e.g., "check for change-detector tests when touching model metadata," "decompose any issue touching provider configs."
4. Feeds these rules back into the analysis skill as advisory pre-flight checks.

This turns historical failure data into an improvement signal — the central self-evolution mechanism. It is lightweight because it only reads GitHub metadata and existing close comments.

Value Proposition

• Impact: 0.7
• Effort: 0.4
• Priority Score: 1.18

Research Evidence

• Software engineering literature on postmortems and defect prediction
• AutoGen/OpenHands community feedback loops on rejected PRs

Implementation Plan

1. New skill evolution-postmortem-miner + cron job.
2. Step 1: fetch closed PRs since last run (bounded window).
3. Step 2: classify close reason from labels + closing comment.
4. Step 3: deduplicate against existing rules.
5. Step 4: emit new rules as structured checklist entries in the analysis skill's config.
6. Output: a rules JSON file consumed by the analysis stage.

Success Criteria

• Closed PRs are classified by close reason automatically.
• Recurring failure patterns produce durable analysis-stage rules.
• The number of PRs rejected for the same reason decreases over subsequent cycles.

[Da-Mikey]

Accepted — PR #599 implements closed-PR postmortem miner. evolution_postmortem_miner.py scans closed/rejected PRs for failure patterns and emits durable analysis rules.

[Da-Mikey]

Rejected by evolution-analysis: already-exists — PR #599 implemented evolution_postmortem_miner.py at scripts/evolution_postmortem_miner.py. The script already scans closed/rejected PRs for failure patterns and emits durable analysis rules. No new work needed.

[Lexus2016]

Rejected by evolution-analysis: already-exists — scripts/evolution_postmortem_miner.py already implements the closed-PR postmortem miner described in this issue.