AR-99: add pr-reviewer merge-on-green handling

[khaliqgant]

Summary

• add merge-on-green handling inside the review pr-reviewer agent across AgentWorkforce repos
• evaluate current PR state before merging: label present, checks complete/passing, requested bot reviewers approved, no bot changes-requested
• merge with the current head SHA through the existing GitHub helper
• add Slack merge-request handling that replies with blockers when a mentioned merge request is not green/satisfied

Validation

• npm test
• npm run typecheck

cloud#2061 was closed unmerged per dispatcher correction. Do not merge this PR without human approval.

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Summary by cubic

Adds merge-on-green to the PR reviewer so PRs in the AgentWorkforce org auto-merge when labeled and all gates pass. Also lets Slack users ask the reviewer to merge; it merges if green or replies with blockers. (Linear AR-99)

• New Features

  • Merge-on-green gate: label merge-on-green, PR open and not draft, no conflicts, green checks, requested bot reviewers approved, and no bot “changes requested”.
  • Listens to issues.labeled, commit status, check_run.completed, review submissions, and sync/open events; resolves PRs from commit-status SHAs.
  • Merges using the current head SHA via the existing GitHub helper.
  • Slack: parses “please merge …PR URL” in the configured channel; merges when ready or replies with specific blockers.

• Refactors

  • Extended PR parsing to handle issue-labeled payloads and normalize label reads.
  • Added decision helpers for merge-on-green evaluation and Slack reply handling, with tests.
  • Kept the persona Slack scope on /slack/channels/** so channel writebacks work for merge replies.

^{Written for commit 752976a. Summary will update on new commits.}

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[coderabbitai]

📝 Walkthrough

Walkthrough

This PR implements merge-on-green automation with Slack support. The agent now evaluates PR readiness based on labels, checks, and bot approvals, routes Slack messages to a dedicated merge handler, extends webhook parsing for issue-based PR references, and orchestrates merge decisions through a centralized event gate.

Changes

Merge-on-green with Slack integration

Layer / File(s)	Summary
State machine foundation and constants review/agent.ts	Documented merge-on-green control flow path and defined controlling org/label constants used throughout the merge gate logic.
Webhook payload parsing extension review/agent.ts	Extended readPr to recognize issue-wrapped pull_request payloads and extract labels from either pull_request.labels or issue.labels, enabling PR data reading from issue-based webhook event shapes.
Merge-on-green readiness evaluation review/agent.ts	Extended PullRequestReadyState with draft/review/labels/check/sha fields and implemented evaluateMergeOnGreenState to compute ready/blocked/pending outcomes based on PR openness, draft status, required label, merge conflicts, check completion/pass, and bot approval derived from reviews and requests.
Slack merge request handling review/agent.ts	Added SlackMessage type, implemented parseSlackMergeRequest to extract PR URLs from Slack text, and exported handleSlackMergeRequest to parse messages, filter bots/subtypes, compute merge decisions, execute merges, and post threaded confirmations or blocking reasons.
Agent handler orchestration and control flow review/agent.ts	Refactored main agent handler to route Slack messages to handleSlackMergeRequest, extended merge-on-green routing to handle both direct PR events and status-derived PR lists via a centralized event-type gate, and rewired PR parsing/decision logic to support label/status/check/review/sync/open triggers.
Slack integration documentation review/persona.ts	Updated pr-reviewer persona comment to clarify that the full channels subtree must remain mounted so both ready/merge pings and merge-request reply messages reach the writeback worker.
Test implementation and coverage tests/review-agent.test.mjs	Added imports for new exported functions (evaluateMergeOnGreenState, handleSlackMergeRequest, parseSlackMergeRequest) and comprehensive test cases covering readPr from labeled issues, readiness evaluation outcomes, Slack PR URL parsing, and threaded merge-blocked replies.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

• AgentWorkforce/agents#48: Both PRs modify review/agent.ts readiness/merge gating logic around PullRequestReadyState by using gh pr view/status-check rollups and mergeability to decide whether a PR is "ready" for human/merge notifications, so the changes overlap at the core readiness-evaluation code level.

Suggested labels

size:L

Poem

🐰 A rabbit hops through checks and labels green,
Slack messages routed to merge machine,
Draft states reviewed, bot approvals weighed,
Thread replies sent, decisions are made! 🎉

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 3.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'AR-99: add pr-reviewer merge-on-green handling' clearly and specifically describes the main change: adding merge-on-green functionality to the PR reviewer agent.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The PR description clearly relates to the changeset, detailing merge-on-green functionality, PR state evaluation, merge execution, and Slack merge-request handling.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ar-99-merge-on-green-agents

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[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

ℹ️ pr-reviewer: review only — no file changes were applied to the PR (nothing to commit after review). The notes below are advisory and were not pushed.

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.

[agent-relay-code]

ℹ️ pr-reviewer: review only — no file changes were applied to the PR (nothing to commit after review). The notes below are advisory and were not pushed.

pr-reviewer could not complete review for #57 in AgentWorkforce/agents.
The review harness exited with code 1.
No review was posted; this needs operator attention.