feat(agents): add mandatory PR compliance checklist to implementation-pool-supervisor

Workers were systematically omitting CHANGELOG.md, CONTRIBUTORS.md, and
commit footer (ISSUES CLOSED: #N), causing all PRs to be blocked from merge.

Added a mandatory 8-item PR Compliance Checklist to implementation-pool-supervisor.md
that supervisors must pass verbatim to every worker prompt. The checklist covers:
1. CHANGELOG.md update under [Unreleased]
2. CONTRIBUTORS.md update
3. Commit footer with ISSUES CLOSED: #N
4. CI verification (all quality gates green)
5. BDD/Behave test coverage
6. Epic reference in PR description
7. Labels applied via forgejo-label-manager
8. Milestone assignment

Populated all subsections with concrete examples for workers to follow.

Closes #9824

.opencode/agents/implementation-pool-supervisor.md

@@ -107,6 +107,7 @@ Launch workers via the `async-agent-manager` subagent. For each worker:
    - The PR number or issue number
    - Repository info, credentials, and git identity
    - The CONTRIBUTING.md rules from your briefing (commit standards, testing, PR requirements)
+   - The **PR Compliance Checklist** (see PR Compliance Checklist section below) — workers must complete all items before creating a PR
    - For PR fix workers: instruct the worker to use the `ci-log-fetcher` subagent to retrieve CI failure logs
 
 ### Worker Attempt Comments
@@ -122,6 +123,104 @@ These comments are how you track escalation state across worker sessions.
 
 Every cycle, search for your workers using `async-agent-manager` by tag pattern (`[AUTO-IMP-ISSUE-*]` and `[AUTO-IMP-PR-*]`). Count active workers, verify they're progressing (by reviewing their session messages via `async-agent-manager`), and note any that have completed or errored. Workers completing is normal — they finished their task. Restart any errors workers via `async-agent-manager`.
 
+## PR Compliance Checklist
+
+Every worker prompt you dispatch **must** include the following mandatory checklist verbatim under a section titled **"PR Compliance Checklist (MANDATORY)"**. Workers must complete **all** items before creating a PR and include the completed checklist in their PR description.
+
+```
+MANDATORY — Complete ALL items before creating a PR:
+[ ] 1. CHANGELOG.md — add entry under [Unreleased] section
+[ ] 2. CONTRIBUTORS.md — add or update contribution entry
+[ ] 3. Commit footer — include `ISSUES CLOSED: #<issue-number>` in the commit message
+[ ] 4. CI passes — all quality gates and tests green before requesting review
+[ ] 5. BDD/Behave tests — added or updated for the changed behaviour
+[ ] 6. Epic reference — PR description references the parent Epic issue number
+[ ] 7. Labels — applied via forgejo-label-manager: State/In Review, Priority/<level>, MoSCoW/<level>, Type/<type>
+[ ] 8. Milestone — PR assigned to the earliest open milestone matching the issue
+```
+
+### CHANGELOG.md Update
+
+Workers must add an entry under the `[Unreleased]` section in `CHANGELOG.md`. Example:
+
+```markdown
+## [Unreleased]
+
+### Added
+- **My Feature** (#1234): Brief description of what was added and why.
+```
+
+Or for a fix:
+
+```markdown
+## [Unreleased]
+
+### Fixed
+- **My Bug Fix** (#1234): Brief description of what was fixed and the root cause.
+```
+
+### CONTRIBUTORS.md Update
+
+Workers must add or update their entry in `CONTRIBUTORS.md`. Example:
+
+```markdown
+# Contributors
+
+* HAL 9000 <hal9000@cleverthis.com>
+
+# Details
+
+* HAL 9000 has contributed <description of contribution> (#<issue-number>).
+```
+
+If HAL 9000 already appears in the list, add a new bullet under `# Details` describing this specific contribution.
+
+### Commit Footer
+
+Every commit that closes an issue must include the `ISSUES CLOSED` footer line. Example commit message:
+
+```
+feat(module): add new capability for X
+
+Implements the Y feature by doing Z. This resolves the problem described
+in issue #1234 where users could not perform the action.
+
+ISSUES CLOSED: #1234
+```
+
+The footer must be on its own line, separated from the body by a blank line, and must use the exact format `ISSUES CLOSED: #<issue-number>`.
+
+### Compliance Verification Pseudocode
+
+Before creating a PR, verify each checklist item:
+
+```python
+# 1. CHANGELOG.md — check [Unreleased] section has new entry
+assert "[Unreleased]" in changelog and new_entry in changelog
+
+# 2. CONTRIBUTORS.md — check HAL 9000 entry exists with this contribution
+assert "HAL 9000" in contributors and issue_reference in contributors
+
+# 3. Commit footer — check last commit message contains ISSUES CLOSED footer
+assert f"ISSUES CLOSED: #{issue_number}" in git_log_last_commit
+
+# 4. CI passes — run all quality gates locally before pushing
+# nox -e lint && nox -e typecheck && nox -e unit_tests
+# nox -e integration_tests && nox -e e2e_tests && nox -e coverage_report
+
+# 5. BDD/Behave tests — check feature file exists or was updated
+assert behave_feature_file_exists_or_updated
+
+# 6. Epic reference — check PR description mentions parent Epic
+assert f"Epic" in pr_description or epic_issue_number in pr_description
+
+# 7. Labels — applied via forgejo-label-manager (not directly)
+# forgejo-label-manager: apply State/In Review, Priority/<level>, MoSCoW/<level>, Type/<type>
+
+# 8. Milestone — PR assigned to earliest open milestone
+assert pr.milestone == earliest_open_milestone
+```
+
 ## Progressive Escalation
 
 Workers start at the cheapest model tier and escalate to more expensive tiers only when the same problem persists across attempts. There are four tiers:

CHANGELOG.md

@@ -325,6 +325,18 @@ The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   `PlanError` if checkpoint metadata cannot be persisted. Writable sandboxable
   resources and write-capable tools now default to `checkpointable=True`, and
   new Behave scenarios cover DI wiring, rollback, and capability defaults. (#1253)
+
+### Changed
+
+- **Implementation Pool Supervisor PR Compliance Checklist** (#9824): Added a mandatory
+  8-item PR Compliance Checklist to `implementation-pool-supervisor.md` that supervisors
+  must pass verbatim to every worker prompt. Checklist covers: CHANGELOG.md update,
+  CONTRIBUTORS.md update, commit footer (`ISSUES CLOSED: #N`), CI verification, BDD tests,
+  Epic reference, label application via `forgejo-label-manager`, and milestone assignment.
+  Populated the four subsections (`### CHANGELOG.md Update`, `### CONTRIBUTORS.md Update`,
+  `### Commit Footer`, `### Compliance Verification Pseudocode`) with concrete examples
+  to guide workers.
+
 ---
 
 ## [3.8.0] — 2026-04-05

CONTRIBUTORS.md

@@ -20,3 +20,4 @@ Below are some of the specific details of various contributions.
 * This project was made possible thanks to considerable donation of time, money, and resources by CleverThis, Inc.
 * HAL 9000 has contributed automated bug fixes, CLI output formatting improvements, and ongoing maintenance as part of the CleverAgents automation system.
 * HAL 9000 has contributed the file edit encoding parameter fix (PR #8258 / issue #7559).
+* HAL 9000 has contributed the mandatory PR compliance checklist to `implementation-pool-supervisor.md` (#9824): added an 8-item checklist with concrete examples for CHANGELOG.md, CONTRIBUTORS.md, commit footer, and compliance verification pseudocode to eliminate systemic PR merge blockers.