Define the pull request template and documentation-impact contract #2669

Problem

The accepted Base governance design and implementation plan identify package 5a as a required deliverable. This issue translates that package into a reviewed, bounded issue/PR train; it does not authorize implementation before the issue reaches Ready.

Expected behavior

Replace the current PR template with one issue/slice link, plan and acceptance trace, validation evidence, the same ten impact categories used by issues, reviewer/round provenance fields required by the accepted design, and a release-note line or reasoned none. Include risk, rollback and notes. Distinguish Fixes #N for a single-PR issue from Part of #N for a named multi-PR slice. Do not mirror issue Project fields onto PRs.

Scope and non-goals

Scope: Replace the current PR template with one issue/slice link, plan and acceptance trace, validation evidence, the same ten impact categories used by issues, reviewer/round provenance fields required by the accepted design, and a release-note line or reasoned none. Include risk, rollback and notes. Distinguish Fixes #N for a single-PR issue from Part of #N for a named multi-PR slice. Do not mirror issue Project fields onto PRs.

Non-goals: Do not silently expand scope, activate unreviewed policy, mirror issue fields onto PRs, grant agents merge/release authority, or make changes outside the named affected areas. Any new product decision or materially new work gets a separate issue and decision record.

Affected areas

• .github/pull_request_template.md, docs/github-workflow.md, CONTRIBUTING.md, and the impact taxonomy in docs/governance/.
• Accepted source: governance design and implementation plan, PR #2664
• Parent tracker: #2665

Impact and evidence

1. Product intent: Implements only the accepted governance design and plan; any product-requirement change must be filed separately.
2. Architecture and contracts: Destination is the package-specific section of the merged governance design/implementation plan plus the affected canonical contract named above.
3. User guidance: The issue identifies likely guidance paths; the implementation PR must name updated user/FAQ/README paths or give a change-specific reason why none is affected.
4. CLI/API and reference: The affected-area list determines whether CLI/API/reference docs change; the implementation PR must cite the exact reference path or justify no impact.
5. Operations and safety: No privileged automation or merge authority is implied; the PR must list operational/security effects and any rollback.
6. Validation and testing: The issue lists the planned tests; the PR must report executed validation and explain any unavailable test.
7. Examples and downstream use: The implementation PR must identify affected examples/consumers or give evidence that this change has no downstream surface.
8. Governance and contributor process: This package changes or preserves the contributor/governance contract as described in Scope; links must point to the canonical rules.
9. Decision records: No new decision is accepted by this issue; any durable deviation requires a proposed decision record and explicit maintainer acceptance.
10. Release notes: The PR must include a user-facing release-note line or a reasoned none; this issue does not pre-decide that disposition.

These are issue-stage dispositions to refine during Triage. Before Ready, every category must have its exact destination or evidence-based no-impact reason; the PR repeats the ten-category evidence for actual changes.

Open questions

• None known. If implementation exposes an unresolved contract, return this issue to Triage and record the decision before implementation continues.

Plan

• S1: One focused PR for this issue. Use Fixes #N only if no additional slice is needed; if the maintainer approves multiple PRs, name each S1…Sn here before the first is opened and use Part of #N.
• Dependencies: the P1 issue
• Acceptance criteria:
• The template covers all ten impact categories, each requiring a destination or evidence-based no-impact reason.
• A PR names its issue and exactly one planned slice; instructions distinguish Fixes from Part of.
• Validation, plan adherence, acceptance criteria, demo impact, risk/rollback/notes and release-note disposition are explicit.
• No duplicated Status/Priority/Size/Area/Initiative/Risk fields or stale Agent Assignment fields remain.
• Legacy AI-context impact is described as an impact disposition, not as a separate tracked-file maintenance assertion.
• Validation:
• Render/check template Markdown and validate required headings/checkboxes with contract fixtures.
• Exercise single-PR and multi-slice examples, including a no-release-note rationale.
• Run docs checks and git diff --check.
• Risks and rollback: Overly rigid checkboxes can encourage empty evidence; keep semantic review manual and make the no-impact rationale concrete. Revert the template if it conflicts with accepted issue contracts.
• Decision impact: No decision is accepted merely by implementing the issue. Record the relevant accepted decision/ADR and file a superseding record if the maintainer approves a change.