Pattern miner: Add PR Fix Assistant archetype for slash-command-driven branch pushes

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Caution

Protected files were modified in this change.
This pull request is in request_review mode and requires explicit human scrutiny before merge.

Protected files: .github/copilot-instructions.md

Upstream evidence

Mined githubnext/agentics workflow sources under /tmp/gh-aw/data/upstream/githubnext-agentics/files/workflows/, cross-checked against github/gh-aw docs under /tmp/gh-aw/data/upstream/github-gh-aw/files/.github/aw/.

Recurring pattern: a slash-command-triggered agent that fixes an existing pull request by pushing corrections directly to its branch with the push-to-pull-request-branch safe output, instead of opening a new pull request. Six upstream workflows demonstrate this shape:

• workflows/pr-fix.md — slash_command: pr-fix + reaction: eyes, safe-outputs: push-to-pull-request-branch, create-issue, add-comment
• workflows/efficiency-improver.md — push-to-pull-request-branch: { target: "*", required-title-prefix: "[efficiency-improver] " }
• workflows/perf-improver.md — same push-to-pull-request-branch + required-title-prefix shape, slash-command-gated follow-up path
• workflows/test-improver.md — same shape
• workflows/repo-assist.md — same shape, with protected-files: allowed
• workflows/lean-squad.md — same shape, with protected-files: allowed

This is also documented as the canonical mapping in github-gh-aw/files/.github/aw/designer-mappings.md ("commit a fix to the PR branch" → push-to-pull-request-branch) and specced in detail in github-gh-aw/files/.github/aw/safe-outputs-management.md (recommended required-title-prefix/required-labels restrictions, target: "*" warnings, checkout fetch: ["*"] requirement).

Why the existing library did not cover it

I checked /tmp/gh-aw/data/current-library.json and every archetype file under patterns/archetypes/. push-to-pull-request-branch was defined only as a generic safe-output alias in patterns/workflow-generation.json (outputs["push-to-pull-request-branch"]) but was never used as a recommended_tools/recommended_safe_outputs entry by any archetype, and no archetype's tips mention it. The closest existing archetypes are distinct:

• pr-iteration-loop — schedule-triggered, one long-running draft PR, not a slash-command on-demand fixer for an arbitrary existing PR.
• nitpick-reviewer — slash-command-triggered but comment-only, never pushes code.
• code-improvement — schedule-triggered, opens new PRs via create-pull-request, not push-to-existing-branch.

None of these represent "push a fix straight onto the branch of the PR that invoked you," so this is additive, not a duplicate.

What changed

• Added patterns/archetypes/pr-fix-assistant.json — new curated archetype (success_rate: null, count: 0, top_repos: []) with slash_command + reaction triggers, pull-requests safe outputs, push-to-pull-request-branch recommended tool, and tips drawn directly from the upstream evidence above (required-title-prefix/required-labels scoping, verify-before-push, comment summary, min-integrity: none rationale).
• Appended pr-fix-assistant to archetypes in patterns/manifest.json.
• Added a pr-fix-assistant entry to patterns/workflow-generation.json (icon, capabilities, permissions, github toolsets, instructions, a slash_command trigger override restricting events to pull_request_comment, prompt body, and min_integrity: none) so the wizard can render this archetype.
• Updated .github/copilot-instructions.md to list the new curated archetype in the "no measured success rate" set and bumped the "user-facing archetypes" count from 29 to 30.
• Updated test/copilot-instructions.test.js — bumped the hardcoded curated-archetype count from 20 to 21 to match the new manifest entry.

Candidates deliberately left out

• Chart/trending narrative workflows (repo-chronicle.md, weekly-issue-activity.md, multi-device-docs-tester.md using matplotlib/seaborn + upload-asset): already covered by the existing generic extras.charts capability (upload-assets safe output) in patterns/workflow-generation.json, which any archetype can already opt into — not a gap.
• Discussion-based periodic narrative reports (plan.md, weekly-issue-activity.md, repo-chronicle.md): already covered by the existing community-digest archetype (schedule + create-discussion).
• glossary-maintainer.md / duplicate-code-detector.md / weekly-repo-map.md: single-instance shapes with no second corroborating upstream workflow or explicit doc recommendation, so they don't meet the two-upstream-workflows bar.
• vex-generator.md: a one-off workflow_dispatch-with-typed-inputs generator; no second upstream example or docs recommendation of this exact shape.

Validation

• npm test: 326/327 tests pass. The one pre-existing failure (test/copilot-instructions.test.js — "describes the committed pattern-library corpus, not stale scan data") already fails identically on main before this change (verified via git stash); it is caused by a stale generated_at date in patterns/manifest.json versus the date hardcoded in .github/copilot-instructions.md, unrelated to this PR.
• npm run build: succeeds, dist/patterns/archetypes/pr-fix-assistant.json is emitted.

Generated by Pattern Miner · copilot · auto · 223.4 AIC · ⌖ 11.6 AIC · ⊞ 8.7K · ◷

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Protected files were modified in this pull request and require manual scrutiny before merge.

Please verify that each protected-file change is intentional, policy-compliant, and safe:

• Protected files: .github/copilot-instructions.md