feat(review): reuse review.instructions/pathInstructions for E2E test generation

[JSONbored]

Summary

• Investigated #4200's original ask (a dedicated review.e2eTestGeneration.instructions/pathInstructions config block, CodeRabbit-path_instructions-style) against the current codebase, and found the codebase already has a fully general-purpose, working mechanism for exactly this: review.instructions (repo-wide brief) and review.pathInstructions ({path, instructions}[]), already parsed, validated, and fed into the AI reviewer's prompt today (resolveReviewPathInstructions in src/signals/focus-manifest.ts).
• Rather than inventing a second, e2e-test-gen-specific instructions schema that would duplicate this exact concept, this PR adds resolveE2eTestGenInstructions — a small pure function that combines the SAME existing review.instructions + matching review.pathInstructions entries into one instructions block for E2eTestGenInput.instructions (the field feat(review): LLM core to turn a PR diff into Playwright E2E test source #4191/PR feat(review): LLM core to turn a PR diff into Playwright E2E test source #4207 already built and wired to accept).
• No new config schema, no new migration, no new OpenAPI field, no new glob-matching logic — this is 100% reuse of already-shipped, already-documented config. A maintainer's repo conventions and path-scoped rules ("use Playwright with our page-object pattern," "always test the payment-failure retry path for src/checkout/**") apply equally well to steering an AI reviewer or an AI test generator, so both now draw from the same maintainer-authored brief, written once.
• Updated the doc comments on pathInstructions/instructions (engine package + both public/self-host .gittensory.yml examples) to note this second consumer, so a maintainer reading the existing docs knows their instructions now also steer test generation once that feature is enabled.

Closes #4200.

Scope

• The PR title follows type(scope): short summary Conventional Commit format.
• This PR is focused — one new pure function, its tests, and doc-comment updates to the exact fields it reuses; no unrelated changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• Linked issue: Closes feat(config): repo/path-scoped test-coverage instructions for e2eTests generation #4200 (part of epic Epic: AI-generated E2E test coverage for pull requests #4189).

Validation

• git diff --check
• npm run typecheck
• npm run test:coverage (targeted at the changed files + the config-example drift tests) — 100% statements/branches/functions/lines on the changed portion of src/services/ai-e2e-test-gen.ts (82/82 stmts, 76/76 branches, 9/9 funcs, 71/71 lines, confirmed via --coverage.include); test/unit/config-templates.test.ts (verifies .gittensory.yml.example ↔ config/examples/gittensory.full.yml byte-for-byte parity) and test/unit/focus-manifest.test.ts both still pass, confirming the doc updates didn't break the existing mirror check.
• npm run docs:drift-check — clean, no new env vars introduced.
• npm audit --audit-level=moderate — N/A, no dependency changes (not re-run this PR; nothing in package.json/lockfiles touched).
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries — 6 new tests: nothing configured (null), null/undefined review config tolerated, repo-wide alone, path-instructions alone, both combined, and a non-matching glob correctly omitted.

Safety

• No secrets, wallet details, hotkeys, coldkeys, user PATs, private keys, raw trust scores, private rankings, or private maintainer evidence are exposed.
• Public GitHub text stays sanitized, low-noise — N/A directly (this reuses the EXISTING parsePublicSafeText-validated fields verbatim; no new text-handling path).
• Auth, cookie, CORS, GitHub App, Cloudflare, or session changes include negative-path tests. — N/A, no auth/session/CORS surface touched.
• API/OpenAPI/MCP behavior is updated and tested where needed — N/A, no new API/OpenAPI/MCP surface (reuses existing fields as-is).
• UI changes use live API data or real empty/error/loading states — N/A, no UI changes.
• Visible UI changes include a UI Evidence section — N/A, no UI changes.
• Public docs/changelogs are updated where needed (doc comments + both .gittensory.yml examples updated to note the new consumer); CHANGELOG.md itself is untouched.

Notes

• This is a legitimate scope simplification from feat(config): repo/path-scoped test-coverage instructions for e2eTests generation #4200's originally-filed text (which assumed a new config block was needed) — implementation revealed the codebase already had a general-purpose mechanism covering the same need, so building a parallel one would have been a needless duplicate abstraction.
• Still dead code from the deployment's perspective until a future PR in the epic (feat(review): dispatch wiring for e2eTests in queue/processors.ts #4194/feat(commands): wire @gittensory generate-tests PR-comment command #4195, dispatch + the @gittensory generate-tests command) actually calls runGittensoryE2eTestGeneration with a resolved instructions value.

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	gittensory-ui	5452058	Commit Preview URL Branch Preview URL	Jul 08 2026, 12:11 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.75%. Comparing base (8048163) to head (5452058).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4208   +/-   ##
=======================================
  Coverage   93.75%   93.75%           
=======================================
  Files         389      389           
  Lines       36495    36499    +4     
  Branches    13373    13376    +3     
=======================================
+ Hits        34217    34221    +4     
  Misses       1621     1621           
  Partials      657      657           

Files with missing lines	Coverage Δ
packages/gittensory-engine/src/focus-manifest.ts	99.16% <ø> (ø)
src/services/ai-e2e-test-gen.ts	100.00% <100.00%> (ø)

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