feat(review): emit fix-handoff blocks into the unified review comment (#1962)

[real-venus]

Summary

Wires the final, missing piece of the fix-handoff feature: emission. The renderer (buildFixHandoffBlock(s), #2175), its config/gate resolver (shouldEmitFixHandoff, #2176), the review.fixHandoff manifest toggle, and the follow-up-issue local-write action (#2177/#2185) all landed in prior slices — but buildFixHandoffBlocks had no caller, so the blocks were never actually shown. This appends a "Fix handoff" collapsible to the unified review comment: one machine-readable "apply this fix" block per inline finding that a contributor's own local coding agent can consume (content only — every block carries the LOCAL_WRITE_BOUNDARY, no server-side write to contributor code).

Closes #1962

Design

Mirrors the merged impact-map / finding-category collapsible slices exactly, so it's a familiar additive shape:

• src/review/unified-comment-bridge.ts: a pure buildFixHandoffCollapsible(blocks) (returns null on empty, so it chains unconditionally) + an optional fixHandoffBlocks? bridge arg, appended in buildUnifiedCommentBody right after the Impact map section (another structural, no-AI collapsible) and ahead of the visual preview.
• src/queue/processors.ts: resolves fixHandoffEnabledForReview once per pass via shouldEmitFixHandoff, which ANDs the operator GITTENSORY_REVIEW_FIX_HANDOFF kill-switch, the per-repo review.fixHandoff manifest opt-in, and the convergence allowlist. The blocks are built at the publish site from this pass's inline findings — the exact same aiReview.inlineFindings source findingCategories uses, so a cache hit never re-emits them.
• Default-OFF ⇒ byte-identical. With the flag off the processor passes nothing and the rendered comment is unchanged. No new config surface (the review.fixHandoff toggle already parses in packages/gittensory-engine), no DB migration, no generated-file changes.

Tests

• test/unit/fix-handoff-collapsible.test.ts (new): buildFixHandoffCollapsible renders one block per finding under a single collapsible (blocker + suggestion, and a path-only nit), carries the no-server-side-write boundary, returns null on empty, isn't raw HTML; and buildUnifiedCommentBody appends the section when blocks are present, omits it when absent/empty (flag-OFF parity), and coexists with the Impact map + Visual preview sections.
• test/unit/queue.test.ts: an end-to-end review with GITTENSORY_REVIEW_FIX_HANDOFF + review.fixHandoff on emits the "Fix handoff" collapsible with the per-finding block (location anchor, instruction, suggested change) into the published unified comment.

Validation

• git diff --check — clean.
• npm run typecheck — clean.
• npm run test:coverage (full, unsharded) — no logic failures; codecov/patch predicted 100% of the changed src/** lines and branches (bridge builder + both chain sides + the processor resolve/emit branch). Only the known Windows spawn claude/codex/docker ENOENT env suites fail locally (green on Linux CI).
• Every new branch is covered: collapsible empty vs non-empty, section present vs absent, and the emit gate ON (integration) vs OFF (every other review test).

If any required check was skipped, explain why:

• test:workers / build:mcp / ui:* / actionlint / npm audit were not run locally — this is an additive backend review-rendering slice touching no worker entrypoint, MCP package, UI, workflow, or dependency; CI covers them.

Safety

• No secrets/wallet/hotkey/trust-score/reward terms exposed — each block wraps InlineFinding.body/suggestion, already sanitized upstream by composeInlineFindings; the collapsible adds only fixed label/marker strings.
• Public GitHub text stays sanitized and low-noise; the section is a single collapsible, default-OFF.
• No auth/cookie/CORS/GitHub App/session change.
• No API/OpenAPI/MCP surface change.
• No UI change.
• No docs/changelog change needed (the review.fixHandoff toggle is already documented in the example config).

UI Evidence

N/A — backend review-comment rendering; no dashboard/frontend/extension surface. (The rendered section is exercised by the unit + integration tests above.)

Notes

• Follows the established fix-handoff slicing (feat(review): fix-handoff block renderer for review findings (boundary-safe, content-only) #2175 renderer → feat(config): add review.fixHandoff toggle (default off) for fix-handoff blocks #2176 config → feat(mcp): follow-up-issue action spec builder for deferred review findings #2177/feat(review): render impact map as a compact section in the unified review comment #2185 follow-up action → this emission). The block's HTML-comment marker is escaped by the public-comment renderer (as every collapsible body is), which is harmless — nothing consumes the raw marker today; the block's human/agent-readable content (location, instruction, suggested change, boundary) is what's delivered.

[superagent-security]

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

[loopover-orb]

Tip

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✅ Gittensory review result - approve/merge recommended

_{Review updated: 2026-07-07 16:13:44 UTC}

4 files · 1 AI reviewer · no blockers · readiness 100/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This wires the already-built fix-handoff renderer into the unified comment: `buildFixHandoffCollapsible` in unified-comment-bridge.ts stitches pre-rendered blocks into a new collapsible, chained correctly between Impact map and Visual preview (`withImpactMap` → `withFixHandoff` → `withVisual`), and processors.ts resolves the gate once via `shouldEmitFixHandoff` and builds blocks only on a cache-miss review from the same `aiReview.inlineFindings` source `findingCategories` already uses, so a cache hit never re-emits them. The flag-off path adds nothing to the args object (spread of an empty object), keeping the rendered comment byte-identical, and tests cover both the pure collapsible builder and full processor wiring at the queue-integration level.

Nits — 4 non-blocking

• The manifest toggle is read directly as `reviewManifestForAutoReview?.review.fixHandoff ?? undefined` (processors.ts) instead of going through a small `resolveXManifestToggle` wrapper the way `reviewMemoryEnabledForReview` does via `resolveReviewMemoryManifestToggle` — worth confirming `shouldEmitFixHandoff` itself handles any DB-vs-manifest precedence, or note why this feature doesn't need that layer.
• unified-comment-bridge.ts:608 references issue Agent fix-handoff blocks + follow-up-issue suggestions #1962 only in a comment, not a real magic-number smell — no action needed.
• The flagged 'generic_secret_assignment' at queue.test.ts:18293 is a test env var (`GITHUB_APP_PRIVATE_KEY: await generatePrivateKeyPem()`), matching the existing pattern used throughout this test file — not a real leaked secret.
• If `shouldEmitFixHandoff`'s convergence-allowlist/DB-fallback behavior isn't already covered by its own unit tests from feat(config): add review.fixHandoff toggle (default off) for fix-handoff blocks #2176, consider a note in the PR description confirming that coverage rather than re-deriving it here.

Signal	Result	Evidence
Code review	✅ No blockers	1 reviewer
Linked issue	✅ Linked	#1962
Related work	✅ No active overlap found	No same-issue or scoped active PR overlap found.
Change scope	✅ 20/20	Low review scope from cached public metadata (1 linked issue).
Validation posture	✅ 25/25	PR body includes validation/test evidence.
Contributor workload	✅ 10/10	Author activity: 113 registered-repo PR(s), 67 merged, 0 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	real-venus; Gittensor profile; 113 PR(s), 0 issue(s).
Gate result	✅ Passing	No configured blocker found.

Review context

• Author: real-venus
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: TypeScript, JavaScript, MDX, Rust, Svelte, Swift
• Official Gittensor activity: 113 PR(s), 0 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Keep the PR focused and include validation evidence before maintainer review.

Signal definitions

• Related work = same linked issue, overlapping active PRs, or title/path similarity.
• Change scope = cached public metadata such as size labels, draft state, and review-burden hints.
• Validation posture = whether the PR provides enough public validation/test evidence for maintainer review.
• Contributor workload = public contributor activity and cleanup pressure, not a repo-wide quality failure.
• Contributor context = public GitHub/Gittensor identity context; non-Gittensor status is not a blocker.

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed}

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.59%. Comparing base (0979321) to head (8f93367).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4053   +/-   ##
=======================================
  Coverage   93.59%   93.59%           
=======================================
  Files         379      379           
  Lines       35575    35582    +7     
  Branches    13044    13049    +5     
=======================================
+ Hits        33295    33302    +7     
  Misses       1618     1618           
  Partials      662      662           

Files with missing lines	Coverage Δ
src/queue/processors.ts	94.95% <100.00%> (+<0.01%)	⬆️
src/review/unified-comment-bridge.ts	99.54% <100.00%> (+<0.01%)	⬆️

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[loopover-orb]

Gittensory approves — the gate is satisfied and CI is green.