test(signals): cover buildReviewRiskExplanation's 5-way branch logic (#9287)

[nghetien]

Summary

• buildReviewRiskExplanation (src/signals/review-risk.ts) previously only had REST/MCP parity coverage — no test asserted what each of its five recommendation branches actually resolves to.
• Adds test/unit/review-risk.test.ts with one direct unit test per branch (likely_duplicate, maintainer_lane, needs_author, review, watch), each using minimal fixture inputs to deterministically trigger that branch, and asserting both recommendation and summary.
• Mirrors the structure of test/unit/contributor-readiness-band.test.ts per the issue's guidance. No implementation changes — coverage-only.

Closes #9287

Scope

• Single area: test coverage only (test/unit/)
• No changes to src/signals/review-risk.ts or any other implementation file
• No changes to site/, CNAME, VitePress, or GitHub Pages

Validation

• npx vitest run test/unit/review-risk.test.ts — 5/5 passing
• npx turbo run build --filter=@loopover/engine — green
• npx turbo run build --filter=@loopover/mcp — green
• npx turbo run build:tsc build:verify --filter=@loopover/miner — green
• Full unsharded npm run test:ci — not completed locally before submission (interrupted by session timeout); test file only exercises existing exported functions/types with no src changes, so risk is low

Safety

• No secrets, tokens, wallets, hotkeys, trust scores, or reward values in code or text
• No auth/CORS surface touched (pure function test only)
• No public/private boundary surface touched

Notes

This is a coverage-only PR requested by #9287; the function under test is unchanged.

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Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-27 13:31:16 UTC}

1 file · 1 AI reviewer · no blockers · readiness 95/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
This is a pure test-addition PR adding five direct unit tests for buildReviewRiskExplanation's recommendation branches (likely_duplicate, maintainer_lane, needs_author, review, watch), closing #9287 as stated. No implementation files are touched, the fixtures are minimal and each test asserts both recommendation and summary output, and all CI checks passed on this commit. The PR correctly links to and closes its authorizing issue and stays narrowly scoped to test/unit/.

Nits — 5 non-blocking

• The full unsharded test:ci run wasn't completed locally per the PR checklist, though this is low-risk for a test-only addition and CI passed regardless.
• test/unit/review-risk.test.ts duplicates the repo/issue/pr fixture builder functions already present in test/contract/predicted-gate-engine-collision-parity.test.ts — consider extracting a shared test-fixtures helper to avoid drift between the two.
• The inline comment referencing signals: add direct unit-test coverage for buildReviewRiskExplanation's 5-way branch logic #9287 at the top of the describe block duplicates context already in the PR description; fine to keep but not load-bearing.
• Consider factoring the repo()/issue()/pr() fixture builders into a shared test helper module since they're now duplicated verbatim across at least two test files.
• If buildReviewRiskExplanation has additional edge cases (e.g., multiple simultaneous high-risk conditions), a follow-up issue could track further branch/priority-ordering coverage.

Decision drivers

• ✅ Code review — No blockers (1 reviewer)
• ✅ Gate result — Passing (No configured blocker found.)

Context & advisory signals — never blocks the verdict

Signal	Result	Evidence
Linked issue	✅ Linked	#9287
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: 10 registered-repo PR(s), 4 merged, 0 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	nghetien; Gittensor profile; 10 PR(s), 0 issue(s).
Improvement	ℹ️ Insufficient signal	risk: clean · value: insufficient-signal · LLM: minor

Linked issue satisfaction

Addressed
The PR adds test/unit/review-risk.test.ts which imports buildReviewRiskExplanation directly, constructs minimal fixture inputs (mirroring the contributor-readiness-band precedent), and includes one test per each of the 5 recommendation branches with assertions on both recommendation and summary, without modifying the implementation file.

Review context

• Author: nghetien
• Role context: outside_contributor
• Public audience mode: oss maintainer
• Lane context: Repository is configured for direct PR review.
• Public profile languages: Dart, JavaScript, Python, CSS, C#, C++, TypeScript
• Official Gittensor activity: 10 PR(s), 0 issue(s).
• PR-specific overlap: none found.

Contributor next steps

• Start here: Triage stale or unlinked PRs.

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.

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

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