fix(engine): align computeMinerGoalLaneFit's no-preference score with computeLaneFit

[nghetien]

Closes #8870

computeMinerGoalLaneFit and computeLaneFit disagreed on what "no preference configured" should score: computeLaneFit's rule 2 returns the neutral 0.5 when neither wantedPaths nor preferredLabels is set, but computeMinerGoalLaneFit's label-only equivalent returned 1 for an unconfigured preferredLabels — a silent 2x divergence that skewed issue-ranking for autonomous targeting toward repos with no configured label preference at all.

Aligned computeMinerGoalLaneFit's no-preference branch to return 0.5 and added a doc comment cross-referencing computeLaneFit's rule so the two scorers stay in sync going forward. Updated the direct unit-test assertions in both packages/loopover-engine/test/miner-goal-lane-fit.test.ts and test/unit/miner-goal-lane-fit.test.ts to expect 0.5.

This neutral-score change flows into buildMetadataRankInput's composite rankScore, so two existing threshold-based tests (test/unit/metadata-min-score.test.ts, test/unit/metadata-top-min-score.test.ts) that relied on unconfigured-label candidates scoring a full 1 needed their fixed thresholds recalibrated from 0.1 to 0.05 — the filtered/ordered issue-number expectations are unchanged, only the threshold value that was tuned against the old (incorrect) neutral score.

No UI files touched — this is a pure src//test/ scoring-logic change with no visible output, so no screenshot evidence applies.

Validation

• npx turbo run build --filter=@loopover/engine && npx turbo run build --filter=@loopover/mcp && npx turbo run build:tsc build:verify --filter=@loopover/miner — green
• npx vitest run --changed=upstream/main --passWithNoTests — 110 files / 1754 tests passed
• npm test — 1177 files / 22009 tests passed (one pre-existing, unrelated environmental failure in check-ui-kit-package.test.ts, resolved by running npm run build --workspace @loopover/ui-kit first)

Residuals

None — the issue's full scope (align the value, update tests, keep coverage on the changed branch) is covered in this PR.

[superagent-security]

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.87%. Comparing base (f32e140) to head (f036478).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9006      +/-   ##
==========================================
+ Coverage   90.56%   93.87%   +3.31%     
==========================================
  Files          96      807     +711     
  Lines       22490    80465   +57975     
  Branches     3884    24397   +20513     
==========================================
+ Hits        20367    75537   +55170     
- Misses       1945     3560    +1615     
- Partials      178     1368    +1190     

Flag	Coverage Δ
backend	95.16% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ackages/loopover-engine/src/miner-goal-lane-fit.ts	90.90% <100.00%> (ø)

... and 710 files with indirect coverage changes

[loopover-orb]

Tip

✅ LoopOver review result - approve/merge recommended

_{Review updated: 2026-07-26 16:05:57 UTC}

5 files · 1 AI reviewer · no blockers · readiness 98/100 · CI green · clean

✅ Suggested Action - Approve/Merge

• safe to merge

Review summary
The AI review returned non-blocking notes for this change but did not include a separate narrative summary. Review the nits below before deciding this PR.

Nits — 1 non-blocking

• packages/loopover-engine/src/miner-goal-lane-fit.ts:43 — the neutral 0.5 is a duplicated magic number relative to computeLaneFit's own 0.5; a shared exported constant would make the cross-reference enforceable rather than just documented.

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	#8870
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: 4 registered-repo PR(s), 1 merged, 0 issue(s).
Contributor context	✅ Confirmed Gittensor contributor	nghetien; Gittensor profile; 4 PR(s), 0 issue(s).
Improvement	✅ Minor	risk: clean · value: minor

Linked issue satisfaction

Addressed
The PR changes computeMinerGoalLaneFit's no-preference branch to return 0.5, adds a cross-referenced doc comment to computeLaneFit's rule, and updates the assertions in test/miner-goal-lane-fit.test.ts:12 (and the unit test variant) to expect 0.5, matching the issue's requested alignment.

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: 4 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.

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

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[loopover-orb]

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