[H-12 / Phase 4] [MEDIUM] Grow scoring-package test coverage

[matthewod11-stack]

Full spec: docs/hardening-roadmap-2026-04-16.md#h-12

Description

packages/scoring/src/__tests__/ has 3 files vs 12 in apps/cli/. Grounding logic, tier edge cases, and red-flag handling are under-covered in the package where correctness matters most.

Current State

• signal-extractor.test.ts, score-calculator.test.ts, narrative-generator.test.ts only.
• No grounding-validator.test.ts.

Suggested Fix

• New grounding-validator.test.ts:
  • all-valid IDs → no violations, no confidence loss
  • all-invalid IDs → signal retained with confidence=0
  • mixed → proportional (post-H-9: policy-dependent) adjustment
  • empty evidence array → no crash
• Expand score-calculator.test.ts:
  • tier boundaries (score = exactly threshold)
  • all confidences = 0 → score = 0
  • negative weights if supported
• Expand narrative-generator.test.ts with post-H-1 injection fixtures — narrative must not echo injected instructions.

Verification

• pnpm build passes
• pnpm test passes
• pnpm typecheck clean
• packages/scoring test count at least doubles
• grounding-validator.ts line coverage > 90%

Automation Hints

scope: packages/scoring/src/tests
do-not-touch: production code unless specifically required
approach: add-tests
risk: low
max-files-changed: 5
blocked-by: #5, #15
bail-if: existing scoring tests break

Priority

Medium