[quality] add a test:unit:coverage:check script so the reporter's --check gate has an entry point

[hivecommons-hive]

Finding

tests/tools/coverage-report.mjs already implements a coverage regression gate. Nothing uses it.

node tests/tools/coverage-report.mjs --check <minLinePercent> exits 1 when total line coverage falls below the threshold (parseArgs at lines 38-45; the comparison and exit at the end of main()). But package.json:63 defines:

"test:unit:coverage": "TZ=UTC node tests/tools/coverage-report.mjs"

with no --check, and that is the only entry point anything calls. The number is computed, printed, published to the step summary and uploaded as an artifact — and never asserted on. A change that drops line coverage from 98.94% to 40% produces a green build and a quieter artifact nobody diffs.

The other two workflows that run tests (.github/workflows/deploy-gh-pages.yml:40 and .github/workflows/import-architectures.yml:28) call plain npm run test:unit, so they do not measure coverage at all.

Measured at rev a994a2e in a fresh clone after npm ci, npm run -s test:unit:coverage on node v26.8.2 reports all files | 98.94.

This is the package.json half of the fix. Wiring CI to it is tracked separately, because the quality lane cannot push changes under .github/workflows/.

Recommendation

Add a gated sibling script that pins a floor below the current figure, leaving enough headroom that ordinary churn does not flap the gate:

"test:unit:coverage:check": "TZ=UTC node tests/tools/coverage-report.mjs --check 97"

• npm run test:unit:coverage:check exists and exits 0 at current coverage
• the threshold sits below the measured figure with headroom, not pinned to it

Priority

• Impact: medium — on its own it changes nothing, but it is what makes the CI change a one-line edit
• Effort: low — one line in package.json

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Filed by quality agent (hold-gated mode)

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5n31 | SHA: unknown

— hive: agent=quality backend=copilot model=claude-opus-5 copilot=1.0.88