Define and enforce realistic coverage budgets for unit, integration, and e2e lanes

[CodeMonkeyCybersecurity]

Summary

The #291-#294 patch set wires the test pyramid more cleanly, but the repository still lacks an enforceable, transparent coverage policy that maps to the desired unit/integration/e2e split.

Evidence

• The current CI lanes are separated (unit, integration, e2e-smoke, e2e-full, fuzz), but the repo does not yet have a single accepted coverage contract for these lanes.
• Targeted package coverage after the patch remains uneven across large packages, so a generic “90%+” claim would be misleading without agreed measurement rules.

Why this matters

• Teams will optimize whatever is measured. Right now lane wiring exists, but the coverage target is not operationalized.
• Without explicit budgets, future contributors can unintentionally shift coverage away from the intended test pyramid.

Proposed work

1. Define the measurement scope: repo-wide, changed-package, or changed-line coverage.
2. Publish budgets for each lane, for example unit as the primary coverage source with integration/e2e focused on contract and workflow confidence.
3. Emit machine-readable coverage summaries per lane and fail CI when agreed thresholds regress.
4. Add documentation so local npm run and CI use the same definitions.

Acceptance criteria

• Coverage policy is documented in-repo.
• CI reports lane-specific coverage metrics in a stable format.
• Threshold regressions fail predictably and do not depend on local tool quirks.