First implementation milestone of the agent-first coverage architecture
(ADR-020, PRD 2026-05-13). Lands the keystone — coverage bands as a
typed declaration in feature.manifest.ts plus a helper that derives
vitest threshold shapes from them.
New file packages/core-shared/src/conformance/coverage.ts (self-
contained, no relative imports — loadable at vitest config time):
- CoverageBand / CoverageBands / CoverageManifest / VitestThresholds
types
- DEFAULT_COVERAGE_BANDS (baseline 80/75/80/80; entities 100/100/100/
100; use-cases + controllers 100/95/100/100) — matches ADR-011
- DEFAULT_MUTATION_SCORE (80) + DEFAULT_MUTATION_TARGETS (entities +
use-cases)
- getCoverageBands / getMutationConfig — manifest -> resolved bands,
with default fallback for missing layers
- vitestThresholdsFromBands / vitestThresholdsFromManifest — convert
to vitest's coverage.thresholds shape with the layer-to-glob
mapping
define-feature.ts gains the optional coverage field on FeatureManifest
(imports its type from coverage.ts to avoid a relative-import cycle
at config-load time).
Exposed via two subpaths: @repo/core-shared/conformance (re-exports
for source/test code) and @repo/core-shared/conformance/coverage
(direct subpath safe to load from vitest configs, bypasses the index
re-export chain that Node ESM doesn't auto-extension-resolve).
Auth wired as proof-of-concept:
- packages/auth/src/feature.manifest.ts declares its coverage section
- packages/auth/vitest.config.ts imports the helper +
DEFAULT_COVERAGE_BANDS and emits thresholds via
vitestThresholdsFromBands(DEFAULT_COVERAGE_BANDS) — no more
hand-maintained per-glob thresholds block.
Verified: 175/175 tests pass; 14/14 typechecks clean; auth coverage
green (21 tests, 93.77% overall, all per-layer 100% bands hold).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
