# ADR 0009 — Vitest coverage config for CI

**Decision**

- Remove mistaken `--reporter=json-summary` (Vitest _test_ reporter, not coverage reporter).
- Add `vitest.config.mjs` to enable `json-summary` among coverage reporters so `coverage/coverage-summary.json` is generated.
- CI now runs `vitest --coverage` and reads the summary in `scripts/ci-check-coverage.mjs`.

**Consequences**

- Centralized Vitest config; default environment `jsdom` for DOM tests.
- LCOV also generated for optional HTML/report viewing.