test: stabilize bun coverage reporting

docs/README.md

@@ -21,6 +21,7 @@ Read when: you need internal architecture, workflow, verification, or release gu
 
 - New feature or refactor: [Workflow](./workflow/README.md), then [Architecture](./architecture/README.md)
 - Test/build/release work: [Verification](./workflow/verification.md), then [Release Guide](./RELEASING.md)
+- Coverage lane selection or LCOV artifact path: [Verification](./workflow/verification.md)
 - “What owns this behavior?”: [Domains](./architecture/domains.md)
 - “Can these modules depend on each other?”: [Layering](./architecture/layering.md)
 - “What doc should exist for this?”: [Catalog](./knowledge-base/catalog.md)

docs/workflow/verification.md

@@ -31,8 +31,15 @@ bun run docs:build
 - Config/schema/defaults: `bun run test:config`, then `bun run generate:config-example` if template/defaults changed
 - Launcher/plugin: `bun run test:launcher` or `bun run test:env`
 - Runtime-compat / compiled behavior: `bun run test:runtime:compat`
+- Coverage for the maintained source lane: `bun run test:coverage:src`
 - Deep/local full gate: default handoff gate above
 
+## Coverage Reporting
+
+- `bun run test:coverage:src` runs the maintained `test:src` lane through a sharded coverage runner: one Bun coverage process per test file, then merged LCOV output.
+- Machine-readable output lands at `coverage/test-src/lcov.info`.
+- CI and release quality-gate runs upload that LCOV file as the `coverage-test-src` artifact.
+
 ## Rules
 
 - Capture exact failing command and error when verification breaks.