add scoped coverage reporting

docs/architecture/validation-map.md

@@ -23,6 +23,34 @@ pnpm nx show projects --withTarget e2e
 | Shared SQLite schema/connection    | `pnpm nx test database`             |
 | Packaging metadata                 | `pnpm nx test packaging`            |
 
+## Coverage Tiers
+
+Use `tools/coverage/coverage-policy.json` as the source of truth for coverage
+ownership.
+
+| Tier | Rule | Validation |
+| --- | --- | --- |
+| A | Product/runtime Angular, Electron, backend, data-access, portal, playlist, workspace, playback, EPG, and shared UI code collects source coverage. | `pnpm run coverage:ci` |
+| B | Validate behavior without percentage coverage, such as `website`, `packaging`, and Playwright E2E projects. | `pnpm nx test website`, `pnpm nx test packaging`, or the closest E2E target |
+| C | Excluded from the source coverage baseline, such as mock servers, test helper libraries, and untested feature shells. | Validate through dependent flows, or add focused tests when changing behavior directly |
+
+`apps/website` is an Astro marketing site. Its useful signal is a successful
+static build plus targeted output checks, not a merged code coverage percentage.
+Projects with a test target but no specs, such as `remote-control-web` and
+`remote-control` today, should not be in Tier A until focused specs exist.
+
+For local coverage inspection:
+
+```bash
+pnpm run coverage:unit:ci
+pnpm run coverage:merge
+pnpm run coverage:health
+```
+
+The merged report is written to `coverage/merged/` as HTML, LCOV, Cobertura,
+and JSON summary output. CI uploads the merged Tier A report to Codecov with the
+`unit` flag and keeps the HTML report as a GitHub artifact.
+
 ## E2E
 
 | Area                  | Command                                         |
@@ -33,6 +61,23 @@ pnpm nx show projects --withTarget e2e
 Use atomized E2E targets when available, for example
 `pnpm nx run web-e2e:e2e-ci--src/xtream.e2e.ts`.
 
+Playwright coverage is measured semantically by tags and critical journeys, not
+by a source-line percentage. E2E reports should use tags such as `@critical`,
+`@electron`, `@web`, `@xtream`, `@stalker`, `@m3u`, `@search`, `@epg`,
+`@persistence`, `@settings`, `@pwa`, and `@self-hosted`.
+
+After an E2E run, generate the semantic summary with:
+
+```bash
+pnpm run coverage:e2e:summary
+```
+
+For local investigation only, Chromium browser V8 coverage can be explored with:
+
+```bash
+pnpm run coverage:e2e:v8:web
+```
+
 ## I18n
 
 ```bash