test: raise unit test coverage to 100% and enforce it

[joshunrau]

Raises unit-test coverage from about 50% to 100% on every metric across apps/{api,gateway,web} and packages/*, then makes 100% the gate locally and in CI.

Coverage

Metric	Before	After
Lines	50.14% (4380/8736)	100.00% (8704/8704)
Statements	50.32% (4659/9258)	100.00% (9129/9129)
Functions	45.81% (1311/2862)	100.00% (2695/2695)
Branches	45.72% (2257/4937)	100.00% (4775/4775)

By workspace (lines / branches)

Workspace	Lines before	Lines after	Branches before	Branches after
apps/api	69.18	100.00	67.42	100.00
apps/gateway	14.02	100.00	7.06	100.00
apps/web	28.07	100.00	23.44	100.00
packages/demo	100.00	100.00	100.00	100.00
packages/instrument-bundler	97.07	100.00	88.72	100.00
packages/instrument-interpreter	100.00	100.00	100.00	100.00
packages/instrument-library	0.00	100.00	0.00	100.00
packages/instrument-stubs	38.18	100.00	0.00	100.00
packages/instrument-utils	99.22	100.00	98.89	100.00
packages/licenses	100.00	100.00	100.00	100.00
packages/playground-url	100.00	100.00	93.55	100.00
packages/react-core	91.28	100.00	84.47	100.00
packages/release-info	100.00	100.00	100.00	100.00
packages/runtime-bundler	98.64	100.00	91.23	100.00
packages/runtime-core	0.00	100.00	0.00	100.00
packages/runtime-internal	11.65	100.00	5.26	100.00
packages/runtime-meta	100.00	100.00	100.00	100.00
packages/schemas	100.00	100.00	97.06	100.00
packages/serve-instrument	88.02	100.00	81.58	100.00
packages/subject-utils	100.00	100.00	100.00	100.00
packages/vite-plugin-runtime	100.00	100.00	100.00	100.00

"Before" is the c6bf765b4 run, recomputed under this PR's coverage scope (see below). The before denominators are larger: they include the phantom SWC entries fixed here and the dead code deleted here. Now 392 test files and 4,392 tests, plus 5 it.fails pinning filed bugs.

What changed

• Unit tests under each workspace's __tests__/, one commit per batch (test(<scope>): …). Each batch was written by one agent, reviewed by a second, adversarial agent and fixed before it was committed.

• Dead code removed (refactor(api|web|react-core|instrument-utils|runtime-internal)). The last ~50 uncovered branches were code no input can reach. Each was proved dead from the types, every caller, or the library contract, then deleted or restructured so the impossible state cannot be written. tsc, the unit suite and e2e confirm nothing reachable went:

  • Radix onOpenChange on dialogs without a trigger (Radix only ever passes false);
  • ?? [] / ?? {} fallbacks on non-null values;
  • guards that repeat an earlier guard;
  • .otherwise(() => null) after exhaustive matches, now .exhaustive();
  • zod 4's never-produced int type name.

  One deletion was wrong and a test caught it before commit: a preview code path shared the expression. It was restored.

• fix(api): the in-memory replica set is now stopped on shutdown (In-memory replica set is never stopped when the api shuts down under NODE_ENV=test #1651).

• Enforcement:

  • The root vitest config sets coverage.thresholds: { 100: true }.
  • CI's unit step runs pnpm test:coverage.
  • A new root AGENTS.md hard rule: uncoverable code is proved dead and deleted, never ignored or excluded. "Before you are done", odc-done, odc-testing, the testing strategy and the playbooks now name pnpm test:coverage.

• New vitest projects for runtime-core, instrument-library and instrument-stubs. instrument-library maps /runtime/v1/* imports to source, so its tests need no build.

• Catalog devDeps: happy-dom and @testing-library/{react,dom} added to gateway, runtime-core and instrument-library, plus react/react-dom workspace links in instrument-library. pnpm install also bumped @testing-library/dom 10.4.1 → 10.4.2 and ws 8.21.0 → 8.22.0 in the lockfile.

• Coverage scope: excludes test fixtures and helpers (__tests__, __mocks__, apps/web/src/testing), the generated route-tree.ts, and the bare entrypoints (web main.tsx, gateway entry-client.tsx and main.ts).

• apps/api/vitest.config.ts: SWC now transforms only apps/api sources. Before this, SWC also transformed the workspace packages the api imports, and the merged report counted each of their functions twice with one copy never hit.

• packages/react-core/vitest.config.ts: sets happy-dom's disableIframePageLoading, so InteractiveContent tests no longer make real requests to localhost:3000.

Bugs found

Verified and filed as #1633–#1653. #1651 is fixed in this PR. The others are pinned by tests: it.fails asserts the correct behaviour, and the remaining tests are named as defects. Each issue says which test to flip when it is fixed.

Verification

• pnpm lint: green (34/34 tasks).
• pnpm test:coverage: green at 100% on all four metrics. vitest list --filesOnly collects every added test file.
• pnpm test:e2e: 277/277 passed.

Exception: no new testing/ spec. The tests and the dead-code removal change no reachable behaviour, and the existing suite passes unchanged.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com