fix(test-harness): review follow-ups from #151 - #167

Resolves the five unresolved Codex review threads on #151. All five were verified against current main before changing anything; every one reproduced.

P1 — bind manifests to their own route loaders

resolveTarget read the manifest from options.manifest but pulled the loader from the process-wide registry by route id alone. A renderRoute(id, { manifest: other }) against a project whose route id collides with the registered one executed the registered project's module while reporting the other manifest's provenance — a silent false pass.

Loaders are now bound to the compilation that produced them: registeredRouteLoader(manifest, routeId) resolves only when the registered manifest matches by digest and project root. A mismatch reports the two digests and the recovery rather than falling back to the generic "no loader registered" wiring message.

P1 — distinguish an absent document value from null

toHaveValue compared document.value ?? null against value ?? null, so toHaveValue(null) passed for a document that emitted nothing, and a real null satisfied toHaveValue(undefined). AgentDocument.value is optional, and those are distinct contract states. Absence and presence are now compared before the structural comparison, and undefined asserts absence.

P2 — validate registry versions when reading

The generated setup module assigns the realm global directly, so registerTestRoutes — the only version guard — never ran for it. A worker resolving a different agent-bundle/test accepted an incompatible registry and failed later with a misleading loader or manifest error. The version is now checked where the helpers read the registry. Generated registration is deliberately left as a direct assignment: that file imports nothing but the project's own route modules, and the reader is the side that knows which helpers actually resolved.

P2 — capture progress with a custom reporter

Supplying context.progress replaced the recording reporter outright, so RenderedRoute.progress was always empty — contradicting the documented result contract. The harness now always records and then delegates to the caller's reporter.

P2 — fix the invalid README context example

context: { cwd, operationId } does not typecheck: RenderRouteContext has neither field. Confirmed by compiling the snippet (error TS2353: 'cwd' does not exist in type 'RenderRouteContext'). Replaced with context.invocation and the runtime's observed-value workspace contract, then recompiled clean. The adjacent sentence describing the return value said "ordered render events"; it returns request-scoped progress, so that is corrected alongside the progress fix.

Tests

Four regression tests, each verified red against the unfixed sources and green after:

• another manifest's route is refused instead of loading the registered module (asserts the loader is never invoked)
• an incompatible registry assigned directly to the realm global is refused
• a document with no value is separated from one whose value is null
• progress is recorded when the caller supplies its own reporter

Plus a positive control that the loader still resolves for the manifest the registry was built from.

Verification

• rstest.unit.config.ts tests/test-harness-manifest.test.ts — 20 passed
• pnpm test:route-unit — 11 passed
• pnpm --filter audiobook-curator test:routes (adoption) — 2 passed
• pnpm typecheck — clean
• pnpm lint — 0 errors, 0 warnings