[architecture] Agent-grade built-app testability contract

[100yenadmin]

Summary

Define the architecture contract that makes dist/WorldOS.app observable and driveable by agents without replacing the real release gate.

This is the parent issue for the app-testability lane. It complements the UX-first sprint in #467 and the blind playtester architecture in #324.

Required architecture decisions

• viewer/server.py exposes a stable, read-only app-status contract for the live OpenWorlds surface.
• A deterministic scripted DM/smoke provider proves the app wiring quickly without Claude/Codex/OpenClaw latency.
• Stable accessibility labels and data-worldos-testid hooks make the browser UI driveable without pixel guessing.
• A single evidence bundle captures screenshots, app-status snapshots, session surface, chat, moves, provider trace, console/network logs, build SHA, art status, and failure bucket.
• Release gates remain split: fast deterministic built-app smoke, short real-provider playtest, and full non-partial five-persona RRI.

Invariants

• Engine remains the sole writer of campaign state.
• GUI/native app remains a thin reader plus /move intent submitter.
• Private art is never committed.
• No proxy preview or harness-created backend can count as release evidence.
• Issues close only after next-build evidence proves non-reproduction.

Acceptance criteria

• A tracked architecture doc defines the app-status v1 schema, deterministic smoke provider, stable UI hooks, evidence bundle, gate split, non-goals, and engine-sole-writer invariant.
• The doc links [playtest][ARCHITECTURE] AI playtester harness — blind UI/UX test with 5 personas (Playwright + claude-p), structured bug reports, scoring rubric #324, release: rerun clean non-partial 5-persona RRI after gate hardening #466, sprint: UX-first release readiness after takeover stabilization #467, Codex DM should avoid safety-cancelled setup/social tool calls #479, and all child issues in this milestone.
• The doc names the local/native lane and remote/support-VM lane separately.

[100yenadmin]

Roadmap container created under milestone #19. Existing spine issues attached: #324, #466, #479. UX sprint dependency remains #467; broad UX bugs stay in their current Graphics milestone.

[100yenadmin]

Architecture contract draft is up in #489, stacked on #488. It documents app-status v1, the scripted provider gate, stable driving hooks, evidence bundles, split gates, non-goals, and the engine sole-writer invariant.

[100yenadmin]

Implementation stack now covers the architecture/doc (#489), app-status (#488), scripted smoke provider (#493), UI hooks (#492), evidence export (#490), and bucket/RRI split (#491). #487 covers the #479 real-provider noise prerequisite.