XZBT/docs/IMPLEMENTATION_STATUS.md

XZBT implementation status

Updated: September 5, 2026 State: Phase 2 common grammar complete; Phase 1 direct-file import/restart observation remains pending Planning baseline: 05fe2b4e021ba86e4a290d05b63c7cae0e386128

Exact demarcation: GC1 direct-file feasibility (10/10 checks), GC2 shared format contracts, GC3 resolution semantics, GC4 clock/PRNG semantics, and GC5 ownership/failure semantics are complete at the Phase 0 contract-oracle level. The Phase 1 production runtime skeleton and Phase 2 common grammar are implemented and pass automated checks, but Phase 1's direct-file two-fixture restart observation remains open. Real audio, visual, cadence/event, scenario, final generated-UI, performance, and soak work remains assigned to later phases.

The user requested sequential implementation with a stop on problems. The manual version 3 evidence verifies embedded data-URL worklet loading in direct-file Chrome. The subsequent user-performed restart test restored Blue Study activity 0.37 and master volume 0.19 immediately on reopening. Native tone output and AudioContext suspend/resume are also observed. Ordinary file import, selection of both exhibits, regular Chrome mode, and directory cancellation/denial fallback have been confirmed.

Phase	Status	Evidence or next prerequisite
0 — Contracts and feasibility	Complete	GC1 passed; GC2–GC5 shared contracts and traces passed; GC6/GC7 later gates scheduled and mapped
1 — Runtime skeleton	Implemented; acceptance pending	Automated evidence passes production-module, lifecycle, PRNG-vector, cache/restore, fixture-validation, and deterministic-build tests. Direct-file two-fixture import/restart remains a user-observed gate.
2 — Common grammar	Complete	Automated evidence covers production GC2 conformance, typed values, signals, actions, same-tick bindings, transitions, override precedence/release, and parameter restoration.
3 — Audio engine	Not started	Earlier phases and audio contracts
4 — Visual engine	Not started	Earlier phases and visual contracts
5 — Events and cadence	Not started	Earlier phases and event/cadence contracts
6 — Scenario director	Not started	Earlier phases and scenario contracts
7 — Dynamic UI	Not started	Earlier phases and UI contracts
8 — Library and persistence hardening	Not started	Earlier phases and library contracts
9 — Reference suite completion/audit	Not started	Earlier phases, challenge coverage, benchmark and soak evidence

Work saved

• A self-contained Phase 0 probe for import, isolated probe caching, settings restoration, user-initiated audio, embedded engine worklet loading, suspend/resume, and injected storage failure.
• Two minimal import fixtures and manual test instructions.
• Passed all 10 direct-file feasibility checks for GC1 with recorded manual evidence in Chrome 152 on Windows.
• Authoritative JSON Schema (schema/xzbt-0.1.schema.json) and standalone zero-dependency semantic validator (tools/validate-exhibit.mjs).
• Automated GC2 conformance test matrix (test/gc2-runner.test.mjs) verifying 12 valid and fault-injected fixtures with zero errors.
• Format Specification Revision 0.3 with exact shared GC3 resolution/binding/transition, GC4 clock/PRNG/audio-alignment, GC5 ownership/failure/dispatch, and GC7 import/update/build contracts.
• Executable Phase 0 contract models and tests for GC3–GC5; the combined Phase 0 run passes 27 tests with zero failures.
• A sequenced implementation plan mapping every MVP completion group, reference challenge, GC6 measurement stage, and GC7 library/build verification stop.
• Preserved user evidence runs for versions 1, 2, 3, offline, file relocation, and directory fallback.

Phase 1 entry condition

The injected-storage-failure run and audio follow-up confirm in-memory activity changes, successful directory import, and heard native playback despite 16 expected failed saves. The user subsequently confirmed the visible session-only warning. The injected-storage-failure check passed; this does not establish real browser permission-denial behavior.

Worklet loading and the user-performed restart/settings test have passed and need not be repeated without a relevant code change. The offline restoration, tone, and worklet check also passed with explicit user confirmation of browser-scoped Offline mode; see offline evidence. The user confirmed regular Chrome mode and ordinary import/activation. The directory-permission/cancellation fallback observation is now complete; see directory fallback evidence. GC1 is fully satisfied.

The browser rejection explicitly forbids agent workarounds through alternate browser surfaces, raw commands, or indirect execution. No workaround was attempted. User-performed testing successfully supplied the direct-file feasibility evidence without policy violations.

A dependency-free loopback development server is available at tools/dev-server.mjs. It serves the workspace at http://localhost:5173/ for later automated development testing only and listens on both IPv4 and IPv6 loopback. It may support source-level UI or regression work after Phase 0, but direct-file operation remains the primary distribution architecture.

Phase 0 remains complete and the Phase 1 implementation now reuses the GC4 PRNG known vectors in the production SeededRNG. The mandatory direct-file Phase 1 observation, combined-load measurements, production subsystem conformance, two-hour development soak, and eight-hour release soak remain outstanding at their mapped gates.

Phase 1 implementation

The modular runtime sources now live in src/runtime and build deterministically with node tools/build-xzbt.mjs into the self-contained root XZBT.html. The artifact has no external runtime dependencies or requests. Two minimal, subject-neutral fixtures live in exhibits; one uses fixed seed 42 and one requests cryptographic entropy. Phase 2 extends both with small common-grammar examples.

Automated Phase 1 checks cover JSON/version/metadata failure, the frozen GC4 state/output vectors, byte-identical import behavior, in-memory restore, prepare-before-teardown activation recovery, and byte-identical standalone builds. The existing GC2–GC5 suites still pass when run in-process. Phase 1 is not marked accepted until the built artifact imports both fixtures directly from disk, restores them after a full browser restart, and records the Phase 1 GC6 environment details required by the implementation plan.