Re-read section 16 before handing the implementation slice onward. Three defects, all of the same classes the Phase 3a review turned up. The 16.5 ending-bound table gave a contribution for every node type except the one that contains other nodes, so a one-shot whose tail lived inside a component had no defined bound. Components now contribute the bound of their own graph by the same rule, terminating on the existing nesting cap. The 16.3 state machine offered no exit from CREATED for a stop arriving before scheduling except FAILED, which would have reported an ordinary cancellation as a fault. Permit CREATED -> FINISHED, and say why it differs from SCHEDULED -> RELEASING: a created instance is connected to nothing, so there is no signal to ramp down. Automation point ordering was a stage conflation. Points had to be in strictly increasing `at` order while `at` was a DurationSpec, which section 6.2 permits to be a procedural TimeSpec resolved at instantiation — so the ordering rule could not have been enforced at the semantic stage where it was filed. This is structurally the same defect as the audioMaxFrequency one closed in Phase 3a. Fix `at` as a duration literal; point values remain full ValueSpecs. Still contract only. No runtime change, and no sound has been heard from any build. Co-Authored-By: Claude Opus 5 <[email protected]> Claude-Session: https://claude.ai/code/session_011FWPdCqKaaDnP9NC3JAwh6
XZBT
Immersive visuals and creative soundscapes.
XZBT is a self-contained browser runtime for declarative procedural audiovisual exhibits. XZBT.html provides capabilities; .xzbt documents define experiences.
Reading order and authority
| Resource | Purpose | Status |
|---|---|---|
| MVP Product Requirements Document | Product scope, user behavior, delivery requirements, and release acceptance | Document revision 0.3; format version remains 0.1 |
| Format Specification 0.1 | Runtime semantics, contract inventory, and required authoring examples | Document revision 0.4; Phase 0 shared contracts and the complete Phase 3a-3c audio subsystem contract, remaining subsystem contracts in dependency order |
| Gap Closure Decisions | Decisions and rationale for the seven pre-implementation gaps | Record revision 0.3; GC1–GC5 Phase 0 evidence complete |
| Verification Gates | Evidence required before architecture commitment, subsystem work, and release | Phase 0 complete; later subsystem, GC6, and GC7 checks scheduled |
| Implementation status | Current phase, stop reason, saved work, and resume prerequisites | Audio contract complete through Phase 3c; Phase 3c implementation, Phase 1 direct-file, and Phase 3 audible observations pending |
| Implementation plan | Sequenced phases, completion/challenge mapping, and GC6/GC7 verification schedule | Phase 1–9 plan recorded |
The PRD is authoritative for product requirements. The format specification is authoritative for runtime semantics where a contract is explicitly defined. The decision record explains those choices; the verification gates define how to check them. These documents must be updated together when a decision changes. An unresolved conflict is a specification defect, not permission for an implementation to choose silently.
The earlier ChatGPT discussion, Discuss Application Vision (conversation 6a9b5c32-1ffc-83e8-a219-fa8113167f03), is historical design input. Its proposals must be reconciled into these local resources before they become implementation contracts. It is not a second source of executable instructions.
Planning entry point
Phase 0 is complete, the production runtime is implemented through Phase 3b, and the audio subsystem contract is written through Phase 3c. Continue with Phase 3c implementation slice 2 (lifecycle and voices) from the implementation plan while preserving the verified launch model, shared semantic contracts, and production GC2/GC3 behavior. Two observations remain open in completed work: the Phase 1 direct-file two-fixture restart, and the Phase 3 audible acceptance — no sound has been heard from any build. Workload measurements and release soak tests remain later explicit gates.
The full PRD completion criteria remain the 0.1 release target. Early integrated demonstrations are milestones, not completed MVPs. Reference exhibits develop alongside the engine; Phase 9 completes and audits the suite.
All 10 Phase 0 direct-file feasibility checks in GC1 are verified, and the GC2–GC5 contract oracles pass. Phase 1 turns those contracts into a standalone runtime shell with import, caching, activation control, diagnostics, and production seeded RNG. Phase 2 adds parameters, state, signals, values, conditions, actions, bindings, transitions, overrides, and per-exhibit parameter persistence. Phases 3a and 3b add the audio authoring contract — all sixteen graph node types, routing and modulation, graph legality, authoring limits, components, sounds and recipes, and buses — together with pure validation and expansion, deterministic instantiation, and Web Audio realization. Later Phase 3c, visual, cadence, scenario, UI, library-hardening, benchmark, and soak gates remain explicit in the implementation plan.
Repository configuration
The storage-failure evidence additionally confirms session settings changes, directory import, and heard native playback during injected write failures. The user also confirmed the visible session-only warning; the injected-storage-failure check passed.
Copy .env.example to .env for local repository configuration. .env and its variants are ignored by Git; never commit real credentials. The example contains placeholders only.
The repository's existing LICENSE is preserved.
Phase 1–2 runtime
Build the standalone, dependency-free runtime with the pinned Node version in .nvmrc:
npm run build
This deterministically combines the modules in src/runtime, the application shell, and local styles into XZBT.html. Open that file directly in a supported desktop Chromium browser, then import the three minimal exhibits from exhibits. Imported definitions and the last active exhibit are cached in IndexedDB and restored on reopen when browser storage is available. The diagnostics panel reports validation, lifecycle, and storage failures; storage failure leaves the current session usable.
Run the Phase 1 production-module, lifecycle, fixture, PRNG-vector, cache, and reproducible-build tests with:
npm run test:phase1
Run the Phase 2 common-grammar conformance suite with:
npm run test:phase2
Run the Phase 3 audio subsystem suite with:
npm run test:phase3
Run every suite with npm test.
The active performance supports typed parameters and state, read-only runtime signals, ValueSpec and ConditionSpec evaluation, ordered set and override actions, same-tick bindings with deterministic smoothing, numeric transitions, and priority-based temporary overrides. The audio subsystem validates and expands declared graphs without touching an AudioContext, instantiates them deterministically from the seeded stream, and realizes them through Web Audio; the application exposes gesture unlock, master volume, per-bus gain, and per-sound triggering. exhibits/minimal-audio.xzbt exercises components, modulation, buses, and both recipe modes.
The Phase 3c contract (section 16) specifies automation, the lifecycle state machine, determinable one-shot endings, voice ceilings, master protection, and unlock behavior, but the runtime does not implement it yet: automation and release are still rejected as unknown fields. No sound has yet been heard from a build, and the audio acceptance challenge, peak and finite-sample capture, and listening observations remain open Phase 3 gates. Visuals, cadence, events, scenarios, and the final schema-driven UI remain assigned to later phases.
Local development server
For automated browser development checks, start the dependency-free loopback server with:
node tools/dev-server.mjs
It binds only to 127.0.0.1:5173 and serves the workspace through http://localhost:5173/; the root route opens the Phase 0 probe for layout or control-flow inspection only. Set XZBT_DEV_PORT to use a different port. This server is a development aid, not part of the delivered runtime.
Do not use localhost results as Phase 0 direct-file evidence. Serving changes the origin, security model, and module-loading path. The final XZBT.html must still be opened and tested directly from disk for every GC1 conclusion.