XZBT/docs/evidence/phase2/2026-09-05-common-grammar.md

Phase 2 common grammar — automated evidence

Date: September 5, 2026 Artifact: XZBT.html SHA-256: 8ea318535e97b25b51760b6c0e59e1a5af89d3f429f079de3b87230165008517 Result: Phase 2 implementation and automated acceptance passed.

Delivered

• typed parameter and simulation-state stores with strict coercion rejection and declared bounds;
• separately persisted parameter snapshots, with state recreated for each performance;
• read-only time, audio-analysis placeholder, pointer, viewport, and scenario-active signals;
• literal, reference, bounded random, weighted-choice, and safe-operation ValueSpec evaluation;
• comparison and short-circuit logical ConditionSpec evaluation;
• deterministic fixed-step common-grammar performance driver with the GC4 stall bound;
• same-tick dependency resolution for parameter/state bindings;
• numeric transforms, clamps, exact one-pole smoothing, conditional disable, and clean re-enable;
• ordered common action execution with when, chance, critical, persistent state set, and temporary override;
• numeric set transitions with the four standard easing modes;
• override runtime IDs, priority/activation-sequence precedence, scenario/duration lifetimes, attack/release transitions, owner release, and live lower-value restoration;
• generic inspection controls and resolved-value placeholders in the subject-neutral application shell;
• two updated minimal exhibits exercising conditional and unconditional common-grammar bindings.

Subsystem-specific sound, event, spawn, remove, and control execution remains unavailable until the owning audio, visual, event/cadence, and scenario phases define and implement their capability contracts. The common executor rejects those actions explicitly instead of approximating their behavior.

Automated verification

npm run test:phase2 passed 9 of 9 production tests:

1. production validator agreement with the GC2 fixture matrix;
2. ValueSpec references, random values, weighted choice, safe operations, and arity failure;
3. ConditionSpec composition, short-circuiting, and strict operand typing;
4. same-tick binding dependency order and exact smoothing;
5. conditional binding disable and re-enable behavior;
6. document-order state actions and parameter mutation rejection;
7. deterministic state transitions and duration parsing;
8. override precedence, stored-edit preservation, and live-base release;
9. duration expiry, compatible stored parameters, and performance disposal.

Regression verification also passed:

• Phase 1 production/build tests: 6 of 6
• GC2 contract oracle: 12 of 12
• GC3 contract oracle: 8 of 8
• GC4 contract oracle: 7 of 7
• GC5 contract oracle: 8 of 8

The standalone build test compiled the generated script and confirmed byte-identical clean outputs with no external runtime script or stylesheet references.

Remaining cross-phase observation

The earlier direct-file browser restriction still prevents an agent-run full-browser restart check. Phase 1’s user-observed two-fixture import/cache/reopen gate therefore remains open; it does not change the passing Phase 2 semantic results above.