- Add SimBridge._last_snapshot = null to P3 before_test() (contamination risk)
- Clarify mono.is_visible is custom property, not CanvasItem builtin
- Camera smoothing test uses approximate equality instead of exact
- Propagate inner _encode_message errors in array/dict encoding
- Add explanatory comment on int_64 encoder branch
- Document unfalsifiable gauntlet guard as intentional future-proof
- Remove loose D-053 citation from LERP_SPEED pin
- Assert FogOverlay is sibling of FogGroup under World
- Add CANVAS_MODAL=30 (ModalLayer) assertion in P3-Z04
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Regression guards for Sprint 9 QA features:
- F12 bug report (2): no-crash without handler, no queued input action
(stubs for when #495 WRONG button lands)
- Gauntlet UI hidden (3): no gauntlet nodes visible in default mode,
no room_id/gauntlet_mode in normal snapshots, stays hidden across
multiple ticks
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>