led2/.planning/phases/05-live-show-execution/05-01-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
05-live-show-execution	01	api	websocket udp cue-scheduler animation fastapi lightsync	phase provides 04-timeline-editor Show model with tracks/cues and encode_animation_cmd UDP encoder	Server-side cue scheduler in websocket tick handler that fires UDP animation commands at correct timestamps Per-connection show state (show, fired_ids, is_playing) scoped to each WebSocket connection preview_update broadcast messages sent to all clients on each tick Seek-safe fired_ids rebuild preventing double-fire or missed cues after seeking	05-02 (live preview UI consumes preview_update messages) 05-03 (keyboard shortcuts drive play/pause/seek which gates cue scheduler)	added patterns Per-connection mutable state pattern for WebSocket handlers (show, fired_ids, is_playing) 60ms LOOKAHEAD window for cue scheduling with fire-and-forget UDP dispatch Seek-safe fired_ids set comprehension rebuild from show cues before seek position active_cue tracking per track for preview state (not just newly-fired cues) Batch preview_update broadcast after each tick's cue scheduling pass	created modified lightsync/api/ws.py	LOOKAHEAD = 0.060 (60ms) defined inline per tick — not a module constant — matches D-02 spec is_playing gate on cue scheduler prevents any cue firing during pause or seek drag Past cues (>100ms behind position) silently marked fired without UDP dispatch — prevents late blasts on seek active_cue tracking includes already-fired cues still within their duration window — preview stays lit for duration of block import lightsync.main as _main inside load handler — deferred import avoids circular import at module level	Pattern: Per-connection WebSocket state — mutable variables scoped inside async handler function Pattern: Seek rebuild — set comprehension over all tracks/cues to mark past cues fired Pattern: Preview batching — collect preview_updates list then broadcast after cue loop	SHW-03	8min	2026-04-07

Phase 5 Plan 01: Live Show Execution — Cue Scheduler Summary

WebSocket tick handler extended with 60ms look-ahead cue scheduler that fires UDP animation commands at exact timestamps, with seek-safe fired_ids rebuild and preview_update broadcast on every tick

Performance

• Duration: 8 min
• Started: 2026-04-07T10:09:19Z
• Completed: 2026-04-07T10:17:00Z
• Tasks: 2
• Files modified: 1

Accomplishments

• Per-connection show state (show, fired_ids, is_playing) integrated into WebSocket handler
• Load message extended to load show from show_store by show_id, resetting scheduler state
• Play/pause handlers gate is_playing flag (pause never touches fired_ids per spec)
• Seek handler rebuilds fired_ids via set comprehension over all cues before seek position
• 60ms LOOKAHEAD cue scheduler fires UDP animation commands during active playback
• Past cues (>100ms behind) silently skipped — no late UDP bursts after seek
• active_cue tracking covers both newly-fired and already-active cues for preview continuity
• preview_update messages broadcast to all connected clients on each tick tick (active and clear states)

Task Commits

Each task was committed atomically:

1. Task 1: Add per-connection show state and load handler to ws.py - 3d36cc5 (feat)
2. Task 2: Add cue scheduling loop and preview_update broadcast to tick handler - 64c49c9 (feat)

Files Created/Modified

• lightsync/api/ws.py - Extended with cue scheduler, show loading, play/pause/seek handlers, preview_update broadcast

Decisions Made

• LOOKAHEAD = 0.060 defined inline inside the tick branch (not as module constant) — keeps it local to the scheduler logic
• Deferred import of lightsync.main as _main inside the load handler body to avoid circular import at module level
• active_cue tracks already-fired cues still within their duration window so preview stays lit for the full block duration, not just at fire time
• Past-cue threshold set at 100ms (not 60ms) to give a small recovery window without causing stale fires

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None. The Python runtime was invoked via uv run python (no python/python3 on PATH in this environment).

Next Phase Readiness

• WebSocket cue scheduler is fully functional — ready for 05-02 (live preview UI consuming preview_update messages)
• preview_update messages broadcast device_id, animation name, and color on each tick — frontend can render device state
• Seek and pause behavior are correct per spec — no double-fire, no late blasts

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Phase: 05-live-show-execution Completed: 2026-04-07