# Feature Context: Demo Mode

## Current State
Starting implementation. No changes made yet.

## Key Architecture Notes
- `EngineRegistry` (class-level dict) holds capture engines, auto-registered in `capture_engines/__init__.py`
- `AudioEngineRegistry` (class-level dict) holds audio engines, auto-registered in `audio/__init__.py`
- `LEDDeviceProvider` instances registered via `register_provider()` in `led_client.py`
- Already has `MockDeviceProvider` + `MockClient` (device type "mock") for testing
- Config is `pydantic_settings.BaseSettings` in `config.py`, loaded from YAML + env vars
- Frontend header in `templates/index.html` line 27-31: title + version badge
- Frontend bundle: `cd server && npm run build` (esbuild)
- Data stored as JSON in `data/` directory, paths configured via `StorageConfig`

## Temporary Workarounds
- None yet

## Cross-Phase Dependencies
- Phase 1 (config flag) is foundational — all other phases depend on `is_demo_mode()`
- Phase 2 & 3 (engines) can be done independently of each other
- Phase 4 (seed data) depends on knowing what entities to create, which is informed by phases 2-3
- Phase 5 (frontend) depends on the system info API field from phase 1
- Phase 6 (engine resolution) depends on engines existing from phases 2-3

## Implementation Notes
- Demo mode activated via `WLED_DEMO=true` env var or `demo: true` in YAML config
- Isolated data directory `data/demo/` keeps demo entities separate from real config
- Demo engines use `ENGINE_TYPE = "demo"` and are always registered but return `is_available() = True` only in demo mode
- The existing `MockDeviceProvider`/`MockClient` can be reused or extended for demo device output
