Tauri event surface

Events are emitted from Rust backend via app_handle.emit_all(). Frontend subscribes with listen().

Event list

Event	Payload	When
`playback_state_changed`	`PlaybackState`	Playback status, position, volume, or track changes
`track_changed`	`TrackStub \| null`	Track auto-advances or changes
`queue_updated`	`QueueState`	After every queue mutation (full state, not diff)
`search_result`	`SearchResultBatch`	Partial results as they arrive per-plugin
`search_done`	`{ query_id: string }`	All plugins responded or timed out
`search_error`	`{ query_id: string, plugin_id: string, error: string }`	Per-plugin search failure
`plugin_status_changed`	`{ plugin_id: string, status: PluginStatus }`	Plugin enters/exits Ready, Crashed, or Disabled
`library_updated`	`{ kind: "saved" \| "removed", track_id: string }`	Library item saved or removed
`platform_ready`	`void`	All services initialized, UI can render
`playback_error`	`{ error: string, source?: PlaySource }`	Stream URL fetch failure, decode failure, etc.

Payload types

interface PlaybackState {
  status: "idle" | "loading" | "playing" | "paused" | "seeking" | "error";
  position_ms: number;
  duration_ms: number | null;
  volume: number;               // 0.0–1.0
  track: TrackStub | null;
}

interface QueueState {
  items: TrackStub[];
  current_index: number | null;
}

interface SearchResultBatch {
  query_id: string;             // frontend correlates responses to queries
  plugin_id: string;
  results: SearchResult[];
}

// Subset surfaced to frontend — see plugin-runtime.md for full 8-state enum
type PluginStatus = "ready" | "busy" | "crashed" | "disabled";

References

ADR-005 (Tauri events for inter-component communication)
ADR-007 (search manager events)
ADR-010 (queue events)