refactor: centralize editor interaction state

Move timeline and preview gestures into dedicated controllers so hooks stay thin around editor state and DOM events.

This also routes drag and playback synchronization through manager APIs and reuses persistent wasm surfaces so scrubbing, seeking, and preview rendering stay in sync.

Made-with: Cursor

3 files changed, 36 insertions, 43 deletions

diff --git a/apps/web/src/core/managers/audio-manager.ts b/apps/web/src/core/managers/audio-manager.ts
index 545565be..d0716aad 100644
--- a/apps/web/src/core/managers/audio-manager.ts
+++ b/apps/web/src/core/managers/audio-manager.ts
@@ -1,9 +1,6 @@
 import type { EditorCore } from "@/core";
 import { TICKS_PER_SECOND } from "@/wasm";
-import {
-	clampRetimeRate,
-	shouldMaintainPitch,
-} from "@/retime/rate";
+import { clampRetimeRate, shouldMaintainPitch } from "@/retime/rate";
 import type { AudioClipSource } from "@/media/audio";
 import { createAudioContext, collectAudioClips } from "@/media/audio";
 import {
@@ -56,10 +53,8 @@ export class AudioManager {
 			this.editor.playback.subscribe(this.handlePlaybackChange),
 			this.editor.timeline.subscribe(this.handleTimelineChange),
 			this.editor.media.subscribe(this.handleTimelineChange),
+			this.editor.playback.onSeek(this.handleSeek),
 		);
-		if (typeof window !== "undefined") {
-			window.addEventListener("playback-seek", this.handleSeek);
-		}
 	}
 
 	dispose(): void {
@@ -68,9 +63,6 @@ export class AudioManager {
 			unsub();
 		}
 		this.unsubscribers = [];
-		if (typeof window !== "undefined") {
-			window.removeEventListener("playback-seek", this.handleSeek);
-		}
 		this.disposeSinks();
 		this.preparedClipBuffers.clear();
 		this.decodedBuffers.clear();
@@ -102,17 +94,14 @@ export class AudioManager {
 		}
 	};
 
-	private handleSeek = (event: Event): void => {
-		const detail = (event as CustomEvent<{ time: number }>).detail;
-		if (!detail) return;
-
+	private handleSeek = (time: number): void => {
 		if (this.editor.playback.getIsScrubbing()) {
 			this.stopPlayback();
 			return;
 		}
 
 		if (this.editor.playback.getIsPlaying()) {
-			void this.startPlayback({ time: detail.time / TICKS_PER_SECOND });
+			void this.startPlayback({ time: time / TICKS_PER_SECOND });
 			return;
 		}
 
@@ -126,7 +115,9 @@ export class AudioManager {
 
 		if (!this.editor.playback.getIsPlaying()) return;
 
-		void this.startPlayback({ time: this.editor.playback.getCurrentTime() / TICKS_PER_SECOND });
+		void this.startPlayback({
+			time: this.editor.playback.getCurrentTime() / TICKS_PER_SECOND,
+		});
 	};
 
 	private ensureAudioContext(): AudioContext | null {
diff --git a/apps/web/src/core/managers/playback-manager.ts b/apps/web/src/core/managers/playback-manager.ts
index 1ea09826..a243dc19 100644
--- a/apps/web/src/core/managers/playback-manager.ts
+++ b/apps/web/src/core/managers/playback-manager.ts
@@ -10,6 +10,8 @@ export class PlaybackManager {
 	private previousVolume = 1;
 	private isScrubbing = false;
 	private listeners = new Set<() => void>();
+	private updateListeners = new Set<(time: number) => void>();
+	private seekListeners = new Set<(time: number) => void>();
 	private playbackTimer: number | null = null;
 	private playbackStartWallTime = 0;
 	private playbackStartTime = 0;
@@ -67,7 +69,7 @@ export class PlaybackManager {
 			this.playbackStartTime = this.currentTime;
 		}
 		this.notify();
-		this.dispatchSeekEvent(this.currentTime);
+		this.notifySeek(this.currentTime);
 	}
 
 	setVolume({ volume }: { volume: number }): void {
@@ -133,6 +135,16 @@ export class PlaybackManager {
 		return () => this.listeners.delete(listener);
 	}
 
+	onUpdate(listener: (time: number) => void): () => void {
+		this.updateListeners.add(listener);
+		return () => this.updateListeners.delete(listener);
+	}
+
+	onSeek(listener: (time: number) => void): () => void {
+		this.seekListeners.add(listener);
+		return () => this.seekListeners.delete(listener);
+	}
+
 	private reconcileTimelineScope(): void {
 		const maxTime = this.editor.timeline.getTotalDuration();
 		const nextTime = this.clampTimeToTimeline(this.currentTime);
@@ -152,7 +164,7 @@ export class PlaybackManager {
 		this.notify();
 
 		if (timeChanged) {
-			this.dispatchSeekEvent(this.currentTime);
+			this.notifySeek(this.currentTime);
 		}
 	}
 
@@ -196,12 +208,12 @@ export class PlaybackManager {
 			this.pause();
 			this.currentTime = maxTime;
 			this.notify();
-			this.dispatchSeekEvent(maxTime);
+			this.notifySeek(maxTime);
 			return;
 		}
 
 		this.currentTime = newTime;
-		this.dispatchUpdateEvent(newTime);
+		this.notifyUpdate(newTime);
 		this.playbackTimer = requestAnimationFrame(this.updateTime);
 	};
 
@@ -210,27 +222,15 @@ export class PlaybackManager {
 		return Math.max(0, Math.min(maxTime, time));
 	}
 
-	private dispatchSeekEvent(time: number): void {
-		if (typeof window === "undefined") {
-			return;
+	private notifySeek(time: number): void {
+		for (const fn of this.seekListeners) {
+			fn(time);
 		}
-
-		window.dispatchEvent(
-			new CustomEvent("playback-seek", {
-				detail: { time },
-			}),
-		);
 	}
 
-	private dispatchUpdateEvent(time: number): void {
-		if (typeof window === "undefined") {
-			return;
+	private notifyUpdate(time: number): void {
+		for (const fn of this.updateListeners) {
+			fn(time);
 		}
-
-		window.dispatchEvent(
-			new CustomEvent("playback-update", {
-				detail: { time },
-			}),
-		);
 	}
 }
diff --git a/apps/web/src/core/managers/timeline-manager.ts b/apps/web/src/core/managers/timeline-manager.ts
index dbc3332b..6f54c5aa 100644
--- a/apps/web/src/core/managers/timeline-manager.ts
+++ b/apps/web/src/core/managers/timeline-manager.ts
@@ -9,6 +9,7 @@ import type {
 	RetimeConfig,
 } from "@/timeline";
 import { calculateTotalDuration } from "@/timeline";
+import { TimelineDragSource } from "@/timeline/drag-source";
 import { findTrackInSceneTracks } from "@/timeline/track-element-update";
 import {
 	canElementBeHidden,
@@ -67,6 +68,7 @@ export class TimelineManager {
 	private listeners = new Set<() => void>();
 	private previewOverlay = new Map<string, Partial<TimelineElement>>();
 	private previewTracks: SceneTracks | null = null;
+	public readonly dragSource = new TimelineDragSource();
 
 	constructor(private editor: EditorCore) {}
 
@@ -706,11 +708,11 @@ export class TimelineManager {
 	previewElements({
 		updates,
 	}: {
-		updates: Array<{
-			trackId: string;
-			elementId: string;
-			updates: Partial<TimelineElement>;
-		}>;
+		updates: readonly {
+			readonly trackId: string;
+			readonly elementId: string;
+			readonly updates: Partial<TimelineElement>;
+		}[];
 	}): void {
 		let changedOverlayCount = 0;
 		for (const { elementId, updates: elementUpdates } of updates) {