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

1 files changed, 17 insertions, 0 deletions

diff --git a/apps/web/src/timeline/creation.ts b/apps/web/src/timeline/creation.ts
index 2ac7f246..2dec3186 100644
--- a/apps/web/src/timeline/creation.ts
+++ b/apps/web/src/timeline/creation.ts
@@ -1,3 +1,20 @@
 import { TICKS_PER_SECOND } from "@/wasm/ticks";
 
 export const DEFAULT_NEW_ELEMENT_DURATION = 5 * TICKS_PER_SECOND;
+
+/**
+ * Resolves the duration in ticks that a newly created timeline element
+ * should have, given an optional source duration in seconds.
+ *
+ * Falls back to {@link DEFAULT_NEW_ELEMENT_DURATION} when the source has
+ * no known duration (e.g. stickers, graphics, text, or media whose
+ * probe failed).
+ */
+export function toElementDurationTicks({
+	seconds,
+}: {
+	seconds: number | null | undefined;
+}): number {
+	if (seconds == null) return DEFAULT_NEW_ELEMENT_DURATION;
+	return Math.round(seconds * TICKS_PER_SECOND);
+}