5 files changed, 90 insertions, 0 deletions
diff --git a/apps/web/src/timeline/snapping/build.ts b/apps/web/src/timeline/snapping/build.ts
new file mode 100644
index 00000000..87d3db2e
--- /dev/null
+++ b/apps/web/src/timeline/snapping/build.ts
@@ -0,0 +1,17 @@
+import type { SnapPoint, TimelineSnapPointSource } from "./types";
+
+export function buildTimelineSnapPoints({
+	sources,
+}: {
+	sources: TimelineSnapPointSource[];
+}): SnapPoint[] {
+	const snapPoints: SnapPoint[] = [];
+
+	for (const source of sources) {
+		for (const snapPoint of source()) {
+			snapPoints.push(snapPoint);
+		}
+	}
+
+	return snapPoints;
+}
diff --git a/apps/web/src/timeline/snapping/index.ts b/apps/web/src/timeline/snapping/index.ts
new file mode 100644
index 00000000..73f49272
--- /dev/null
+++ b/apps/web/src/timeline/snapping/index.ts
@@ -0,0 +1,9 @@
+export { buildTimelineSnapPoints } from "./build";
+export { resolveTimelineSnap } from "./resolve";
+export { getTimelineSnapThresholdInTicks } from "./threshold";
+export type {
+	SnapPoint,
+	SnapPointType,
+	SnapResult,
+	TimelineSnapPointSource,
+} from "./types";
diff --git a/apps/web/src/timeline/snapping/resolve.ts b/apps/web/src/timeline/snapping/resolve.ts
new file mode 100644
index 00000000..2f00d081
--- /dev/null
+++ b/apps/web/src/timeline/snapping/resolve.ts
@@ -0,0 +1,28 @@
+import type { SnapPoint, SnapResult } from "./types";
+
+export function resolveTimelineSnap({
+	targetTime,
+	snapPoints,
+	maxSnapDistance,
+}: {
+	targetTime: number;
+	snapPoints: SnapPoint[];
+	maxSnapDistance: number;
+}): SnapResult {
+	let closestSnapPoint: SnapPoint | null = null;
+	let closestDistance = Infinity;
+
+	for (const snapPoint of snapPoints) {
+		const distance = Math.abs(targetTime - snapPoint.time);
+		if (distance <= maxSnapDistance && distance < closestDistance) {
+			closestDistance = distance;
+			closestSnapPoint = snapPoint;
+		}
+	}
+
+	return {
+		snappedTime: closestSnapPoint ? closestSnapPoint.time : targetTime,
+		snapPoint: closestSnapPoint,
+		snapDistance: closestDistance,
+	};
+}
diff --git a/apps/web/src/timeline/snapping/threshold.ts b/apps/web/src/timeline/snapping/threshold.ts
new file mode 100644
index 00000000..f03111dc
--- /dev/null
+++ b/apps/web/src/timeline/snapping/threshold.ts
@@ -0,0 +1,15 @@
+import { BASE_TIMELINE_PIXELS_PER_SECOND } from "@/timeline/scale";
+import { TICKS_PER_SECOND } from "@/wasm";
+
+const DEFAULT_TIMELINE_SNAP_THRESHOLD_PX = 10;
+
+export function getTimelineSnapThresholdInTicks({
+	zoomLevel,
+	snapThresholdPx = DEFAULT_TIMELINE_SNAP_THRESHOLD_PX,
+}: {
+	zoomLevel: number;
+	snapThresholdPx?: number;
+}): number {
+	const pixelsPerSecond = BASE_TIMELINE_PIXELS_PER_SECOND * zoomLevel;
+	return (snapThresholdPx / pixelsPerSecond) * TICKS_PER_SECOND;
+}
diff --git a/apps/web/src/timeline/snapping/types.ts b/apps/web/src/timeline/snapping/types.ts
new file mode 100644
index 00000000..2a6d0903
--- /dev/null
+++ b/apps/web/src/timeline/snapping/types.ts
@@ -0,0 +1,21 @@
+export type SnapPointType =
+	| "element-start"
+	| "element-end"
+	| "playhead"
+	| "bookmark"
+	| "keyframe";
+
+export interface SnapPoint {
+	time: number;
+	type: SnapPointType;
+	elementId?: string;
+	trackId?: string;
+}
+
+export interface SnapResult {
+	snappedTime: number;
+	snapPoint: SnapPoint | null;
+	snapDistance: number;
+}
+
+export type TimelineSnapPointSource = () => Iterable<SnapPoint>;