chore: import upstream snapshot with attribution

2026-07-13 12:58:35 +08:00
commit 85453da49f
4031 changed files with 710987 additions and 0 deletions
@@ -0,0 +1,36 @@
+import { describe, expect, it } from "vitest";
+import { clipToTweenPercentage } from "./KeyframeNavigation";
+
+/**
+ * Regression: keyframe add/remove are keyed by TWEEN-relative percentage (what the
+ * GSAP writer + runtime use), NOT the clip-relative playhead used for display/seek.
+ * The Layout-panel diamond used to emit clip-relative %, so the mutation missed
+ * every keyframe (off by the tween's offset/scale) → a silent no-op on disk that
+ * the optimistic cache hid, so the motion path never refreshed.
+ */
+
+// A tween that starts partway through the element's lifetime and is shorter than
+// it: the clip→tween map is linear with tween% = (clip% - 20) * 2.5 over [20, 60].
+const KEYFRAMES = [
+  { percentage: 20, tweenPercentage: 0, properties: { x: 0 } },
+  { percentage: 30, tweenPercentage: 25, properties: { x: -180 } },
+  { percentage: 50, tweenPercentage: 75, properties: { x: -320 } },
+  { percentage: 60, tweenPercentage: 100, properties: { x: -460 } },
+];
+
+describe("clipToTweenPercentage", () => {
+  it("maps anchor keyframes to their tween-relative percentages", () => {
+    expect(clipToTweenPercentage(KEYFRAMES, 20)).toBeCloseTo(0, 5);
+    expect(clipToTweenPercentage(KEYFRAMES, 60)).toBeCloseTo(100, 5);
+  });
+
+  it("linearly interpolates a clip-relative playhead into tween space", () => {
+    // clip 40% is the midpoint of the tween's clip span [20, 60] → tween 50%.
+    expect(clipToTweenPercentage(KEYFRAMES, 40)).toBeCloseTo(50, 5);
+  });
+
+  it("falls back to the input when there's no usable mapping", () => {
+    expect(clipToTweenPercentage([], 40)).toBe(40);
+    expect(clipToTweenPercentage([{ percentage: 10 }], 40)).toBe(40);
+  });
+});