Merge pull request #1069 from func25/fix/preview-reuse-and-waapi-seek-baselines

packages/core/src/runtime/adapters/waapi.test.ts

@@ -1,7 +1,24 @@
-import { describe, it, expect, vi } from "vitest";
+import { beforeEach, afterEach, describe, it, expect, vi } from "vitest";
 import { createWaapiAdapter } from "./waapi";
 
 describe("waapi adapter", () => {
+  const originalDocument = (globalThis as { document?: unknown }).document;
+
+  beforeEach(() => {
+    (globalThis as { document?: unknown }).document = {
+      getAnimations: vi.fn(() => []),
+    };
+  });
+
+  afterEach(() => {
+    if (originalDocument === undefined) {
+      delete (globalThis as { document?: unknown }).document;
+      return;
+    }
+
+    (globalThis as { document?: unknown }).document = originalDocument;
+  });
+
   it("has correct name", () => {
     expect(createWaapiAdapter().name).toBe("waapi");
   });
@@ -87,4 +104,76 @@ describe("waapi adapter", () => {
     const adapter = createWaapiAdapter();
     expect(() => adapter.discover()).not.toThrow();
   });
+
+  it("anchors newly discovered WAAPI animations to the seek where they first appear", () => {
+    const existing = { pause: vi.fn(), currentTime: 0 };
+    const dynamic = { pause: vi.fn(), currentTime: 0 };
+    let includeDynamic = false;
+    (document as any).getAnimations = vi.fn(() =>
+      includeDynamic ? [existing, dynamic] : [existing],
+    );
+
+    const adapter = createWaapiAdapter();
+    adapter.discover();
+
+    adapter.seek({ time: 0.6 });
+    expect(existing.currentTime).toBe(600);
+
+    includeDynamic = true;
+    adapter.seek({ time: 0.7 });
+    expect(existing.currentTime).toBe(700);
+    expect(dynamic.currentTime).toBe(0);
+
+    adapter.seek({ time: 0.8 });
+    expect(dynamic.currentTime).toBe(100);
+
+    delete (document as any).getAnimations;
+  });
+
+  it("rebases newly discovered WAAPI animations that inherit absolute composition time", () => {
+    const existing = { pause: vi.fn(), currentTime: 0 };
+    const dynamic = { pause: vi.fn(), currentTime: 700 };
+    let includeDynamic = false;
+    (document as any).getAnimations = vi.fn(() =>
+      includeDynamic ? [existing, dynamic] : [existing],
+    );
+
+    const adapter = createWaapiAdapter();
+    adapter.discover();
+
+    adapter.seek({ time: 0.6 });
+    expect(existing.currentTime).toBe(600);
+
+    includeDynamic = true;
+    adapter.seek({ time: 0.7 });
+    expect(dynamic.currentTime).toBe(0);
+
+    adapter.seek({ time: 0.8 });
+    expect(dynamic.currentTime).toBe(100);
+
+    delete (document as any).getAnimations;
+  });
+
+  it("does not double-count inherited absolute time when discover runs again after time has advanced", () => {
+    const existing = { pause: vi.fn(), currentTime: 0 };
+    const dynamic = { pause: vi.fn(), currentTime: 700 };
+    let includeDynamic = false;
+    (document as any).getAnimations = vi.fn(() =>
+      includeDynamic ? [existing, dynamic] : [existing],
+    );
+
+    const adapter = createWaapiAdapter();
+    adapter.discover();
+
+    adapter.seek({ time: 0.6 });
+    expect(existing.currentTime).toBe(600);
+
+    includeDynamic = true;
+    adapter.discover();
+    adapter.seek({ time: 0.7 });
+
+    expect(dynamic.currentTime).toBe(200);
+
+    delete (document as any).getAnimations;
+  });
 });

packages/core/src/runtime/adapters/waapi.ts

@@ -2,15 +2,77 @@ import type { RuntimeDeterministicAdapter } from "../types";
 import { swallow } from "../diagnostics";
 
 export function createWaapiAdapter(): RuntimeDeterministicAdapter {
+  let didDiscover = false;
+  let lastSeekTimeMs = 0;
+  const baselines = new WeakMap<
+    Animation,
+    {
+      compositionTimeMs: number;
+      animationTimeMs: number;
+    }
+  >();
+
+  const snapshotAnimations = () => {
+    if (!document.getAnimations) return [];
+    try {
+      return document.getAnimations();
+    } catch {
+      return [];
+    }
+  };
+
+  const readAnimationTimeMs = (animation: Animation) => {
+    const raw = Number(animation.currentTime);
+    return Number.isFinite(raw) && raw > 0 ? raw : 0;
+  };
+
+  const normalizeInitialAnimationTimeMs = (animationTimeMs: number, compositionTimeMs: number) => {
+    if (compositionTimeMs <= 0) {
+      return animationTimeMs;
+    }
+
+    if (animationTimeMs >= compositionTimeMs) {
+      return Math.max(0, animationTimeMs - compositionTimeMs);
+    }
+
+    return animationTimeMs;
+  };
+
+  const ensureBaseline = (animation: Animation, compositionTimeMs: number) => {
+    const existing = baselines.get(animation);
+    if (existing) {
+      return existing;
+    }
+
+    const baseline = {
+      compositionTimeMs,
+      animationTimeMs: didDiscover
+        ? normalizeInitialAnimationTimeMs(readAnimationTimeMs(animation), compositionTimeMs)
+        : readAnimationTimeMs(animation),
+    };
+    baselines.set(animation, baseline);
+    return baseline;
+  };
+
   return {
     name: "waapi",
-    discover: () => {},
+    discover: () => {
+      didDiscover = true;
+      for (const animation of snapshotAnimations()) {
+        ensureBaseline(animation, lastSeekTimeMs);
+      }
+    },
     seek: (ctx) => {
-      if (!document.getAnimations) return;
       const timeMs = Math.max(0, (Number(ctx.time) || 0) * 1000);
-      for (const animation of document.getAnimations()) {
+      lastSeekTimeMs = timeMs;
+      for (const animation of snapshotAnimations()) {
+        const baseline = didDiscover
+          ? ensureBaseline(animation, timeMs)
+          : ensureBaseline(animation, 0);
+        const localTimeMs =
+          baseline.animationTimeMs + Math.max(0, timeMs - baseline.compositionTimeMs);
         try {
-          animation.currentTime = timeMs;
+          animation.currentTime = localTimeMs;
         } catch (err) {
           // ignore animations that reject currentTime writes
           swallow("runtime.adapters.waapi.site1", err);