perf(map): reduce tile snapshot work during zoom

src/components/olmap/core/tileSnapshotScheduler.test.ts

@@ -0,0 +1,46 @@
+import { createTileSnapshotScheduler } from "./tileSnapshotScheduler";
+
+describe("createTileSnapshotScheduler", () => {
+  beforeEach(() => {
+    jest.useFakeTimers();
+  });
+
+  afterEach(() => {
+    jest.useRealTimers();
+  });
+
+  it("defers and coalesces tile snapshots until movement ends", () => {
+    const publish = jest.fn();
+    const scheduler = createTileSnapshotScheduler({ publish, wait: 50 });
+
+    scheduler.beginMove();
+    scheduler.markDirty();
+    scheduler.markDirty();
+    jest.advanceTimersByTime(100);
+    expect(publish).not.toHaveBeenCalled();
+
+    scheduler.endMove();
+    jest.advanceTimersByTime(49);
+    expect(publish).not.toHaveBeenCalled();
+    jest.advanceTimersByTime(1);
+    expect(publish).toHaveBeenCalledTimes(1);
+  });
+
+  it("batches settled tile arrivals and cancels pending work", () => {
+    const publish = jest.fn();
+    const scheduler = createTileSnapshotScheduler({ publish, wait: 50 });
+
+    scheduler.markDirty();
+    jest.advanceTimersByTime(25);
+    scheduler.markDirty();
+    jest.advanceTimersByTime(49);
+    expect(publish).not.toHaveBeenCalled();
+    jest.advanceTimersByTime(1);
+    expect(publish).toHaveBeenCalledTimes(1);
+
+    scheduler.markDirty();
+    scheduler.cancel();
+    jest.runAllTimers();
+    expect(publish).toHaveBeenCalledTimes(1);
+  });
+});