fix(cli): preserve snapshot timestamp precision (#2494)

packages/cli/src/commands/snapshot.test.ts

@@ -2,12 +2,22 @@ import { describe, expect, it } from "vitest";
 import { readFileSync } from "node:fs";
 import {
   computeSnapshotTimes,
+  formatSnapshotTimestamp,
   parseZoomScale,
   requireSnapshotFfmpeg,
   resolveSnapshotVideoFrameTime,
   tailFrameTime,
 } from "./snapshot.js";
 
+describe("formatSnapshotTimestamp", () => {
+  it.each([
+    [1.12, "1.12s"],
+    [0.30000000000000004, "0.3s"],
+  ])("formats %s without discarding useful precision", (time, expected) => {
+    expect(formatSnapshotTimestamp(time)).toBe(expected);
+  });
+});
+
 // --zoom's crop-region math (selector bbox + padding + clamp, exact region
 // form, no-match error) is owned by and tested in
 // ../capture/captureCompositionFrame.test.ts alongside its implementation.

packages/cli/src/commands/snapshot.ts

@@ -60,6 +60,11 @@ function orbitStageSource(): string {
  * `hyperframes snapshot` indefinitely. */
 const FFMPEG_EXTRACT_TIMEOUT_MS = 30_000;
 
+/** Keep millisecond-level snapshot timing proof without leaking floating-point noise. */
+export function formatSnapshotTimestamp(time: number): string {
+  return `${Number(time.toFixed(3))}s`;
+}
+
 /** Keep an exact clip-end snapshot aligned with the renderer's inclusive media
  * window. This intentionally differs from the live player's exclusive-end
  * visibility so an explicit end-boundary review does not become blank. FFmpeg
@@ -503,7 +508,7 @@ async function captureSnapshots(
           }
         }
 
-        const timeLabel = `${time.toFixed(1)}s`;
+        const timeLabel = formatSnapshotTimestamp(time);
         const filename = `frame-${String(i).padStart(2, "0")}-at-${timeLabel}.png`;
         const framePath = join(snapshotDir, filename);
 
@@ -626,7 +631,7 @@ export default defineCommand({
     const zoomScale = parseZoomScale(args["zoom-scale"]);
 
     const label = atTimestamps
-      ? `${atTimestamps.length} frames at [${atTimestamps.map((t) => t.toFixed(1) + "s").join(", ")}]`
+      ? `${atTimestamps.length} frames at [${atTimestamps.map(formatSnapshotTimestamp).join(", ")}]`
       : `${frames} frames`;
     const angleLabel =
       camera && (camera.yaw !== 0 || camera.pitch !== 0)