fix(dub): carry rounded timestamp seconds into minutes

CHANGELOG.md

@@ -14,6 +14,8 @@ metadata and the backend fallback mirror it.
 
 ### Fixed
 
+- Carry rounded dubbing timestamp seconds into minutes, avoiding invalid labels such as `0:60.0` — thanks @rudycelekli! (#2660)
+
 - MCP speech tools wait through model loading and progress-extended CPU renders instead of timing out before the backend (#2609)
 
 ## [0.5.7] — 2026-10-05

docs/dubbing/export.md

@@ -23,3 +23,5 @@ filters; POSIX filenames keep literal backslashes. Two caption styles are availa
 Smart Fit exports burn captions after the video retime, so both styles follow
 the fitted timeline. The karaoke script can also be downloaded on its own from
 `GET /dub/ass/{job_id}` as an `.ass` sidecar.
+
+The dubbing timeline displays elapsed times in minutes and tenths of seconds. A rounded second carries into the minute, so a boundary such as 59.96 seconds displays as `1:00.0`, keeping timestamp labels consistent in the timeline and segment editor. Display rounding does not change segment timing or exported timestamps.

electron/src/renderer/src/features/dub/dub-timeline.tsx

@@ -1,3 +1,4 @@
+import { formatTime } from '@shared/utils/format';
 import { HeadphonesIcon, LoaderCircleIcon, PlayIcon, TriangleAlertIcon, ZoomInIcon, ZoomOutIcon, MaximizeIcon } from 'lucide-react';
 import { useEffect, useMemo, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
@@ -28,10 +29,7 @@ type Gesture = {
   end: number;
 };
 
-const formatTime = (seconds: number) => {
-  const minutes = Math.floor(seconds / 60);
-  return `${minutes}:${(seconds % 60).toFixed(1).padStart(4, '0')}`;
-};
+
 
 export function DubTimeline({
   segments,

electron/src/shared/utils/format.d.ts

@@ -0,0 +1,2 @@
+export function formatTime(seconds: number): string;
+export function probeAudioDuration(file: Blob): Promise<number | null>;

electron/src/shared/utils/format.js

@@ -1,6 +1,8 @@
 export function formatTime(s) {
-  const m = Math.floor(s / 60);
-  const sec = (s % 60).toFixed(1);
+  // Round once before decomposing, so a tenths carry advances the minute.
+  const tenths = Math.round(s * 10);
+  const m = Math.floor(tenths / 600);
+  const sec = ((tenths % 600) / 10).toFixed(1);
   return `${m}:${sec.padStart(4, '0')}`;
 }
 

electron/src/shared/utils/utils.test.js

@@ -23,6 +23,10 @@ describe('format utils', () => {
     expect(formatTime(0)).toBe('0:00.0');
     expect(formatTime(61)).toBe('1:01.0');
     expect(formatTime(3661)).toBe('61:01.0');
+    expect(formatTime(59.94)).toBe('0:59.9');
+    expect(formatTime(59.96)).toBe('1:00.0');
+    expect(formatTime(119.96)).toBe('2:00.0');
+    expect(formatTime(3599.96)).toBe('60:00.0');
   });
 });