fix(anki): clip mined media on the sub-delay retimed timeline

mpv's sub-start/sub-end and parsed cues carry the subtitle file's own
timestamps; sub-delay (z/x, sub-step) only moves where mpv plays them.
Mining now shifts subtitle timings onto the video clock before media
generation, review, and MiscInfo timestamps.

src/core/services/index.ts

@@ -22,6 +22,7 @@ export {
   handleMultiCopyDigit,
   markLastCardAsAudioCard,
   mineSentenceCard,
+  shiftSubtitleRangeToVideoClock,
   triggerFieldGrouping,
   updateLastCardFromClipboard,
 } from './mining';

src/core/services/mining.test.ts

@@ -77,6 +77,7 @@ test('mineSentenceCard handles missing integration and disconnected mpv', async
         currentSubText: 'line',
         currentSubStart: 1,
         currentSubEnd: 2,
+        currentSubDelay: 0,
       },
       showMpvOsd: (text) => osd.push(text),
     }),
@@ -109,6 +110,7 @@ test('mineSentenceCard creates sentence card from mpv subtitle state', async ()
       currentSubText: 'subtitle line',
       currentSubStart: 10,
       currentSubEnd: 12,
+      currentSubDelay: 0,
       currentSecondarySubText: 'secondary line',
     },
     showMpvOsd: () => {},
@@ -148,6 +150,7 @@ test('mineSentenceCard prefers a canonical primary subtitle snapshot', async ()
       currentSubText: '今今今手手手',
       currentSubStart: 11.4,
       currentSubEnd: 11.8,
+      currentSubDelay: 0,
       currentSecondarySubText: 'English subtitle',
     },
     primarySubtitle: {
@@ -187,6 +190,7 @@ test('mineSentenceCard uses normalized secondary subtitle state instead of raw m
       currentSubText: '日本語字幕',
       currentSubStart: 10,
       currentSubEnd: 12,
+      currentSubDelay: 0,
       currentSecondarySubText: 'Your\nmosaic',
       requestProperty: async () => {
         requestedRawSecondaryText = true;
@@ -218,6 +222,7 @@ test('mineSentenceCard omits normalized secondary text that matches the primary
       currentSubText: '日本語字幕',
       currentSubStart: 10,
       currentSubEnd: 12,
+      currentSubDelay: 0,
       currentSecondarySubText: '日本語字幕',
     },
     showMpvOsd: () => {},
@@ -396,7 +401,7 @@ test('handleMineSentenceDigit joins per-entry secondary subtitles when available
 
 test('captureLiveSubtitleMiningContext snapshots the current line and timings', () => {
   const context = captureLiveSubtitleMiningContext(
-    { currentSubText: ' 食べる ', currentSubStart: 12.5, currentSubEnd: 15.25 },
+    { currentSubText: ' 食べる ', currentSubStart: 12.5, currentSubEnd: 15.25, currentSubDelay: 0 },
     () => 1234,
   );
 
@@ -409,6 +414,16 @@ test('captureLiveSubtitleMiningContext snapshots the current line and timings',
   });
 });
 
+test('captureLiveSubtitleMiningContext moves sub-delay retimed lines onto the video clock', () => {
+  const context = captureLiveSubtitleMiningContext(
+    { currentSubText: '食べる', currentSubStart: 5, currentSubEnd: 8, currentSubDelay: -1.5 },
+    () => 1234,
+  );
+
+  assert.equal(context?.startTime, 3.5);
+  assert.equal(context?.endTime, 6.5);
+});
+
 test('captureLiveSubtitleMiningContext rejects missing client, empty text and bad timings', () => {
   assert.equal(captureLiveSubtitleMiningContext(null), null);
   assert.equal(
@@ -416,6 +431,7 @@ test('captureLiveSubtitleMiningContext rejects missing client, empty text and ba
       currentSubText: '  ',
       currentSubStart: 1,
       currentSubEnd: 2,
+      currentSubDelay: 0,
     }),
     null,
   );
@@ -424,6 +440,7 @@ test('captureLiveSubtitleMiningContext rejects missing client, empty text and ba
       currentSubText: 'line',
       currentSubStart: 5,
       currentSubEnd: 5,
+      currentSubDelay: 0,
     }),
     null,
   );
@@ -432,6 +449,7 @@ test('captureLiveSubtitleMiningContext rejects missing client, empty text and ba
       currentSubText: 'line',
       currentSubStart: NaN,
       currentSubEnd: 2,
+      currentSubDelay: 0,
     }),
     null,
   );

src/core/services/mining.ts

@@ -25,6 +25,7 @@ interface MpvClientLike {
   currentSubText: string;
   currentSubStart: number;
   currentSubEnd: number;
+  currentSubDelay: number;
   currentSecondarySubText?: string;
   requestProperty?: (name: string) => Promise<unknown>;
 }
@@ -55,6 +56,21 @@ export function handleMultiCopyDigit(
   }
 }
 
+/**
+ * mpv's `sub-start`/`sub-end` and parsed cues carry the subtitle file's own timestamps,
+ * but mpv plays each line `sub-delay` seconds later (z/x retiming). Media is cut from the
+ * video, so subtitle timings move onto the video clock before they reach mining.
+ */
+export function shiftSubtitleRangeToVideoClock<T extends { startTime: number; endTime: number }>(
+  range: T,
+  subDelay: number,
+): T {
+  if (!Number.isFinite(subDelay) || subDelay === 0) {
+    return range;
+  }
+  return { ...range, startTime: range.startTime + subDelay, endTime: range.endTime + subDelay };
+}
+
 /**
  * Snapshot the live mpv subtitle line and its timings as a mining context. Media
  * generation can run tens of seconds after the user mines (slow audio extraction),
@@ -62,7 +78,10 @@ export function handleMultiCopyDigit(
  * line is on screen by then; callers capture here at mining time instead.
  */
 export function captureLiveSubtitleMiningContext(
-  client: Pick<MpvClientLike, 'currentSubText' | 'currentSubStart' | 'currentSubEnd'> | null,
+  client: Pick<
+    MpvClientLike,
+    'currentSubText' | 'currentSubStart' | 'currentSubEnd' | 'currentSubDelay'
+  > | null,
   now: () => number = Date.now,
 ): SubtitleMiningContext | null {
   if (!client) {
@@ -73,7 +92,10 @@ export function captureLiveSubtitleMiningContext(
   if (!text || !Number.isFinite(startTime) || !Number.isFinite(endTime) || endTime <= startTime) {
     return null;
   }
-  return { source: 'overlay', text, startTime, endTime, capturedAtMs: now() };
+  return shiftSubtitleRangeToVideoClock<SubtitleMiningContext>(
+    { source: 'overlay', text, startTime, endTime, capturedAtMs: now() },
+    client.currentSubDelay,
+  );
 }
 
 export function copyCurrentSubtitle(deps: {
@@ -167,6 +189,7 @@ export async function markLastCardAsAudioCard(deps: {
 export async function mineSentenceCard(deps: {
   ankiIntegration: AnkiIntegrationLike | null;
   mpvClient: MpvClientLike | null;
+  /** Already on the video clock, like every `SubtitleMiningContext`. */
   primarySubtitle?: Pick<SubtitleMiningContext, 'text' | 'startTime' | 'endTime'>;
   showMpvOsd: (text: string) => void;
 }): Promise<boolean> {
@@ -185,10 +208,16 @@ export async function mineSentenceCard(deps: {
   }
 
   const secondarySubText = getCurrentSecondarySubTextForSentenceCard(mpvClient, primaryText);
+  const range =
+    deps.primarySubtitle ??
+    shiftSubtitleRangeToVideoClock(
+      { startTime: mpvClient.currentSubStart, endTime: mpvClient.currentSubEnd },
+      mpvClient.currentSubDelay,
+    );
   return await anki.createSentenceCard(
     primaryText,
-    deps.primarySubtitle?.startTime ?? mpvClient.currentSubStart,
-    deps.primarySubtitle?.endTime ?? mpvClient.currentSubEnd,
+    range.startTime,
+    range.endTime,
     secondarySubText,
   );
 }

src/core/services/mpv-properties.ts

@@ -38,6 +38,7 @@ const MPV_SUBTITLE_PROPERTY_OBSERVATIONS: string[] = [
   'path',
   'sub-start',
   'sub-end',
+  'sub-delay',
   'time-pos',
   'secondary-sub-text',
   'aid',

src/core/services/mpv-protocol.test.ts

@@ -73,6 +73,7 @@ function createDeps(overrides: Partial<MpvProtocolHandleMessageDeps> = {}): {
       getCurrentSubStart: () => 0,
       setCurrentSubEnd: () => {},
       getCurrentSubEnd: () => 0,
+      setCurrentSubDelay: () => {},
       emitMediaPathChange: (payload) => {
         state.mediaPath = payload.path;
       },
@@ -131,6 +132,22 @@ test('dispatchMpvProtocolMessage emits subtitle text on property change', async
   assert.deepEqual(state.events, [{ text: '字幕', isOverlayVisible: false }]);
 });
 
+test('dispatchMpvProtocolMessage tracks sub-delay retiming', async () => {
+  const delays: number[] = [];
+  const { deps } = createDeps({ setCurrentSubDelay: (value) => delays.push(value) });
+
+  await dispatchMpvProtocolMessage(
+    { event: 'property-change', name: 'sub-delay', data: 1.5 },
+    deps,
+  );
+  await dispatchMpvProtocolMessage(
+    { event: 'property-change', name: 'sub-delay', data: null },
+    deps,
+  );
+
+  assert.deepEqual(delays, [1.5, 0]);
+});
+
 test('dispatchMpvProtocolMessage widens halfwidth katakana in subtitle text', async () => {
   const { deps, state } = createDeps();
 

src/core/services/mpv-protocol.ts

@@ -64,6 +64,7 @@ export interface MpvProtocolHandleMessageDeps {
   getCurrentSubStart: () => number;
   setCurrentSubEnd: (value: number) => void;
   getCurrentSubEnd: () => number;
+  setCurrentSubDelay: (value: number) => void;
   emitMediaPathChange: (payload: { path: string }) => void;
   emitMediaTitleChange: (payload: { title: string | null }) => void;
   emitTimePosChange: (payload: { time: number }) => void;
@@ -272,6 +273,9 @@ export async function dispatchMpvProtocolMessage(
         start: deps.getCurrentSubStart(),
         end: deps.getCurrentSubEnd(),
       });
+    } else if (msg.name === 'sub-delay') {
+      const delay = typeof msg.data === 'number' ? msg.data : Number(msg.data);
+      deps.setCurrentSubDelay(Number.isFinite(delay) ? delay : 0);
     } else if (msg.name === 'secondary-sub-text') {
       const nextSubText = (msg.data as string) || '';
       deps.setCurrentSecondarySubText(nextSubText);

src/core/services/mpv.ts

@@ -160,6 +160,8 @@ export class MpvIpcClient implements MpvClient {
   public currentTimePos = 0;
   public currentSubStart = 0;
   public currentSubEnd = 0;
+  /** mpv `sub-delay`: seconds each primary line plays after its `sub-start`/`sub-end`. */
+  public currentSubDelay = 0;
   public currentSubText = '';
   public currentSecondarySubText = '';
   public currentAudioStreamIndex: number | null = null;
@@ -459,6 +461,9 @@ export class MpvIpcClient implements MpvClient {
         this.currentSubEnd = value;
       },
       getCurrentSubEnd: () => this.currentSubEnd,
+      setCurrentSubDelay: (value: number) => {
+        this.currentSubDelay = value;
+      },
       emitMediaPathChange: (payload) => {
         this.emit('media-path-change', payload);
       },