fix(mining): copy multi-line subtitles backward from current line (#231)

src/core/services/mining.test.ts

@@ -244,6 +244,35 @@ test('handleMultiCopyDigit copies available history and reports truncation', ()
   assert.equal(osd.at(-1), 'Only 2 lines available, copied 2');
 });
 
+test('handleMultiCopyDigit copies backward from the current subtitle after a backward seek', () => {
+  const copied: string[] = [];
+  const tracker = new SubtitleTimingTracker();
+
+  try {
+    tracker.recordSubtitle('A', 1, 2);
+    tracker.recordSubtitle('B', 3, 4);
+    tracker.recordSubtitle('C', 5, 6);
+    tracker.recordSubtitle('B', 3, 4);
+
+    const deps = {
+      subtitleTimingTracker: tracker,
+      writeClipboardText: (text: string) => copied.push(text),
+      showMpvOsd: () => {},
+    };
+
+    handleMultiCopyDigit(1, deps);
+    handleMultiCopyDigit(2, deps);
+
+    assert.deepEqual(copied, ['B', 'A\n\nB']);
+    assert.deepEqual(tracker.getRecentEntries(2), [
+      { displayText: 'A', startTime: 1, endTime: 2, secondaryText: undefined },
+      { displayText: 'B', startTime: 3, endTime: 4, secondaryText: undefined },
+    ]);
+  } finally {
+    tracker.destroy();
+  }
+});
+
 test('handleMineSentenceDigit reports async create failures', async () => {
   const osd: string[] = [];
   const logs: Array<{ message: string; err: unknown }> = [];
@@ -344,6 +373,22 @@ test('handleMineSentenceDigit keeps per-entry timings when subtitle text repeats
   }
 });
 
+test('subtitle timing history preserves adjacent repeated text with distinct timings', () => {
+  const tracker = new SubtitleTimingTracker();
+
+  try {
+    tracker.recordSubtitle('same', 1, 2);
+    tracker.recordSubtitle('same', 3, 4);
+
+    assert.deepEqual(tracker.getRecentEntries(2), [
+      { displayText: 'same', startTime: 1, endTime: 2, secondaryText: undefined },
+      { displayText: 'same', startTime: 3, endTime: 4, secondaryText: undefined },
+    ]);
+  } finally {
+    tracker.destroy();
+  }
+});
+
 test('handleMineSentenceDigit joins per-entry secondary subtitles when available', async () => {
   const created: Array<{ sentence: string; secondarySub?: string }> = [];
   const tracker = new SubtitleTimingTracker();

src/main/runtime/mpv-main-event-main-deps.test.ts

@@ -503,14 +503,21 @@ test('canonical ASS cues replace live glyph spam for display, history, and immer
   assert.deepEqual(timing.slice(3), [{ text: '今　手にある物差しでは', start: 1.2, end: 3.8 }]);
   assert.equal(immersion.length, 3);
 
-  // A jump of exactly the seek threshold counts as a seek, matching the time-pos
-  // handler's own `>=` boundary.
-  handlers.onTimePosUpdate?.(4.5);
-  handlers.onTimePosUpdate?.(2);
+  // Jumping back to a brief previous line moves time-pos by less than the general
+  // seek threshold. It is still a backward seek, so the revisited line records
+  // again; otherwise multi-line copy would keep treating the later line as current.
+  handlers.onTimePosUpdate?.(3.9);
+  handlers.onTimePosUpdate?.(2.9);
   handlers.recordSubtitleTiming('今', 0.8, 1.5);
 
   assert.deepEqual(timing.slice(4), [{ text: '今　手にある物差しでは', start: 1.2, end: 3.8 }]);
 
+  // Tiny time-pos jitter is not a seek and must not re-record the line.
+  handlers.onTimePosUpdate?.(3.0);
+  handlers.onTimePosUpdate?.(2.9);
+  handlers.recordSubtitleTiming('今', 0.8, 1.5);
+  assert.equal(timing.length, 5);
+
   handlers.recordImmersionSubtitleLine('Maid\nCafe', 10, 12);
   handlers.recordSubtitleTiming('Maid\nCafe', 10, 12);
   assert.equal(immersion.length, 3);

src/main/runtime/mpv-main-event-main-deps.ts

@@ -1,6 +1,5 @@
 import { createSubtitleLineDedupGate } from '../../core/services/subtitle-line-dedup-gate';
 import type { MergedToken, SubtitleCue, SubtitleData } from '../../types';
-import { SEEK_LIKE_TIME_DELTA_SECONDS } from './mpv-main-event-actions';
 import {
   resolveCanonicalPrimarySubtitle,
   resolvePrimarySubtitleText,
@@ -115,6 +114,8 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
   // after the change is dropped instead of landing in the next session.
   let subtitleSessionEpoch = 0;
   let lastTimePosForTimingReset: number | null = null;
+  // Small margin so time-pos jitter is not mistaken for a backward seek.
+  const BACKWARD_SEEK_TIMING_RESET_SECONDS = 0.25;
   const canonicalCueKey = (cue: SubtitleCue): string =>
     `${cue.startTime}|${cue.endTime}|${cue.text}`;
   const resetSubtitleDeduplication = (): void => {
@@ -344,13 +345,15 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
       deps.reportJellyfinRemoteProgress(forceImmediate),
     consumeExplicitSeek: deps.consumeExplicitSeek,
     onTimePosUpdate: (time: number) => {
-      // Timing history is a viewing log: after a real backward seek, a rewatched
-      // canonical line should enter it again. Immersion stats keep their
-      // once-per-media deduplication and are not reset here.
+      // Timing history is a viewing log: after any backward seek, a rewatched canonical
+      // line should enter it again so multi-line copy treats it as the current line.
+      // Playback never moves time-pos backward on its own, so even a short jump to a
+      // brief previous line counts. Immersion stats keep their once-per-media
+      // deduplication and are not reset here.
       if (
         Number.isFinite(time) &&
         lastTimePosForTimingReset !== null &&
-        time <= lastTimePosForTimingReset - SEEK_LIKE_TIME_DELTA_SECONDS
+        time <= lastTimePosForTimingReset - BACKWARD_SEEK_TIMING_RESET_SECONDS
       ) {
         recordedTimingCanonicalKeys.clear();
       }

src/subtitle-timing-tracker.ts

@@ -67,8 +67,13 @@ export class SubtitleTimingTracker {
 
     // Check for duplicate of most recent entry (deduplicate adjacent repeats)
     const lastEntry = this.history[this.history.length - 1];
-    if (lastEntry && lastEntry.timingKey === timingKey) {
-      // Update timing to most recent occurrence
+    if (
+      lastEntry &&
+      lastEntry.timingKey === timingKey &&
+      lastEntry.startTime === startTime &&
+      lastEntry.endTime === endTime
+    ) {
+      // Refresh metadata for repeated notifications of the same subtitle event.
       lastEntry.startTime = startTime;
       lastEntry.endTime = endTime;
       lastEntry.secondaryText = displaySecondaryText;
@@ -107,28 +112,20 @@ export class SubtitleTimingTracker {
   }
 
   /**
-   * Get recent subtitle blocks in chronological order.
-   * Returns the last `count` subtitle events (oldest → newest).
+   * Get recent subtitle blocks in timeline order.
+   * Returns up to `count` known subtitle events ending at the current event.
    * Blocks preserve internal line breaks and are joined with blank lines.
    */
   getRecentBlocks(count: number): string[] {
-    if (count <= 0) return [];
-    if (count > this.history.length) {
-      count = this.history.length;
-    }
-    return this.history.slice(-count).map((entry) => entry.displayText);
+    return this.getRecentTimelineEntries(count).map((entry) => entry.displayText);
   }
 
   /**
-   * Get recent subtitle blocks with their original event timings.
-   * Returns the last `count` subtitle events (oldest → newest).
+   * Get recent subtitle blocks with their original event timings in timeline order.
+   * Returns up to `count` known subtitle events ending at the current event.
    */
   getRecentEntries(count: number): SubtitleTimingBlock[] {
-    if (count <= 0) return [];
-    if (count > this.history.length) {
-      count = this.history.length;
-    }
-    return this.history.slice(-count).map((entry) => ({
+    return this.getRecentTimelineEntries(count).map((entry) => ({
       displayText: entry.displayText,
       startTime: entry.startTime,
       endTime: entry.endTime,
@@ -144,6 +141,43 @@ export class SubtitleTimingTracker {
     return lastEntry ? lastEntry.displayText : null;
   }
 
+  private getRecentTimelineEntries(count: number): HistoryEntry[] {
+    if (count <= 0) return [];
+
+    const currentEntry = this.history[this.history.length - 1];
+    if (!currentEntry) return [];
+
+    const timelineEntries: HistoryEntry[] = [];
+    for (const entry of this.history) {
+      const existingIndex = timelineEntries.findIndex((candidate) =>
+        this.isSameSubtitleEvent(candidate, entry),
+      );
+      if (existingIndex === -1) {
+        timelineEntries.push(entry);
+      } else {
+        timelineEntries[existingIndex] = entry;
+      }
+    }
+
+    timelineEntries.sort(
+      (left, right) => left.startTime - right.startTime || left.endTime - right.endTime,
+    );
+    const currentIndex = timelineEntries.findIndex((entry) =>
+      this.isSameSubtitleEvent(entry, currentEntry),
+    );
+    if (currentIndex === -1) return [];
+
+    return timelineEntries.slice(Math.max(0, currentIndex - count + 1), currentIndex + 1);
+  }
+
+  private isSameSubtitleEvent(left: HistoryEntry, right: HistoryEntry): boolean {
+    return (
+      left.timingKey === right.timingKey &&
+      left.startTime === right.startTime &&
+      left.endTime === right.endTime
+    );
+  }
+
   private findFuzzyMatch(text: string): { startTime: number; endTime: number } | null {
     let bestMatch: TimingEntry | null = null;
     let bestScore = 0;