fix(subtitles): collapse duplicate primary ASS style layers

- Use parsed cues when they fully explain mpv live text
- Preserve unmatched overlapping dialogue and signs

changes/fix-primary-ass-layer-duplication.md

@@ -0,0 +1,4 @@
+type: fixed
+area: subtitles
+
+- Primary ASS subtitles now use the active parsed cue when it fully accounts for mpv's live text, preventing fill, border, blur, and shadow copies of the same full-span lyric from appearing repeatedly while preserving unmatched overlapping dialogue and signs.

docs/architecture/subtitle-overlay-priming.md

@@ -3,7 +3,7 @@
 # Subtitle Overlay Priming
 
 Status: active
-Last verified: 2026-08-17
+Last verified: 2026-08-18
 Owner: Kyle Yasuda
 Read when: debugging subtitle state or blank Linux/X11 overlay windows when the visible overlay is shown or recreated
 
@@ -69,6 +69,11 @@ coming and prefetching would otherwise idle for the rest of the cue.
 
 ## Live Cue Delivery
 
+- Primary live text first resolves recovered canonical ASS animations. Otherwise, when
+  every live mpv line matches an active parsed cue, it uses the parsed cue text so exact
+  full-span style layers appear once instead of repeating for fill, border, blur, and
+  shadow events. Any unmatched live line keeps the complete live stack, preserving
+  dialogue or signs that overlap a lyric.
 - A tokenization cache miss emits the plain cue synchronously. Tokenization remains serialized so
   live work does not contend for Yomitan state.
 - If a newer cue arrives while an older line is still tokenizing, the newer plain cue or empty

src/main/runtime/primary-subtitle-text.test.ts

@@ -1,11 +1,80 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
+import { parseSubtitleCues } from '../../core/services/subtitle-cue-parser';
 import {
   resolveCanonicalPrimarySubtitle,
   resolvePrimarySubtitleText,
   stripCanonicalFragmentLines,
 } from './primary-subtitle-text';
 
+test('resolvePrimarySubtitleText collapses full-span ASS style layers through parsed cues', () => {
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 3,0:22:40.05,0:22:45.76,EDJP,,0,0,0,,{\\fad(400,400)\\bord0\\blur0.8}鏡の奥まで目を凝らして',
+    'Dialogue: 2,0:22:40.05,0:22:45.76,EDJP,,0,0,0,,{\\fad(400,400)}鏡の奥まで目を凝らして',
+    'Dialogue: 1,0:22:40.05,0:22:45.76,EDJP,,0,0,0,,{\\fad(400,400)\\bord6}鏡の奥まで目を凝らして',
+    'Dialogue: 0,0:22:40.05,0:22:45.76,EDJP,,0,0,0,,{\\fad(400,400)\\bord8\\blur4}鏡の奥まで目を凝らして',
+  ].join('\n');
+  const cues = parseSubtitleCues(ass, 'polar-opposites-s01e08.ass');
+
+  assert.deepEqual(cues, [
+    { startTime: 22 * 60 + 40.05, endTime: 22 * 60 + 45.76, text: '鏡の奥まで目を凝らして' },
+  ]);
+
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText: [
+        '鏡の奥まで目を凝らして',
+        '鏡の奥まで目を凝らして',
+        '鏡の奥まで目を凝らして',
+        '鏡の奥まで目を凝らして',
+      ].join('\n'),
+      currentTimeSec: 22 * 60 + 44,
+      cues,
+    }),
+    '鏡の奥まで目を凝らして',
+  );
+});
+
+test('resolvePrimarySubtitleText keeps live text when active parsed cues do not explain it all', () => {
+  const liveText = '普通のセリフ\n鏡の奥まで目を凝らして\n鏡の奥まで目を凝らして';
+
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText,
+      currentTimeSec: 2,
+      cues: [{ startTime: 1, endTime: 3, text: '鏡の奥まで目を凝らして' }],
+    }),
+    liveText,
+  );
+});
+
+test('resolvePrimarySubtitleText combines unique simultaneous parsed cues', () => {
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText: '一行目\n一行目\n二行目\n二行目',
+      currentTimeSec: 2,
+      cues: [
+        { startTime: 1, endTime: 3, text: '一行目' },
+        { startTime: 1, endTime: 3, text: '二行目' },
+      ],
+    }),
+    '一行目\n二行目',
+  );
+});
+
+test('resolvePrimarySubtitleText tolerates stale time-pos at a parsed cue edge', () => {
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText: '新しい行\n新しい行',
+      currentTimeSec: 0.8,
+      cues: [{ startTime: 1, endTime: 3, text: '新しい行' }],
+    }),
+    '新しい行',
+  );
+});
+
 test('resolvePrimarySubtitleText prefers an active canonical cue over flattened mpv glyphs', () => {
   // mpv renders each simultaneously active ASS event on its own sub-text line.
   const text = resolvePrimarySubtitleText({

src/main/runtime/primary-subtitle-text.ts

@@ -3,13 +3,13 @@ import type { SubtitleCue } from '../../types';
 // Slack on top of each cue's recorded animation envelope, for time-pos observation
 // staleness and small user sub-delay offsets. The envelope itself covers how far
 // entrance/exit frames actually run past the authored timing.
-const CANONICAL_ANIMATION_EDGE_TOLERANCE_SECONDS = 1;
+const LIVE_CUE_EDGE_TOLERANCE_SECONDS = 1;
 
 export interface ResolvedPrimarySubtitle {
   text: string;
   startTime: number;
   endTime: number;
-  /** The canonical cues behind `text`, for consumers that record lines individually. */
+  /** The parsed cues behind `text`, for consumers that record lines individually. */
   cues: SubtitleCue[];
 }
 
@@ -30,8 +30,8 @@ function nearbyCanonicalCues(
     }
     const span = animationSpan(cue);
     return (
-      span.end >= currentTimeSec - CANONICAL_ANIMATION_EDGE_TOLERANCE_SECONDS &&
-      span.start <= currentTimeSec + CANONICAL_ANIMATION_EDGE_TOLERANCE_SECONDS
+      span.end >= currentTimeSec - LIVE_CUE_EDGE_TOLERANCE_SECONDS &&
+      span.start <= currentTimeSec + LIVE_CUE_EDGE_TOLERANCE_SECONDS
     );
   });
 }
@@ -40,6 +40,65 @@ function compactWhitespace(text: string): string {
   return text.replace(/\s+/gu, '');
 }
 
+function compactLineSegments(text: string): string[] {
+  return text.split('\n').map(compactWhitespace).filter(Boolean);
+}
+
+/**
+ * Parsed cues have already collapsed exact ASS layers and animation runs. Trust that
+ * cleaner view only when every live mpv line is accounted for by an active parsed cue.
+ * This keeps unrelated concurrent dialogue on the live fallback while removing style
+ * stacks where mpv repeats one full lyric for fill, border, blur, and shadow layers.
+ */
+function resolveActiveParsedPrimarySubtitle(options: {
+  liveText: string;
+  currentTimeSec: number;
+  cues: readonly SubtitleCue[] | null | undefined;
+}): ResolvedPrimarySubtitle | null {
+  if (!Number.isFinite(options.currentTimeSec)) {
+    return null;
+  }
+
+  const liveSegments = compactLineSegments(options.liveText);
+  if (liveSegments.length === 0) {
+    return null;
+  }
+  const liveSegmentSet = new Set(liveSegments);
+  const selected = (options.cues ?? []).filter((cue) => {
+    if (
+      cue.startTime > options.currentTimeSec + LIVE_CUE_EDGE_TOLERANCE_SECONDS ||
+      cue.endTime <= options.currentTimeSec - LIVE_CUE_EDGE_TOLERANCE_SECONDS
+    ) {
+      return false;
+    }
+    const cueSegments = compactLineSegments(cue.text);
+    return cueSegments.length > 0 && cueSegments.every((segment) => liveSegmentSet.has(segment));
+  });
+  if (selected.length === 0) {
+    return null;
+  }
+
+  const parsedSegmentSet = new Set(selected.flatMap((cue) => compactLineSegments(cue.text)));
+  if (!liveSegments.every((segment) => parsedSegmentSet.has(segment))) {
+    return null;
+  }
+
+  const texts: string[] = [];
+  const seen = new Set<string>();
+  for (const cue of selected) {
+    if (!seen.has(cue.text)) {
+      seen.add(cue.text);
+      texts.push(cue.text);
+    }
+  }
+  return {
+    text: texts.join('\n'),
+    startTime: Math.min(...selected.map((cue) => cue.startTime)),
+    endTime: Math.max(...selected.map((cue) => cue.endTime)),
+    cues: selected,
+  };
+}
+
 /**
  * mpv's `sub-text` renders each simultaneously active ASS event on its own line, so
  * while a generated animation plays every live line is a contiguous piece of the
@@ -155,6 +214,8 @@ export function resolvePrimarySubtitleText(options: {
       liveText: options.liveText,
       currentTimeSec: options.currentTimeSec,
       cues: options.cues,
-    })?.text ?? options.liveText
+    })?.text ??
+    resolveActiveParsedPrimarySubtitle(options)?.text ??
+    options.liveText
   );
 }