fix(subtitles): improve secondary subtitle extraction and display (#215)

src/renderer/style.css

@@ -1928,10 +1928,6 @@ body.layer-modal #overlay {
   text-align: center;
   font-size: 24px;
   line-height: 1.5;
-  /* Backstop: pathological tracks (karaoke typesetting, sign spam) must never grow
-     the hover-pause band beyond a top strip. ~4 lines at line-height 1.5. */
-  max-height: 6em;
-  overflow: hidden;
   color: #ffffff;
   -webkit-text-stroke: 0.45px rgba(0, 0, 0, 0.7);
   paint-order: stroke fill;

src/renderer/subtitle-render.test.ts

@@ -1424,11 +1424,8 @@ test('subtitle annotation CSS underlines JLPT tokens without changing token colo
   );
 });
 
-test('prepareSecondarySubtitleLines preserves short stacks without layer metadata', () => {
+test('prepareSecondarySubtitleLines collapses exact short copies in stacks', () => {
   assert.deepEqual(prepareSecondarySubtitleLines('Your\\NYour\\NYour\\NYour\\Nmosaic'), [
-    'Your',
-    'Your',
-    'Your',
     'Your',
     'mosaic',
   ]);
@@ -1438,6 +1435,15 @@ test('prepareSecondarySubtitleLines preserves short stacks without layer metadat
   ]);
 });
 
+test('prepareSecondarySubtitleLines collapses exact short sign copies beside dialogue', () => {
+  const liveText = "And for today's sports festival...\nEntrance\nEntrance";
+
+  assert.deepEqual(prepareSecondarySubtitleLines(liveText), [
+    "And for today's sports festival...",
+    'Entrance',
+  ]);
+});
+
 test('prepareSecondarySubtitleLines collapses karaoke syllable spam into one deduped line', () => {
   // Karaoke-typeset OP/ED: one ASS event per syllable, duplicated across layers,
   // joined with \N by mpv's secondary-sub-text.
@@ -1448,10 +1454,10 @@ test('prepareSecondarySubtitleLines collapses karaoke syllable spam into one ded
   assert.deepEqual(prepareSecondarySubtitleLines(karaoke), ['ya This no ma ups']);
 });
 
-test('prepareSecondarySubtitleLines preserves repeated short dialogue without layer metadata', () => {
+test('prepareSecondarySubtitleLines collapses exact repeated short lines', () => {
   const dialogue = ['Wait', 'Wait', 'Wait'];
 
-  assert.deepEqual(prepareSecondarySubtitleLines(dialogue.join('\\N')), dialogue);
+  assert.deepEqual(prepareSecondarySubtitleLines(dialogue.join('\\N')), ['Wait']);
 });
 
 test('prepareSecondarySubtitleLines collapses punctuation variants of a full-sentence fallback', () => {
@@ -1469,6 +1475,10 @@ test('prepareSecondarySubtitleLines preserves short simultaneous dialogue withou
   assert.deepEqual(prepareSecondarySubtitleLines(dialogue.join('\\N')), dialogue);
 });
 
+test('prepareSecondarySubtitleLines preserves distinct short lines with internal whitespace', () => {
+  assert.deepEqual(prepareSecondarySubtitleLines('AB\\NA B'), ['AB', 'A B']);
+});
+
 test('prepareSecondarySubtitleLines keeps normal dialogue lines intact', () => {
   const dialogue = ' I never expected this. \\N\\N But here we are. ';
 
@@ -1490,13 +1500,13 @@ test('prepareSecondarySubtitleLines strips ASS override tags and handles empty i
   assert.deepEqual(prepareSecondarySubtitleLines('{\\an8}'), []);
 });
 
-test('secondary subtitle root CSS caps height so hover-pause band stays a top strip', () => {
+test('secondary subtitle root CSS does not clip long subtitle stacks', () => {
   const srcCssPath = path.join(process.cwd(), 'src', 'renderer', 'style.css');
   const cssText = fs.readFileSync(srcCssPath, 'utf-8');
 
   const secondaryRootBlock = extractClassBlock(cssText, '#secondarySubRoot');
-  assert.match(secondaryRootBlock, /max-height:\s*6em;/);
-  assert.match(secondaryRootBlock, /overflow:\s*hidden;/);
+  assert.doesNotMatch(secondaryRootBlock, /max-height\s*:/);
+  assert.doesNotMatch(secondaryRootBlock, /overflow\s*:\s*hidden/);
 });
 
 test('applySubtitleStyle sets known-word maturity color variables', () => {

src/renderer/subtitle-render.ts

@@ -667,12 +667,17 @@ function isKaraokeLikeLineSet(lines: string[]): boolean {
 }
 
 function collapseFullLineFallbackCopies(lines: string[]): string[] {
-  const seen = new Set<string>();
+  const seenExact = new Set<string>();
+  const seenFlattened = new Set<string>();
   return lines.filter((line) => {
-    const identity = flattenedSecondarySubtitleLineIdentity(line);
-    if (!identity) return true;
-    if (seen.has(identity)) return false;
-    seen.add(identity);
+    const exactIdentity = line.normalize('NFKC');
+    if (seenExact.has(exactIdentity)) return false;
+    seenExact.add(exactIdentity);
+
+    const flattenedIdentity = flattenedSecondarySubtitleLineIdentity(line);
+    if (!flattenedIdentity) return true;
+    if (seenFlattened.has(flattenedIdentity)) return false;
+    seenFlattened.add(flattenedIdentity);
     return true;
   });
 }