fix(subtitles): keep overlapping lines that join an already active cue (#221)

src/core/services/ass-text.test.ts

@@ -218,3 +218,18 @@ test('removeLiveGlyphFragmentLines leaves ordinary short lines alone', () => {
   const text = 'え\nはい。\nそうだな';
   assert.equal(removeLiveGlyphFragmentLines(text), text);
 });
+
+test('normalizePlainSubtitleText folds cue-boundary blank lines for text consumers', () => {
+  // The display layer splits on the blank line before normalizing; everyone else --
+  // tokenizer, cache key, dedup gate, mined sentence -- wants the plain line form.
+  assert.equal(
+    normalizePlainSubtitleText('\u4e00\u884c\u76ee\n\n\u4e8c\u884c\u76ee'),
+    '\u4e00\u884c\u76ee\n\u4e8c\u884c\u76ee',
+  );
+  assert.equal(
+    normalizePlainSubtitleText('\u4e00\u884c\u76ee\n\n\u4e8c\u884c\u76ee', {
+      collapseLineBreaks: true,
+    }),
+    '\u4e00\u884c\u76ee \u4e8c\u884c\u76ee',
+  );
+});

src/core/services/ass-text.ts

@@ -153,6 +153,10 @@ export function normalizePlainSubtitleText(
   );
   if (collapseLineBreaks) {
     normalized = normalized.replace(/\n/g, ' ').replace(/\s+/g, ' ');
+  } else {
+    // Simultaneous cues reach the display layer separated by a blank line; every other
+    // consumer wants the plain one-break-per-line form.
+    normalized = normalized.replace(/\n{2,}/g, '\n');
   }
 
   return trim ? normalized.trim() : normalized;

src/core/services/subtitle-cue-parser.test.ts

@@ -1927,9 +1927,7 @@ test('parseSubtitleCues does not double a line rendered whole beside its glyph s
     ['わ', 1022],
     ['ね', 1064],
   ] as const;
-  const wholeLine = glyphs
-    .map(([glyph]) => `{\\an5\\fad(300,500)\\pos(960,50)}${glyph}`)
-    .join('');
+  const wholeLine = glyphs.map(([glyph]) => `{\\an5\\fad(300,500)\\pos(960,50)}${glyph}`).join('');
   const content = [
     ...eventsHeader,
     `Dialogue: 1,0:00:17.29,0:00:18.99,OP - JP,,0,0,0,,${wholeLine}`,
@@ -1952,7 +1950,7 @@ test('parseSubtitleCues drops a wall of near-invisible positioned texture string
   // faint translation is one or two events and stays published.
   const content = [
     ...eventsHeader,
-    'Dialogue: 90,0:00:12.66,0:00:14.91,Default,,0,0,0,,We\'ll play as a band, and then...',
+    "Dialogue: 90,0:00:12.66,0:00:14.91,Default,,0,0,0,,We'll play as a band, and then...",
     ...Array.from(
       { length: 12 },
       (_, index) =>
@@ -1997,3 +1995,25 @@ test('parseSubtitleCues keeps hidden events hidden when a transform animates an
     ['grows into view', 'wipes into view'],
   );
 });
+
+test('parseAssCues records the vertical band from style alignment, overrides, and \\pos', () => {
+  const ass = [
+    '[Script Info]',
+    'PlayResY: 720',
+    '',
+    '[V4+ Styles]',
+    'Format: Name, Fontname, Fontsize, PrimaryColour, Bold, Alignment, MarginV, Encoding',
+    'Style: Bottom,Arial,54,&H00FFFFFF,0,2,30,1',
+    'Style: TopSong,Arial,54,&H00FFFFFF,0,9,12,1',
+    '',
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,Bottom,,0,0,0,,\u4e0b\u306e\u30bb\u30ea\u30d5',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,TopSong,,0,0,0,,\u6b4c\u8a5e\u306e\u884c',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,Bottom,,0,0,0,,{\\an8}\u4e0a\u66f8\u304d\u306e\u884c',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,Bottom,,0,0,0,,{\\pos(640,20)}\u770b\u677f\u306e\u884c',
+  ].join('\n');
+
+  const bands = parseAssCues(ass).map((cue) => cue.assLayout?.verticalBand);
+  assert.deepEqual(bands, ['bottom', 'top', 'top', 'top']);
+});

src/core/services/subtitle-cue-parser.ts

@@ -10,10 +10,13 @@ import {
 } from './ass-text';
 import { hasAssAnimationEvidence, mergeDuplicateCues } from './subtitle-cue-dedup';
 
+/** Vertical third of the screen a cue is authored to occupy. */
+export type AssVerticalBand = 'top' | 'middle' | 'bottom';
+
 export type AssCueLayout =
-  | { kind: 'positioned'; sourceOrder: number; y: number }
-  | { kind: 'fragment-grid'; sourceOrder: number }
-  | { kind: 'source-order'; sourceOrder: number };
+  | { kind: 'positioned'; sourceOrder: number; y: number; verticalBand?: AssVerticalBand }
+  | { kind: 'fragment-grid'; sourceOrder: number; verticalBand?: AssVerticalBand }
+  | { kind: 'source-order'; sourceOrder: number; verticalBand?: AssVerticalBand };
 
 export interface SubtitleCue {
   startTime: number;
@@ -481,9 +484,7 @@ function structuralOverrideSignature(cue: AnnotatedSubtitleCue): string {
   let signature = structuralSignatureCache.get(cue);
   if (signature === undefined) {
     const names = new Set(
-      cue.overrides.map(
-        (command) => `${command.animated ? '~' : ''}${command.name.toLowerCase()}`,
-      ),
+      cue.overrides.map((command) => `${command.animated ? '~' : ''}${command.name.toLowerCase()}`),
     );
     signature = [...names].sort().join(',');
     structuralSignatureCache.set(cue, signature);
@@ -544,9 +545,7 @@ function buildCoalescedCopy(members: readonly AnnotatedSubtitleCue[]): Annotated
  * while the anchor says one glyph. Merging each stack into a single presence spanning
  * the union window lets timing clusters see the authored line instead of its phases.
  */
-function coalesceAssAnchorCopies(
-  events: readonly AnnotatedSubtitleCue[],
-): AnnotatedSubtitleCue[] {
+function coalesceAssAnchorCopies(events: readonly AnnotatedSubtitleCue[]): AnnotatedSubtitleCue[] {
   const buckets = new Map<string, number[]>();
   const anchorPoints: (AssFragmentPosition[] | null)[] = events.map(() => null);
   events.forEach((event, index) => {
@@ -1362,8 +1361,7 @@ function isRepeatedGlyphText(cue: AnnotatedSubtitleCue): boolean {
 
 function isClippedRepeatedGlyphFragment(cue: AnnotatedSubtitleCue): boolean {
   return (
-    isRepeatedGlyphText(cue) &&
-    (hasStaticOverride(cue, 'clip') || hasStaticOverride(cue, 'iclip'))
+    isRepeatedGlyphText(cue) && (hasStaticOverride(cue, 'clip') || hasStaticOverride(cue, 'iclip'))
   );
 }
 
@@ -2055,6 +2053,111 @@ function recoverCanonicalAssEvents({
   );
 }
 
+function bandFromNumpadAlignment(alignment: number): AssVerticalBand | null {
+  if (alignment >= 7 && alignment <= 9) return 'top';
+  if (alignment >= 4 && alignment <= 6) return 'middle';
+  if (alignment >= 1 && alignment <= 3) return 'bottom';
+  return null;
+}
+
+// SSA v4 alignment reuses the legacy `\a` codes: 1-3 bottom, +4 top, +8 middle.
+function bandFromLegacyAlignment(alignment: number): AssVerticalBand | null {
+  if (alignment >= 9 && alignment <= 11) return 'middle';
+  if (alignment >= 5 && alignment <= 7) return 'top';
+  if (alignment >= 1 && alignment <= 3) return 'bottom';
+  return null;
+}
+
+interface AssPlacementContext {
+  playResY: number | null;
+  /** Lowercased style name -> vertical band from the style's Alignment column. */
+  styleBands: Map<string, AssVerticalBand>;
+}
+
+const EMPTY_PLACEMENT_CONTEXT: AssPlacementContext = { playResY: null, styleBands: new Map() };
+
+function parseAssPlacementContext(content: string): AssPlacementContext {
+  const styleBands = new Map<string, AssVerticalBand>();
+  let playResY: number | null = null;
+  let section: 'info' | 'v4plus' | 'v4' | null = null;
+  let alignmentIndex = -1;
+  let nameIndex = -1;
+
+  for (const line of content.split(/\r?\n/)) {
+    const trimmed = line.trim();
+    if (trimmed.startsWith('[') && trimmed.endsWith(']')) {
+      const sectionName = trimmed.toLowerCase();
+      section =
+        sectionName === '[script info]'
+          ? 'info'
+          : sectionName === '[v4+ styles]'
+            ? 'v4plus'
+            : sectionName === '[v4 styles]'
+              ? 'v4'
+              : null;
+      alignmentIndex = -1;
+      nameIndex = -1;
+      continue;
+    }
+    if (section === 'info') {
+      const resMatch = trimmed.match(/^playresy\s*:\s*(\d+(?:\.\d+)?)\s*$/i);
+      if (resMatch) playResY = Number(resMatch[1]);
+      continue;
+    }
+    if (section !== 'v4plus' && section !== 'v4') continue;
+    const separator = trimmed.indexOf(':');
+    if (separator < 0) continue;
+    const key = trimmed.slice(0, separator).trim().toLowerCase();
+    const fields = trimmed.slice(separator + 1).split(',');
+    if (key === 'format') {
+      const names = fields.map((field) => field.trim().toLowerCase());
+      alignmentIndex = names.indexOf('alignment');
+      nameIndex = names.indexOf('name');
+      continue;
+    }
+    if (key !== 'style' || alignmentIndex < 0 || nameIndex < 0) continue;
+    const styleName = fields[nameIndex]?.trim().toLowerCase();
+    const alignment = Number(fields[alignmentIndex]?.trim());
+    if (!styleName || !Number.isFinite(alignment)) continue;
+    const band =
+      section === 'v4plus'
+        ? bandFromNumpadAlignment(alignment)
+        : bandFromLegacyAlignment(alignment);
+    if (band) styleBands.set(styleName, band);
+  }
+
+  return { playResY, styleBands };
+}
+
+/**
+ * Where on screen mpv will draw this event: an explicit `\pos`/`\move` coordinate when
+ * the script declares its coordinate space, else an `\an`/`\a` override, else the
+ * style's Alignment. Constant for the life of the event, which is what lets simultaneous
+ * lines keep a stable stacking order in the overlay.
+ */
+function resolveVerticalBand(
+  overrides: readonly AssOverrideCommand[],
+  y: number | null,
+  style: string,
+  context: AssPlacementContext,
+): AssVerticalBand | undefined {
+  if (y !== null && context.playResY && context.playResY > 0) {
+    const ratio = y / context.playResY;
+    return ratio < 1 / 3 ? 'top' : ratio < 2 / 3 ? 'middle' : 'bottom';
+  }
+  for (const command of overrides) {
+    if (command.animated) continue;
+    const name = command.name.toLowerCase();
+    if (name !== 'an' && name !== 'a') continue;
+    const band =
+      name === 'an'
+        ? bandFromNumpadAlignment(Number(command.args))
+        : bandFromLegacyAlignment(Number(command.args));
+    if (band) return band;
+  }
+  return context.styleBands.get(style.trim().toLowerCase());
+}
+
 function parseAssCoordinate(value: string | undefined): number | null {
   if (!value?.trim()) return null;
   const coordinate = Number(value.trim());
@@ -2064,6 +2167,8 @@ function parseAssCoordinate(value: string | undefined): number | null {
 function buildAssCueLayout(
   overrides: readonly AssOverrideCommand[],
   sourceOrder: number,
+  style: string,
+  placement: AssPlacementContext,
 ): AssCueLayout {
   let y: number | null = null;
   for (const command of overrides) {
@@ -2081,14 +2186,18 @@ function buildAssCueLayout(
       y = (startY + endY) / 2;
     }
   }
-  return y === null
-    ? { kind: 'source-order', sourceOrder }
-    : { kind: 'positioned', sourceOrder, y };
+  const verticalBand = resolveVerticalBand(overrides, y, style, placement);
+  const base: AssCueLayout =
+    y === null ? { kind: 'source-order', sourceOrder } : { kind: 'positioned', sourceOrder, y };
+  return verticalBand ? { ...base, verticalBand } : base;
 }
 
 function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
   const cues: AnnotatedSubtitleCue[] = [];
   const comments: AnnotatedSubtitleCue[] = [];
+  const placement = content.includes('[')
+    ? parseAssPlacementContext(content)
+    : EMPTY_PLACEMENT_CONTEXT;
   const lines = content.split(/\r?\n/);
   let inEventsSection = false;
   let eventOrder = 0;
@@ -2185,12 +2294,13 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
     const effect = readField(fields, fieldIndex.effect);
     const layer = Number(readField(fields, fieldIndex.layer));
     const overrides = collectAssOverrideCommands(rawText);
+    const style = readField(fields, fieldIndex.style);
     const cue: AnnotatedSubtitleCue = {
       startTime,
       endTime,
       text,
       rawText,
-      style: readField(fields, fieldIndex.style),
+      style,
       layer: Number.isFinite(layer) ? layer : 0,
       name: readField(fields, fieldIndex.name),
       effect,
@@ -2198,7 +2308,7 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
       overrides,
       overrideSignature: assOverrideSignature(overrides),
       order: eventOrder,
-      assLayout: buildAssCueLayout(overrides, eventOrder),
+      assLayout: buildAssCueLayout(overrides, eventOrder, style, placement),
     };
     eventOrder += 1;
     if (eventPrefix === ASS_COMMENT_PREFIX) {

src/core/services/subtitle-processing-controller.ts

@@ -134,7 +134,7 @@ export function createSubtitleProcessingController(
         try {
           const cachedTokenized = getCachedTokenization(text);
           if (cachedTokenized) {
-            output = cachedTokenized;
+            output = { ...cachedTokenized, text };
           } else {
             // Cache miss: show the plain line on time; the tokenized payload
             // upgrades it once ready. Skipped on refreshes of an already
@@ -266,7 +266,7 @@ export function createSubtitleProcessingController(
       lastEmittedText = text;
       lastEmittedGeneration = cacheGeneration;
       lastPlainEmittedText = null;
-      return cached;
+      return { ...cached, text };
     },
     hasCachedSubtitle: (text: string) => {
       const cacheKey = normalizeSubtitleCacheKey(text);

src/core/services/tokenizer.test.ts

@@ -84,6 +84,17 @@ function createDeferred<T>() {
   };
 }
 
+test('tokenizeSubtitle keeps the blank line separating simultaneous cues', async () => {
+  // The tokenized payload's text drives display; folding the cue boundary would merge
+  // two speakers back onto one line the moment tokenization upgrades the plain emit.
+  const result = await tokenizeSubtitle(
+    '\u4e00\u884c\u76ee\n\n\u4e8c\u884c\u76ee',
+    makeDeps({ getYomitanExt: () => null }),
+  );
+
+  assert.equal(result.text, '\u4e00\u884c\u76ee\n\n\u4e8c\u884c\u76ee');
+});
+
 test('tokenizeSubtitle splits same-line grammar endings before applying annotations', async () => {
   const result = await tokenizeSubtitle(
     '猫です',
@@ -1682,6 +1693,12 @@ test('tokenizeSubtitle normalizes newlines before Yomitan parse request', async
   assert.equal(result.tokens, null);
 });
 
+test('tokenizeSubtitle preserves CRLF boundaries between simultaneous cues', async () => {
+  const result = await tokenizeSubtitle('a\r\n\r\nb', makeDeps());
+
+  assert.deepEqual(result, { text: 'a\n\nb', tokens: null });
+});
+
 test('tokenizeSubtitle collapses zero-width separators before Yomitan parse request', async () => {
   let parseInput = '';
   const result = await tokenizeSubtitle(

src/core/services/tokenizer.ts

@@ -887,7 +887,15 @@ export async function tokenizeSubtitle(
   text: string,
   deps: TokenizerServiceDeps,
 ): Promise<SubtitleData> {
-  const displayText = normalizePlainSubtitleText(text);
+  // Normalize per cue group: the blank line separating simultaneous cues is display
+  // structure the payload text must keep, or the tokenized upgrade re-merges lines the
+  // provisional plain emit already showed apart.
+  const displayText = text
+    .replace(/\r\n/g, '\n')
+    .split(/\n{2,}/)
+    .map((part) => normalizePlainSubtitleText(part))
+    .filter(Boolean)
+    .join('\n\n');
 
   // ASS decoding already happened upstream (cue parser for files, mpv for live text), so
   // all this drops is whitespace -- but a whitespace-only line still normalizes to empty.