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

chore(release): prepare v0.19.4-beta.4
chore(workflow): add release skill
2026-08-23 12:15:28 -07:00 · 2026-08-23 01:56:49 -07:00 · 2026-08-23 01:23:16 -07:00 · 2026-08-23 01:14:03 -07:00 · 2026-08-23 00:58:24 -07:00 · 2026-08-22 23:32:35 -07:00
55 changed files with 1889 additions and 170 deletions
@@ -0,0 +1,34 @@
+---
+name: subminer-release
+description: Prepare, cut, publish, or repair SubMiner stable and prerelease releases. Use for hands-on release work; do not use for general release questions.
+---
+
+# SubMiner release
+
+Carry out the requested release phase using the repository's current release process.
+
+## Source of truth
+
+Read `docs/RELEASING.md` completely before changing files or release state. Treat it as canonical. Read `changes/README.md` when the work touches change fragments or generated release notes.
+
+Do not copy release commands or policy into this skill. If this skill disagrees with the release guide, follow the guide and reconcile the skill before handoff.
+
+## Workflow
+
+1. Identify whether the request is for a stable release, prerelease, release preparation, publication, or repair.
+2. Inspect the current branch, worktree status, package version, pending change fragments, relevant tags, and latest CI state before making changes.
+3. Follow the matching procedure in `docs/RELEASING.md` in order. Review generated changelog and release-note Markdown before it can be committed or published.
+4. Run every required gate for the requested release phase. Do not treat a cheaper test lane as a substitute for the documented release gate.
+5. Before a stable tag, confirm the package and tag versions match and no pending `changes/*.md` fragments remain. Preserve fragments for prereleases as documented.
+6. Report the resulting version, completed checks, local commit and tag state, remote publication state, skipped platform checks, and any remaining manual work.
+
+## Authorization boundaries
+
+- A request to prepare a release stops before commit, tag, push, or remote publication unless the user also authorizes those actions.
+- A clear request to cut or publish a release includes the documented commit, tag, and push steps. Ask before the first remote mutation when the wording is ambiguous.
+- Do not edit an existing GitHub release, publish to the AUR, change secrets, or alter signing configuration unless the user explicitly requests that operation.
+- Do not switch branches without consent.
+
+## Stop conditions
+
+Stop and report the blocker when required CI or a release gate fails, authentication is missing, versions disagree, required artifacts are absent, or the worktree contains unexpected changes that overlap the release. Do not tag or publish a partially verified release.
@@ -49,6 +49,7 @@ tests/*
 !.agents/skills/
 .agents/skills/*
 !.agents/skills/subminer-change-verification/
+!.agents/skills/subminer-release/
 !.agents/skills/subminer-scrum-master/
 .agents/skills/subminer-change-verification/*
 !.agents/skills/subminer-change-verification/SKILL.md
@@ -56,6 +57,8 @@ tests/*
 .agents/skills/subminer-change-verification/scripts/*
 !.agents/skills/subminer-change-verification/scripts/classify_subminer_diff.sh
 !.agents/skills/subminer-change-verification/scripts/verify_subminer_change.sh
+.agents/skills/subminer-release/*
+!.agents/skills/subminer-release/SKILL.md
 .agents/skills/subminer-scrum-master/*
 !.agents/skills/subminer-scrum-master/SKILL.md
 favicon.png
@@ -0,0 +1,4 @@
+type: fixed
+area: subtitles
+
+- Prevented embedded subtitle parsing from starving network playback: mounted SMB/NFS media now uses deduplicated mpv live text, while duplicate extraction requests for local media share one ffmpeg process.
@@ -0,0 +1,4 @@
+type: fixed
+area: overlay
+
+- The macOS window-tracking helper is now built for macOS 12.0+, so the overlay attaches to mpv on older systems (previously the helper required the macOS version of the build machine and crashed on e.g. Ventura, leaving the overlay stuck on "Overlay loading").
@@ -1,4 +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.
+- Primary and secondary ASS subtitles now collapse layered and whitespace variants of full-span lyrics, including when playback starts or seeks into a line, reconstruct fragment-only karaoke per style, preserve authored stack order, keep canonical signs visible for their complete generated animation, navigate song lyrics by sanitized lines instead of generated animation events, and keep sidebar selections on the requested overlapping lyric while preserving unmatched dialogue and signs.
@@ -1,4 +1,4 @@
 type: fixed
 area: overlay

- Secondary subtitles now parse the selected ASS/SRT/VTT source with the primary subtitle deduplication pipeline, preventing layered animation text from appearing several times in the overlay, mined cards, and statistics. Live mpv text remains the fallback for unreadable tracks.
+- Secondary subtitles now parse the selected ASS/SRT/VTT source with the primary subtitle deduplication pipeline, preventing layered animation text from appearing several times in the overlay, mined cards, and statistics. Fragmented ASS karaoke keeps spaces authored at event boundaries instead of joining every word together. Long ASS lines repeated as dialogue and positioned signs are also collapsed when they differ only in whitespace or terminal punctuation. Dense multi-row sign layouts no longer become one concatenated secondary line. Live mpv text remains the fallback for unreadable tracks and applies full-line duplicate filtering before display.
@@ -0,0 +1,4 @@
+type: fixed
+area: overlay
+
+- Secondary subtitle overlays now show every rendered line instead of clipping text after roughly four lines.
@@ -6,7 +6,7 @@ For internal architecture/workflow guidance, use `docs/README.md` at the repo ro

 - [Bun](https://bun.sh)
 - A system `lua` interpreter for `bun run test:launcher` / `bun run test:plugin:src`
- macOS builds compile a Swift helper via `scripts/build-macos-helper.sh` (skip with `SUBMINER_SKIP_MACOS_HELPER_BUILD=1`)
+- macOS builds compile a Swift helper via `scripts/prepare-build-assets.mjs` (skip with `SUBMINER_SKIP_MACOS_HELPER_BUILD=1`)

 ## Setup

@@ -108,8 +108,12 @@ The secondary bar is a compact top-strip region in the same overlay window. It s
 - Quick comprehension checks without leaving the mining flow.
 - Auto-populating the translation field on mined cards - when a card is created, SubMiner uses the secondary subtitle text as the translation field value (unless AI translation is configured to override it).

+For local media, SubMiner can parse supported embedded secondary tracks into timed cues. For remote URLs and files on network mounts, it uses mpv's live secondary subtitle text instead of scanning the media with ffmpeg.
+
 It is controlled by `secondarySub` configuration and shares its lifecycle with the main overlay window. Cycle which track feeds it with `Shift+J`.

+SubMiner collapses duplicate ASS layers in parsed secondary tracks. Exact repeated lines collapse at any length, while distinct simultaneous short lines remain separate. Long dialogue and positioned-sign copies also collapse when they differ only in whitespace or terminal punctuation. Dense multi-row sign layouts, such as translated timetables, are excluded instead of being concatenated into the secondary bar.
+
 ### Display Modes

 Both the primary and secondary subtitle bars share the same three visibility modes, and each can be changed independently at runtime:
@@ -9,7 +9,7 @@ The sidebar is enabled by default. Set `subtitleSidebar.enabled` to `false` if y
 When SubMiner parses the active subtitle source into a cue list, the sidebar becomes available. Toggle it with the `\` key (configurable via `subtitleSidebar.toggleKey`). While open:

 - The active cue is highlighted and kept in view as playback advances (when `autoScroll` is `true`).
- Clicking any cue seeks mpv to that timestamp.
+- Clicking any cue seeks mpv into that line. For overlapping ASS karaoke, SubMiner moves past the previous line's exit animation when the selected cue has enough time remaining.
 - The sidebar stays synchronized with the overlay - media transitions and subtitle source changes update both simultaneously.

 For typeset ASS karaoke and animated signs, SubMiner collapses generated animation frames and repeated full-line color phases before they reach the sidebar. It recovers a clean complete line from a matching timed authoring comment or from full-line events surrounding generated fragments. Ordinary ASS comments, editor notes, alternate lines, repeated dialogue, and separately positioned signs remain distinct.
@@ -3,7 +3,7 @@
 # Subtitle Overlay Priming

 Status: active
-Last verified: 2026-08-18
+Last verified: 2026-08-19
 Owner: Kyle Yasuda
 Read when: debugging subtitle state or blank Linux/X11 overlay windows when the visible overlay is shown or recreated

@@ -71,11 +71,24 @@ coming and prefetching would otherwise idle for the rest of the cue.

 - 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.
+  full-span style layers appear once instead of repeating for fill, border, blur, shadow,
+  or equivalent whitespace variants. 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.
+- The initial `time-pos`, explicit renderer seeks, and later seek-like jumps reprocess mpv's
+  current raw `sub-text` after the new playback time is stored. Explicit intent matters because
+  adjacent subtitle jumps can be shorter than the general seek-distance threshold. This corrects
+  ASS cleanup when mpv delivered the destination subtitle before the destination timestamp.
+- Renderer `sub-seek` commands use the active parsed cue list when available. Simultaneous cues
+  share one boundary, overlapping lyrics advance from the latest active boundary, and mpv's native
+  command remains the fallback when no parsed destination exists. This prevents generated karaoke
+  frames from consuming next/previous subtitle presses.
+- Subtitle sidebar selections seek past the preceding sanitized cue's overlapping exit span when
+  the selected cue has enough time remaining. This keeps direct row selection on the requested
+  karaoke line while clamping the seek inside that cue.
+- If startup paints raw text before embedded ASS parsing finishes, parsed cue arrival may replace
+  that provisional line. The one-prime-per-media guard still suppresses identical repeats.
 - If a newer cue arrives while an older line is still tokenizing, the newer plain cue or empty
  clear payload is emitted immediately. The older tokenization result is dropped before it can
  replace the current cue.
@@ -84,17 +97,36 @@ coming and prefetching would otherwise idle for the rest of the cue.

 ## Secondary Subtitle Flow

- `secondary-sub-text` remains the immediate fallback, so unreadable and remote subtitle sources
-  still appear without waiting for file resolution.
+- `secondary-sub-text` remains the immediate fallback, so unreadable subtitle sources, remote URLs,
+  and files on network mounts still appear without waiting for file resolution. Embedded-track
+  extraction is skipped for those sources to avoid competing with playback for network bandwidth.
+- Parsed secondary text and the live fallback remove exact repeated lines at any length. A
+  flattened-line identity also removes long dialogue/sign repetitions that differ only in
+  whitespace or terminal punctuation, while distinct simultaneous short lines remain separate.
 - `secondary-subtitle-track.ts` resolves `secondary-sid` against mpv's track list. External tracks
  are read directly; supported embedded text tracks are extracted through the same ffmpeg-backed
  source resolver used by primary subtitle prefetching.
 - The selected source is parsed with `parseSubtitleCues()`, including metadata-aware ASS duplicate
  and animation collapse. Playback `time-pos` selects the active parsed cue after applying
  `secondary-sub-delay`.
+- Fragment reconstruction marks positioned parts that span multiple vertical rows as a grid.
+  Secondary text omits those grids instead of flattening a translated table or schedule into one
+  synthetic line. Reconstructed single-line karaoke remains eligible for display.
 - The resolved text is stored in `mpvClient.currentSecondarySubText` before it is broadcast. The
  overlay, mining, timing tracker, and immersion statistics therefore consume the same secondary
  text when a readable source is available.
+- Simultaneous parsed cues use whitespace-insensitive identity, so ASS layers that vary only
+  between ordinary, hard, or ideographic spaces appear once.
+- Simultaneous ASS lines are flattened in top-to-bottom positioned order, falling back to their
+  authored source order when no usable position exists.
+- Fragment-only ASS karaoke is reconstructed per style before publication. Explicit spaces
+  survive concatenation, while scripts that discarded their word boundaries remain compact
+  instead of gaining false spaces between syllables. Short runs qualify only when overlapping
+  positioned events also show changing overrides or repeated layer copies; an English or romaji
+  style name alone never turns ordinary dialogue into a lyric.
+- Recovered canonical ASS text remains active for the generated animation envelope. For
+  reconstructed lyric styles, the longest-lived active line wins over brief entrance and exit
+  fragments from the same style.
 - Media and `secondary-sid` changes clear the previous parsed state before refreshing the source;
  track-list changes refresh without discarding an unchanged source. Observed
  `secondary-sub-delay` changes retime the active parsed cue without rereading the file. If loading,
@@ -19,7 +19,7 @@ Read when: finding internal docs or checking verification status
 | Quality scorecard | `docs/knowledge-base/quality.md` | active | 2026-03-13 | quality grades and gaps |
 | Workflow index | `docs/workflow/README.md` | active | 2026-08-13 | execution map |
 | Planning guide | `docs/workflow/planning.md` | active | 2026-05-23 | lightweight vs execution plans |
-| Agent skills | `docs/workflow/agent-skills.md` | active | 2026-08-13 | repo-local workflow skill ownership |
+| Agent skills | `docs/workflow/agent-skills.md` | active | 2026-08-23 | repo-local workflow skill ownership |
 | Verification guide | `docs/workflow/verification.md` | active | 2026-08-13 | maintained verification lanes |
 | Release guide | `docs/RELEASING.md` | active | 2026-05-23 | release checklist |

@@ -3,7 +3,7 @@
 # Agent Skills

 Status: active
-Last verified: 2026-08-13
+Last verified: 2026-08-23
 Owner: Kyle Yasuda
 Read when: using, adding, or changing a repo-local agent workflow skill

@@ -12,6 +12,9 @@ Read when: using, adding, or changing a repo-local agent workflow skill
 - `.agents/skills/subminer-change-verification/`
  - Selects the cheapest sufficient repo-native verification lane.
  - Defers command ownership to `package.json` and `docs/workflow/verification.md`.
+- `.agents/skills/subminer-release/`
+  - Prepares, cuts, publishes, or repairs stable and prerelease releases.
+  - Defers release procedure and policy to `docs/RELEASING.md`.

 Repo-local workflows stay as standalone skills. Do not add plugin packaging, marketplace metadata, or compatibility shims unless the workflow is intentionally being distributed beyond this repository.

@@ -2,7 +2,7 @@
  "name": "subminer",
  "productName": "SubMiner",
  "desktopName": "SubMiner.desktop",
-  "version": "0.19.4-beta.2",
+  "version": "0.19.4-beta.4",
  "description": "All-in-one sentence mining overlay with AnkiConnect and dictionary integration",
  "packageManager": "bun@1.3.5",
  "main": "dist/main-entry.js",
@@ -6,38 +6,41 @@
 ### Added

 - Library Merge & Reassignment
-  - Duplicate library entries for the same show can now be merged: pick entries in "Select" mode and use "Merge Selected" to combine sessions, mined cards, and watch time onto one card.
-  - Episodes can be moved to a different library entry with a per-episode "→" button, fixing cases where a stray filename split off its own entry; manual assignments now survive later filename parsing, Jellyfin refreshes, and season repair.
-  - Exact AniList matches with compatible seasons now merge automatically, and likely (fuzzy) matches surface as a dismissible "Possible duplicate" suggestion instead of merging silently.
+  - Duplicate library cards for the same show can be combined: select entries in "Select" mode and use "Merge Selected" to combine their sessions, mined cards, and watch time onto one card.
+  - Episodes can be moved to a different entry with a per-episode "→" button, fixing stray files that split off their own entry; manual assignments now survive later filename parsing, Jellyfin refreshes, and season repair.
+  - Exact AniList matches with compatible seasons merge automatically, while likely (fuzzy) matches surface as a dismissible "Possible duplicate" suggestion instead of merging silently.

 - Duplicate Line Cleanup
-  - The Vocabulary tab's new **Duplicates** button scans a chosen time window for the repeated-line bursts described under Fixed below and collapses each burst to a single line once you confirm it; a matching `subminer stats cleanup --duplicate-lines` command (with `--dry-run` and `--lookback-days <n>`) is available from the terminal.
+  - The Vocabulary tab's new **Duplicates** button scans a chosen time window for the repeated-line bursts described under Fixed below and collapses each burst to a single line once confirmed.
+  - A matching `subminer stats cleanup --duplicate-lines` command (with `--dry-run` and `--lookback-days <n>`) is available from the terminal.
  - Only the affected subtitle lines and the vocabulary counts they inflated are touched; watch time and lines-seen totals are left as recorded.

 ### Fixed

 - Subtitle Duplication from Karaoke & Animated Signs
  - Typeset ASS karaoke and animated signs no longer flood the overlay, subtitle sidebar, immersion history, mined cards, or stats with repeated glyph fragments or per-frame duplicates; the complete authored line is recovered instead, without merging genuinely repeated dialogue or separately positioned signs.
-  - The secondary overlay now shares the same deduplication logic as the primary overlay, so layered animation text no longer appears multiple times there or in what gets mined.
-  - Vocabulary stats no longer count every animation frame of a karaoke opening as a separate line, which previously could push an OP lyric to the top of "Top Repeated Words."
+  - Fragmented karaoke now preserves the spaces the author placed between words instead of joining them together, and lyric transitions (including seeking into the middle of a line) resolve to the clean line instead of a stray entrance or exit frame.
+  - The secondary overlay shares the same deduplication logic as the primary overlay, including collapsing lines that differ only by whitespace or trailing punctuation, and sidebar navigation moves between clean lyric lines while keeping the right line selected.

 - Anki Media Generation
  - Sentence-audio generation no longer times out on slow network-mounted video files with many subtitle and font streams, and a failed extraction now reports a clear error instead of a raw `ENOENT`.
  - Mined audio and animated AVIF clips now capture the subtitle line you actually mined, instead of whatever line happened to be on screen once slow audio extraction finished.

 - Character Dictionary Performance & Notifications
-  - Character dictionary generation, merged rebuilds, and imports no longer freeze the app on large dictionaries, and cached results are reused across launches instead of regenerating character data and portraits every time.
+  - Character dictionary generation, merged rebuilds, and imports no longer freeze the app on large dictionaries, and cached results (including character portraits) are reused across launches instead of regenerating everything every time.
+  - Portraits also now display correctly if their cache finishes loading after subtitles have already started showing.
  - Desktop progress notifications, including on Linux AppImage installs, now update in place instead of flickering closed and reopening.

 - Overlay Reliability
-  - Overlay modals (settings, stats, etc.) now open promptly on the first shortcut press and appear above fullscreen mpv on macOS instead of switching Spaces or opening off-screen.
+  - Overlay modals (settings, stats, etc.) now open promptly on the first shortcut press, including on repeated sessions on Windows, and appear above fullscreen mpv on macOS instead of switching Spaces or opening off-screen.
+  - The macOS window-tracking helper is now built for macOS 12.0+, so the overlay attaches to mpv on older systems like Ventura instead of crashing and getting stuck on "Overlay loading."
  - The overlay no longer gets stuck on "Overlay loading" indefinitely if mpv's connection stalls; it now retries and shows an actionable error after 30 seconds.
-  - Fixed native Wayland drag-and-drop from file managers like Thunar, so subtitle and video files dropped on the overlay reach mpv.
-  - Fixed system-wide mouse lag on Windows caused by the overlay's click-through handling and repeated mpv window lookups.
+  - Fixed native Wayland drag-and-drop from file managers like Thunar, and fixed system-wide mouse lag on Windows caused by the overlay's click-through handling.

 - Stats Dashboard
  - Deletes, library merges, video moves, and AniList reassignments no longer freeze the stats dashboard or rebuild lifetime totals from scratch; large deletes that used to take minutes now finish in milliseconds.
-  - Vocabulary totals and charts now count all tracked vocabulary instead of just the first page, new-word history uses corrected daily rollups, calendar labels respect time zones west of UTC, and vocabulary cards refresh automatically after editing the word exclusion list.
+  - Vocabulary totals and charts now count all tracked vocabulary instead of just the first page, and new-word history uses corrected daily rollups.
+  - Calendar labels respect time zones west of UTC, and vocabulary cards refresh automatically after editing the word exclusion list (with a Retry option if a load fails).

 - Linux Launcher Thumbnails
  - Fixed missing MKV thumbnails in the Linux rofi picker when the system thumbnailer only registers legacy Matroska MIME aliases.
@@ -1,54 +0,0 @@
-#!/bin/bash
-# Build macOS window tracking helper binary
-
-set -e
-
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-SWIFT_SOURCE="$SCRIPT_DIR/get-mpv-window-macos.swift"
-OUTPUT_DIR="$SCRIPT_DIR/../dist/scripts"
-OUTPUT_BINARY="$OUTPUT_DIR/get-mpv-window-macos"
-OUTPUT_SOURCE_COPY="$OUTPUT_DIR/get-mpv-window-macos.swift"
-
-fallback_to_source() {
-  echo "Falling back to source fallback: $OUTPUT_SOURCE_COPY"
-  mkdir -p "$OUTPUT_DIR"
-  cp "$SWIFT_SOURCE" "$OUTPUT_SOURCE_COPY"
-}
-
-build_swift_helper() {
-  echo "Compiling macOS window tracking helper..."
-  if ! command -v swiftc >/dev/null 2>&1; then
-    echo "swiftc not found in PATH; skipping compilation."
-    return 1
-  fi
-
-  if ! swiftc -O "$SWIFT_SOURCE" -o "$OUTPUT_BINARY"; then
-    return 1
-  fi
-
-  chmod +x "$OUTPUT_BINARY"
-  echo "✓ Built $OUTPUT_BINARY"
-  return 0
-}
-
-# Optional skip flag for non-macOS CI/dev environments
-if [[ "${SUBMINER_SKIP_MACOS_HELPER_BUILD:-}" == "1" ]]; then
-  echo "Skipping macOS helper build (SUBMINER_SKIP_MACOS_HELPER_BUILD=1)"
-  fallback_to_source
-  exit 0
-fi
-
-# Only build on macOS
-if [[ "$(uname)" != "Darwin" ]]; then
-  echo "Skipping macOS helper build (not on macOS)"
-  fallback_to_source
-  exit 0
-fi
-
-# Create output directory
-mkdir -p "$OUTPUT_DIR"
-
-# Compile Swift script to binary, fallback to source if unavailable or compilation fails
-if ! build_swift_helper; then
-  fallback_to_source
-fi
@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+FILE="${1:-}"
+
+if [[ ! -f "$FILE" ]]; then
+	printf 'Not a file: %s\n' "${FILE:-<missing>}" >&2
+	exit 1
+fi
+
+if ! mpv --no-config --no-terminal --msg-level=all=no --vo=null --ao=null --frames=1 -- "$FILE"; then
+	printf 'Not playable by mpv: %s\n' "$FILE" >&2
+	exit 1
+fi
+
+exec subminer app --dev --launch-mpv "$FILE"
@@ -1,4 +1,5 @@
 import fs from 'node:fs';
+import os from 'node:os';
 import path from 'node:path';
 import { execFileSync } from 'node:child_process';
 import { fileURLToPath } from 'node:url';
@@ -52,6 +53,16 @@ function fallbackToMacosSource() {
  process.stdout.write(`Staged macOS helper source fallback: ${macosHelperSourceCopyPath}\n`);
 }

+// Pin the minimum macOS to the app's own floor (Electron's `minos`). Without an
+// explicit target, swiftc stamps the build machine's OS version as the binary's
+// minimum and the helper fails to load on older systems (#213). The arch stays
+// the host's, matching the single-arch app electron-builder packages here.
+const MACOS_HELPER_DEPLOYMENT_TARGET = '12.0';
+
+function macosHelperTarget() {
+  return `${os.arch() === 'x64' ? 'x86_64' : 'arm64'}-apple-macos${MACOS_HELPER_DEPLOYMENT_TARGET}`;
+}
+
 function shouldSkipMacosHelperBuild() {
  return process.env.SUBMINER_SKIP_MACOS_HELPER_BUILD === '1';
 }
@@ -72,9 +83,13 @@ function buildMacosHelper() {
  ensureDir(scriptsOutputDir);

  try {
-    execFileSync('swiftc', ['-O', macosHelperSourcePath, '-o', macosHelperBinaryPath], {
-      stdio: 'inherit',
-    });
+    execFileSync(
+      'swiftc',
+      ['-O', '-target', macosHelperTarget(), macosHelperSourcePath, '-o', macosHelperBinaryPath],
+      {
+        stdio: 'inherit',
+      },
+    );
    fs.chmodSync(macosHelperBinaryPath, 0o755);
    process.stdout.write(`Built macOS helper: ${macosHelperBinaryPath}\n`);
  } catch (error) {
@@ -8,7 +8,7 @@ test('macOS helper build creates dist scripts directory before swiftc output', (
  const buildFunctionIndex = source.indexOf('function buildMacosHelper()');
  assert.notEqual(buildFunctionIndex, -1);

-  const swiftcIndex = source.indexOf("execFileSync('swiftc'", buildFunctionIndex);
+  const swiftcIndex = source.indexOf("'swiftc'", buildFunctionIndex);
  assert.notEqual(swiftcIndex, -1);

  const ensureDirIndex = source.lastIndexOf('ensureDir(scriptsOutputDir)', swiftcIndex);
@@ -18,3 +18,10 @@ test('macOS helper build creates dist scripts directory before swiftc output', (
    'buildMacosHelper must create dist/scripts before swiftc writes the helper binary',
  );
 });
+
+// Regression guard for #213: an untargeted swiftc stamps the build machine's OS
+// version as the helper's minimum, so released builds refuse to load on older macOS.
+test('macOS helper is compiled with an explicit deployment target', () => {
+  assert.match(source, /-target/);
+  assert.match(source, /apple-macos\$\{MACOS_HELPER_DEPLOYMENT_TARGET\}/);
+});
@@ -50,6 +50,11 @@ export {
 } from './tokenizer/yomitan-parser-runtime';
 export { syncYomitanDefaultAnkiServer } from './tokenizer/yomitan-parser-runtime';
 export { createSubtitleProcessingController } from './subtitle-processing-controller';
+export {
+  resolveSanitizedSubtitleSeekCommand,
+  subtitleCueListSeekTime,
+  subtitleCueSeekTime,
+} from './subtitle-cue-navigation';
 export { createFrequencyDictionaryLookup } from './frequency-dictionary';
 export { createJlptVocabularyLookup } from './jlpt-vocab';
 export {
@@ -0,0 +1,15 @@
+const MIN_FLATTENED_DUPLICATE_LENGTH = 16;
+const TERMINAL_SENTENCE_PUNCTUATION = /[.!?。！？…⋯]+$/gu;
+
+/**
+ * Identifies long lines that become duplicates when positioned ASS events are
+ * flattened into the secondary subtitle bar. Short dialogue stays distinct.
+ */
+export function flattenedSecondarySubtitleLineIdentity(text: string): string | null {
+  const identity = text
+    .normalize('NFKC')
+    .replace(/\s+/gu, '')
+    .replace(TERMINAL_SENTENCE_PUNCTUATION, '');
+
+  return identity.length >= MIN_FLATTENED_DUPLICATE_LENGTH ? identity : null;
+}
@@ -149,8 +149,8 @@ function collectRepeatedPhaseRuns(cues: AnnotatedSubtitleCue[]): RepeatedPhaseRu
      const isFlush =
        Math.abs(next.startTime - current.endTime) <= DUPLICATE_CUE_GAP_TOLERANCE_SECONDS;
      if (
-        first.source === 'canonical-ass' ||
-        next.source === 'canonical-ass' ||
+        first.source !== undefined ||
+        next.source !== undefined ||
        next.text !== first.text ||
        assStyleKey(next) !== styleKey ||
        !isFlush
@@ -223,7 +223,7 @@ function countFramesShorterThan(run: AnnotatedSubtitleCue[], maxSeconds: number)
 * anything wrapped in `\t(...)`), an animated `Effect` column, or a value that actually
 * changes from event to event, which is how per-frame typesetting is authored.
 */
-export function hasAssAnimationEvidence(run: AnnotatedSubtitleCue[]): boolean {
+export function hasAssAnimationEvidence(run: readonly AnnotatedSubtitleCue[]): boolean {
  if (run.every((cue) => hasAssTemporalOverride(cue.overrides))) {
    return true;
  }
@@ -0,0 +1,108 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import {
+  resolveSanitizedSubtitleSeekCommand,
+  subtitleCueListSeekTime,
+  subtitleCueSeekTime,
+} from './subtitle-cue-navigation';
+
+test('next subtitle navigation skips generated ASS events and seeks to the next sanitized cue', () => {
+  const cues = [
+    {
+      startTime: 10,
+      endTime: 13,
+      text: 'first lyric',
+      source: 'canonical-ass' as const,
+      animationStartTime: 9.7,
+      animationEndTime: 13.4,
+    },
+    {
+      startTime: 13,
+      endTime: 16,
+      text: 'second lyric',
+      source: 'canonical-ass' as const,
+      animationStartTime: 12.7,
+      animationEndTime: 16.4,
+    },
+  ];
+
+  assert.deepEqual(resolveSanitizedSubtitleSeekCommand(['sub-seek', 1], cues, 10.2), [
+    'seek',
+    13.08,
+    'absolute+exact',
+  ]);
+});
+
+test('next subtitle navigation treats simultaneous sanitized cues as one line boundary', () => {
+  const cues = [
+    { startTime: 10, endTime: 13, text: 'romaji' },
+    { startTime: 10.02, endTime: 13, text: 'English' },
+    { startTime: 13, endTime: 16, text: 'next romaji' },
+    { startTime: 13.02, endTime: 16, text: 'Next English' },
+  ];
+
+  assert.deepEqual(resolveSanitizedSubtitleSeekCommand(['sub-seek', 1], cues, 10.1), [
+    'seek',
+    13.08,
+    'absolute+exact',
+  ]);
+});
+
+test('next subtitle navigation advances past the latest overlapping lyric', () => {
+  const cues = [
+    { startTime: 10, endTime: 14, text: 'exiting lyric' },
+    { startTime: 13, endTime: 16, text: 'current lyric' },
+    { startTime: 16, endTime: 19, text: 'next lyric' },
+  ];
+
+  assert.deepEqual(resolveSanitizedSubtitleSeekCommand(['sub-seek', 1], cues, 13.2), [
+    'seek',
+    16.08,
+    'absolute+exact',
+  ]);
+});
+
+test('previous subtitle navigation leaves the current cue and seeks to the prior cue', () => {
+  const cues = [
+    { startTime: 10, endTime: 12, text: 'first line' },
+    { startTime: 13, endTime: 16, text: 'current line' },
+  ];
+
+  assert.deepEqual(resolveSanitizedSubtitleSeekCommand(['sub-seek', -1], cues, 14.5), [
+    'seek',
+    10.08,
+    'absolute+exact',
+  ]);
+});
+
+test('subtitle navigation falls back when no sanitized destination exists', () => {
+  const cues = [{ startTime: 10, endTime: 13, text: 'only line' }];
+
+  assert.equal(resolveSanitizedSubtitleSeekCommand(['sub-seek', 1], cues, 10.2), null);
+  assert.equal(resolveSanitizedSubtitleSeekCommand(['seek', 5], cues, 10.2), null);
+});
+
+test('sidebar cue seeks share the boundary-safe sanitized cue timestamp', () => {
+  assert.equal(subtitleCueSeekTime({ startTime: 1, endTime: 2, text: 'line' }), 1.08);
+  assert.equal(subtitleCueSeekTime({ startTime: 1, endTime: 1.04, text: 'short' }), 1.03);
+});
+
+test('sidebar cue selection clears an overlapping previous lyric', () => {
+  const cues = [
+    { startTime: 1, endTime: 3.4, text: 'previous lyric' },
+    { startTime: 3, endTime: 5, text: 'selected lyric' },
+  ];
+
+  assert.equal(subtitleCueListSeekTime(cues, cues[1]!), 3.48);
+});
+
+test('sidebar cue selection remains inside a short cue when overlap cannot be cleared', () => {
+  const cues = [
+    { startTime: 1, endTime: 3.4, text: 'previous lyric' },
+    { startTime: 3, endTime: 3.2, text: 'selected lyric' },
+  ];
+
+  const seekTime = subtitleCueListSeekTime(cues, cues[1]!);
+  assert.ok(seekTime >= 3.19);
+  assert.ok(seekTime < cues[1]!.endTime);
+});
@@ -0,0 +1,128 @@
+import type { SubtitleCue } from './subtitle-cue-parser';
+
+const CUE_START_GROUP_TOLERANCE_SECONDS = 0.05;
+const CUE_BOUNDARY_SEEK_OFFSET_SECONDS = 0.08;
+const CUE_END_GUARD_SECONDS = 0.01;
+
+type CueGroup = {
+  startTime: number;
+  endTime: number;
+  cue: SubtitleCue;
+};
+
+function isValidCue(cue: SubtitleCue): boolean {
+  return (
+    Number.isFinite(cue.startTime) && Number.isFinite(cue.endTime) && cue.endTime > cue.startTime
+  );
+}
+
+function groupCueBoundaries(cues: readonly SubtitleCue[]): CueGroup[] {
+  const sorted = cues.filter(isValidCue).sort((left, right) => {
+    return left.startTime - right.startTime || left.endTime - right.endTime;
+  });
+  const groups: CueGroup[] = [];
+
+  for (const cue of sorted) {
+    const current = groups.at(-1);
+    if (current && cue.startTime - current.startTime <= CUE_START_GROUP_TOLERANCE_SECONDS) {
+      current.endTime = Math.max(current.endTime, cue.endTime);
+      continue;
+    }
+    groups.push({ startTime: cue.startTime, endTime: cue.endTime, cue });
+  }
+
+  return groups;
+}
+
+/** A small offset avoids asking mpv to render exactly on a subtitle boundary. */
+export function subtitleCueSeekTime(cue: SubtitleCue): number {
+  return Math.max(
+    cue.startTime,
+    Math.min(cue.endTime - CUE_END_GUARD_SECONDS, cue.startTime + CUE_BOUNDARY_SEEK_OFFSET_SECONDS),
+  );
+}
+
+/**
+ * Choose a stable point inside a selected cue. Karaoke lines can overlap while the
+ * previous line animates out, so a sidebar selection should clear that overlap when
+ * the selected cue has enough time remaining.
+ */
+export function subtitleCueListSeekTime(
+  cues: readonly SubtitleCue[],
+  selectedCue: SubtitleCue,
+): number {
+  const groups = groupCueBoundaries(cues);
+  const selectedGroupIndex = groups.findIndex(
+    (group) =>
+      selectedCue.startTime >= group.startTime &&
+      selectedCue.startTime - group.startTime <= CUE_START_GROUP_TOLERANCE_SECONDS,
+  );
+  const previousGroupEndTime =
+    selectedGroupIndex > 0 ? groups[selectedGroupIndex - 1]?.endTime : undefined;
+  if (previousGroupEndTime === undefined || previousGroupEndTime <= selectedCue.startTime) {
+    return subtitleCueSeekTime(selectedCue);
+  }
+
+  return Math.max(
+    selectedCue.startTime,
+    Math.min(
+      selectedCue.endTime - CUE_END_GUARD_SECONDS,
+      previousGroupEndTime + CUE_BOUNDARY_SEEK_OFFSET_SECONDS,
+    ),
+  );
+}
+
+/**
+ * Translate mpv subtitle-line navigation onto parsed cues. Generated ASS karaoke can
+ * contain hundreds of subtitle events for one visible line, while the parsed list has
+ * already collapsed those events into the authored lines the user expects to navigate.
+ */
+export function resolveSanitizedSubtitleSeekCommand(
+  command: readonly (string | number)[],
+  cues: readonly SubtitleCue[],
+  currentTimeSec: number,
+): (string | number)[] | null {
+  if (
+    command.length < 2 ||
+    command[0] !== 'sub-seek' ||
+    (command[1] !== -1 && command[1] !== 1) ||
+    !Number.isFinite(currentTimeSec)
+  ) {
+    return null;
+  }
+
+  const groups = groupCueBoundaries(cues);
+  if (groups.length === 0) {
+    return null;
+  }
+
+  let activeIndex = -1;
+  for (const [index, group] of groups.entries()) {
+    if (group.startTime <= currentTimeSec && group.endTime > currentTimeSec) {
+      activeIndex = index;
+    }
+  }
+
+  let destination: CueGroup | undefined;
+  if (command[1] === 1) {
+    destination =
+      activeIndex >= 0
+        ? groups[activeIndex + 1]
+        : groups.find((group) => group.startTime > currentTimeSec);
+  } else if (activeIndex >= 0) {
+    destination = groups[activeIndex - 1];
+  } else {
+    for (let index = groups.length - 1; index >= 0; index -= 1) {
+      const group = groups[index]!;
+      if (group.startTime < currentTimeSec) {
+        destination = group;
+        break;
+      }
+    }
+  }
+
+  if (!destination) {
+    return null;
+  }
+  return ['seek', subtitleCueSeekTime(destination.cue), 'absolute+exact'];
+}
@@ -570,6 +570,63 @@ test('parseSubtitleCues does not promote a short animated fragment as a complete
  );
 });

+test('parseSubtitleCues keeps short animated English dialogue as separate cues', () => {
+  const content = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 0,0:00:01.00,0:00:02.00,English Dialogue,,0,0,0,,{\\t(0,100,\\fscx110)}Hi',
+    'Dialogue: 0,0:00:02.00,0:00:03.00,English Dialogue,,0,0,0,,{\\t(0,100,\\fscx110)}No',
+  ].join('\n');
+
+  assert.deepEqual(parseSubtitleCues(content, 'test.ass'), [
+    { startTime: 1, endTime: 2, text: 'Hi' },
+    { startTime: 2, endTime: 3, text: 'No' },
+  ]);
+});
+
+test('parseSubtitleCues does not reconstruct an already canonical English cue', () => {
+  const content = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Comment: 0,0:00:01.00,0:00:03.00,OP English,,0,0,0,,{\\move(100,100,120,100)}POOF',
+    'Dialogue: 0,0:00:01.00,0:00:01.04,OP English,,0,0,0,,{\\pos(100,100)\\clip(m 1 1)}POOF',
+    'Dialogue: 0,0:00:01.04,0:00:01.08,OP English,,0,0,0,,{\\pos(100,100)\\clip(m 2 2)}POOF',
+    'Dialogue: 0,0:00:01.08,0:00:03.00,OP English,,0,0,0,,{\\pos(100,100)\\clip(m 3 3)}POOF',
+  ].join('\n');
+
+  assert.deepEqual(parseSubtitleCues(content, 'test.ass'), [
+    {
+      startTime: 1,
+      endTime: 3,
+      text: 'POOF',
+      source: 'canonical-ass',
+      animationStartTime: 1,
+      animationEndTime: 3,
+    },
+  ]);
+});
+
+test('parseSubtitleCues reconstructs a short positioned fragment without a lyric style name', () => {
+  const content = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,Karaoke,,0,0,0,,{\\pos(100,100)\\t(0,100,\\fscx110)}Oh',
+    'Dialogue: 1,0:00:01.00,0:00:03.00,Karaoke,,0,0,0,,{\\pos(100,100)\\t(0,100,\\fscx110)}Oh',
+  ].join('\n');
+
+  assert.deepEqual(parseSubtitleCues(content, 'test.ass'), [
+    {
+      startTime: 1,
+      endTime: 3,
+      text: 'Oh',
+      source: 'reconstructed-ass',
+      animationStartTime: 1,
+      animationEndTime: 3,
+      assStyle: 'Karaoke',
+    },
+  ]);
+});
+
 test('parseSubtitleCues ignores timed comments without a matching animated dialogue cluster', () => {
  const content = [
    '[Events]',
@@ -8,19 +8,27 @@ import {
 } from './ass-text';
 import { hasAssAnimationEvidence, mergeDuplicateCues } from './subtitle-cue-dedup';

+export type AssCueLayout =
+  | { kind: 'positioned'; sourceOrder: number; y: number }
+  | { kind: 'fragment-grid'; sourceOrder: number }
+  | { kind: 'source-order'; sourceOrder: number };
+
 export interface SubtitleCue {
  startTime: number;
  endTime: number;
  text: string;
-  /** A complete authored line recovered from matching generated ASS animation events. */
-  source?: 'canonical-ass';
+  /** How a complete line was recovered from generated ASS animation events. */
+  source?: 'canonical-ass' | 'reconstructed-ass';
  /**
-   * Full span of the generated animation events a canonical cue replaced. Entrance and
-   * exit frames routinely run past the authored `startTime`/`endTime`, so live-text
-   * matching must use this envelope while display and history keep the authored timing.
+   * Full span of the generated animation events a recovered cue replaced. Entrance and
+   * exit frames can run past canonical authored timing.
   */
  animationStartTime?: number;
  animationEndTime?: number;
+  /** ASS style retained only for fragment-reconstructed lines. */
+  assStyle?: string;
+  /** Authored ASS ordering metadata used when flattening simultaneous positioned cues. */
+  assLayout?: AssCueLayout;
 }

 /**
@@ -29,7 +37,7 @@ export interface SubtitleCue {
 * override commands it carries, whether the `Effect` column was set -- to tell a karaoke
 * burst apart from two characters saying the same word in turn. None of it is meaningful
 * outside the parser, so the public API exposes only timing, text, and the optional
- * canonical-source marker used by live subtitle consumers.
+ * recovery marker used by live subtitle consumers.
 */
 export interface AnnotatedSubtitleCue extends SubtitleCue {
  /** Text exactly as authored, override blocks and all. */
@@ -75,15 +83,55 @@ function parseTimestamp(
 * line breaks, matching what mpv hands over for the same line played live. No layer
 * downstream decodes ASS again.
 */
+function decodeSubtitleCueText(text: string): string {
+  return assToPlainText(text, '\n').replace(HTML_SUBTITLE_TAG_PATTERN, '');
+}
+
 function sanitizeSubtitleCueText(text: string): string {
-  return assToPlainText(text, '\n').replace(HTML_SUBTITLE_TAG_PATTERN, '').trim();
+  return decodeSubtitleCueText(text).trim();
+}
+
+function attachAssLayout<T extends SubtitleCue>(cue: T, assLayout: AssCueLayout | undefined): T {
+  if (assLayout) {
+    Object.defineProperty(cue, 'assLayout', { value: assLayout, enumerable: false });
+  }
+  return cue;
 }

 function toPublicCues(cues: AnnotatedSubtitleCue[]): SubtitleCue[] {
-  return cues.map(({ startTime, endTime, text, source, animationStartTime, animationEndTime }) =>
-    source
-      ? { startTime, endTime, text, source, animationStartTime, animationEndTime }
-      : { startTime, endTime, text },
+  return cues.map(
+    ({
+      startTime,
+      endTime,
+      text,
+      source,
+      animationStartTime,
+      animationEndTime,
+      style,
+      assLayout,
+    }) => {
+      const common = {
+        startTime,
+        endTime,
+        text,
+      };
+      if (source === 'reconstructed-ass') {
+        return attachAssLayout(
+          {
+            ...common,
+            source,
+            animationStartTime,
+            animationEndTime,
+            assStyle: style,
+          },
+          assLayout,
+        );
+      }
+      return attachAssLayout(
+        source ? { ...common, source, animationStartTime, animationEndTime } : common,
+        assLayout,
+      );
+    },
  );
 }

@@ -159,6 +207,11 @@ const MIN_CANONICAL_ANIMATION_EVENTS = 3;
 // A tiny animated fragment can itself be composed from still smaller glyph events. It is
 // not enough evidence that the fragment represents an authored line boundary.
 const MIN_CANONICAL_DIALOGUE_TEXT_LENGTH = 4;
+const MIN_FRAGMENT_LINE_EVENTS = 8;
+const MIN_FRAGMENT_LINE_PARTS = 4;
+const MAX_FRAGMENT_MEDIAN_LENGTH = 4;
+const MAX_FRAGMENT_LINE_TIMING_VARIANCE_SECONDS = 2;
+const MAX_FRAGMENT_LINE_VERTICAL_SPAN = 48;

 function parseAssTimestamp(raw: string): number | null {
  const match = ASS_TIMING_PATTERN.exec(raw.trim());
@@ -296,6 +349,240 @@ function isRepeatedFragmentCopy(
  );
 }

+function hasRelaxedAssFragmentEvidence(events: readonly AnnotatedSubtitleCue[]): boolean {
+  if (events.length < 2 || !events.every((event) => fragmentPlacementAnchors(event).size > 0)) {
+    return false;
+  }
+
+  const latestStart = events.reduce(
+    (latest, event) => Math.max(latest, event.startTime),
+    -Infinity,
+  );
+  const earliestEnd = events.reduce(
+    (earliest, event) => Math.min(earliest, event.endTime),
+    Infinity,
+  );
+  if (latestStart >= earliestEnd) {
+    return false;
+  }
+
+  const first = events[0]!;
+  const hasChangingOverrides = events.some(
+    (event) => event.overrideSignature !== first.overrideSignature,
+  );
+  const hasPositionedLayerCopy = events.some((event, index) =>
+    events
+      .slice(0, index)
+      .some(
+        (previous) =>
+          compactCueMatchText(previous) === compactCueMatchText(event) &&
+          isRepeatedFragmentCopy(previous, event),
+      ),
+  );
+  return hasChangingOverrides || hasPositionedLayerCopy;
+}
+
+interface AssFragmentPart {
+  cue: AnnotatedSubtitleCue;
+  text: string;
+}
+
+function reconstructedAssFragmentLayout(
+  parts: readonly AssFragmentPart[],
+  owner: AnnotatedSubtitleCue,
+): AssCueLayout | undefined {
+  let positionedPartCount = 0;
+  let minimumY = Infinity;
+  let maximumY = -Infinity;
+  for (const part of parts) {
+    const layout = part.cue.assLayout;
+    if (layout?.kind !== 'positioned') continue;
+    positionedPartCount += 1;
+    minimumY = Math.min(minimumY, layout.y);
+    maximumY = Math.max(maximumY, layout.y);
+  }
+
+  if (
+    positionedPartCount >= MIN_FRAGMENT_LINE_PARTS &&
+    maximumY - minimumY > MAX_FRAGMENT_LINE_VERTICAL_SPAN
+  ) {
+    return { kind: 'fragment-grid', sourceOrder: owner.order };
+  }
+  return owner.assLayout;
+}
+
+interface AssFragmentTimingCluster {
+  events: AnnotatedSubtitleCue[];
+  minStartTime: number;
+  maxStartTime: number;
+  minEndTime: number;
+  maxEndTime: number;
+}
+
+function addToFragmentTimingCluster(
+  cluster: AssFragmentTimingCluster,
+  cue: AnnotatedSubtitleCue,
+): void {
+  cluster.events.push(cue);
+  cluster.minStartTime = Math.min(cluster.minStartTime, cue.startTime);
+  cluster.maxStartTime = Math.max(cluster.maxStartTime, cue.startTime);
+  cluster.minEndTime = Math.min(cluster.minEndTime, cue.endTime);
+  cluster.maxEndTime = Math.max(cluster.maxEndTime, cue.endTime);
+}
+
+function fragmentTimingDistance(
+  cluster: AssFragmentTimingCluster,
+  cue: AnnotatedSubtitleCue,
+): number {
+  const nextMinStart = Math.min(cluster.minStartTime, cue.startTime);
+  const nextMaxStart = Math.max(cluster.maxStartTime, cue.startTime);
+  const nextMinEnd = Math.min(cluster.minEndTime, cue.endTime);
+  const nextMaxEnd = Math.max(cluster.maxEndTime, cue.endTime);
+  if (
+    nextMaxStart - nextMinStart > MAX_FRAGMENT_LINE_TIMING_VARIANCE_SECONDS ||
+    nextMaxEnd - nextMinEnd > MAX_FRAGMENT_LINE_TIMING_VARIANCE_SECONDS
+  ) {
+    return Infinity;
+  }
+  return (
+    Math.abs(cue.startTime - (cluster.minStartTime + cluster.maxStartTime) / 2) +
+    Math.abs(cue.endTime - (cluster.minEndTime + cluster.maxEndTime) / 2)
+  );
+}
+
+function clusterAssFragmentEvents(
+  events: readonly AnnotatedSubtitleCue[],
+): AssFragmentTimingCluster[] {
+  const clusters: AssFragmentTimingCluster[] = [];
+  for (const cue of events) {
+    let nearest: AssFragmentTimingCluster | null = null;
+    let nearestDistance = Infinity;
+    for (const cluster of clusters) {
+      const distance = fragmentTimingDistance(cluster, cue);
+      if (distance < nearestDistance) {
+        nearest = cluster;
+        nearestDistance = distance;
+      }
+    }
+    if (nearest) {
+      addToFragmentTimingCluster(nearest, cue);
+    } else {
+      clusters.push({
+        events: [cue],
+        minStartTime: cue.startTime,
+        maxStartTime: cue.startTime,
+        minEndTime: cue.endTime,
+        maxEndTime: cue.endTime,
+      });
+    }
+  }
+  return clusters;
+}
+
+function decodeSingleAssFragment(cue: AnnotatedSubtitleCue): string | null {
+  const visibleLines = decodeSubtitleCueText(cue.rawText)
+    .split('\n')
+    .filter((line) => line.trim().length > 0);
+  return visibleLines.length === 1 ? visibleLines[0]! : null;
+}
+
+function reconstructAssFragmentLine(
+  events: readonly AnnotatedSubtitleCue[],
+): AnnotatedSubtitleCue | null {
+  const hasRelaxedEvidence = hasRelaxedAssFragmentEvidence(events);
+  const minimumEvents = hasRelaxedEvidence ? 2 : MIN_FRAGMENT_LINE_EVENTS;
+  if (events.length < minimumEvents || !hasAssAnimationEvidence(events)) {
+    return null;
+  }
+
+  const parts: AssFragmentPart[] = [];
+  for (const cue of events) {
+    const text = decodeSingleAssFragment(cue);
+    if (text === null) {
+      return null;
+    }
+    const compactText = compactAssMatchText(text);
+    const isLayerCopy = parts.some(
+      (part) =>
+        compactAssMatchText(part.text) === compactText && isRepeatedFragmentCopy(part.cue, cue),
+    );
+    if (!isLayerCopy) {
+      parts.push({ cue, text });
+    }
+  }
+
+  const minimumParts = hasRelaxedEvidence ? 1 : MIN_FRAGMENT_LINE_PARTS;
+  if (parts.length < minimumParts || (!hasRelaxedEvidence && parts.length === events.length)) {
+    return null;
+  }
+  const lengths = parts
+    .map((part) => compactAssMatchText(part.text).length)
+    .sort((left, right) => left - right);
+  if ((lengths[Math.floor(lengths.length / 2)] ?? Infinity) > MAX_FRAGMENT_MEDIAN_LENGTH) {
+    return null;
+  }
+
+  const text = parts
+    .map((part) => part.text)
+    .join('')
+    .trim();
+  if (!text) {
+    return null;
+  }
+  const owner = parts[0]!.cue;
+  const animationStartTime = earliestStartTime(events);
+  const animationEndTime = latestEndTime(events);
+  return {
+    ...owner,
+    startTime: animationStartTime,
+    endTime: animationEndTime,
+    text,
+    rawText: text,
+    source: 'reconstructed-ass',
+    animationStartTime,
+    animationEndTime,
+    assLayout: reconstructedAssFragmentLayout(parts, owner),
+    overrides: [],
+    overrideSignature: '',
+  };
+}
+
+function recoverFragmentOnlyAssLines(dialogue: AnnotatedSubtitleCue[]): AnnotatedSubtitleCue[] {
+  const groups = new Map<string, AnnotatedSubtitleCue[]>();
+  for (const cue of dialogue) {
+    if (cue.source !== undefined) {
+      continue;
+    }
+    const key = assEventGroupKey(cue);
+    const group = groups.get(key);
+    if (group) {
+      group.push(cue);
+    } else {
+      groups.set(key, [cue]);
+    }
+  }
+
+  const recovered: AnnotatedSubtitleCue[] = [];
+  const suppressed = new Set<AnnotatedSubtitleCue>();
+  for (const events of groups.values()) {
+    for (const cluster of clusterAssFragmentEvents(events)) {
+      const line = reconstructAssFragmentLine(cluster.events);
+      if (!line) {
+        continue;
+      }
+      recovered.push(line);
+      cluster.events.forEach((event) => suppressed.add(event));
+    }
+  }
+  if (recovered.length === 0) {
+    return dialogue;
+  }
+  return [...dialogue.filter((cue) => !suppressed.has(cue)), ...recovered].sort(
+    (left, right) =>
+      left.startTime - right.startTime || left.endTime - right.endTime || left.order - right.order,
+  );
+}
+
 function groupConsecutiveAssFragments(events: readonly AnnotatedSubtitleCue[]): FragmentGroup[] {
  const groups: FragmentGroup[] = [];
  for (const event of events) {
@@ -507,6 +794,37 @@ function recoverCanonicalAssEvents({
  );
 }

+function parseAssCoordinate(value: string | undefined): number | null {
+  if (!value?.trim()) return null;
+  const coordinate = Number(value.trim());
+  return Number.isFinite(coordinate) ? coordinate : null;
+}
+
+function buildAssCueLayout(
+  overrides: readonly AssOverrideCommand[],
+  sourceOrder: number,
+): AssCueLayout {
+  let y: number | null = null;
+  for (const command of overrides) {
+    if (command.animated) continue;
+    const name = command.name.toLowerCase();
+    const args = command.args.split(',');
+    if (name === 'pos') {
+      y = parseAssCoordinate(args[1]) ?? y;
+      continue;
+    }
+    if (name !== 'move') continue;
+    const startY = parseAssCoordinate(args[1]);
+    const endY = parseAssCoordinate(args[3]);
+    if (startY !== null && endY !== null) {
+      y = (startY + endY) / 2;
+    }
+  }
+  return y === null
+    ? { kind: 'source-order', sourceOrder }
+    : { kind: 'positioned', sourceOrder, y };
+}
+
 function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
  const cues: AnnotatedSubtitleCue[] = [];
  const comments: AnnotatedSubtitleCue[] = [];
@@ -535,6 +853,10 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {

  for (const line of lines) {
    const trimmed = line.trim();
+    // Event text can end in an authored space. Fragmented karaoke commonly uses that
+    // space to retain word boundaries when its separately positioned events are joined
+    // back into a line, so only remove indentation before slicing the event fields.
+    const eventLine = line.trimStart();

    if (trimmed.startsWith('[') && trimmed.endsWith(']')) {
      inEventsSection = trimmed.toLowerCase() === '[events]';
@@ -565,9 +887,9 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
      continue;
    }

-    const eventPrefix = trimmed.startsWith(ASS_DIALOGUE_PREFIX)
+    const eventPrefix = eventLine.startsWith(ASS_DIALOGUE_PREFIX)
      ? ASS_DIALOGUE_PREFIX
-      : trimmed.startsWith(ASS_COMMENT_PREFIX)
+      : eventLine.startsWith(ASS_COMMENT_PREFIX)
        ? ASS_COMMENT_PREFIX
        : null;
    if (!eventPrefix) {
@@ -578,7 +900,7 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
      continue;
    }

-    const fields = trimmed.slice(eventPrefix.length).split(',');
+    const fields = eventLine.slice(eventPrefix.length).split(',');
    if (
      fieldIndex.start >= fields.length ||
      fieldIndex.end >= fields.length ||
@@ -615,6 +937,7 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
      overrides,
      overrideSignature: assOverrideSignature(overrides),
      order: eventOrder,
+      assLayout: buildAssCueLayout(overrides, eventOrder),
    };
    eventOrder += 1;
    if (eventPrefix === ASS_COMMENT_PREFIX) {
@@ -628,7 +951,7 @@ function parseAnnotatedAssEvents(content: string): ParsedAssEvents {
 }

 function parseAnnotatedAssCues(content: string): AnnotatedSubtitleCue[] {
-  return recoverCanonicalAssEvents(parseAnnotatedAssEvents(content));
+  return recoverFragmentOnlyAssLines(recoverCanonicalAssEvents(parseAnnotatedAssEvents(content)));
 }

 export function parseAssCues(content: string): SubtitleCue[] {
@@ -312,6 +312,7 @@ import {
  promoteSettingsWindowAboveOverlay,
  registerGlobalShortcuts as registerGlobalShortcutsCore,
  replayCurrentSubtitleRuntime,
+  resolveSanitizedSubtitleSeekCommand,
  resolveJellyfinPlaybackPlanRuntime,
  runStartupBootstrapRuntime,
  saveJellyfinSubtitleDelay,
@@ -587,9 +588,10 @@ import {
 import { buildSubtitleSidebarSourceKey } from './main/runtime/subtitle-prefetch-source';
 import { createSubtitlePrefetchInitController } from './main/runtime/subtitle-prefetch-init';
 import {
+  createCachedInternalSubtitleTrackExtractor,
  loadSubtitleSourceText,
-  extractInternalSubtitleTrackToTempFile,
 } from './main/runtime/internal-subtitle-extraction';
+import { createRemoteMediaPathDetector } from './main/runtime/network-media-path';
 import { applyCharacterDictionarySelection } from './main/character-dictionary-selection';
 import { getSubsyncConfig } from './subsync/utils';

@@ -1958,6 +1960,31 @@ let linuxVisibleOverlayOwnerBindingKey: string | null = null;
 let linuxVisibleOverlayWindowModeSwitchToken = 0;
 let subtitleSidebarRequestedOpen = false;
 const SEEK_THRESHOLD_SECONDS = 3;
+const EXPLICIT_SEEK_INTENT_TTL_MS = 2000;
+let explicitSeekIntentExpiresAtMs = 0;
+
+function isExplicitMpvSeekCommand(command: readonly (string | number)[]): boolean {
+  return command[0] === 'seek' || command[0] === 'sub-seek';
+}
+
+function sendRendererMpvCommand(rawCommand: (string | number)[]): void {
+  const command =
+    resolveSanitizedSubtitleSeekCommand(
+      rawCommand,
+      appState.activeParsedSubtitleCues,
+      appState.mpvClient?.currentTimePos ?? Number.NaN,
+    ) ?? rawCommand;
+  if (isExplicitMpvSeekCommand(command)) {
+    explicitSeekIntentExpiresAtMs = Date.now() + EXPLICIT_SEEK_INTENT_TTL_MS;
+  }
+  sendMpvCommandRuntime(appState.mpvClient, command);
+}
+
+function consumeExplicitSeekIntent(): boolean {
+  const pending = explicitSeekIntentExpiresAtMs >= Date.now();
+  explicitSeekIntentExpiresAtMs = 0;
+  return pending;
+}

 const autoplaySubtitlePrimingRuntime = createAutoplaySubtitlePrimingRuntime({
  getCurrentMediaPath: () => appState.currentMediaPath,
@@ -2028,10 +2055,13 @@ const subtitlePrefetchInitController = createSubtitlePrefetchInitController({
    }
  },
 });
+const cachedInternalSubtitleTrackExtractor = createCachedInternalSubtitleTrackExtractor();
+const detectRemoteMediaPath = createRemoteMediaPathDetector();
 const resolveActiveSubtitleSidebarSourceHandler = createResolveActiveSubtitleSidebarSourceHandler({
  getFfmpegPath: () => configService.getConfig().subsync.ffmpeg_path.trim() || 'ffmpeg',
+  isRemoteMediaPath: detectRemoteMediaPath,
  extractInternalSubtitleTrack: (ffmpegPath, videoPath, track) =>
-    extractInternalSubtitleTrackToTempFile(ffmpegPath, videoPath, track),
+    cachedInternalSubtitleTrackExtractor.extract(ffmpegPath, videoPath, track),
  logDebug: (message) => logger.debug(message),
 });

@@ -2060,8 +2090,8 @@ const refreshSubtitlePrefetchFromActiveTrackHandler =
    // Remote media has no extractable on-disk track to fall back to, so a transient
    // resolve miss (sid briefly 'no', a cycle onto an embedded stream track) would
    // otherwise drop a working cue list for the rest of the episode.
-    shouldKeepExistingCuesOnMissingSource: (videoPath) =>
-      isYoutubeMediaPath(videoPath) || isRemoteMediaPath(videoPath),
+    shouldKeepExistingCuesOnMissingSource: async (videoPath) =>
+      isYoutubeMediaPath(videoPath) || (await detectRemoteMediaPath(videoPath)),
    subtitlePrefetchInitController,
    resolveActiveSubtitleSidebarSource: (input) => resolveActiveSubtitleSidebarSourceHandler(input),
    logDebug: (message) => logger.debug(message),
@@ -3936,6 +3966,7 @@ const {
      appState.yomitanSettingsWindow = null;
    },
    stopJellyfinRemoteSession: () => stopJellyfinRemoteSession(),
+    cleanupInternalSubtitleTrackCache: () => cachedInternalSubtitleTrackExtractor.clear(),
    cleanupYoutubeSubtitleTempDirs: () => youtubeFlowRuntime.cleanupSubtitleTempDirs(),
    cleanupYoutubeMediaCache: () => youtubeMediaCache.cleanup(),
    cleanupJellyfinSubtitleCache: () => cleanupJellyfinSubtitleCache(),
@@ -4496,6 +4527,7 @@ const {
        appState.activeParsedSubtitleMediaPath,
      );
      if ((normalizedPath || null) !== previousPath) {
+        cachedInternalSubtitleTrackExtractor.clear();
        secondarySubtitleTrackController.reset();
        const resetSubtitlePayload = { text: '', tokens: null };
        const frequencyDictionary = configService.getConfig().subtitleStyle.frequencyDictionary;
@@ -4580,6 +4612,7 @@ const {
    reportJellyfinRemoteProgress: (forceImmediate) => {
      void reportJellyfinRemoteProgress(forceImmediate);
    },
+    consumeExplicitSeek: () => consumeExplicitSeekIntent(),
    onTimePosUpdate: (time) => {
      const delta = time - lastObservedTimePos;
      if (subtitlePrefetchService && (delta > SEEK_THRESHOLD_SECONDS || delta < 0)) {
@@ -5485,8 +5518,7 @@ const { registerIpcRuntimeHandlers } = composeIpcRuntimeHandlers({
    showPlaybackFeedback: (text: string) => showConfiguredPlaybackFeedback(text),
    replayCurrentSubtitle: () => replayCurrentSubtitleRuntime(appState.mpvClient),
    playNextSubtitle: () => playNextSubtitleRuntime(appState.mpvClient),
-    sendMpvCommand: (rawCommand: (string | number)[]) =>
-      sendMpvCommandRuntime(appState.mpvClient, rawCommand),
+    sendMpvCommand: (rawCommand: (string | number)[]) => sendRendererMpvCommand(rawCommand),
    getMpvClient: () => appState.mpvClient,
    isMpvConnected: () => Boolean(appState.mpvClient && appState.mpvClient.connected),
    hasRuntimeOptionsManager: () => appState.runtimeOptionsManager !== null,
@@ -183,7 +183,10 @@ test('remote media keeps parsed cues when the active subtitle source cannot be r
  )?.groups?.body;

  assert.ok(actionBlock);
-  assert.match(actionBlock, /isYoutubeMediaPath\(videoPath\) \|\| isRemoteMediaPath\(videoPath\)/);
+  assert.match(
+    actionBlock,
+    /isYoutubeMediaPath\(videoPath\) \|\| \(await detectRemoteMediaPath\(videoPath\)\)/,
+  );
 });

 test('jellyfin subtitle preload seeds the tokenization prefetch directly', () => {
@@ -860,3 +863,18 @@ test('subtitle sidebar snapshot prefers cached YouTube parsed cues before active
      snapshotBlock.indexOf('resolveActiveSubtitleSidebarSourceHandler'),
  );
 });
+
+test('main process guards internal subtitle extraction with the remote media detector', () => {
+  const source = readMainSource();
+  const resolverWiring = source.match(
+    /const resolveActiveSubtitleSidebarSourceHandler = createResolveActiveSubtitleSidebarSourceHandler\(\{(?<body>[\s\S]*?)\n\}\);/,
+  )?.groups?.body;
+
+  assert.ok(resolverWiring);
+  assert.match(source, /const detectRemoteMediaPath = createRemoteMediaPathDetector\(\);/);
+  assert.match(resolverWiring, /isRemoteMediaPath:\s*detectRemoteMediaPath/);
+  assert.match(
+    resolverWiring,
+    /extractInternalSubtitleTrack:[\s\S]*cachedInternalSubtitleTrackExtractor\.extract/,
+  );
+});
@@ -43,6 +43,7 @@ test('on will quit cleanup handler runs all cleanup steps', () => {
    destroyYomitanSettingsWindow: () => calls.push('destroy-yomitan-settings-window'),
    clearYomitanSettingsWindow: () => calls.push('clear-yomitan-settings-window'),
    stopJellyfinRemoteSession: () => calls.push('stop-jellyfin-remote'),
+    cleanupInternalSubtitleTrackCache: () => calls.push('cleanup-internal-subtitles'),
    cleanupYoutubeSubtitleTempDirs: () => calls.push('cleanup-youtube-subtitles'),
    cleanupYoutubeMediaCache: () => calls.push('cleanup-youtube-media'),
    cleanupJellyfinSubtitleCache: () => calls.push('cleanup-jellyfin-subtitles'),
@@ -50,10 +51,11 @@ test('on will quit cleanup handler runs all cleanup steps', () => {
  });

  cleanup();
-  assert.equal(calls.length, 34);
+  assert.equal(calls.length, 35);
  assert.equal(calls[0], 'destroy-tray');
  assert.equal(calls[calls.length - 1], 'stop-discord-presence');
  assert.ok(calls.includes('cleanup-jellyfin-subtitles'));
+  assert.ok(calls.includes('cleanup-internal-subtitles'));
  assert.ok(calls.includes('clear-windows-visible-overlay-poll'));
  assert.ok(calls.includes('clear-linux-mpv-fullscreen-overlay-refresh-timeouts'));
  assert.ok(calls.includes('cleanup-youtube-subtitles'));
@@ -97,6 +99,7 @@ test('on will quit cleanup handler cleans jellyfin subtitle cache when stopping
      calls.push('stop-jellyfin-remote');
      throw new Error('stop failed');
    },
+    cleanupInternalSubtitleTrackCache: () => calls.push('cleanup-internal-subtitles'),
    cleanupYoutubeSubtitleTempDirs: () => calls.push('cleanup-youtube-subtitles'),
    cleanupYoutubeMediaCache: () => calls.push('cleanup-youtube-media'),
    cleanupJellyfinSubtitleCache: () => calls.push('cleanup-jellyfin-subtitles'),
@@ -104,7 +107,11 @@ test('on will quit cleanup handler cleans jellyfin subtitle cache when stopping
  });

  assert.throws(() => cleanup(), /stop failed/);
-  assert.deepEqual(calls, ['stop-jellyfin-remote', 'cleanup-jellyfin-subtitles']);
+  assert.deepEqual(calls, [
+    'stop-jellyfin-remote',
+    'cleanup-jellyfin-subtitles',
+    'cleanup-internal-subtitles',
+  ]);
 });

 test('should restore windows on activate requires initialized runtime and no windows', () => {
@@ -29,6 +29,7 @@ export function createOnWillQuitCleanupHandler(deps: {
  destroyYomitanSettingsWindow: () => void;
  clearYomitanSettingsWindow: () => void;
  stopJellyfinRemoteSession: () => void;
+  cleanupInternalSubtitleTrackCache: () => void;
  cleanupYoutubeSubtitleTempDirs: () => void;
  cleanupYoutubeMediaCache: () => void;
  cleanupJellyfinSubtitleCache: () => void;
@@ -67,7 +68,11 @@ export function createOnWillQuitCleanupHandler(deps: {
    try {
      deps.stopJellyfinRemoteSession();
    } finally {
-      deps.cleanupJellyfinSubtitleCache();
+      try {
+        deps.cleanupJellyfinSubtitleCache();
+      } finally {
+        deps.cleanupInternalSubtitleTrackCache();
+      }
    }
    deps.cleanupYoutubeSubtitleTempDirs();
    deps.cleanupYoutubeMediaCache();
@@ -72,6 +72,7 @@ test('cleanup deps builder returns handlers that guard optional runtime objects'
    clearYomitanSettingsWindow: () => calls.push('clear-yomitan-settings-window'),

    stopJellyfinRemoteSession: () => calls.push('stop-jellyfin-remote'),
+    cleanupInternalSubtitleTrackCache: () => calls.push('cleanup-internal-subtitles'),
    cleanupYoutubeSubtitleTempDirs: () => calls.push('cleanup-youtube-subtitles'),
    cleanupYoutubeMediaCache: () => calls.push('cleanup-youtube-media'),
    cleanupJellyfinSubtitleCache: () => calls.push('cleanup-jellyfin-subtitles'),
@@ -95,6 +96,7 @@ test('cleanup deps builder returns handlers that guard optional runtime objects'
  assert.ok(calls.includes('destroy-first-run-window'));
  assert.ok(calls.includes('destroy-yomitan-settings-window'));
  assert.ok(calls.includes('stop-jellyfin-remote'));
+  assert.ok(calls.includes('cleanup-internal-subtitles'));
  assert.ok(calls.includes('cleanup-youtube-subtitles'));
  assert.ok(calls.includes('cleanup-youtube-media'));
  assert.ok(calls.includes('cleanup-jellyfin-subtitles'));
@@ -152,6 +154,7 @@ test('cleanup deps builder skips destroyed yomitan window', () => {
    getYomitanSettingsWindow: () => null,
    clearYomitanSettingsWindow: () => {},
    stopJellyfinRemoteSession: () => {},
+    cleanupInternalSubtitleTrackCache: () => {},
    cleanupYoutubeSubtitleTempDirs: () => {},
    cleanupYoutubeMediaCache: () => {},
    cleanupJellyfinSubtitleCache: () => {},
@@ -204,6 +207,7 @@ test('cleanup deps builder skips global shortcut cleanup before app ready', () =
    getYomitanSettingsWindow: () => null,
    clearYomitanSettingsWindow: () => {},
    stopJellyfinRemoteSession: () => {},
+    cleanupInternalSubtitleTrackCache: () => {},
    cleanupYoutubeSubtitleTempDirs: () => {},
    cleanupYoutubeMediaCache: () => {},
    cleanupJellyfinSubtitleCache: () => {},
@@ -58,6 +58,7 @@ export function createBuildOnWillQuitCleanupDepsHandler(deps: {
  clearYomitanSettingsWindow: () => void;

  stopJellyfinRemoteSession: () => void;
+  cleanupInternalSubtitleTrackCache: () => void;
  cleanupYoutubeSubtitleTempDirs: () => void;
  cleanupYoutubeMediaCache: () => void;
  cleanupJellyfinSubtitleCache: () => void;
@@ -144,6 +145,7 @@ export function createBuildOnWillQuitCleanupDepsHandler(deps: {
    },
    clearYomitanSettingsWindow: () => deps.clearYomitanSettingsWindow(),
    stopJellyfinRemoteSession: () => deps.stopJellyfinRemoteSession(),
+    cleanupInternalSubtitleTrackCache: () => deps.cleanupInternalSubtitleTrackCache(),
    cleanupYoutubeSubtitleTempDirs: () => deps.cleanupYoutubeSubtitleTempDirs(),
    cleanupYoutubeMediaCache: () => deps.cleanupYoutubeMediaCache(),
    cleanupJellyfinSubtitleCache: () => deps.cleanupJellyfinSubtitleCache(),
@@ -1,5 +1,6 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
+import { parseSubtitleCues } from '../../core/services/subtitle-cue-parser';
 import { createSubtitleProcessingController } from '../../core/services/subtitle-processing-controller';
 import type { SubtitleData } from '../../types';
 import {
@@ -211,6 +212,69 @@ test('primeCurrentSubtitleForAutoplay emits raw first paint on cache miss before
  ]);
 });

+test('parsed cues replace a duplicate raw autoplay subtitle that was already primed', async () => {
+  const rawText = 'ジグザグな道を抜け\nジグザグな道を抜け';
+  const correctedText = 'ジグザグな道を抜け';
+  const mediaPath = '/media/video.mkv';
+  let currentSubText = '';
+  const emitted: string[] = [];
+  const client = {
+    connected: true,
+    currentVideoPath: mediaPath,
+    currentTimePos: 90,
+    currentSubText: rawText,
+    requestProperty: async (name: string) => {
+      if (name === 'sub-text') return rawText;
+      if (name === 'time-pos') return 90;
+      return null;
+    },
+  };
+  const cues = parseSubtitleCues(
+    [
+      '[Events]',
+      'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+      `Dialogue: 1,0:01:29.00,0:01:32.00,EDJP,,0,0,0,,${correctedText}`,
+      `Dialogue: 0,0:01:29.00,0:01:32.00,EDJP,,0,0,0,,${correctedText}`,
+    ].join('\n'),
+    'startup-ending.ass',
+  );
+  let activeCues = cues.slice(0, 0);
+  const runtime = createAutoplaySubtitlePrimingRuntime({
+    getCurrentMediaPath: () => mediaPath,
+    getMpvClient: () => client,
+    setCurrentSubText: (text) => {
+      currentSubText = text;
+    },
+    getCurrentSubText: () => currentSubText,
+    getCurrentSubtitleData: () => null,
+    getActiveParsedSubtitleCues: () => activeCues,
+    setActiveParsedSubtitleMediaPath: () => {},
+    subtitleProcessingController: {
+      consumeCachedSubtitle: () => null,
+      onSubtitleChange: () => true,
+      refreshCurrentSubtitle: () => true,
+      notePlainSubtitleEmitted: () => {},
+    },
+    emitSubtitlePayload: (payload) => emitted.push(payload.text),
+    getSubtitlePrefetchService: () => null,
+    getLastObservedTimePos: () => 90,
+    getVisibleOverlayVisible: () => true,
+    emitSecondarySubtitle: () => {},
+    initSubtitlePrefetch: async () => {},
+    refreshSubtitlePrefetchFromActiveTrack: async () => {},
+    logDebug: () => {},
+  });
+
+  await runtime.primeCurrentSubtitleForAutoplay(mediaPath);
+  assert.equal(currentSubText, rawText);
+
+  activeCues = cues;
+  await runtime.primeAutoplaySubtitleFromParsedCues(mediaPath, cues);
+
+  assert.equal(currentSubText, correctedText);
+  assert.deepEqual(emitted, [rawText, correctedText]);
+});
+
 // Driven by the real processing controller rather than a stub: the failure this
 // covers is a disagreement between the priming path and the controller's own
 // staleness rules, which a hand-written stub cannot reproduce.
@@ -12,6 +12,7 @@ type AutoplaySubtitlePrimingMpvClient = {
  requestProperty: (name: string) => Promise<unknown>;
  currentVideoPath?: string;
  currentTimePos?: number;
+  currentSubText?: string;
  currentSecondarySubText?: string;
  setCurrentSecondarySubText?: (text: string) => void;
 };
@@ -107,11 +108,19 @@ export function createAutoplaySubtitlePrimingRuntime(deps: AutoplaySubtitlePrimi
    autoplaySubtitlePrimedMediaPath = null;
  }

-  function emitAutoplayPrimedSubtitle(mediaPath: string, text: string): boolean {
+  function emitAutoplayPrimedSubtitle(
+    mediaPath: string,
+    text: string,
+    options: { replaceExisting?: boolean } = {},
+  ): boolean {
    if (!text.trim() || !isCurrentAutoplayMediaPath(mediaPath)) {
      return false;
    }
-    if (!markAutoplaySubtitlePrimeConsumed(mediaPath)) {
+    if (autoplaySubtitlePrimedMediaPath === mediaPath) {
+      if (!options.replaceExisting || deps.getCurrentSubText() === text) {
+        return false;
+      }
+    } else if (!markAutoplaySubtitlePrimeConsumed(mediaPath)) {
      return false;
    }

@@ -252,11 +261,7 @@ export function createAutoplaySubtitlePrimingRuntime(deps: AutoplaySubtitlePrimi
    mediaPath: string,
    cues: SubtitleCue[],
  ): Promise<void> {
-    if (
-      cues.length === 0 ||
-      autoplaySubtitlePrimedMediaPath === mediaPath ||
-      !isCurrentAutoplayMediaPath(mediaPath)
-    ) {
+    if (cues.length === 0 || !isCurrentAutoplayMediaPath(mediaPath)) {
      return;
    }

@@ -265,16 +270,21 @@ export function createAutoplaySubtitlePrimingRuntime(deps: AutoplaySubtitlePrimi
    const currentTimeSeconds = Number(
      timePosRaw ?? client?.currentTimePos ?? deps.getLastObservedTimePos() ?? 0,
    );
+    const resolvedTimeSeconds = Number.isFinite(currentTimeSeconds) ? currentTimeSeconds : 0;
    const cue = selectAutoplayStartupCue(
      cues,
-      Number.isFinite(currentTimeSeconds) ? currentTimeSeconds : 0,
+      resolvedTimeSeconds,
      AUTOPLAY_SUBTITLE_PRIME_LOOKAHEAD_SECONDS,
    );
-    if (!cue) {
+    const liveText = client?.currentSubText ?? '';
+    const text = liveText.trim()
+      ? resolvePrimarySubtitleText({ liveText, currentTimeSec: resolvedTimeSeconds, cues })
+      : (cue?.text ?? '');
+    if (!text) {
      return;
    }

-    emitAutoplayPrimedSubtitle(mediaPath, cue.text);
+    emitAutoplayPrimedSubtitle(mediaPath, text, { replaceExisting: true });
  }

  function clearScheduledSubtitlePrefetchRefresh(): void {
@@ -49,6 +49,7 @@ test('composeStartupLifecycleHandlers returns callable startup lifecycle handler
      getYomitanSettingsWindow: () => null,
      clearYomitanSettingsWindow: () => {},
      stopJellyfinRemoteSession: async () => {},
+      cleanupInternalSubtitleTrackCache: () => {},
      cleanupYoutubeSubtitleTempDirs: () => {},
      cleanupYoutubeMediaCache: () => {},
      cleanupJellyfinSubtitleCache: () => {},
@@ -6,6 +6,7 @@ import process from 'node:process';
 import test from 'node:test';
 import {
  buildFfmpegSubtitleExtractionArgs,
+  createCachedInternalSubtitleTrackExtractor,
  extractInternalSubtitleTrackToTempFile,
  parseTrackId,
 } from './internal-subtitle-extraction';
@@ -22,6 +23,65 @@ test('parseTrackId rejects negative track ids', () => {
  assert.equal(parseTrackId(' -2 '), null);
 });

+test('cached internal subtitle extraction shares concurrent and repeated track requests', async () => {
+  let extractionCalls = 0;
+  let cleanupCalls = 0;
+  let resolveExtraction:
+    | ((result: { path: string; cleanup: () => Promise<void> }) => void)
+    | undefined;
+  const firstExtraction = new Promise<{ path: string; cleanup: () => Promise<void> }>((resolve) => {
+    resolveExtraction = resolve;
+  });
+  const extractor = createCachedInternalSubtitleTrackExtractor({
+    extract: async () => {
+      extractionCalls += 1;
+      if (extractionCalls === 1) {
+        return firstExtraction;
+      }
+      return {
+        path: `/tmp/subtitle-${extractionCalls}.ass`,
+        cleanup: async () => {
+          cleanupCalls += 1;
+        },
+      };
+    },
+  });
+  const request = () =>
+    extractor.extract('ffmpeg', '/Volumes/media/episode.mkv', {
+      'ff-index': 3,
+      codec: 'ass',
+    });
+
+  const concurrent = Array.from({ length: 6 }, request);
+  assert.equal(extractionCalls, 1);
+  if (!resolveExtraction) {
+    throw new Error('extraction did not start');
+  }
+  resolveExtraction({
+    path: '/tmp/subtitle-1.ass',
+    cleanup: async () => {
+      cleanupCalls += 1;
+    },
+  });
+
+  const results = await Promise.all(concurrent);
+  assert.deepEqual(
+    results.map((result) => result?.path),
+    Array.from({ length: 6 }, () => '/tmp/subtitle-1.ass'),
+  );
+  await Promise.all(results.map((result) => result?.cleanup()));
+  assert.equal(cleanupCalls, 0);
+
+  assert.equal((await request())?.path, '/tmp/subtitle-1.ass');
+  assert.equal(extractionCalls, 1);
+
+  extractor.clear();
+  await new Promise((resolve) => setImmediate(resolve));
+  assert.equal(cleanupCalls, 1);
+  assert.equal((await request())?.path, '/tmp/subtitle-2.ass');
+  assert.equal(extractionCalls, 2);
+});
+
 test('extractInternalSubtitleTrackToTempFile times out stalled ffmpeg process', async () => {
  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-ffmpeg-timeout-'));
  const videoPath = path.join(root, 'video.mkv');
@@ -35,6 +35,17 @@ export type MpvSubtitleTrackLike = {
  'external-filename'?: unknown;
 };

+export type ExtractedInternalSubtitleTrack = {
+  path: string;
+  cleanup: () => Promise<void>;
+};
+
+export type InternalSubtitleTrackExtractor = (
+  ffmpegPath: string,
+  videoPath: string,
+  track: MpvSubtitleTrackLike,
+) => Promise<ExtractedInternalSubtitleTrack | null>;
+
 const DEFAULT_EXTRACTION_TIMEOUT_MS = 30_000;

 export function parseTrackId(value: unknown): number | null {
@@ -80,7 +91,7 @@ export async function extractInternalSubtitleTrackToTempFile(
  videoPath: string,
  track: MpvSubtitleTrackLike,
  options: { extractionTimeoutMs?: number; spawnArgsOverride?: string[] } = {},
-): Promise<{ path: string; cleanup: () => Promise<void> } | null> {
+): Promise<ExtractedInternalSubtitleTrack | null> {
  const ffIndex = parseTrackId(track['ff-index']);
  const codec = typeof track.codec === 'string' ? track.codec : null;
  const extension = codecToExtension(codec ?? undefined);
@@ -145,3 +156,69 @@ export async function extractInternalSubtitleTrackToTempFile(
    },
  };
 }
+
+type CachedExtraction = {
+  promise: Promise<ExtractedInternalSubtitleTrack | null>;
+};
+
+function buildCachedExtractionKey(
+  ffmpegPath: string,
+  videoPath: string,
+  track: MpvSubtitleTrackLike,
+): string {
+  const codec = typeof track.codec === 'string' ? track.codec : null;
+  return JSON.stringify([ffmpegPath, videoPath, parseTrackId(track['ff-index']), codec]);
+}
+
+const releaseCachedExtraction = async (): Promise<void> => {};
+
+/**
+ * Owns extracted subtitle files for the active media and shares one extraction between callers.
+ * Caller cleanup releases only its view; clear removes the owned files on media changes or quit.
+ */
+export function createCachedInternalSubtitleTrackExtractor(
+  deps: { extract?: InternalSubtitleTrackExtractor } = {},
+): {
+  extract: InternalSubtitleTrackExtractor;
+  clear: () => void;
+} {
+  const extractTrack = deps.extract ?? extractInternalSubtitleTrackToTempFile;
+  const extractions = new Map<string, CachedExtraction>();
+
+  const extract: InternalSubtitleTrackExtractor = async (ffmpegPath, videoPath, track) => {
+    const key = buildCachedExtractionKey(ffmpegPath, videoPath, track);
+    let cached = extractions.get(key);
+    if (!cached) {
+      const next: CachedExtraction = {
+        promise: extractTrack(ffmpegPath, videoPath, track),
+      };
+      cached = next;
+      extractions.set(key, next);
+      void next.promise.catch(() => {
+        if (extractions.get(key) === next) {
+          extractions.delete(key);
+        }
+      });
+    }
+
+    const result = await cached.promise;
+    if (extractions.get(key) !== cached || !result) {
+      return null;
+    }
+
+    return {
+      path: result.path,
+      cleanup: releaseCachedExtraction,
+    };
+  };
+
+  const clear = (): void => {
+    const staleExtractions = [...extractions.values()];
+    extractions.clear();
+    for (const extraction of staleExtractions) {
+      void extraction.promise.then((result) => result?.cleanup()).catch(() => undefined);
+    }
+  };
+
+  return { extract, clear };
+}
@@ -358,6 +358,30 @@ test('time-pos handler forces Jellyfin progress when mpv position jumps', () =>
  ]);
 });

+test('time-pos handler treats an explicit short jump as a seek', () => {
+  const updateKinds: string[] = [];
+  let explicitSeekPending = false;
+  const timeHandler = createHandleMpvTimePosChangeHandler({
+    recordPlaybackPosition: () => {},
+    reportJellyfinRemoteProgress: () => {},
+    refreshDiscordPresence: () => {},
+    maybeRunAnilistPostWatchUpdate: async () => {},
+    consumeExplicitSeek: () => {
+      const pending = explicitSeekPending;
+      explicitSeekPending = false;
+      return pending;
+    },
+    onTimePosUpdate: (_time, kind) => updateKinds.push(kind),
+  });
+
+  timeHandler({ time: 10 });
+  explicitSeekPending = true;
+  timeHandler({ time: 11.5 });
+  timeHandler({ time: 11.6 });
+
+  assert.deepEqual(updateKinds, ['initial', 'seek', 'playback']);
+});
+
 test('time-pos handler passes fresh playback time to AniList post-watch', async () => {
  const watchedSeconds: unknown[] = [];
  const timeHandler = createHandleMpvTimePosChangeHandler({
@@ -4,6 +4,8 @@ type AnilistPostWatchRunOptions = {
  watchedSeconds?: number;
 };

+type TimePosUpdateKind = 'initial' | 'playback' | 'seek';
+
 /** Jump size that marks a time-pos change as a seek rather than normal playback. */
 export const SEEK_LIKE_TIME_DELTA_SECONDS = 2.5;

@@ -138,12 +140,20 @@ export function createHandleMpvTimePosChangeHandler(deps: {
  refreshDiscordPresence: () => void;
  maybeRunAnilistPostWatchUpdate?: (options?: AnilistPostWatchRunOptions) => Promise<void>;
  logError?: (message: string, error: unknown) => void;
-  onTimePosUpdate?: (time: number) => void;
+  onTimePosUpdate?: (time: number, kind: TimePosUpdateKind) => void;
+  consumeExplicitSeek?: () => boolean;
 }) {
  let lastObservedTime: number | null = null;

  return ({ time }: { time: number }): void => {
-    const forceImmediate = isSeekLikeTimeChange(lastObservedTime, time);
+    const explicitSeek = deps.consumeExplicitSeek?.() ?? false;
+    const updateKind: TimePosUpdateKind =
+      lastObservedTime === null
+        ? 'initial'
+        : explicitSeek || isSeekLikeTimeChange(lastObservedTime, time)
+          ? 'seek'
+          : 'playback';
+    const forceImmediate = updateKind === 'seek';
    if (Number.isFinite(time)) {
      lastObservedTime = time;
    }
@@ -153,7 +163,7 @@ export function createHandleMpvTimePosChangeHandler(deps: {
    void deps.maybeRunAnilistPostWatchUpdate?.({ watchedSeconds: time }).catch((error) => {
      deps.logError?.('AniList post-watch update failed unexpectedly', error);
    });
-    deps.onTimePosUpdate?.(time);
+    deps.onTimePosUpdate?.(time, updateKind);
  };
 }

@@ -1,10 +1,23 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
+import { parseSubtitleCues } from '../../core/services/subtitle-cue-parser';
 import { createBindMpvMainEventHandlersHandler } from './mpv-main-event-bindings';
+import { resolvePrimarySubtitleText } from './primary-subtitle-text';

 test('main mpv event binder wires callbacks through to runtime deps', () => {
  const handlers = new Map<string, (payload: unknown) => void>();
  const calls: string[] = [];
+  let currentTime = 0;
+  const seekLiveText = '少しだけ好きになる\n少しだけ好きになる';
+  const seekCues = parseSubtitleCues(
+    [
+      '[Events]',
+      'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+      'Dialogue: 1,0:01:29.00,0:01:32.00,EDJP,,0,0,0,,少しだけ好きになる',
+      'Dialogue: 0,0:01:29.00,0:01:32.00,EDJP,,0,0,0,,少しだけ好きになる',
+    ].join('\n'),
+    'seek-ending.ass',
+  );

  const bind = createBindMpvMainEventHandlersHandler({
    reportJellyfinRemoteStopped: () => calls.push('remote-stopped'),
@@ -27,6 +40,9 @@ test('main mpv event binder wires callbacks through to runtime deps', () => {
      calls.push(`post-watch:${options?.watchedSeconds ?? 'none'}`);
    },
    logSubtitleTimingError: () => calls.push('subtitle-error'),
+    resolveSubtitleText: (liveText) =>
+      resolvePrimarySubtitleText({ liveText, currentTimeSec: currentTime, cues: seekCues }),
+    getCurrentLiveSubtitleText: () => seekLiveText,
    setCurrentSubText: (text) => calls.push(`set-sub:${text}`),
    getImmediateSubtitlePayload: (text) => ({ text, tokens: [] }),
    broadcastSubtitle: (payload) => calls.push(`broadcast-sub:${payload.text}`),
@@ -60,6 +76,9 @@ test('main mpv event binder wires callbacks through to runtime deps', () => {
    recordMediaDuration: (duration) => calls.push(`duration:${duration}`),
    reportJellyfinRemoteProgress: (forceImmediate) =>
      calls.push(`progress:${forceImmediate ? 'force' : 'normal'}`),
+    onTimePosUpdate: (time) => {
+      currentTime = time;
+    },
    recordPauseState: (paused) => calls.push(`pause:${paused ? 'yes' : 'no'}`),

    updateSubtitleRenderMetrics: () => calls.push('subtitle-metrics'),
@@ -83,7 +102,13 @@ test('main mpv event binder wires callbacks through to runtime deps', () => {
  handlers.get('media-path-change')?.({ path: '' });
  handlers.get('media-title-change')?.({ title: 'Episode 1' });
  handlers.get('subtitle-timing')?.({ text: 'timed line', start: 899, end: 901 });
+  handlers.get('subtitle-change')?.({ text: seekLiveText });
+  handlers.get('time-pos-change')?.({ time: 90 });
+  assert.ok(calls.includes('set-sub:少しだけ好きになる'));
+
  handlers.get('time-pos-change')?.({ time: 2.5 });
+  handlers.get('subtitle-change')?.({ text: seekLiveText });
+  handlers.get('time-pos-change')?.({ time: 90 });
  handlers.get('pause-change')?.({ paused: true });

  assert.ok(calls.includes('set-sub:line'));
@@ -44,6 +44,7 @@ export function createBindMpvMainEventHandlersHandler(deps: {

  setCurrentSubText: (text: string) => void;
  resolveSubtitleText?: (text: string) => string;
+  getCurrentLiveSubtitleText?: () => string;
  getImmediateSubtitlePayload?: (text: string) => SubtitleData | null;
  emitImmediateSubtitle?: (payload: SubtitleData) => void;
  broadcastSubtitle: (payload: SubtitleData) => void;
@@ -78,6 +79,7 @@ export function createBindMpvMainEventHandlersHandler(deps: {
  recordMediaDuration: (durationSec: number) => void;
  reportJellyfinRemoteProgress: (forceImmediate: boolean) => void;
  onTimePosUpdate?: (time: number) => void;
+  consumeExplicitSeek?: () => boolean;
  onFullscreenChange?: (fullscreen: boolean) => void;
  recordPauseState: (paused: boolean) => void;

@@ -171,7 +173,15 @@ export function createBindMpvMainEventHandlersHandler(deps: {
      refreshDiscordPresence: () => deps.refreshDiscordPresence(),
      maybeRunAnilistPostWatchUpdate: (options) => deps.maybeRunAnilistPostWatchUpdate(options),
      logError: (message, error) => deps.logSubtitleTimingError(message, error),
-      onTimePosUpdate: (time) => deps.onTimePosUpdate?.(time),
+      consumeExplicitSeek: deps.consumeExplicitSeek,
+      onTimePosUpdate: (time, updateKind) => {
+        deps.onTimePosUpdate?.(time);
+        if (updateKind === 'playback') return;
+        const liveText = deps.getCurrentLiveSubtitleText?.();
+        if (liveText !== undefined) {
+          handleMpvSubtitleChange({ text: liveText });
+        }
+      },
    });
    const handleMpvPauseChange = createHandleMpvPauseChangeHandler({
      recordPauseState: (paused) => deps.recordPauseState(paused),
@@ -21,6 +21,7 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
    overlayRuntimeInitialized: boolean;
    mpvClient: {
      connected?: boolean;
+      currentSubText?: string;
      currentSecondarySubText?: string;
      currentTimePos?: number;
      requestProperty?: (name: string) => Promise<unknown>;
@@ -85,6 +86,7 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
  resetAnilistMediaGuessState: () => void;
  reportJellyfinRemoteProgress: (forceImmediate: boolean) => void;
  onTimePosUpdate?: (time: number) => void;
+  consumeExplicitSeek?: () => boolean;
  onFullscreenChange?: (fullscreen: boolean) => void;
  updateSubtitleRenderMetrics: (patch: Record<string, unknown>) => void;
  refreshDiscordPresence: () => void;
@@ -160,6 +162,7 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
        currentTimeSec: Number(deps.appState.mpvClient?.currentTimePos),
        cues: deps.appState.activeParsedSubtitleCues,
      }),
+    getCurrentLiveSubtitleText: () => deps.appState.mpvClient?.currentSubText ?? '',
    recordImmersionSubtitleLine: (text: string, start: number, end: number) => {
      deps.ensureImmersionTrackerInitialized();
      const tracker = deps.appState.immersionTracker;
@@ -332,6 +335,7 @@ export function createBuildBindMpvMainEventHandlersMainDepsHandler(deps: {
    },
    reportJellyfinRemoteProgress: (forceImmediate: boolean) =>
      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
@@ -0,0 +1,64 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { createRemoteMediaPathDetector } from './network-media-path';
+
+test('remote media detector recognizes mounted network filesystems', async () => {
+  const detectRemoteMedia = createRemoteMediaPathDetector({
+    platform: 'darwin',
+    readMountOutput: async () =>
+      [
+        '/dev/disk3s5 on /System/Volumes/Data (apfs, local, journaled)',
+        '//viewer@media/jellyfin on /Volumes/jellyfin (smbfs, nodev, nosuid)',
+      ].join('\n'),
+  });
+
+  assert.equal(await detectRemoteMedia('/Volumes/jellyfin/movie.mkv'), true);
+  assert.equal(await detectRemoteMedia('/Volumes/jellyfin-another/movie.mkv'), false);
+  assert.equal(await detectRemoteMedia('/Users/viewer/movie.mkv'), false);
+});
+
+test('remote media detector recognizes Linux network mount output', async () => {
+  const detectRemoteMedia = createRemoteMediaPathDetector({
+    platform: 'linux',
+    readMountOutput: async () =>
+      '//media/jellyfin on /mnt/Jellyfin\\040Media type cifs (rw,relatime)',
+  });
+
+  assert.equal(await detectRemoteMedia('/mnt/Jellyfin Media/movie.mkv'), true);
+});
+
+test('remote media detector shares its mount lookup between concurrent callers', async () => {
+  let mountReads = 0;
+  const detectRemoteMedia = createRemoteMediaPathDetector({
+    platform: 'darwin',
+    readMountOutput: async () => {
+      mountReads += 1;
+      return '//viewer@media/jellyfin on /Volumes/jellyfin (smbfs, nodev, nosuid)';
+    },
+  });
+
+  const results = await Promise.all(
+    Array.from({ length: 6 }, () => detectRemoteMedia('/Volumes/jellyfin/movie.mkv')),
+  );
+
+  assert.deepEqual(
+    results,
+    Array.from({ length: 6 }, () => true),
+  );
+  assert.equal(mountReads, 1);
+});
+
+test('remote media detector recognizes URLs and Windows UNC paths without reading mounts', async () => {
+  let mountReads = 0;
+  const detectRemoteMedia = createRemoteMediaPathDetector({
+    platform: 'win32',
+    readMountOutput: async () => {
+      mountReads += 1;
+      return '';
+    },
+  });
+
+  assert.equal(await detectRemoteMedia('https://media.example/movie.mkv'), true);
+  assert.equal(await detectRemoteMedia('\\\\media-server\\jellyfin\\movie.mkv'), true);
+  assert.equal(mountReads, 0);
+});
@@ -0,0 +1,142 @@
+import { execFile } from 'node:child_process';
+import path from 'node:path';
+import process from 'node:process';
+import { resolveSubtitleSourcePath } from './subtitle-prefetch-source';
+
+const DEFAULT_MOUNT_CACHE_TTL_MS = 5_000;
+const NETWORK_FILESYSTEM_TYPES = new Set([
+  '9p',
+  'afpfs',
+  'cifs',
+  'davfs',
+  'davfs2',
+  'fuse.sshfs',
+  'nfs',
+  'nfs4',
+  'smbfs',
+  'sshfs',
+  'webdav',
+]);
+
+function isRemoteUrl(value: string): boolean {
+  try {
+    const url = new URL(value);
+    return url.protocol === 'http:' || url.protocol === 'https:';
+  } catch {
+    return false;
+  }
+}
+
+function decodeMountPath(value: string): string {
+  return value.replace(/\\([0-7]{3})/g, (_match, digits: string) =>
+    String.fromCharCode(Number.parseInt(digits, 8)),
+  );
+}
+
+function parseNetworkMountPaths(output: string): string[] {
+  const networkMountPaths: string[] = [];
+  for (const line of output.split('\n')) {
+    const optionsStart = line.lastIndexOf(' (');
+    if (optionsStart < 0) continue;
+
+    let mountDescription = line.slice(0, optionsStart);
+    const options = line.slice(optionsStart + 2, line.indexOf(')', optionsStart));
+    const linuxTypeSeparator = mountDescription.lastIndexOf(' type ');
+    const filesystemType = (
+      linuxTypeSeparator >= 0
+        ? mountDescription.slice(linuxTypeSeparator + ' type '.length)
+        : (options.split(',').at(0) ?? '')
+    )
+      .trim()
+      .toLowerCase();
+    if (!NETWORK_FILESYSTEM_TYPES.has(filesystemType)) continue;
+
+    if (linuxTypeSeparator >= 0) {
+      mountDescription = mountDescription.slice(0, linuxTypeSeparator);
+    }
+    const mountSeparator = mountDescription.indexOf(' on ');
+    if (mountSeparator < 0) continue;
+    networkMountPaths.push(
+      path.posix.normalize(decodeMountPath(mountDescription.slice(mountSeparator + 4).trim())),
+    );
+  }
+  return networkMountPaths;
+}
+
+function readMountOutput(platform: NodeJS.Platform): Promise<string> {
+  if (platform === 'win32') return Promise.resolve('');
+  const command = platform === 'darwin' ? '/sbin/mount' : 'mount';
+  return new Promise((resolve, reject) => {
+    execFile(
+      command,
+      [],
+      { encoding: 'utf8', timeout: 1_000, maxBuffer: 1024 * 1024 },
+      (error, stdout) => {
+        if (error) {
+          reject(error);
+          return;
+        }
+        resolve(stdout);
+      },
+    );
+  });
+}
+
+function isPathWithinMount(filePath: string, mountPath: string): boolean {
+  const relativePath = path.posix.relative(mountPath, filePath);
+  return (
+    relativePath === '' ||
+    (relativePath !== '..' &&
+      !relativePath.startsWith(`..${path.posix.sep}`) &&
+      !path.posix.isAbsolute(relativePath))
+  );
+}
+
+export type RemoteMediaPathDetector = (mediaPath: string) => Promise<boolean>;
+
+export function createRemoteMediaPathDetector(
+  deps: {
+    platform?: NodeJS.Platform;
+    readMountOutput?: () => Promise<string>;
+    now?: () => number;
+    mountCacheTtlMs?: number;
+  } = {},
+): RemoteMediaPathDetector {
+  const platform = deps.platform ?? process.platform;
+  const getMountOutput = deps.readMountOutput ?? (() => readMountOutput(platform));
+  const now = deps.now ?? Date.now;
+  const mountCacheTtlMs = deps.mountCacheTtlMs ?? DEFAULT_MOUNT_CACHE_TTL_MS;
+  let mountCache: { expiresAt: number; networkMountPaths: Promise<readonly string[]> } | undefined;
+
+  const getNetworkMountPaths = (): Promise<readonly string[]> => {
+    const currentTime = now();
+    if (mountCache && currentTime < mountCache.expiresAt) {
+      return mountCache.networkMountPaths;
+    }
+
+    const networkMountPaths = getMountOutput()
+      .then(parseNetworkMountPaths)
+      .catch(() => []);
+    mountCache = {
+      expiresAt: currentTime + mountCacheTtlMs,
+      networkMountPaths,
+    };
+    return networkMountPaths;
+  };
+
+  return async (mediaPath): Promise<boolean> => {
+    const source = mediaPath.trim();
+    if (!source) return false;
+    if (isRemoteUrl(source)) return true;
+
+    const filePath = resolveSubtitleSourcePath(source);
+    if (platform === 'win32') {
+      return filePath.startsWith('\\\\');
+    }
+    if (!path.posix.isAbsolute(filePath)) return false;
+
+    const networkMountPaths = await getNetworkMountPaths();
+    const normalizedPath = path.posix.normalize(filePath);
+    return networkMountPaths.some((mountPath) => isPathWithinMount(normalizedPath, mountPath));
+  };
+}
@@ -64,6 +64,30 @@ test('resolvePrimarySubtitleText combines unique simultaneous parsed cues', () =
  );
 });

+test('resolvePrimarySubtitleText collapses whitespace variants of one ASS lyric', () => {
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 2,0:00:01.00,0:00:03.00,EDJP,,0,0,0,,少しだけ好きになる',
+    'Dialogue: 1,0:00:01.00,0:00:03.00,EDJP,,0,0,0,,少しだけ\\h好きになる',
+    'Dialogue: 0,0:00:01.00,0:00:03.00,EDJP,,0,0,0,,少しだけ　好きになる',
+  ].join('\n');
+  const cues = parseSubtitleCues(ass, 'polar-opposites-s01e10.ass');
+
+  assert.deepEqual(
+    cues.map((cue) => cue.text),
+    ['少しだけ好きになる', '少しだけ 好きになる', '少しだけ　好きになる'],
+  );
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText: ['少しだけ好きになる', '少しだけ 好きになる', '少しだけ　好きになる'].join('\n'),
+      currentTimeSec: 2,
+      cues,
+    }),
+    '少しだけ好きになる',
+  );
+});
+
 test('resolvePrimarySubtitleText tolerates stale time-pos at a parsed cue edge', () => {
  assert.equal(
    resolvePrimarySubtitleText({
@@ -184,6 +208,20 @@ test('resolvePrimarySubtitleText combines simultaneous canonical cues in source
  assert.equal(text, 'first\nsecond');
 });

+test('resolvePrimarySubtitleText collapses whitespace variants of a canonical lyric', () => {
+  assert.equal(
+    resolvePrimarySubtitleText({
+      liveText: '少しだけ好きになる\n少しだけ　好きになる',
+      currentTimeSec: 2,
+      cues: [
+        { startTime: 1, endTime: 3, text: '少しだけ好きになる', source: 'canonical-ass' },
+        { startTime: 1, endTime: 3, text: '少しだけ　好きになる', source: 'canonical-ass' },
+      ],
+    }),
+    '少しだけ好きになる',
+  );
+});
+
 test('resolveCanonicalPrimarySubtitle covers a nearby generated animation edge', () => {
  const cue = {
    startTime: 1.2,
@@ -25,7 +25,7 @@ function nearbyCanonicalCues(
  currentTimeSec: number,
 ): SubtitleCue[] {
  return (cues ?? []).filter((cue) => {
-    if (cue.source !== 'canonical-ass') {
+    if (cue.source !== 'canonical-ass' && cue.source !== 'reconstructed-ass') {
      return false;
    }
    const span = animationSpan(cue);
@@ -40,6 +40,21 @@ function compactWhitespace(text: string): string {
  return text.replace(/\s+/gu, '');
 }

+// ASS layers can encode the same visible spacing with ordinary, hard, or
+// ideographic spaces. Matching and emission must use the same identity or each
+// layer reappears as a copy.
+function uniqueCueTexts(cues: readonly SubtitleCue[]): string[] {
+  const texts: string[] = [];
+  const seen = new Set<string>();
+  for (const cue of cues) {
+    const compactText = compactWhitespace(cue.text);
+    if (seen.has(compactText)) continue;
+    seen.add(compactText);
+    texts.push(cue.text);
+  }
+  return texts;
+}
+
 function compactLineSegments(text: string): string[] {
  return text.split('\n').map(compactWhitespace).filter(Boolean);
 }
@@ -83,14 +98,7 @@ function resolveActiveParsedPrimarySubtitle(options: {
    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);
-    }
-  }
+  const texts = uniqueCueTexts(selected);
  return {
    text: texts.join('\n'),
    startTime: Math.min(...selected.map((cue) => cue.startTime)),
@@ -159,14 +167,7 @@ export function resolveCanonicalPrimarySubtitle(options: {
    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);
-    }
-  }
+  const texts = uniqueCueTexts(selected);
  return {
    text: texts.join('\n'),
    startTime: Math.min(...selected.map((cue) => cue.startTime)),
@@ -20,6 +20,229 @@ test('findActiveSubtitleText combines unique simultaneous parsed cues', () => {
  );
 });

+test('findActiveSubtitleText collapses whitespace variants of one ASS lyric', () => {
+  assert.equal(
+    findActiveSubtitleText(
+      [
+        { startTime: 1, endTime: 3, text: '少しだけ好きになる' },
+        { startTime: 1, endTime: 3, text: '少しだけ 好きになる' },
+        { startTime: 1, endTime: 3, text: '少しだけ　好きになる' },
+      ],
+      2,
+    ),
+    '少しだけ好きになる',
+  );
+});
+
+test('parsed secondary text collapses a positioned sign that repeats dialogue without punctuation', () => {
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 10,0:03:58.49,0:04:00.34,GJM_Main_1080p,Nar,0,0,0,,{\\i1}A question veiled as an insult!',
+    'Dialogue: 1,0:03:58.59,0:04:00.34,iFanzSigns,,0,0,0,,{\\pos(960,75)}A question veiled as an insult',
+  ].join('\n');
+  const cues = parseSubtitleCues(ass, 'kaguya-s02e10.ass');
+
+  assert.equal(findActiveSubtitleText(cues, 238.48), '');
+  assert.equal(findActiveSubtitleText(cues, 238.5), 'A question veiled as an insult!');
+  assert.equal(findActiveSubtitleText(cues, 239), 'A question veiled as an insult!');
+  assert.equal(findActiveSubtitleText(cues, 240.34), '');
+});
+
+test('parsed secondary text drops a reconstructed grid of positioned sign fragments', () => {
+  const signFragment = (text: string, x: number, y: number) =>
+    `Dialogue: 1,0:00:01.00,0:00:03.00,Signs,,0,0,0,,{\\pos(${x},${y})\\t(0,100,\\fscx101)}${text}`;
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 10,0:00:01.00,0:00:03.00,Default,Speaker,0,0,0,,Come on, wake up!',
+    signFragment('Timetable', 1700, 150),
+    signFragment('Mon', 1750, 230),
+    signFragment('Tue', 1850, 230),
+    signFragment('1', 1650, 320),
+    signFragment('2', 1650, 390),
+    signFragment('Civics', 1750, 320),
+    signFragment('Math', 1850, 390),
+    signFragment('PE', 1850, 460),
+  ].join('\n');
+
+  assert.equal(
+    findActiveSubtitleText(parseSubtitleCues(ass, 'kaguya-s02e11.ass'), 2),
+    'Come on, wake up!',
+  );
+});
+
+test('parsed secondary lyrics keep explicit ASS vertical order when durations alternate', () => {
+  const lyric = (options: { start: string; end: string; style: string; y: number; text: string }) =>
+    `Dialogue: 0,0:00:${options.start},0:00:${options.end},${options.style},,0,0,0,fx,{\\move(100,${options.y},120,${options.y})\\t(0,200,\\fscx110)}${options.text}\\N{\\p1}m 0 0 l 0 5`;
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    lyric({
+      start: '01.00',
+      end: '02.20',
+      style: 'ed_romaji',
+      y: 66,
+      text: 'ima wo kakusarechau mae ni',
+    }),
+    lyric({
+      start: '01.00',
+      end: '02.00',
+      style: 'ed_english',
+      y: 1020,
+      text: 'Before the present moment gets hidden away.',
+    }),
+    lyric({
+      start: '03.00',
+      end: '04.00',
+      style: 'ed_romaji',
+      y: 66,
+      text: 'ame mitai ni hikatteru',
+    }),
+    lyric({
+      start: '03.00',
+      end: '04.20',
+      style: 'ed_english',
+      y: 1020,
+      text: 'Is shining like rain.',
+    }),
+  ].join('\n');
+  const cues = parseSubtitleCues(ass, 'polar-opposites-s01e08.ass');
+
+  assert.equal(
+    findActiveSubtitleText(cues, 1.5),
+    'ima wo kakusarechau mae ni\nBefore the present moment gets hidden away.',
+  );
+  assert.equal(findActiveSubtitleText(cues, 3.5), 'ame mitai ni hikatteru\nIs shining like rain.');
+});
+
+test('unpositioned secondary lyrics fall back to ASS source order', () => {
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    'Dialogue: 0,0:00:01.00,0:00:02.20,ED Romaji,,0,0,0,,ima wo kakusarechau mae ni',
+    'Dialogue: 0,0:00:01.00,0:00:02.00,ED English,,0,0,0,,Before the present moment gets hidden away.',
+  ].join('\n');
+
+  assert.equal(
+    findActiveSubtitleText(parseSubtitleCues(ass, 'ending.ass'), 1.5),
+    'ima wo kakusarechau mae ni\nBefore the present moment gets hidden away.',
+  );
+});
+
+test('findActiveSubtitleText keeps a canonical ASS cue for its generated animation span', () => {
+  const poof = {
+    startTime: 1110.67,
+    endTime: 1110.71,
+    text: 'POOF',
+    source: 'canonical-ass' as const,
+    animationStartTime: 1110.67,
+    animationEndTime: 1111.59,
+  };
+
+  assert.equal(findActiveSubtitleText([poof], 1111.58), 'POOF');
+  assert.equal(findActiveSubtitleText([poof], 1111.59), '');
+});
+
+test('ASS fragment karaoke stays separated by style with authored word spacing', () => {
+  const lineEvents = (
+    style: string,
+    fragments: readonly string[],
+    y: number,
+    baseTime = 1,
+  ): string[] => {
+    const events: string[] = [];
+    for (const layer of [0, 1]) {
+      fragments.forEach((fragment, index) => {
+        const x = 100 + index * 40;
+        const start = (baseTime + index * 0.25).toFixed(2).padStart(5, '0');
+        const end = (baseTime + 3 + index * 0.2).toFixed(2).padStart(5, '0');
+        events.push(
+          `Dialogue: ${layer},0:00:${start},0:00:${end},${style},,0,0,0,,{\\pos(${x},${y})\\t(0,200,\\fscx110)}${fragment}\\N{\\p1}m 0 0 l 0 10`,
+        );
+      });
+    }
+    return events;
+  };
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    ...lineEvents('ed_romaji', ['ji', 'gu', 'za', 'gu ', 'na', 'mi'], 70),
+    ...lineEvents('ed_english', ['Pas', 'si', 'ng ', 'thro', 'u', 'gh '], 110),
+    ...lineEvents('op_english', ['I', 'want', 'to', 'go'], 110, 7),
+  ].join('\n');
+
+  assert.equal(
+    findActiveSubtitleText(parseSubtitleCues(ass, 'ending.ass'), 2.5),
+    'jiguzagu nami\nPassing through',
+  );
+  // Some generated scripts discard spaces and retain only positioned chunks. Joining
+  // without invented separators avoids turning one word into spaced syllables.
+  assert.equal(findActiveSubtitleText(parseSubtitleCues(ass, 'ending.ass'), 8.5), 'Iwanttogo');
+});
+
+test('ASS fragment karaoke preserves word spaces authored at event boundaries', () => {
+  const fragments = [
+    'The ',
+    'shoot',
+    'ing ',
+    'stars ',
+    'arc',
+    'ing ',
+    'across ',
+    'the ',
+    'sky ',
+    'I ',
+    'wish ',
+    'upon,',
+  ];
+  const events: string[] = [];
+  for (const layer of [0, 1]) {
+    fragments.forEach((fragment, index) => {
+      events.push(
+        `Dialogue: ${layer},0:00:01.00,0:00:04.00,op_english,,0,0,0,,{\\pos(${100 + index * 40},110)\\t(0,200,\\fscx110)}${fragment}`,
+      );
+    });
+  }
+  const ass = [
+    '[Events]',
+    'Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text',
+    ...events,
+  ].join('\n');
+
+  assert.equal(
+    findActiveSubtitleText(parseSubtitleCues(ass, 'bravern-s01e10.ass'), 2),
+    'The shooting stars arcing across the sky I wish upon,',
+  );
+});
+
+test('findActiveSubtitleText keeps a complete reconstructed line over entrance fragments', () => {
+  const current = {
+    startTime: 1,
+    endTime: 4,
+    text: 'Complete current line',
+    source: 'reconstructed-ass' as const,
+    assStyle: 'op_english',
+  };
+  const nextEntrance = {
+    startTime: 3.8,
+    endTime: 4.2,
+    text: 'Ne',
+    source: 'reconstructed-ass' as const,
+    assStyle: 'op_english',
+  };
+  const nextLine = {
+    startTime: 4,
+    endTime: 7,
+    text: 'Next complete line',
+    source: 'reconstructed-ass' as const,
+    assStyle: 'op_english',
+  };
+
+  assert.equal(findActiveSubtitleText([current, nextEntrance], 3.9), current.text);
+  assert.equal(findActiveSubtitleText([current, nextEntrance, nextLine], 4.1), nextLine.text);
+});
+
 test('secondary track controller parses the selected ASS file before publishing', async () => {
  const broadcasts: string[] = [];
  let currentText = '';
@@ -1,4 +1,5 @@
 import type { SubtitleCue } from '../../types/subtitle';
+import { flattenedSecondarySubtitleLineIdentity } from '../../core/services/secondary-subtitle-line-identity';

 type SecondarySubtitleMpvClient = {
  connected?: boolean;
@@ -58,16 +59,108 @@ function buildSelectedTrackIdentity(
  ]);
 }

+type IndexedSubtitleCue = { cue: SubtitleCue; index: number };
+
+function compareAuthoredSubtitleOrder(left: IndexedSubtitleCue, right: IndexedSubtitleCue): number {
+  const leftLayout = left.cue.assLayout;
+  const rightLayout = right.cue.assLayout;
+  if (leftLayout?.kind === 'positioned' && rightLayout?.kind === 'positioned') {
+    const verticalOrder = leftLayout.y - rightLayout.y;
+    if (verticalOrder !== 0) return verticalOrder;
+  }
+  if (leftLayout && rightLayout) {
+    const sourceOrder = leftLayout.sourceOrder - rightLayout.sourceOrder;
+    if (sourceOrder !== 0) return sourceOrder;
+  }
+  return left.index - right.index;
+}
+
 export function findActiveSubtitleText(cues: readonly SubtitleCue[], timeSeconds: number): string {
  if (!Number.isFinite(timeSeconds)) return '';

-  const seen = new Set<string>();
+  const authoredCanonical = cues.filter(
+    (cue) =>
+      cue.source === 'canonical-ass' && cue.startTime <= timeSeconds && cue.endTime > timeSeconds,
+  );
+  const selectedCanonical = new Set<SubtitleCue>(authoredCanonical);
+  if (selectedCanonical.size === 0) {
+    const animatedCanonical = cues.filter(
+      (cue) =>
+        cue.source === 'canonical-ass' &&
+        (cue.animationStartTime ?? cue.startTime) <= timeSeconds &&
+        (cue.animationEndTime ?? cue.endTime) > timeSeconds,
+    );
+    const nearestDistance = animatedCanonical.reduce((nearest, cue) => {
+      const distance =
+        timeSeconds < cue.startTime
+          ? cue.startTime - timeSeconds
+          : Math.max(0, timeSeconds - cue.endTime);
+      return Math.min(nearest, distance);
+    }, Infinity);
+    for (const cue of animatedCanonical) {
+      const distance =
+        timeSeconds < cue.startTime
+          ? cue.startTime - timeSeconds
+          : Math.max(0, timeSeconds - cue.endTime);
+      if (distance === nearestDistance) {
+        selectedCanonical.add(cue);
+      }
+    }
+  }
+
+  const activeReconstructed = cues.filter(
+    (cue) =>
+      cue.source === 'reconstructed-ass' &&
+      cue.assLayout?.kind !== 'fragment-grid' &&
+      cue.startTime <= timeSeconds &&
+      cue.endTime > timeSeconds,
+  );
+  const reconstructedByStyle = new Map<string, SubtitleCue>();
+  for (const cue of activeReconstructed) {
+    const style = cue.assStyle ?? '';
+    const existing = reconstructedByStyle.get(style);
+    if (!existing) {
+      reconstructedByStyle.set(style, cue);
+      continue;
+    }
+    const duration = cue.endTime - cue.startTime;
+    const existingDuration = existing.endTime - existing.startTime;
+    if (
+      duration > existingDuration ||
+      (duration === existingDuration && cue.text.length > existing.text.length) ||
+      (duration === existingDuration &&
+        cue.text.length === existing.text.length &&
+        cue.startTime > existing.startTime)
+    ) {
+      reconstructedByStyle.set(style, cue);
+    }
+  }
+  const selectedReconstructed = new Set(reconstructedByStyle.values());
+
+  const seenExact = new Set<string>();
+  const seenFlattened = new Set<string>();
  const activeText: string[] = [];
-  for (const cue of cues) {
-    if (cue.startTime > timeSeconds || cue.endTime <= timeSeconds) continue;
+  const activeCues: IndexedSubtitleCue[] = [];
+  cues.forEach((cue, index) => {
+    const active =
+      cue.source === 'canonical-ass'
+        ? selectedCanonical.has(cue)
+        : cue.source === 'reconstructed-ass'
+          ? selectedReconstructed.has(cue)
+          : cue.startTime <= timeSeconds && cue.endTime > timeSeconds;
+    if (active) activeCues.push({ cue, index });
+  });
+  activeCues.sort(compareAuthoredSubtitleOrder);
+
+  for (const { cue } of activeCues) {
    const text = cue.text.trim();
-    if (!text || seen.has(text)) continue;
-    seen.add(text);
+    const compactText = text.replace(/\s+/gu, '');
+    if (!compactText || seenExact.has(compactText)) continue;
+    seenExact.add(compactText);
+
+    const flattenedIdentity = flattenedSecondarySubtitleLineIdentity(text);
+    if (flattenedIdentity && seenFlattened.has(flattenedIdentity)) continue;
+    if (flattenedIdentity) seenFlattened.add(flattenedIdentity);
    activeText.push(text);
  }
  return activeText.join('\n');
@@ -101,6 +101,32 @@ test('subtitle prefetch runtime preserves parsed cues when YouTube active track
  assert.deepEqual(calls, []);
 });

+test('subtitle prefetch runtime preserves parsed cues when a network mount source is unresolved', async () => {
+  const calls: string[] = [];
+  const refresh = createRefreshSubtitlePrefetchFromActiveTrackHandler({
+    getMpvClient: () => ({
+      connected: true,
+      requestProperty: async (name) => (name === 'path' ? '/Volumes/jellyfin/movie.mkv' : null),
+    }),
+    getLastObservedTimePos: () => 12,
+    subtitlePrefetchInitController: {
+      cancelPendingInit: () => {
+        calls.push('cancel');
+      },
+      initSubtitlePrefetch: async () => {
+        calls.push('init');
+      },
+    },
+    resolveActiveSubtitleSidebarSource: async () => null,
+    shouldKeepExistingCuesOnMissingSource: async (videoPath) =>
+      videoPath.startsWith('/Volumes/jellyfin/'),
+  });
+
+  await refresh();
+
+  assert.deepEqual(calls, []);
+});
+
 test('subtitle prefetch runtime does not extract internal subtitle tracks from remote media urls', async () => {
  let extracted = false;
  const resolveSource = createResolveActiveSubtitleSidebarSourceHandler({
@@ -131,6 +157,34 @@ test('subtitle prefetch runtime does not extract internal subtitle tracks from r
  assert.equal(extracted, false);
 });

+test('subtitle prefetch runtime does not extract internal subtitle tracks from network mounts', async () => {
+  let extracted = false;
+  const resolveSource = createResolveActiveSubtitleSidebarSourceHandler({
+    getFfmpegPath: () => 'ffmpeg-custom',
+    isRemoteMediaPath: async (videoPath) => videoPath.startsWith('/Volumes/jellyfin/'),
+    extractInternalSubtitleTrack: async () => {
+      extracted = true;
+      return null;
+    },
+  });
+
+  const resolved = await resolveSource({
+    currentExternalFilenameRaw: null,
+    currentTrackRaw: {
+      type: 'sub',
+      id: 3,
+      'ff-index': 7,
+      codec: 'ass',
+    },
+    trackListRaw: [],
+    sidRaw: 3,
+    videoPath: '/Volumes/jellyfin/movie.mkv',
+  });
+
+  assert.equal(resolved, null);
+  assert.equal(extracted, false);
+});
+
 test('subtitle prefetch refresh logs a warning when source resolution throws', async () => {
  const warnings: string[] = [];
  const refresh = createRefreshSubtitlePrefetchFromActiveTrackHandler({
@@ -17,6 +17,8 @@ type ActiveSubtitleSidebarSource = {
  cleanup?: () => Promise<void>;
 };

+type RemoteMediaPathDetector = (mediaPath: string) => boolean | Promise<boolean>;
+
 function parseTrackId(value: unknown): number | null {
  if (typeof value === 'number' && Number.isInteger(value)) {
    return value;
@@ -28,7 +30,7 @@ function parseTrackId(value: unknown): number | null {
  return null;
 }

-function isRemoteMediaPath(value: string): boolean {
+function isRemoteMediaUrl(value: string): boolean {
  try {
    const url = new URL(value);
    return url.protocol === 'http:' || url.protocol === 'https:';
@@ -86,6 +88,7 @@ function getActiveSubtitleTrack(

 export function createResolveActiveSubtitleSidebarSourceHandler(deps: {
  getFfmpegPath: () => string;
+  isRemoteMediaPath?: RemoteMediaPathDetector;
  extractInternalSubtitleTrack: (
    ffmpegPath: string,
    videoPath: string,
@@ -126,7 +129,8 @@ export function createResolveActiveSubtitleSidebarSourceHandler(deps: {
      return { path: externalFilename, sourceKey: externalFilename };
    }

-    if (isRemoteMediaPath(input.videoPath)) {
+    const isRemoteMediaPath = deps.isRemoteMediaPath ?? isRemoteMediaUrl;
+    if (await isRemoteMediaPath(input.videoPath)) {
      deps.logDebug?.('[subtitle-prefetch] skipping internal subtitle extraction for remote media');
      return null;
    }
@@ -156,7 +160,7 @@ export function createRefreshSubtitlePrefetchFromActiveTrackHandler(deps: {
    requestProperty: (name: string) => Promise<unknown>;
  } | null;
  getLastObservedTimePos: () => number;
-  shouldKeepExistingCuesOnMissingSource?: (videoPath: string) => boolean;
+  shouldKeepExistingCuesOnMissingSource?: (videoPath: string) => boolean | Promise<boolean>;
  subtitlePrefetchInitController: SubtitlePrefetchInitController;
  resolveActiveSubtitleSidebarSource: (
    input: Parameters<ReturnType<typeof createResolveActiveSubtitleSidebarSourceHandler>>[0],
@@ -195,7 +199,7 @@ export function createRefreshSubtitlePrefetchFromActiveTrackHandler(deps: {
        videoPath,
      });
      if (!resolvedSource) {
-        if (deps.shouldKeepExistingCuesOnMissingSource?.(videoPath) === true) {
+        if ((await deps.shouldKeepExistingCuesOnMissingSource?.(videoPath)) === true) {
          deps.logDebug?.(
            '[subtitle-prefetch] no active subtitle source resolved; keeping existing cues',
          );
@@ -240,14 +240,15 @@ test('subtitle sidebar modal opens from snapshot and clicking cue seeks playback

  const snapshot: SubtitleSidebarSnapshot = {
    cues: [
-      { startTime: 1, endTime: 2, text: 'first' },
+      { startTime: 1, endTime: 3.4, text: 'first' },
      { startTime: 3, endTime: 4, text: 'second' },
    ],
    currentSubtitle: {
      text: 'second',
-      startTime: 3,
+      startTime: 3.5,
      endTime: 4,
    },
+    currentTimeSec: 3.5,
    config: {
      enabled: true,
      autoOpen: false,
@@ -361,6 +362,9 @@ test('subtitle sidebar modal opens from snapshot and clicking cue seeks playback
    modal.seekToCue(snapshot.cues[0]!);
    assert.deepEqual(mpvCommands.at(-1), ['seek', 1.08, 'absolute+exact']);

+    modal.seekToCue(snapshot.cues[1]!);
+    assert.deepEqual(mpvCommands.at(-1), ['seek', 3.48, 'absolute+exact']);
+
    modal.closeSubtitleSidebarModal();
    assert.deepEqual(visibilityChanges, [true, false]);
    assert.deepEqual(modalNotifications, ['open:subtitle-sidebar', 'close:subtitle-sidebar']);
@@ -4,6 +4,7 @@ import type {
  SubtitleMiningContext,
  SubtitleSidebarSnapshot,
 } from '../../types';
+import { subtitleCueListSeekTime } from '../../core/services/subtitle-cue-navigation.js';
 import type { ModalStateReader, RendererContext } from '../context';
 import { syncOverlayMouseIgnoreState } from '../overlay-mouse-ignore.js';
 import {
@@ -14,7 +15,6 @@ import {

 const MANUAL_SCROLL_HOLD_MS = 1500;
 const ACTIVE_CUE_LOOKAHEAD_SEC = 0.18;
-const CLICK_SEEK_OFFSET_SEC = 0.08;
 const SNAPSHOT_POLL_INTERVAL_MS = 80;
 const EMBEDDED_SIDEBAR_MIN_WIDTH_PX = 240;
 const EMBEDDED_SIDEBAR_MAX_RATIO = 0.45;
@@ -392,10 +392,9 @@ export function createSubtitleSidebarModal(
  }

  function seekToCue(cue: SubtitleCue): void {
-    const targetTime = Math.min(cue.endTime - 0.01, cue.startTime + CLICK_SEEK_OFFSET_SEC);
    window.electronAPI.sendMpvCommand([
      'seek',
-      Math.max(cue.startTime, targetTime),
+      subtitleCueListSeekTime(ctx.state.subtitleSidebarCues, cue),
      'absolute+exact',
    ]);
  }
@@ -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;
@@ -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 +1454,19 @@ 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', () => {
+  const dialogue = 'A question veiled as an insult!';
+  const positionedSign = 'A question veiled as an insult';
+
+  assert.deepEqual(prepareSecondarySubtitleLines([dialogue, positionedSign].join('\\N')), [
+    dialogue,
+  ]);
 });

 test('prepareSecondarySubtitleLines preserves short simultaneous dialogue without repeats', () => {
@@ -1460,6 +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. ';

@@ -1481,13 +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', () => {
@@ -6,6 +6,7 @@ import type {
  SubtitleRendererStyleConfig,
 } from '../types';
 import { assToPlainText, normalizePlainSubtitleText } from '../core/services/ass-text.js';
+import { flattenedSecondarySubtitleLineIdentity } from '../core/services/secondary-subtitle-line-identity.js';
 import type { RendererContext } from './context';
 import { PRIMARY_SUB_VISIBLE_ON_YOMITAN_POPUP_CLASS } from './yomitan-popup.js';

@@ -665,6 +666,22 @@ function isKaraokeLikeLineSet(lines: string[]): boolean {
  return median <= KARAOKE_MAX_MEDIAN_LINE_LENGTH;
 }

+function collapseFullLineFallbackCopies(lines: string[]): string[] {
+  const seenExact = new Set<string>();
+  const seenFlattened = new Set<string>();
+  return lines.filter((line) => {
+    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;
+  });
+}
+
 export function prepareSecondarySubtitleLines(text: string): string[] {
  // The one display-side ASS decode: secondary text also reaches the overlay from
  // websocket clients that forward their source line untouched, so unlike the primary
@@ -678,7 +695,7 @@ export function prepareSecondarySubtitleLines(text: string): string[] {
    .map((line) => line.trim())
    .filter((line) => line.length > 0);
  if (!isKaraokeLikeLineSet(lines)) {
-    return lines;
+    return collapseFullLineFallbackCopies(lines);
  }

  const seen = new Set<string>();
Author	SHA1	Message	Date
sudacode	509dc5bf7f	fix(subtitles): improve secondary subtitle extraction and display (#215 )	2026-08-23 01:56:49 -07:00
sudacode	0a0aa3ec98	chore(release): prepare v0.19.4-beta.4	2026-08-23 01:23:16 -07:00
sudacode	b87cc3cfdd	chore(workflow): add release skill	2026-08-23 01:14:03 -07:00
sudacode	8cb3c8c90a	fix(macos): pin window helper deployment target to fix older systems - Build the Swift window-tracking helper with an explicit `-target ...-apple-macos12.0` instead of letting swiftc stamp the build machine's OS, so the overlay attaches to mpv on older macOS (e.g. Ventura) instead of crashing at load - Fold the standalone build-macos-helper.sh into prepare-build-assets.mjs and update docs/tests to match	2026-08-23 00:58:24 -07:00
sudacode	03ea903927	fix(subtitles): preserve authored spaces in fragmented ASS karaoke - Only trim indentation before slicing ASS event fields so a trailing authored space at a fragment's end is kept, preventing words from being joined together when fragmented karaoke lines are reconstructed - Add regression test covering event-boundary word spacing	2026-08-22 23:32:35 -07:00
sudacode	3aea42e6f8	chore(release): prepare v0.19.4-beta.3	2026-08-21 23:25:37 -07:00
sudacode	88bb3edfa4	fix(subtitles): preserve lyric selection and deduplicate secondary text - Seek sidebar selections past overlapping karaoke exit spans - Collapse duplicate long ASS lines and omit reconstructed sign grids	2026-08-21 01:28:00 -07:00
sudacode	9445aef004	fix(subtitles): navigate by sanitized cues across ASS animation - Route subtitle navigation through parsed cue boundaries - Treat explicit short seeks as subtitle priming events	2026-08-20 00:20:51 -07:00
sudacode	c01bcd9d0f	fix(subtitles): collapse layered ASS lyrics across startup and seeks - Reconstruct fragment-only karaoke while preserving canonical animated signs - Reprocess live subtitles after initial playback and seek updates - Add a development launcher for playable media files	2026-08-19 22:55:10 -07:00