feat(sidebar): add dialogue selection and copying

- Support multi-row selection with clean clipboard text
- Preserve selections across playback updates and clear them on source changes

src/renderer/handlers/keyboard.test.ts

@@ -1863,6 +1863,29 @@ test('keyboard mode: popup hidden after mode off clears stale selected token hig
   }
 });
 
+test('Yomitan popup dismissal and subtitle updates preserve selection outside the overlay subtitle', async () => {
+  const { ctx, handlers, testGlobals } = createKeyboardHandlerHarness();
+  let cleared = false;
+  try {
+    Object.defineProperty(window, 'getSelection', {
+      configurable: true,
+      value: () => ({
+        anchorNode: {},
+        removeAllRanges: () => {
+          cleared = true;
+        },
+      }),
+    });
+    Object.assign(ctx.dom.subtitleRoot, { contains: () => false });
+    await handlers.setupMpvInputForwarding();
+    testGlobals.dispatchWindowEvent(YOMITAN_POPUP_HIDDEN_EVENT);
+    handlers.syncKeyboardTokenSelection();
+    assert.equal(cleared, false);
+  } finally {
+    testGlobals.restore();
+  }
+});
+
 test('keyboard mode: closing lookup keeps controller selection but clears native text selection', async () => {
   const { ctx, handlers, testGlobals } = createKeyboardHandlerHarness();
 

src/renderer/handlers/keyboard.ts

@@ -436,7 +436,10 @@ export function createKeyboardHandlers(
   }
 
   function clearNativeSubtitleSelection(): void {
-    window.getSelection()?.removeAllRanges();
+    const selection = window.getSelection();
+    if (!selection?.anchorNode || ctx.dom.subtitleRoot.contains(selection.anchorNode)) {
+      selection?.removeAllRanges();
+    }
     ctx.dom.subtitleRoot.classList.remove('has-selection');
   }
 

src/renderer/index.html

@@ -731,6 +731,7 @@
         <div id="subtitleSidebarContent" class="modal-content subtitle-sidebar-content">
           <div class="modal-header">
             <div class="modal-title">Subtitle Sidebar</div>
+            <button id="subtitleSidebarCopy" class="modal-close" type="button" hidden>Copy</button>
             <button id="subtitleSidebarClose" class="modal-close" type="button">Close</button>
           </div>
           <div class="modal-body subtitle-sidebar-body">

src/renderer/modals/subtitle-sidebar-selection.electron-fixture.ts

@@ -0,0 +1,126 @@
+import type { ElectronAPI, SubtitleSidebarSnapshot } from '../../types';
+import { SUBTITLE_DEFAULT_CONFIG } from '../../config/definitions/defaults-subtitle';
+import { createRendererState } from '../state';
+import { resolveRendererDom } from '../utils/dom';
+import { resolvePlatformInfo } from '../utils/platform';
+import { createSubtitleSidebarModal } from './subtitle-sidebar';
+import {
+  getSubtitleSidebarSelection,
+  wireSubtitleSidebarSelection,
+} from './subtitle-sidebar-selection';
+
+export async function setup() {
+  const commands: unknown[] = [];
+  const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'episode-1:track-1',
+    cues: [
+      { text: '最初の台詞', startTime: 0, endTime: 1 },
+      { text: '同じ台詞\n二行目', startTime: 1, endTime: 2 },
+      { text: '同じ台詞', startTime: 2, endTime: 3 },
+      ...Array.from({ length: 30 }, (_, i) => ({
+        text: `後の台詞${i}`,
+        startTime: i + 3,
+        endTime: i + 4,
+      })),
+    ],
+    currentSubtitle: { text: '最初の台詞', startTime: 0, endTime: 1 },
+    currentTimeSec: 0,
+    config: {
+      ...SUBTITLE_DEFAULT_CONFIG.subtitleSidebar,
+      enabled: true,
+      layout: 'overlay',
+      pauseVideoOnHover: false,
+      autoScroll: true,
+      css: {},
+    },
+  };
+  Object.defineProperty(window, 'electronAPI', {
+    value: {
+      getSubtitleSidebarSnapshot: async () => snapshot,
+      copySubtitleSidebarSelection: async (text) => {
+        if (!('copyTestSelection' in window) || typeof window.copyTestSelection !== 'function')
+          throw new Error('Missing test clipboard bridge');
+        window.copyTestSelection(text);
+      },
+      getOverlayLayer: () => 'visible',
+      sendMpvCommand: (command) => {
+        commands.push(command);
+      },
+      setIgnoreMouseEvents: () => {},
+    } satisfies Pick<
+      ElectronAPI,
+      | 'getSubtitleSidebarSnapshot'
+      | 'copySubtitleSidebarSelection'
+      | 'getOverlayLayer'
+      | 'sendMpvCommand'
+      | 'setIgnoreMouseEvents'
+    >,
+  });
+  const ctx = {
+    dom: resolveRendererDom(),
+    state: createRendererState(),
+    platform: resolvePlatformInfo(),
+  };
+  const modal = createSubtitleSidebarModal(ctx, {
+    modalStateReader: { isAnyModalOpen: () => false },
+  });
+  modal.wireDomEvents();
+  wireSubtitleSidebarSelection(ctx);
+  await modal.openSubtitleSidebarModal();
+  const list = ctx.dom.subtitleSidebarList;
+  list.style.height = '180px';
+  list.style.overflowY = 'auto';
+  const selection = window.getSelection();
+  if (!selection) throw new Error('Native selection unavailable');
+  const textNode = (index: number) => {
+    const node = list.children[index]?.querySelector('.subtitle-sidebar-text')?.firstChild;
+    if (!node) throw new Error(`Missing cue ${index}`);
+    return node;
+  };
+  const select = (backward = false) => {
+    const start = textNode(0);
+    const end = textNode(2);
+    selection.setBaseAndExtent(backward ? end : start, 2, backward ? start : end, 2);
+    document.dispatchEvent(new Event('selectionchange'));
+    return getSubtitleSidebarSelection(list);
+  };
+  // This is the same competing action as the renderer's current-subtitle shortcut.
+  let fallbackCopies = 0;
+  document.addEventListener('keydown', (event) => {
+    if ((event.ctrlKey || event.metaKey) && event.key.toLowerCase() === 'c') fallbackCopies += 1;
+  });
+  return {
+    select,
+    selected: () => getSubtitleSidebarSelection(list),
+    buttonVisible: () => !ctx.dom.subtitleSidebarCopy.hidden,
+    fallbackCopies: () => fallbackCopies,
+    dragPoints: () =>
+      [0, 2].map((index) => {
+        const range = document.createRange();
+        range.setStart(textNode(index), 2);
+        range.collapse(true);
+        const rect = range.getBoundingClientRect();
+        return { x: Math.round(rect.x), y: Math.round(rect.y + rect.height / 2) };
+      }),
+    clickCopy: () => ctx.dom.subtitleSidebarCopy.click(),
+    clickCue: () => {
+      const before = commands.length;
+      list.children[0]?.dispatchEvent(new MouseEvent('click', { bubbles: true }));
+      return commands.length - before;
+    },
+    updatePlayback: async () => {
+      list.scrollTop = 0;
+      snapshot.currentTimeSec = 25;
+      snapshot.currentSubtitle = { text: '後の台詞22', startTime: 25, endTime: 26 };
+      await modal.refreshSubtitleSidebarSnapshot();
+      return list.scrollTop;
+    },
+    changeSource: async () => {
+      snapshot.sourceKey = 'episode-2:track-1';
+      await modal.refreshSubtitleSidebarSnapshot();
+      return getSubtitleSidebarSelection(list);
+    },
+    clear: () => selection.removeAllRanges(),
+    close: () => modal.closeSubtitleSidebarModal(),
+  };
+}

src/renderer/modals/subtitle-sidebar-selection.test.ts

@@ -0,0 +1,127 @@
+import assert from 'node:assert/strict';
+import { execFile } from 'node:child_process';
+import { mkdtemp, readFile, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join, resolve } from 'node:path';
+import { promisify } from 'node:util';
+import test from 'node:test';
+import { build } from 'esbuild';
+
+// This check opens Electron and uses the clipboard. Keep it out of normal code-only lanes.
+test(
+  'sidebar selection copies clean chronological text without seeking or losing context',
+  {
+    skip:
+      process.env.SUBMINER_ELECTRON_TESTS !== '1' ||
+      (process.platform === 'linux' && !process.env.DISPLAY),
+    timeout: 30_000,
+  },
+  async () => {
+    const dir = await mkdtemp(join(tmpdir(), 'subminer-sidebar-selection-'));
+    await build({
+      entryPoints: [resolve('src/renderer/modals/subtitle-sidebar-selection.electron-fixture.ts')],
+      bundle: true,
+      platform: 'browser',
+      format: 'iife',
+      globalName: 'sidebarTest',
+      outfile: join(dir, 'fixture.js'),
+    });
+    const html = (await readFile('src/renderer/index.html', 'utf8'))
+      .replace(
+        '<script type="module" src="renderer.js"></script>',
+        '<script src="fixture.js"></script>',
+      )
+      .replace(
+        'href="style.css"',
+        `href="${new URL(`file://${resolve('src/renderer/style.css')}`).href}"`,
+      );
+    await writeFile(join(dir, 'index.html'), html);
+    await writeFile(
+      join(dir, 'clipboard.cjs'),
+      'const { clipboard, contextBridge } = require("electron"); contextBridge.exposeInMainWorld("copyTestSelection", text => clipboard.writeText(text));',
+    );
+    await build({
+      entryPoints: [resolve('src/core/services/overlay-window-input.ts')],
+      bundle: true,
+      platform: 'node',
+      format: 'cjs',
+      outfile: join(dir, 'input.cjs'),
+    });
+    await writeFile(
+      join(dir, 'run.cjs'),
+      `
+const { app, BrowserWindow, clipboard } = require('electron');
+const assert = require('node:assert/strict');
+const { handleOverlayWindowBeforeInputEvent } = require('./input.cjs');
+app.setPath('userData', ${JSON.stringify(join(dir, 'user-data'))});
+app.whenReady().then(async () => {
+  const window = new BrowserWindow({ width: 900, height: 700, show: false, webPreferences: { preload: ${JSON.stringify(join(dir, 'clipboard.cjs'))}, sandbox: false } });
+  window.webContents.on('console-message', (_event, details) => {
+    if (details.level === 'error') console.error(details.message);
+  });
+  let intercepted = 0;
+  window.webContents.on('before-input-event', (event, input) => handleOverlayWindowBeforeInputEvent({
+    kind: 'visible', windowVisible: true, input,
+    preventDefault: () => event.preventDefault(),
+    sendKeyboardModeToggleRequested() {}, sendLookupWindowToggleRequested() {}, forwardTabToMpv() {},
+    tryHandleOverlayShortcutLocalFallback() { intercepted++; return true; },
+  }));
+  await window.loadFile(${JSON.stringify(join(dir, 'index.html'))});
+  const run = (code) => window.webContents.executeJavaScript(code, true);
+  await run('sidebarTest.setup().then(checks => { window.checks = checks; })');
+  const expected = { text: 'の台詞\\n\\n同じ台詞\\n二行目\\n\\n同じ', cueCount: 3 };
+  assert.deepEqual(await run('checks.select()'), expected);
+  assert.deepEqual(await run('checks.select(true)'), expected);
+  assert.equal(await run('checks.buttonVisible()'), true);
+  assert.equal(await run('checks.clickCue()'), 0);
+  assert.equal(await run('checks.updatePlayback()'), 0);
+  assert.deepEqual(await run('checks.selected()'), expected);
+  const previousClipboard = clipboard.readText();
+  try {
+    clipboard.writeText('sentinel');
+    window.show(); app.focus({ steal: true }); window.focus(); window.webContents.focus();
+    await new Promise(resolve => setTimeout(resolve, 100));
+    await run('checks.clear()');
+    const [start, end] = await run('checks.dragPoints()');
+    window.webContents.sendInputEvent({ type: 'mouseDown', ...start, button: 'left', clickCount: 1 });
+    window.webContents.sendInputEvent({ type: 'mouseMove', ...end, button: 'left' });
+    window.webContents.sendInputEvent({ type: 'mouseUp', ...end, button: 'left', clickCount: 1 });
+    await new Promise(resolve => setTimeout(resolve, 100));
+    assert.deepEqual(await run('checks.selected()'), expected);
+    window.webContents.sendInputEvent({ type: 'keyDown', keyCode: 'C', modifiers: [process.platform === 'darwin' ? 'meta' : 'control'] });
+    window.webContents.sendInputEvent({ type: 'keyUp', keyCode: 'C', modifiers: [process.platform === 'darwin' ? 'meta' : 'control'] });
+    await new Promise(resolve => setTimeout(resolve, 100));
+    assert.equal(intercepted, 0);
+    assert.equal(await run('checks.fallbackCopies()'), 0);
+    assert.equal(clipboard.readText() === expected.text, true, 'Keyboard copies the selected excerpt');
+    clipboard.writeText('sentinel');
+    await run('checks.clickCopy()');
+    await new Promise(resolve => setTimeout(resolve, 100));
+    assert.equal(clipboard.readText() === expected.text, true, 'Button copies the selected excerpt');
+  } finally { clipboard.writeText(previousClipboard); }
+  await run('document.dispatchEvent(new KeyboardEvent("keydown", {key:"Escape", bubbles:true}))');
+  assert.equal(await run('checks.selected()'), null);
+  assert.equal(await run('checks.buttonVisible()'), false);
+  assert.equal(await run('checks.clickCue()'), 1);
+  await run('document.dispatchEvent(new KeyboardEvent("keydown", {key:"c", ctrlKey:true, bubbles:true}))');
+  assert.equal(await run('checks.fallbackCopies()'), 1);
+  await run('checks.select()');
+  assert.equal(await run('checks.changeSource()'), null);
+  await run('checks.select(); checks.close()');
+  assert.equal(await run('checks.selected()'), null);
+  window.destroy();
+  console.log('SIDEBAR_SELECTION_OK');
+  app.quit();
+}).catch(error => { console.error(error); app.exit(1); });
+`,
+    );
+    const env = { ...process.env };
+    delete env.ELECTRON_RUN_AS_NODE;
+    const { stdout } = await promisify(execFile)(
+      resolve('node_modules/.bin/electron'),
+      [join(dir, 'run.cjs')],
+      { env, timeout: 25_000 },
+    );
+    assert.match(stdout, /SIDEBAR_SELECTION_OK/);
+  },
+);

src/renderer/modals/subtitle-sidebar-selection.ts

@@ -0,0 +1,150 @@
+import type { RendererContext } from '../context';
+import { syncOverlayMouseIgnoreState } from '../overlay-mouse-ignore';
+
+function isEditingText(target: EventTarget | null): boolean {
+  return (
+    target instanceof HTMLElement &&
+    (target.isContentEditable ||
+      target instanceof HTMLInputElement ||
+      target instanceof HTMLTextAreaElement)
+  );
+}
+
+function getSelectionRange(list: HTMLElement): Range | null {
+  const selection = list.ownerDocument?.defaultView?.getSelection();
+  if (!selection || selection.isCollapsed || selection.rangeCount === 0) return null;
+  const range = selection.getRangeAt(0);
+  return list.contains(range.startContainer) && list.contains(range.endContainer) ? range : null;
+}
+
+export function hasSubtitleSidebarSelection(list: HTMLElement): boolean {
+  return getSelectionRange(list) !== null;
+}
+
+// Read only dialogue nodes, preserving partial first/last lines and DOM cue order.
+export function getSubtitleSidebarSelection(list: HTMLElement): {
+  text: string;
+  cueCount: number;
+} | null {
+  const range = getSelectionRange(list);
+  if (!range) return null;
+
+  const parts: string[] = [];
+  for (const text of list.querySelectorAll<HTMLElement>('.subtitle-sidebar-text')) {
+    if (!range.intersectsNode(text)) continue;
+    const part = list.ownerDocument.createRange();
+    part.selectNodeContents(text);
+    if (range.compareBoundaryPoints(Range.START_TO_START, part) > 0) {
+      part.setStart(range.startContainer, range.startOffset);
+    }
+    if (range.compareBoundaryPoints(Range.END_TO_END, part) < 0) {
+      part.setEnd(range.endContainer, range.endOffset);
+    }
+    const selectedText = part.toString();
+    if (selectedText.trim()) parts.push(selectedText);
+  }
+  return parts.length > 0 ? { text: parts.join('\n\n'), cueCount: parts.length } : null;
+}
+
+export function clearSubtitleSidebarSelection(list: HTMLElement): void {
+  const selection = list.ownerDocument?.defaultView?.getSelection();
+  if (selection?.anchorNode && list.contains(selection.anchorNode)) {
+    selection.removeAllRanges();
+  }
+}
+
+export function wireSubtitleSidebarSelection(ctx: RendererContext): () => void {
+  const list = ctx.dom.subtitleSidebarList;
+  const button = ctx.dom.subtitleSidebarCopy;
+  const doc = list.ownerDocument;
+  const abort = new AbortController();
+  const { signal } = abort;
+
+  const updateButton = () => {
+    const selected = getSubtitleSidebarSelection(list);
+    button.hidden = !selected;
+    button.textContent = selected
+      ? `Copy ${selected.cueCount} ${selected.cueCount === 1 ? 'line' : 'lines'}`
+      : 'Copy';
+  };
+  const copied = () => {
+    ctx.dom.subtitleSidebarStatus.textContent = 'Selection copied.';
+  };
+  const copySelection = async () => {
+    const selected = getSubtitleSidebarSelection(list);
+    if (!selected) return;
+    try {
+      await window.electronAPI.copySubtitleSidebarSelection(selected.text);
+      copied();
+    } catch {
+      ctx.dom.subtitleSidebarStatus.textContent = 'Could not copy selection. Try again.';
+    }
+  };
+
+  doc.addEventListener('selectionchange', updateButton, { signal });
+  doc.addEventListener(
+    'copy',
+    (event) => {
+      if (!ctx.state.subtitleSidebarModalOpen || isEditingText(event.target)) return;
+      const selected = getSubtitleSidebarSelection(list);
+      if (!selected || !event.clipboardData) return;
+      event.preventDefault();
+      event.clipboardData.setData('text/plain', selected.text);
+      copied();
+    },
+    { signal },
+  );
+  // Capture before modal Escape handling and the current-subtitle copy shortcut.
+  doc.addEventListener(
+    'keydown',
+    (event) => {
+      if (
+        !ctx.state.subtitleSidebarModalOpen ||
+        isEditingText(event.target) ||
+        !getSubtitleSidebarSelection(list)
+      )
+        return;
+      if (event.key === 'Escape') {
+        event.preventDefault();
+        event.stopImmediatePropagation();
+        clearSubtitleSidebarSelection(list);
+        updateButton();
+      } else if (
+        (event.ctrlKey || event.metaKey) &&
+        !event.altKey &&
+        !event.shiftKey &&
+        event.key.toLowerCase() === 'c'
+      ) {
+        event.preventDefault();
+        event.stopImmediatePropagation();
+        void copySelection();
+      }
+    },
+    { capture: true, signal },
+  );
+  button.addEventListener('mousedown', (event) => event.preventDefault(), { signal });
+  button.addEventListener('click', copySelection, { signal });
+  list.addEventListener(
+    'pointerdown',
+    (event) => {
+      if (event.button === 0) {
+        list.dataset.selecting = 'true';
+        list.scrollTo({ top: list.scrollTop, behavior: 'instant' });
+        syncOverlayMouseIgnoreState(ctx);
+      }
+    },
+    { signal },
+  );
+  const stopDragging = () => {
+    delete list.dataset.selecting;
+    syncOverlayMouseIgnoreState(ctx);
+  };
+  doc.addEventListener('pointerup', stopDragging, { signal });
+  doc.addEventListener('pointercancel', stopDragging, { signal });
+  doc.defaultView?.addEventListener('blur', stopDragging, { signal });
+  updateButton();
+  return () => {
+    abort.abort();
+    stopDragging();
+  };
+}

src/renderer/modals/subtitle-sidebar.test.ts

@@ -239,6 +239,7 @@ test('subtitle sidebar modal opens from snapshot and clicking cue seeks playback
   const modalNotifications: string[] = [];
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [
       { startTime: 1, endTime: 3.4, text: 'first' },
       { startTime: 3, endTime: 4, text: 'second' },
@@ -381,6 +382,7 @@ test('subtitle sidebar rows support keyboard activation', async () => {
   const mpvCommands: Array<Array<string | number>> = [];
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [
       { startTime: 1, endTime: 2, text: 'first' },
       { startTime: 3, endTime: 4, text: 'second' },
@@ -487,6 +489,7 @@ test('subtitle sidebar renders hour-long cue timestamps as HH:MM:SS', async () =
   const previousDocument = globals.document;
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 3665, endTime: 3670, text: 'long cue' }],
     currentSubtitle: {
       text: 'long cue',
@@ -580,6 +583,7 @@ test('subtitle sidebar does not open when the feature is disabled', async () =>
   const previousWindow = globals.window;
   const previousDocument = globals.document;
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [],
     currentSubtitle: {
       text: '',
@@ -676,6 +680,7 @@ test('subtitle sidebar auto-open on startup only opens when enabled and configur
   const previousDocument = globals.document;
 
   let snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -786,6 +791,7 @@ test('subtitle sidebar auto-open restores previously open sidebar after renderer
   const previousDocument = globals.document;
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -884,6 +890,7 @@ test('subtitle sidebar refresh closes and clears state when config becomes disab
   const previousDocument = globals.document;
   const bodyClassList = createClassList();
   let snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -1008,6 +1015,7 @@ test('subtitle sidebar keeps nearby repeated cue when subtitle update lacks timi
   const previousDocument = globals.document;
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [
       { startTime: 1, endTime: 2, text: 'same' },
       { startTime: 3, endTime: 4, text: 'other' },
@@ -1125,6 +1133,7 @@ test('subtitle sidebar does not regress to previous cue on text-only transition
   const previousDocument = globals.document;
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [
       { startTime: 1, endTime: 2, text: 'first' },
       { startTime: 3, endTime: 4, text: 'second' },
@@ -1233,6 +1242,7 @@ test('subtitle sidebar jumps to first resolved active cue, then resumes smooth a
   const previousDocument = globals.document;
 
   let snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: Array.from({ length: 12 }, (_, index) => ({
       startTime: index * 2,
       endTime: index * 2 + 1.5,
@@ -1403,6 +1413,7 @@ test('subtitle sidebar polling schedules serialized timeouts instead of interval
   });
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -1515,6 +1526,7 @@ test('subtitle sidebar closes and resumes a hover pause', async () => {
   const contentListeners = new Map<string, Array<() => void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -1633,6 +1645,7 @@ test('subtitle sidebar hover pause ignores playback-state IPC failures', async (
   const contentListeners = new Map<string, Array<() => Promise<void> | void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -1752,6 +1765,7 @@ test('subtitle sidebar keeps hover pause while a Yomitan lookup popup remains op
   const windowListeners = new Map<string, Array<() => Promise<void> | void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -1881,6 +1895,7 @@ test('subtitle sidebar embedded layout reserves and releases mpv right margin',
   const mpvCommands: Array<Array<string | number>> = [];
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2040,6 +2055,7 @@ test('subtitle sidebar embedded layout measures reserved width after embedded cl
   const contentClassList = createClassList();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2161,6 +2177,7 @@ test('subtitle sidebar embedded layout restores macOS and Windows passthrough ou
   const contentListeners = new Map<string, Array<() => void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2290,6 +2307,7 @@ test('subtitle sidebar overlay layout restores macOS and Windows passthrough out
   const contentListeners = new Map<string, Array<() => void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2417,6 +2435,7 @@ test('subtitle sidebar overlay layout only stays interactive while focus remains
   const contentListeners = new Map<string, Array<(event?: FocusEvent) => void>>();
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2532,6 +2551,7 @@ test('closing embedded subtitle sidebar recomputes passthrough from remaining su
   const ignoreMouseCalls: Array<[boolean, { forward?: boolean } | undefined]> = [];
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',
@@ -2640,6 +2660,7 @@ test('subtitle sidebar resets embedded mpv margin on startup while closed', asyn
   const mpvCommands: Array<Array<string | number>> = [];
 
   const snapshot: SubtitleSidebarSnapshot = {
+    sourceKey: 'test-subtitles',
     cues: [{ startTime: 1, endTime: 2, text: 'first' }],
     currentSubtitle: {
       text: 'first',

src/renderer/modals/subtitle-sidebar.ts

@@ -7,6 +7,10 @@ import type {
 import { subtitleCueListSeekTime } from '../../core/services/subtitle-cue-navigation.js';
 import type { ModalStateReader, RendererContext } from '../context';
 import { syncOverlayMouseIgnoreState } from '../overlay-mouse-ignore.js';
+import {
+  clearSubtitleSidebarSelection,
+  hasSubtitleSidebarSelection,
+} from './subtitle-sidebar-selection.js';
 import {
   YOMITAN_POPUP_HIDDEN_EVENT,
   YOMITAN_POPUP_SHOWN_EVENT,
@@ -209,6 +213,7 @@ export function createSubtitleSidebarModal(
   let subtitleSidebarYomitanPopupVisible = false;
   let subtitleSidebarPauseHeldByYomitanPopup = false;
   let lastSubtitleSidebarLookupCueIndex = -1;
+  let subtitleSourceKey: string | null = null;
 
   function restoreEmbeddedSidebarPassthrough(): void {
     syncOverlayMouseIgnoreState(ctx);
@@ -469,6 +474,8 @@ export function createSubtitleSidebarModal(
   ): void {
     if (
       !ctx.state.subtitleSidebarAutoScroll ||
+      ctx.dom.subtitleSidebarList.dataset?.selecting === 'true' ||
+      hasSubtitleSidebarSelection(ctx.dom.subtitleSidebarList) ||
       ctx.state.subtitleSidebarActiveCueIndex < 0 ||
       (!force && ctx.state.subtitleSidebarActiveCueIndex === previousActiveCueIndex) ||
       nowForUiTiming() < ctx.state.subtitleSidebarManualScrollUntilMs
@@ -565,8 +572,14 @@ export function createSubtitleSidebarModal(
 
   async function refreshSnapshot(): Promise<SubtitleSidebarSnapshot> {
     const snapshot = await window.electronAPI.getSubtitleSidebarSnapshot();
+    if (snapshot.sourceKey !== subtitleSourceKey) {
+      clearSubtitleSidebarSelection(ctx.dom.subtitleSidebarList);
+      lastSubtitleSidebarLookupCueIndex = -1;
+      subtitleSourceKey = snapshot.sourceKey;
+    }
     applyConfig(snapshot);
     if (!snapshot.config.enabled) {
+      clearSubtitleSidebarSelection(ctx.dom.subtitleSidebarList);
       resumeSubtitleSidebarHoverPause();
       clearSidebarInteractionState();
       ctx.state.subtitleSidebarCues = [];
@@ -586,6 +599,7 @@ export function createSubtitleSidebarModal(
 
     const cuesChanged = !subtitleCueListsEqual(ctx.state.subtitleSidebarCues, snapshot.cues);
     if (cuesChanged) {
+      clearSubtitleSidebarSelection(ctx.dom.subtitleSidebarList);
       ctx.state.subtitleSidebarCues = snapshot.cues;
       if (ctx.state.subtitleSidebarModalOpen) {
         renderCueList();
@@ -670,6 +684,7 @@ export function createSubtitleSidebarModal(
     if (!ctx.state.subtitleSidebarModalOpen) {
       return;
     }
+    clearSubtitleSidebarSelection(ctx.dom.subtitleSidebarList);
     resumeSubtitleSidebarHoverPause();
     clearSidebarInteractionState();
     ctx.state.subtitleSidebarModalOpen = false;
@@ -710,6 +725,7 @@ export function createSubtitleSidebarModal(
       closeSubtitleSidebarModal();
     });
     ctx.dom.subtitleSidebarList.addEventListener('click', (event) => {
+      if (hasSubtitleSidebarSelection(ctx.dom.subtitleSidebarList)) return;
       const target = event.target;
       if (!(target instanceof Element)) {
         return;

src/renderer/overlay-mouse-ignore.ts

@@ -27,7 +27,9 @@ function isYomitanPopupInteractionActive(state: RendererState): boolean {
 
 export function syncOverlayMouseIgnoreState(ctx: RendererContext): void {
   const shouldKeepWindowInteractive =
-    isYomitanPopupInteractionActive(ctx.state) || isBlockingOverlayModalOpen(ctx.state);
+    ctx.dom.subtitleSidebarList?.dataset?.selecting === 'true' ||
+    isYomitanPopupInteractionActive(ctx.state) ||
+    isBlockingOverlayModalOpen(ctx.state);
   const shouldStayInteractive =
     ctx.state.isOverSubtitle ||
     ctx.state.isOverSubtitleSidebar ||

src/renderer/renderer.ts

@@ -40,6 +40,7 @@ import { createPlaylistBrowserModal } from './modals/playlist-browser.js';
 import { createSessionHelpModal } from './modals/session-help.js';
 import { createChangelogModal } from './modals/changelog.js';
 import { createSubtitleSidebarModal } from './modals/subtitle-sidebar.js';
+import { wireSubtitleSidebarSelection } from './modals/subtitle-sidebar-selection.js';
 import { isControllerInteractionBlocked } from './controller-interaction-blocking.js';
 import { createCharacterDictionaryModal } from './modals/character-dictionary.js';
 import { createRuntimeOptionsModal } from './modals/runtime-options.js';
@@ -239,6 +240,8 @@ const subtitleSidebarModal = createSubtitleSidebarModal(ctx, {
     measurementReporter.emitNow();
   },
 });
+const disposeSubtitleSidebarSelection = wireSubtitleSidebarSelection(ctx);
+window.addEventListener('beforeunload', disposeSubtitleSidebarSelection, { once: true });
 const kikuModal = createKikuModal(ctx, {
   modalStateReader: { isAnyModalOpen },
   syncSettingsModalSubtitleSuppression,

src/renderer/style.css

@@ -3690,6 +3690,7 @@ body.subtitle-sidebar-embedded-open #subtitleSidebarContent {
 }
 
 .subtitle-sidebar-timestamp {
+  user-select: none;
   font-size: 0.72em;
   font-weight: 600;
   font-variant-numeric: tabular-nums;
@@ -3712,6 +3713,8 @@ body.subtitle-sidebar-embedded-open #subtitleSidebarContent {
 }
 
 .subtitle-sidebar-text {
+  user-select: text;
+  cursor: text;
   white-space: pre-wrap;
   line-height: 1.5;
   font-size: 1em;

src/renderer/utils/dom.ts

@@ -157,6 +157,7 @@ export type RendererDom = {
   subtitleSidebarModal: HTMLDivElement;
   subtitleSidebarContent: HTMLDivElement;
   subtitleSidebarClose: HTMLButtonElement;
+  subtitleSidebarCopy: HTMLButtonElement;
   subtitleSidebarStatus: HTMLDivElement;
   subtitleSidebarList: HTMLUListElement;
 
@@ -405,6 +406,7 @@ export function resolveRendererDom(): RendererDom {
     subtitleSidebarModal: getRequiredElement<HTMLDivElement>('subtitleSidebarModal'),
     subtitleSidebarContent: getRequiredElement<HTMLDivElement>('subtitleSidebarContent'),
     subtitleSidebarClose: getRequiredElement<HTMLButtonElement>('subtitleSidebarClose'),
+    subtitleSidebarCopy: getRequiredElement<HTMLButtonElement>('subtitleSidebarCopy'),
     subtitleSidebarStatus: getRequiredElement<HTMLDivElement>('subtitleSidebarStatus'),
     subtitleSidebarList: getRequiredElement<HTMLUListElement>('subtitleSidebarList'),