Code cleanup and stability sprint. Also, more robust search for calibre.

bookstorm.py

@@ -201,6 +201,9 @@ class BookReader:
         # Playback state
         self.isRunning = False
         self.isPlaying = False
+        self.hasPendingSpeechCompletion = False
+        self.pendingSpeechCompletionToken = None
+        self.expectedSpeechCompletionToken = 0
 
         # Sleep timer fade-out state
         self.isFadingOut = False
@@ -902,23 +905,8 @@ class BookReader:
                         self._handle_pygame_key(event)
 
                     elif event.type == SPEECH_FINISHED_EVENT:
-                        # Callback-driven paragraph finished, advance to next
-                        # Don't auto-advance if in any menu
-                        inAnyMenu = (self.optionsMenu.is_in_menu() or
-                                    self.bookSelector.is_in_browser() or
-                                    self.sleepTimerMenu.is_in_menu() or
-                                    self.helpMenu.is_in_menu() or
-                                    self.recentBooksMenu.is_in_menu() or
-                                    (self.absMenu and self.absMenu.is_in_menu()))
-
-                        if self.isPlaying and not inAnyMenu and self.book:
-                            if not self.next_paragraph():
-                                self.displayText = "End of book reached"
-                                self.isPlaying = False
-                                self.save_bookmark(speakFeedback=False)
-                            else:
-                                # Start next paragraph
-                                self._start_paragraph_playback()
+                        completionToken = getattr(event, 'completionToken', None)
+                        self._process_speech_completion(completionToken)
 
                 # Explicitly delete event objects to help GC
                 del events
@@ -956,12 +944,9 @@ class BookReader:
                 isAudioBook = self.book and hasattr(self.book, 'isAudioBook') and self.book.isAudioBook
                 readerEngine = self.config.get_reader_engine()
                 # Don't auto-advance if in any menu
-                inAnyMenu = (self.optionsMenu.is_in_menu() or
-                            self.bookSelector.is_in_browser() or
-                            self.sleepTimerMenu.is_in_menu() or
-                            self.helpMenu.is_in_menu() or
-                            self.recentBooksMenu.is_in_menu() or
-                            (self.absMenu and self.absMenu.is_in_menu()))
+                inAnyMenu = self._is_in_any_menu()
+
+                self._flush_pending_speech_completion()
 
                 if self.isPlaying and not inAnyMenu and self.book:
                     if isAudioBook:
@@ -1015,9 +1000,6 @@ class BookReader:
                 # Every ~10 seconds (300 frames at 30 FPS) run GC
                 gcCounter += 1
                 if gcCounter >= 300:
-                    # Clear any accumulated pygame events before GC
-                    pygame.event.clear()
-
                     # Alternate between fast (gen 0) and full GC
                     # At 300: gen 0 only (fast)
                     # At 600: full collection (all generations)
@@ -1284,18 +1266,23 @@ class BookReader:
                 self.speechEngine.speak("No book loaded")
                 return
 
+            isAudioBook = hasattr(self.book, 'isAudioBook') and self.book.isAudioBook
             readerEngine = self.config.get_reader_engine()
 
             # Pause playback while saving
             wasPaused = False
-            if readerEngine in ['speechd', 'screenreader']:
+            if isAudioBook:
+                wasPaused = self.audioPlayer.is_paused()
+                if not wasPaused and self.audioPlayer.is_audio_file_playing():
+                    self.audioPlayer.pause_audio_file()
+            elif readerEngine in ['speechd', 'screenreader']:
                 wasPaused = self.readingEngine.is_reading_paused()
                 if not wasPaused and self.readingEngine.is_reading_active():
                     self.readingEngine.pause_reading()
             else:
                 wasPaused = self.audioPlayer.is_paused()
-                if not wasPaused and self.audioPlayer.is_playing():
-                    self.audioPlayer.pause()
+                if not wasPaused and self.audioPlayer.is_audio_file_playing():
+                    self.audioPlayer.pause_audio_file()
 
             # Re-enable auto-saving if it was disabled
             self.bookmarkCleared = False
@@ -1305,10 +1292,12 @@ class BookReader:
 
             # Resume playback
             if not wasPaused and self.isPlaying:
-                if readerEngine in ['speechd', 'screenreader']:
+                if isAudioBook:
+                    self.audioPlayer.resume_audio_file()
+                elif readerEngine in ['speechd', 'screenreader']:
                     self.readingEngine.resume_reading()
                 else:
-                    self.audioPlayer.resume()
+                    self.audioPlayer.resume_audio_file()
 
         elif event.key == pygame.K_PAGEUP:
             # Increase speech rate
@@ -1672,6 +1661,73 @@ class BookReader:
                     else:
                         self.speechEngine.speak("End of chapter")
 
+    def _is_in_any_menu(self):
+        """Return True when any modal menu/browser is active."""
+        return (
+            self.optionsMenu.is_in_menu() or
+            self.bookmarksMenu.is_in_menu() or
+            self.bookSelector.is_in_browser() or
+            self.sleepTimerMenu.is_in_menu() or
+            self.helpMenu.is_in_menu() or
+            self.recentBooksMenu.is_in_menu() or
+            (self.absMenu and self.absMenu.is_in_menu())
+        )
+
+    def _queue_pending_speech_completion(self, completionToken=None):
+        """Store a completion event to process after menus close."""
+        self.hasPendingSpeechCompletion = True
+        self.pendingSpeechCompletionToken = completionToken
+
+    def _process_speech_completion(self, completionToken=None):
+        """Advance paragraph/chapter for callback-driven completion events."""
+        if not (self.isPlaying and self.book):
+            return
+        if hasattr(self.book, 'isAudioBook') and self.book.isAudioBook:
+            return
+
+        readerEngine = self.config.get_reader_engine()
+        if readerEngine not in ['speechd', 'screenreader']:
+            return
+
+        if completionToken is None:
+            return
+        try:
+            tokenInt = int(completionToken)
+        except Exception:
+            return
+        if tokenInt != self.expectedSpeechCompletionToken:
+            return
+
+        if self._is_in_any_menu():
+            self._queue_pending_speech_completion(tokenInt)
+            return
+
+        if self.readingEngine and self.readingEngine.is_reading_paused():
+            return
+        if self.readingEngine:
+            tokenCheck = getattr(self.readingEngine, 'is_completion_token_current', None)
+            if callable(tokenCheck) and not tokenCheck(tokenInt):
+                return
+
+        if not self.next_paragraph():
+            self.displayText = "End of book reached"
+            self.isPlaying = False
+            self.save_bookmark(speakFeedback=False)
+        else:
+            self._start_paragraph_playback()
+
+    def _flush_pending_speech_completion(self):
+        """Process a deferred completion event once menus are closed."""
+        if not self.hasPendingSpeechCompletion:
+            return
+        if self._is_in_any_menu():
+            return
+
+        completionToken = self.pendingSpeechCompletionToken
+        self.hasPendingSpeechCompletion = False
+        self.pendingSpeechCompletionToken = None
+        self._process_speech_completion(completionToken)
+
     def _is_help_key(self, event):
         """Return True when the key event should open or close help."""
         if event.key == pygame.K_F1:
@@ -2166,6 +2222,11 @@ class BookReader:
         if self.book:
             self.save_bookmark(speakFeedback=False)
             self._close_abs_session()
+            if self.readingEngine and hasattr(self.readingEngine, 'cancel_reading'):
+                self.readingEngine.cancel_reading()
+            self.expectedSpeechCompletionToken += 1
+            self.hasPendingSpeechCompletion = False
+            self.pendingSpeechCompletionToken = None
             self.audioPlayer.stop()
             if self.audioPlayer.is_audio_file_loaded():
                 self.audioPlayer.stop_audio_file()
@@ -2549,6 +2610,11 @@ class BookReader:
             self._close_abs_session()
 
         # Stop current playback
+        if self.readingEngine and hasattr(self.readingEngine, 'cancel_reading'):
+            self.readingEngine.cancel_reading()
+        self.expectedSpeechCompletionToken += 1
+        self.hasPendingSpeechCompletion = False
+        self.pendingSpeechCompletionToken = None
         self.audioPlayer.stop()
         self._cancel_buffer()
         self.isPlaying = False
@@ -2636,14 +2702,23 @@ class BookReader:
 
         if readerEngine in ['speechd', 'screenreader']:
             # Use callback-driven reading engines
-            def on_speech_finished(finishType):
+            self.expectedSpeechCompletionToken += 1
+            paragraphToken = self.expectedSpeechCompletionToken
+
+            def on_speech_finished(finishType, completionToken=None):
                 """
                 Callback when a paragraph finishes speaking.
                 Post pygame event instead of mutating state in callback thread.
                 """
                 if finishType == 'COMPLETED' and self.isPlaying:
                     # Post pygame event to handle in main loop
-                    pygame.event.post(pygame.event.Event(SPEECH_FINISHED_EVENT))
+                    eventData = {'completionToken': paragraphToken}
+                    if completionToken is not None:
+                        try:
+                            eventData['completionToken'] = int(completionToken)
+                        except Exception:
+                            pass
+                    pygame.event.post(pygame.event.Event(SPEECH_FINISHED_EVENT, eventData))
 
             self.readingEngine.speak_reading(paragraph, callback=on_speech_finished)
         else:

src/bookmark_manager.py

@@ -91,6 +91,20 @@ class BookmarkManager:
         bookPath = str(Path(bookPath).resolve())
         return hashlib.sha256(bookPath.encode()).hexdigest()[:16]
 
+    def _get_unique_named_bookmark_name(self, cursor, bookId, baseName):
+        """Return an unused bookmark name for a given book."""
+        candidateName = baseName
+        suffixIndex = 2
+        while True:
+            cursor.execute('''
+                SELECT 1 FROM named_bookmarks
+                WHERE book_id = ? AND name = ?
+            ''', (bookId, candidateName))
+            if cursor.fetchone() is None:
+                return candidateName
+            candidateName = f"{baseName} ({suffixIndex})"
+            suffixIndex += 1
+
     def save_bookmark(self, bookPath, bookTitle, chapterIndex, paragraphIndex, sentenceIndex=0, audioPosition=0.0):
         """
         Save bookmark for a book
@@ -322,13 +336,23 @@ class BookmarkManager:
                 row = cursor.fetchone()
                 if row:
                     bookmarkId = row[0]
-                    cursor.execute('''
-                        UPDATE named_bookmarks
-                        SET name = ?, chapter_index = ?, paragraph_index = ?, audio_position = ?,
-                            "server_created_at" = ?, created_at = ?
-                        WHERE id = ?
-                    ''', (name, chapterIndex, paragraphIndex, audioPosition,
-                          serverCreatedAt, timestamp, bookmarkId))
+                    try:
+                        cursor.execute('''
+                            UPDATE named_bookmarks
+                            SET name = ?, chapter_index = ?, paragraph_index = ?, audio_position = ?,
+                                "server_created_at" = ?, created_at = ?
+                            WHERE id = ?
+                        ''', (name, chapterIndex, paragraphIndex, audioPosition,
+                              serverCreatedAt, timestamp, bookmarkId))
+                    except sqlite3.IntegrityError:
+                        # Keep the existing local name if requested server name collides.
+                        cursor.execute('''
+                            UPDATE named_bookmarks
+                            SET chapter_index = ?, paragraph_index = ?, audio_position = ?,
+                                "server_created_at" = ?, created_at = ?
+                            WHERE id = ?
+                        ''', (chapterIndex, paragraphIndex, audioPosition,
+                              serverCreatedAt, timestamp, bookmarkId))
                     conn.commit()
                     return bookmarkId
 
@@ -345,11 +369,32 @@ class BookmarkManager:
                 return cursor.lastrowid
 
             cursor.execute('''
-                SELECT id FROM named_bookmarks
+                SELECT id, server_library_item_id, server_time FROM named_bookmarks
                 WHERE book_id = ? AND name = ?
             ''', (bookId, name))
             row = cursor.fetchone()
             bookmarkId = row[0] if row else None
+            existingServerItemId = row[1] if row else None
+            existingServerTime = row[2] if row else None
+
+            hasServerIdentity = serverLibraryItemId is not None and serverTime is not None
+            if bookmarkId and hasServerIdentity:
+                sameServerBookmark = (
+                    existingServerItemId == serverLibraryItemId and
+                    existingServerTime == serverTime
+                )
+                if not sameServerBookmark:
+                    uniqueName = self._get_unique_named_bookmark_name(cursor, bookId, name)
+                    cursor.execute('''
+                        INSERT INTO named_bookmarks
+                        (book_id, name, chapter_index, paragraph_index, audio_position, created_at,
+                         server_library_item_id, server_time, server_created_at)
+                        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+                    ''', (bookId, uniqueName, chapterIndex, paragraphIndex, audioPosition, timestamp,
+                          serverLibraryItemId, serverTime, serverCreatedAt))
+                    conn.commit()
+                    return cursor.lastrowid
+
             if bookmarkId:
                 cursor.execute('''
                     UPDATE named_bookmarks

src/help_menu.py

@@ -29,7 +29,13 @@ class HelpMenu:
         Args:
             helpLines: List of help lines to navigate
         """
-        self.helpLines = helpLines if isinstance(helpLines, list) else []
+        if isinstance(helpLines, str) or helpLines is None:
+            self.helpLines = []
+        else:
+            try:
+                self.helpLines = [str(line) for line in list(helpLines)]
+            except Exception:
+                self.helpLines = []
         self.currentIndex = -1
         self.inMenu = True
 
@@ -37,7 +43,7 @@ class HelpMenu:
             self.speechEngine.speak("Help opened. No help text available.")
             return
 
-        self.speechEngine.speak("Help opened. Press up or down arrows to navigate.")
+        self.speechEngine.speak("Help opened. Press down to hear the first line, then use up or down to navigate.")
 
     def exit_menu(self):
         """Close help menu."""

src/mobi_parser.py

@@ -10,6 +10,7 @@ Uses Calibre's ebook-convert to convert MOBI to EPUB, then parses the EPUB.
 import tempfile
 import shutil
 import subprocess
+import os
 from pathlib import Path
 
 from src.book import Book, Chapter
@@ -24,6 +25,29 @@ class MobiParser:
         self.tempDir = None
         self.epubParser = None
 
+    def _find_ebook_convert(self):
+        """Locate Calibre's ebook-convert binary."""
+        overridePath = os.environ.get('BOOKSTORM_EBOOK_CONVERT') or os.environ.get('EBOOK_CONVERT')
+        if overridePath:
+            overrideCandidate = Path(overridePath).expanduser()
+            if overrideCandidate.exists() and os.access(overrideCandidate, os.X_OK):
+                return str(overrideCandidate)
+
+        pathCandidate = shutil.which('ebook-convert')
+        if pathCandidate:
+            return pathCandidate
+
+        commonCandidates = [
+            Path('/opt/calibre/ebook-convert'),
+            Path('/opt/calibre/bin/ebook-convert'),
+            Path('/opt/bin/ebook-convert'),
+        ]
+        for binaryPath in commonCandidates:
+            if binaryPath.exists() and os.access(binaryPath, os.X_OK):
+                return str(binaryPath)
+
+        return None
+
     def parse(self, mobiPath):
         """
         Parse MOBI file
@@ -47,8 +71,14 @@ class MobiParser:
             # Convert MOBI to EPUB using Calibre's ebook-convert
             epubPath = tempPath / f"{mobiPath.stem}.epub"
 
-            # Check if ebook-convert is available
-            convertCmd = ['ebook-convert', str(mobiPath), str(epubPath)]
+            convertBinary = self._find_ebook_convert()
+            if not convertBinary:
+                raise Exception(
+                    "Calibre's ebook-convert tool is required for MOBI support, but it was not found in PATH or common /opt locations. "
+                    "Set BOOKSTORM_EBOOK_CONVERT to the full path if needed."
+                )
+
+            convertCmd = [convertBinary, str(mobiPath), str(epubPath)]
 
             try:
                 # Run ebook-convert with error capture
@@ -63,11 +93,7 @@ class MobiParser:
                     raise Exception(f"ebook-convert failed: {result.stderr}")
 
             except FileNotFoundError:
-                raise Exception(
-                    "Calibre's ebook-convert tool is required for MOBI support. "
-                    "Install Calibre: sudo pacman -S calibre (Arch) or "
-                    "sudo apt install calibre (Debian/Ubuntu)"
-                )
+                raise Exception("ebook-convert binary was found but could not be executed")
             except subprocess.TimeoutExpired:
                 raise Exception("MOBI conversion timed out (>60 seconds)")
 

src/options_menu.py

@@ -55,7 +55,8 @@ class OptionsMenu:
         """Return user-facing labels for available engine values."""
         engineLabels = {
             'piper': 'Piper-TTS',
-            'speechd': 'Speech-Dispatcher'
+            'speechd': 'Speech-Dispatcher',
+            'screenreader': 'Screen Reader'
         }
         if self.screenReaderName:
             engineLabels['screenreader'] = self.screenReaderName
@@ -77,7 +78,7 @@ class OptionsMenu:
         """
         readerEngine = self.config.get_reader_engine()
         engineLabels = self._get_engine_labels()
-        readerEngineText = engineLabels.get(readerEngine, 'Piper-TTS')
+        readerEngineText = engineLabels.get(readerEngine, str(readerEngine))
 
         menuItems = [
             {
@@ -180,17 +181,18 @@ class OptionsMenu:
         """Cycle reader engine: piper-tts, speech-dispatcher, screen reader."""
         self._refresh_screen_reader_target()
         currentEngine = self.config.get_reader_engine()
+        validEngines = {'piper', 'speechd', 'screenreader'}
+        oldEngine = currentEngine if currentEngine in validEngines else 'piper'
         engineOrder = self._get_engine_cycle_order()
         engineLabels = self._get_engine_labels()
 
         if currentEngine not in engineOrder:
             currentEngine = 'piper'
 
-        oldEngine = currentEngine
         currentIndex = engineOrder.index(currentEngine)
         newEngine = engineOrder[(currentIndex + 1) % len(engineOrder)]
         self.config.set_reader_engine(newEngine)
-        message = f"Reader engine: {engineLabels.get(newEngine, 'Piper-TTS')}."
+        message = f"Reader engine: {engineLabels.get(newEngine, newEngine)}."
 
         # Reload TTS engine if callback available
         needsRestart = False
@@ -231,6 +233,7 @@ class OptionsMenu:
         if readerEngine == 'speechd':
             return self._select_speechd_voice()
 
+        self._refresh_screen_reader_target()
         readerName = self.screenReaderName if self.screenReaderName else "your active screen reader"
         self.speechEngine.speak(f"Voice selection is managed by {readerName}.")
         return True
@@ -466,7 +469,9 @@ class OptionsMenu:
             sys.exit(0)
         else:
             # Cancel - revert engine change
-            self.config.set_reader_engine(self.previousEngine)
+            validEngines = {'piper', 'speechd', 'screenreader'}
+            revertEngine = self.previousEngine if self.previousEngine in validEngines else 'piper'
+            self.config.set_reader_engine(revertEngine)
             self.inRestartMenu = False
             self.speechEngine.speak("Cancelled. Engine change reverted.")
             # Speak current main menu item
@@ -477,7 +482,9 @@ class OptionsMenu:
 
     def exit_restart_menu(self):
         """Exit restart confirmation menu (same as cancel)"""
-        self.config.set_reader_engine(self.previousEngine)
+        validEngines = {'piper', 'speechd', 'screenreader'}
+        revertEngine = self.previousEngine if self.previousEngine in validEngines else 'piper'
+        self.config.set_reader_engine(revertEngine)
         self.inRestartMenu = False
         self.speechEngine.speak("Cancelled. Engine change reverted.")
         # Speak current main menu item

src/screen_reader_engine.py

@@ -21,6 +21,9 @@ except ImportError:
 from .text_validator import is_valid_text
 
 
+DBUS_ENV_LOCK = threading.Lock()
+
+
 class ScreenReaderRemoteController:
     """D-Bus helper for a single screen reader service."""
 
@@ -31,6 +34,8 @@ class ScreenReaderRemoteController:
         self.displayName = displayName
         self.proxy = None
         self.speechProxy = None
+        self.callLock = threading.Lock()
+        self.pendingCallThread = None
         self.available = self._test_availability()
 
     def _call_with_timeout(self, func, timeoutSeconds=2):
@@ -44,12 +49,24 @@ class ScreenReaderRemoteController:
             except Exception as error:
                 exception[0] = error
 
-        workerThread = threading.Thread(target=wrapper, daemon=True)
+        with self.callLock:
+            # Avoid unbounded daemon thread buildup if a previous call is stuck.
+            if self.pendingCallThread and self.pendingCallThread.is_alive():
+                return None
+
+            workerThread = threading.Thread(target=wrapper, daemon=True)
+            self.pendingCallThread = workerThread
+
         workerThread.start()
         workerThread.join(timeout=timeoutSeconds)
 
         if workerThread.is_alive():
             return None
+
+        with self.callLock:
+            if self.pendingCallThread is workerThread:
+                self.pendingCallThread = None
+
         if exception[0]:
             raise exception[0]
         return result[0]
@@ -103,22 +120,23 @@ class ScreenReaderRemoteController:
                 if not busAddress:
                     return False
 
-                oldAddress = os.environ.get("DBUS_SESSION_BUS_ADDRESS")
-                try:
-                    os.environ["DBUS_SESSION_BUS_ADDRESS"] = busAddress
-                    bus = SessionMessageBus()
-                    self.proxy = bus.get_proxy(self.serviceName, self.mainPath)
-                    self.proxy.ListCommands()
-                    self.speechProxy = bus.get_proxy(
-                        self.serviceName,
-                        f"{self.mainPath}/SpeechAndVerbosityManager"
-                    )
-                    return True
-                finally:
-                    if oldAddress is not None:
-                        os.environ["DBUS_SESSION_BUS_ADDRESS"] = oldAddress
-                    elif "DBUS_SESSION_BUS_ADDRESS" in os.environ:
-                        del os.environ["DBUS_SESSION_BUS_ADDRESS"]
+                with DBUS_ENV_LOCK:
+                    oldAddress = os.environ.get("DBUS_SESSION_BUS_ADDRESS")
+                    try:
+                        os.environ["DBUS_SESSION_BUS_ADDRESS"] = busAddress
+                        bus = SessionMessageBus()
+                        self.proxy = bus.get_proxy(self.serviceName, self.mainPath)
+                        self.proxy.ListCommands()
+                        self.speechProxy = bus.get_proxy(
+                            self.serviceName,
+                            f"{self.mainPath}/SpeechAndVerbosityManager"
+                        )
+                        return True
+                    finally:
+                        if oldAddress is not None:
+                            os.environ["DBUS_SESSION_BUS_ADDRESS"] = oldAddress
+                        elif "DBUS_SESSION_BUS_ADDRESS" in os.environ:
+                            del os.environ["DBUS_SESSION_BUS_ADDRESS"]
 
         try:
             return bool(self._call_with_timeout(test_connection, timeoutSeconds=2))
@@ -131,9 +149,7 @@ class ScreenReaderRemoteController:
             return False
 
         try:
-            result = self._call_with_timeout(lambda: self.proxy.PresentMessage(str(message)), timeoutSeconds=2)
-            if result is None:
-                return False
+            result = self.proxy.PresentMessage(str(message))
             return bool(result) if isinstance(result, bool) else True
         except Exception:
             return False
@@ -145,24 +161,27 @@ class ScreenReaderRemoteController:
 
         try:
             if self.speechProxy:
-                result = self._call_with_timeout(
-                    lambda: self.speechProxy.ExecuteCommand("InterruptSpeech", False),
-                    timeoutSeconds=2
-                )
-                if result is None:
-                    return False
+                result = self.speechProxy.ExecuteCommand("InterruptSpeech", False)
                 return bool(result) if isinstance(result, bool) else True
 
             if self.proxy:
-                result = self._call_with_timeout(lambda: self.proxy.ExecuteCommand("InterruptSpeech", False), timeoutSeconds=2)
-                if result is None:
-                    return False
+                result = self.proxy.ExecuteCommand("InterruptSpeech", False)
                 return bool(result) if isinstance(result, bool) else True
         except Exception:
             pass
 
         return False
 
+    def is_responsive(self):
+        """Return True if the controller still responds to a benign command."""
+        if not self.available or not self.proxy:
+            return False
+        try:
+            commands = self._call_with_timeout(lambda: self.proxy.ListCommands(), timeoutSeconds=1)
+            return commands is not None
+        except Exception:
+            return False
+
 
 class ScreenReaderEngine:
     """Book reading engine that speaks via active screen reader D-Bus APIs."""
@@ -288,7 +307,7 @@ class ScreenReaderEngine:
 
     def close(self):
         """Release resources and stop in-flight reading state."""
-        self.cancel_reading()
+        self.cancel_reading(interrupt=False)
 
     def cleanup(self):
         """Cleanup resources - alias for close()."""
@@ -297,11 +316,12 @@ class ScreenReaderEngine:
     def _estimate_duration_seconds(self, text):
         """Estimate speech duration for callback timing."""
         words = max(1, len(str(text).split()))
-        adjustedWpm = max(90.0, min(500.0, 180.0 + (float(self.speechRate) * 2.5)))
+        adjustedWpm = max(70.0, min(360.0, 150.0 + (float(self.speechRate) * 1.8)))
         wordsDuration = (words / adjustedWpm) * 60.0
         punctuationCount = str(text).count(".") + str(text).count("!") + str(text).count("?")
-        punctuationPause = punctuationCount * 0.12
-        return max(0.8, wordsDuration + punctuationPause)
+        punctuationPause = punctuationCount * 0.2
+        estimatedDuration = wordsDuration + punctuationPause + 0.25
+        return max(1.0, estimatedDuration * 1.2)
 
     def _start_completion_timer(self, readingGeneration, text):
         """Start background completion timer and invoke callback on completion."""
@@ -314,8 +334,9 @@ class ScreenReaderEngine:
             while elapsed < duration:
                 time.sleep(interval)
                 elapsed += interval
-                if readingGeneration != self.readingGeneration:
-                    return
+                with self.speechLock:
+                    if readingGeneration != self.readingGeneration:
+                        return
 
             callback = None
             with self.speechLock:
@@ -326,7 +347,18 @@ class ScreenReaderEngine:
                 callback = self.readingCallback
 
             if callback:
-                callback('COMPLETED')
+                try:
+                    callback('COMPLETED', readingGeneration)
+                except TypeError as error:
+                    errorText = str(error)
+                    signatureMismatch = (
+                        "positional argument" in errorText or
+                        ("takes" in errorText and "given" in errorText)
+                    )
+                    if signatureMismatch:
+                        callback('COMPLETED')
+                    else:
+                        print(f"Screen reader completion callback error: {error}")
 
         workerThread = threading.Thread(target=completion_thread, daemon=True)
         workerThread.start()
@@ -335,16 +367,32 @@ class ScreenReaderEngine:
         """Try to switch to another available controller."""
         if not self.availableControllers:
             return False
-        if not self.activeController:
-            self.activeController = self.availableControllers[0]
-            return True
 
-        for controller in self.availableControllers:
-            if controller is self.activeController:
+        previousController = self.activeController
+        candidates = []
+        if not self.activeController:
+            candidates = list(self.availableControllers)
+        else:
+            candidates = [
+                controller for controller in self.availableControllers
+                if controller is not self.activeController
+            ]
+
+        for controller in candidates:
+            if not self._is_process_running(controller.processName):
+                continue
+            if not controller.is_responsive():
                 continue
             self.activeController = controller
+            self.isAvailable = True
             return True
 
+        # Re-discover controllers in case the active reader restarted.
+        self._initialize_controllers()
+        if self.activeController and self.activeController is not previousController:
+            return True
+
+        self.isAvailable = self.activeController is not None
         return False
 
     def speak(self, text, interrupt=True):
@@ -413,6 +461,15 @@ class ScreenReaderEngine:
                     self.isReading = False
             return
 
+        with self.speechLock:
+            generationStillCurrent = (
+                currentGeneration == self.readingGeneration and
+                self.isReading and
+                not self.isPausedReading
+            )
+        if not generationStillCurrent:
+            return
+
         self._start_completion_timer(currentGeneration, textStr)
 
     def pause_reading(self):
@@ -438,7 +495,7 @@ class ScreenReaderEngine:
 
         self.speak_reading(textToResume, callback=callback)
 
-    def cancel_reading(self):
+    def cancel_reading(self, interrupt=True):
         """Cancel current reading."""
         with self.speechLock:
             self.readingGeneration += 1
@@ -446,7 +503,7 @@ class ScreenReaderEngine:
             self.isPausedReading = False
             self.readingCallback = None
 
-        if self.activeController:
+        if interrupt and self.activeController:
             self.activeController.interrupt_speech()
 
     def is_reading_active(self):
@@ -457,6 +514,15 @@ class ScreenReaderEngine:
         """Check if reading is paused."""
         return self.isPausedReading
 
+    def is_completion_token_current(self, tokenValue):
+        """Return True when completion token still matches active generation."""
+        try:
+            tokenInt = int(tokenValue)
+        except Exception:
+            return False
+        with self.speechLock:
+            return tokenInt == self.readingGeneration
+
     def set_rate(self, rate):
         """Store virtual speech rate used for completion timing estimation."""
         try: