diff --git a/abogen/book_handler.py b/abogen/book_handler.py
index c640401..05201ec 100644
--- a/abogen/book_handler.py
+++ b/abogen/book_handler.py
@@ -48,13 +48,14 @@ logging.basicConfig(
 _BRACKETED_NUMBERS_PATTERN = re.compile(r"\[\s*\d+\s*\]")
 _STANDALONE_PAGE_NUMBERS_PATTERN = re.compile(r"^\s*\d+\s*$", re.MULTILINE)
 _PAGE_NUMBERS_AT_END_PATTERN = re.compile(r"\s+\d+\s*$", re.MULTILINE)
-_PAGE_NUMBERS_WITH_DASH_PATTERN = re.compile(r"\s+[-–—]\s*\d+\s*[-–—]?\s*$", re.MULTILINE)
+_PAGE_NUMBERS_WITH_DASH_PATTERN = re.compile(
+    r"\s+[-–—]\s*\d+\s*[-–—]?\s*$", re.MULTILINE
+)
 _HTML_TAG_PATTERN = re.compile(r"<[^>]+>")
 _LEADING_DASH_PATTERN = re.compile(r"^\s*[-–—]\s*")
 _LEADING_SIMPLE_DASH_PATTERN = re.compile(r"^\s*-\s*")
 
 
-
 class HandlerDialog(QDialog):
     # Class variables to remember checkbox states between dialog instances
     _save_chapters_separately = False
@@ -2407,7 +2408,9 @@ class HandlerDialog(QDialog):
                         included_text_ids.add(child_id)
                     if combined_text.strip():
                         # Use pre-compiled pattern for better performance
-                        title = _LEADING_SIMPLE_DASH_PATTERN.sub("", parent_title).strip()
+                        title = _LEADING_SIMPLE_DASH_PATTERN.sub(
+                            "", parent_title
+                        ).strip()
                         marker = f"<<CHAPTER_MARKER:{title}>>"
                         section_titles.append((title, marker + "\n" + combined_text))
                         included_text_ids.add(parent_id)
diff --git a/abogen/conversion.py b/abogen/conversion.py
index d9bacbc..a4f10df 100644
--- a/abogen/conversion.py
+++ b/abogen/conversion.py
@@ -29,7 +29,9 @@ import subprocess
 import platform
 
 # Configuration constants
-_USER_RESPONSE_TIMEOUT = 0.1  # Timeout in seconds for checking user response/cancellation
+_USER_RESPONSE_TIMEOUT = (
+    0.1  # Timeout in seconds for checking user response/cancellation
+)
 
 # Pre-compile frequently used regex patterns for better performance
 _METADATA_TAG_PATTERN = re.compile(r"<<METADATA_[^:]+:[^>]*>>")
@@ -48,7 +50,9 @@ _VTT_TIMESTAMP_PATTERN = re.compile(r"([\d:.]+)\s*-->\s*([\d:.]+)")
 _TIMESTAMP_ONLY_PATTERN = re.compile(r"^(\d{1,2}:\d{2}:\d{2}(?:[.,]\d{1,3})?)$")
 _WINDOWS_ILLEGAL_CHARS_PATTERN = re.compile(r'[<>:"/\\|?*]')
 _CONTROL_CHARS_PATTERN = re.compile(r"[\x00-\x1f]")
-_LINUX_CONTROL_CHARS_PATTERN = re.compile(r"[\x01-\x1f]")  # Linux: exclude \x00 for separate handling
+_LINUX_CONTROL_CHARS_PATTERN = re.compile(
+    r"[\x01-\x1f]"
+)  # Linux: exclude \x00 for separate handling
 _MACOS_ILLEGAL_CHARS_PATTERN = re.compile(r"[:]")
 _LINUX_ILLEGAL_CHARS_PATTERN = re.compile(r"[/\x00]")
 
@@ -221,7 +225,9 @@ def detect_timestamps_in_text(file_path):
         # Count lines that are ONLY timestamps (no other text)
         # Supports HH:MM:SS or HH:MM:SS,ms format
         # Use pre-compiled pattern for better performance
-        timestamp_lines = sum(1 for line in lines if _TIMESTAMP_ONLY_PATTERN.match(line))
+        timestamp_lines = sum(
+            1 for line in lines if _TIMESTAMP_ONLY_PATTERN.match(line)
+        )
 
         # Must have at least 2 timestamp-only lines and they should be >5% of total lines
         return timestamp_lines >= 2 and (timestamp_lines / max(len(lines), 1)) > 0.05
@@ -369,7 +375,9 @@ def parse_ass_file(file_path):
                 # Clean text of ASS styling tags using pre-compiled patterns
                 text = _ASS_STYLING_PATTERN.sub("", text)  # Remove {tags}
                 text = _ASS_NEWLINE_N_PATTERN.sub("\n", text)  # Convert \N to newline
-                text = _ASS_NEWLINE_LOWER_N_PATTERN.sub("\n", text)  # Convert \n to newline
+                text = _ASS_NEWLINE_LOWER_N_PATTERN.sub(
+                    "\n", text
+                )  # Convert \n to newline
                 # Remove chapter markers and metadata tags
                 text = clean_subtitle_text(text)
 
@@ -643,7 +651,9 @@ class ConversionThread(QThread):
         elif subtitle_mode == "Sentence":
             return r"(?<=[{}]){}|\n+".format(self.PUNCTUATION_SENTENCE, spacing_pattern)
         elif subtitle_mode == "Sentence + Comma":
-            return r"(?<=[{}]){}|\n+".format(self.PUNCTUATION_SENTENCE_COMMA, spacing_pattern)
+            return r"(?<=[{}]){}|\n+".format(
+                self.PUNCTUATION_SENTENCE_COMMA, spacing_pattern
+            )
         else:
             return r"\n+"  # Default to line breaks
 
@@ -745,7 +755,9 @@ class ConversionThread(QThread):
                 # Clear segment bytes from memory
                 del segment_bytes
             except Exception as e:
-                self.log_updated.emit((f"Error processing segment {i}: {str(e)}", "red"))
+                self.log_updated.emit(
+                    (f"Error processing segment {i}: {str(e)}", "red")
+                )
                 raise
 
         return samples_processed
@@ -803,7 +815,9 @@ class ConversionThread(QThread):
             self.log_updated.emit(
                 f"- Subtitle format: {next((label for value, label in SUBTITLE_FORMATS if value == getattr(self, 'subtitle_format', 'srt')), getattr(self, 'subtitle_format', 'srt'))}"
             )
-            self.log_updated.emit(f"- Use spaCy for sentence segmentation: {'Yes' if getattr(self, 'use_spacy_segmentation', False) else 'No'}")
+            self.log_updated.emit(
+                f"- Use spaCy for sentence segmentation: {'Yes' if getattr(self, 'use_spacy_segmentation', False) else 'No'}"
+            )
             self.log_updated.emit(f"- Save option: {self.save_option}")
             if self.replace_single_newlines:
                 self.log_updated.emit(f"- Replace single newlines: Yes")
@@ -884,11 +898,15 @@ class ConversionThread(QThread):
                     )
                 elif file_ext == ".txt" and detect_timestamps_in_text(self.file_name):
                     is_timestamp_text = True
-                    self.log_updated.emit(("\nDetected timestamps in text file", "grey"))
+                    self.log_updated.emit(
+                        ("\nDetected timestamps in text file", "grey")
+                    )
                     # Signal to ask user (-1 indicates timestamp detection)
                     self.chapters_detected.emit(-1)
                     # Wait for user response using event with timeout for responsive cancellation
-                    while not self._timestamp_response_event.wait(timeout=_USER_RESPONSE_TIMEOUT):
+                    while not self._timestamp_response_event.wait(
+                        timeout=_USER_RESPONSE_TIMEOUT
+                    ):
                         if self.cancel_requested:
                             self.conversion_finished.emit("Cancelled", None)
                             return
@@ -1029,7 +1047,9 @@ class ConversionThread(QThread):
                 )
                 # Only check for files with allowed extensions (extension without dot, case-insensitive)
                 # Use generator expression to avoid processing all files upfront
-                file_parts = (os.path.splitext(fname) for fname in os.listdir(parent_dir))
+                file_parts = (
+                    os.path.splitext(fname) for fname in os.listdir(parent_dir)
+                )
                 clash = any(
                     name == f"{sanitized_base_name}{suffix}"
                     and ext[1:].lower() in allowed_exts
@@ -1380,7 +1400,7 @@ class ConversionThread(QThread):
                 else:
                     chapter_subtitle_path = None
                     chapter_subtitle_file = None
-                
+
                 # Determine if spaCy segmentation should be used for PRE-TTS segmentation
                 # Only non-English languages use spaCy for pre-segmentation
                 # English uses spaCy only for subtitle generation (post-TTS)
@@ -1389,7 +1409,8 @@ class ConversionThread(QThread):
                 is_subtitle_input = (
                     not self.is_direct_text
                     and self.file_name
-                    and os.path.splitext(self.file_name)[1].lower() in [".srt", ".ass", ".vtt"]
+                    and os.path.splitext(self.file_name)[1].lower()
+                    in [".srt", ".ass", ".vtt"]
                 )
                 use_spacy = (
                     getattr(self, "use_spacy_segmentation", False)
@@ -1399,33 +1420,60 @@ class ConversionThread(QThread):
                 spacy_sentences = None
                 active_split_pattern = self.split_pattern
                 spacing_pattern = r"\s*" if self.lang_code in ["z", "j"] else r"\s+"
-                
+
                 # Pre-load spaCy model for English if it will be needed for subtitle generation
-                if use_spacy and self.lang_code in ["a", "b"] and self.subtitle_mode in ["Sentence", "Sentence + Comma"]:
+                if (
+                    use_spacy
+                    and self.lang_code in ["a", "b"]
+                    and self.subtitle_mode in ["Sentence", "Sentence + Comma"]
+                ):
                     from abogen.spacy_utils import get_spacy_model
-                    nlp = get_spacy_model(self.lang_code, log_callback=lambda msg: self.log_updated.emit(msg))
+
+                    nlp = get_spacy_model(
+                        self.lang_code,
+                        log_callback=lambda msg: self.log_updated.emit(msg),
+                    )
                     if nlp:
-                        self.log_updated.emit(("\nUsing spaCy for sentence segmentation (only for subtitles)...", "grey"))
-                
+                        self.log_updated.emit(
+                            (
+                                "\nUsing spaCy for sentence segmentation (only for subtitles)...",
+                                "grey",
+                            )
+                        )
+
                 if use_spacy and self.lang_code not in ["a", "b"]:
                     # Non-English: use spaCy for pre-TTS segmentation
-                    self.log_updated.emit(("\nUsing spaCy for sentence segmentation (pre-TTS)...", "grey"))
+                    self.log_updated.emit(
+                        ("\nUsing spaCy for sentence segmentation (pre-TTS)...", "grey")
+                    )
                     from abogen.spacy_utils import segment_sentences
+
                     spacy_sentences = segment_sentences(
-                        chapter_text, 
-                        self.lang_code, 
-                        log_callback=lambda msg: self.log_updated.emit(msg)
+                        chapter_text,
+                        self.lang_code,
+                        log_callback=lambda msg: self.log_updated.emit(msg),
                     )
                     if spacy_sentences:
-                        self.log_updated.emit((f"\nspaCy: Text segmented into {len(spacy_sentences)} sentences...", "grey"))
+                        self.log_updated.emit(
+                            (
+                                f"\nspaCy: Text segmented into {len(spacy_sentences)} sentences...",
+                                "grey",
+                            )
+                        )
                         # For Sentence + Comma mode, still split on commas within spaCy sentences
                         if self.subtitle_mode == "Sentence + Comma":
-                            active_split_pattern = r"(?<=[{}]){}|\n+".format(self.PUNCTUATION_COMMAS, spacing_pattern)
+                            active_split_pattern = r"(?<=[{}]){}|\n+".format(
+                                self.PUNCTUATION_COMMAS, spacing_pattern
+                            )
                         else:
-                            active_split_pattern = "\n"  # Use newline splitting for Sentence mode
+                            active_split_pattern = (
+                                "\n"  # Use newline splitting for Sentence mode
+                            )
                     else:
-                        self.log_updated.emit(("\nspaCy: Fallback to default segmentation...", "grey"))
-                
+                        self.log_updated.emit(
+                            ("\nspaCy: Fallback to default segmentation...", "grey")
+                        )
+
                 # Process text - either as spaCy sentences or as single text
                 text_segments = spacy_sentences if spacy_sentences else [chapter_text]
 
@@ -1498,7 +1546,9 @@ class ConversionThread(QThread):
                                         self.end_ts = end
                                         self.whitespace = ""
 
-                                tokens_list = [FakeToken(result.graphemes, 0, chunk_dur)]
+                                tokens_list = [
+                                    FakeToken(result.graphemes, 0, chunk_dur)
+                                ]
 
                             tokens_with_timestamps = []
                             chapter_tokens_with_timestamps = []
@@ -1518,7 +1568,8 @@ class ConversionThread(QThread):
                                         {
                                             "start": chapter_current_time
                                             + (tok.start_ts or 0),
-                                            "end": chapter_current_time + (tok.end_ts or 0),
+                                            "end": chapter_current_time
+                                            + (tok.end_ts or 0),
                                             "text": tok.text,
                                             "whitespace": tok.whitespace,
                                         }
@@ -1602,7 +1653,10 @@ class ConversionThread(QThread):
                                 chapter_current_time += chunk_dur
                         # Calculate percentage based on characters processed
                         percent = min(
-                            int(self.processed_char_count / self.total_char_count * 100), 99
+                            int(
+                                self.processed_char_count / self.total_char_count * 100
+                            ),
+                            99,
                         )
 
                         # Calculate ETR based on characters processed
@@ -1615,7 +1669,9 @@ class ConversionThread(QThread):
                             chars_done > 0 and elapsed > 0.5
                         ):  # Check elapsed > 0.5 to avoid instability
                             avg_time_per_char = elapsed / chars_done
-                            remaining = self.total_char_count - self.processed_char_count
+                            remaining = (
+                                self.total_char_count - self.processed_char_count
+                            )
                             if remaining > 0:
                                 secs = avg_time_per_char * remaining
                                 h = int(secs // 3600)
@@ -1818,7 +1874,9 @@ class ConversionThread(QThread):
                 )
                 return
 
-            self.log_updated.emit((f"\nFound {len(subtitles)} subtitle entries", "grey"))
+            self.log_updated.emit(
+                (f"\nFound {len(subtitles)} subtitle entries", "grey")
+            )
 
             # Setup output paths
             base_name = os.path.splitext(os.path.basename(base_path))[0]
@@ -2000,7 +2058,11 @@ class ConversionThread(QThread):
                     int(start_time % 60),
                 )
                 ms1 = int((start_time - int(start_time)) * 1000)
-                is_last = is_timestamp_text or (use_gaps and idx == len(subtitles)) or end_time is None
+                is_last = (
+                    is_timestamp_text
+                    or (use_gaps and idx == len(subtitles))
+                    or end_time is None
+                )
                 if is_last:
                     time_str = (
                         f"{h1:02d}:{m1:02d}:{s1:02d}"
@@ -2403,7 +2465,7 @@ class ConversionThread(QThread):
             return
 
         processed_tokens = tokens_with_timestamps  # Use tokens directly
-        
+
         # For English with spaCy enabled and sentence-based modes, use spaCy for sentence boundaries
         # spaCy is disabled when subtitle mode is "Disabled" or "Line"
         use_spacy_for_english = (
@@ -2477,7 +2539,10 @@ class ConversionThread(QThread):
             if use_spacy_for_english and self.subtitle_mode != "Line":
                 # Use spaCy for English sentence boundary detection (model already loaded)
                 from abogen.spacy_utils import get_spacy_model
-                nlp = get_spacy_model(self.lang_code)  # No log_callback since model is already loaded
+
+                nlp = get_spacy_model(
+                    self.lang_code
+                )  # No log_callback since model is already loaded
                 if nlp:
                     # Build full text and track character positions to token indices
                     full_text = ""
@@ -2487,31 +2552,37 @@ class ConversionThread(QThread):
                         text_part = token["text"] + (token.get("whitespace", "") or "")
                         full_text += text_part
                         char_to_token.extend([idx] * len(text_part))
-                    
+
                     # Get sentence boundaries from spaCy
                     doc = nlp(full_text)
                     sentence_boundaries = [sent.end_char for sent in doc.sents]
-                    
+
                     # For "Sentence + Comma" mode, also split on commas
                     if self.subtitle_mode == "Sentence + Comma":
-                        comma_positions = [i + 1 for i, c in enumerate(full_text) if c == ',']
-                        sentence_boundaries = sorted(set(sentence_boundaries + comma_positions))
-                    
+                        comma_positions = [
+                            i + 1 for i, c in enumerate(full_text) if c == ","
+                        ]
+                        sentence_boundaries = sorted(
+                            set(sentence_boundaries + comma_positions)
+                        )
+
                     # Group tokens by sentence boundaries
                     current_sentence = []
                     word_count = 0
                     current_char_pos = 0
                     boundary_idx = 0
-                    
+
                     for idx, token in enumerate(processed_tokens):
                         current_sentence.append(token)
                         word_count += 1
-                        text_len = len(token["text"]) + len(token.get("whitespace", "") or "")
+                        text_len = len(token["text"]) + len(
+                            token.get("whitespace", "") or ""
+                        )
                         current_char_pos += text_len
-                        
+
                         # Check if we've hit a sentence boundary or max words
                         at_boundary = (
-                            boundary_idx < len(sentence_boundaries) 
+                            boundary_idx < len(sentence_boundaries)
                             and current_char_pos >= sentence_boundaries[boundary_idx]
                         )
                         if at_boundary or word_count >= max_subtitle_words:
@@ -2522,12 +2593,14 @@ class ConversionThread(QThread):
                                     t["text"] + (t.get("whitespace", "") or "")
                                     for t in current_sentence
                                 )
-                                subtitle_entries.append((start_time, end_time, sentence_text.strip()))
+                                subtitle_entries.append(
+                                    (start_time, end_time, sentence_text.strip())
+                                )
                                 current_sentence = []
                                 word_count = 0
                             if at_boundary:
                                 boundary_idx += 1
-                    
+
                     # Add remaining tokens
                     if current_sentence:
                         start_time = current_sentence[0]["start"]
@@ -2536,8 +2609,10 @@ class ConversionThread(QThread):
                             t["text"] + (t.get("whitespace", "") or "")
                             for t in current_sentence
                         )
-                        subtitle_entries.append((start_time, end_time, sentence_text.strip()))
-                    
+                        subtitle_entries.append(
+                            (start_time, end_time, sentence_text.strip())
+                        )
+
                     # Fallback for last entry
                     if subtitle_entries and fallback_end_time is not None:
                         last_entry = subtitle_entries[-1]
@@ -2545,7 +2620,7 @@ class ConversionThread(QThread):
                         if end is None or end <= start or end <= 0:
                             subtitle_entries[-1] = (start, fallback_end_time, text)
                     return  # Exit early, spaCy processing complete
-            
+
             # Default regex-based processing (non-English or spaCy unavailable)
             # Define separator pattern based on mode
             if self.subtitle_mode == "Line":
diff --git a/abogen/gui.py b/abogen/gui.py
index 7ff96a3..0093e67 100644
--- a/abogen/gui.py
+++ b/abogen/gui.py
@@ -1145,10 +1145,10 @@ class abogen(QWidget):
         except Exception:
             # Fail-safe: don't crash UI if model manipulation isn't supported on some platforms
             pass
-        
+
         # Enable/disable subtitle options based on selected language (profile or voice)
         self.update_subtitle_options_availability()
-        
+
         controls_layout.addLayout(subtitle_format_layout)
 
         # Replace single newlines dropdown (acts like checkbox)
@@ -2851,7 +2851,7 @@ class abogen(QWidget):
 
         # Cleanup pygame mixer if initialized
         try:
-            pygame = sys.modules.get('pygame')
+            pygame = sys.modules.get("pygame")
             if pygame and pygame.mixer.get_init():
                 pygame.mixer.quit()
         except Exception:
@@ -3222,7 +3222,9 @@ class abogen(QWidget):
         menu.addSeparator()
 
         # Add "Pre-download models and voices for offline use" option
-        predownload_action = QAction("Pre-download models and voices for offline use", self)
+        predownload_action = QAction(
+            "Pre-download models and voices for offline use", self
+        )
         predownload_action.triggered.connect(self.show_predownload_dialog)
         menu.addAction(predownload_action)
 
@@ -3294,6 +3296,7 @@ class abogen(QWidget):
         self.use_spacy_segmentation = enabled
         self.config["use_spacy_segmentation"] = enabled
         save_config(self.config)
+
     def restart_app(self):
 
         import sys
@@ -3592,6 +3595,7 @@ Categories=AudioVideo;Audio;Utility;
     def show_predownload_dialog(self):
         """Show the pre-download models and voices dialog."""
         from abogen.predownload_gui import PreDownloadDialog
+
         dialog = PreDownloadDialog(self)
         dialog.exec()
 
diff --git a/abogen/predownload_gui.py b/abogen/predownload_gui.py
index 15dec3f..47138f1 100644
--- a/abogen/predownload_gui.py
+++ b/abogen/predownload_gui.py
@@ -10,7 +10,15 @@ from typing import List, Optional, Tuple
 import importlib
 import importlib.util
 
-from PyQt6.QtWidgets import QDialog, QVBoxLayout, QHBoxLayout, QLabel, QPushButton, QSpacerItem, QSizePolicy
+from PyQt6.QtWidgets import (
+    QDialog,
+    QVBoxLayout,
+    QHBoxLayout,
+    QLabel,
+    QPushButton,
+    QSpacerItem,
+    QSizePolicy,
+)
 from PyQt6.QtCore import QThread, pyqtSignal
 
 from abogen.constants import COLORS, VOICES_INTERNAL
@@ -100,7 +108,9 @@ class PreDownloadWorker(QThread):
         try:
             from huggingface_hub import hf_hub_download, try_to_load_from_cache
         except Exception:
-            self.progress.emit("voice", "warning", "huggingface_hub not installed, skipping voices...")
+            self.progress.emit(
+                "voice", "warning", "huggingface_hub not installed, skipping voices..."
+            )
             self._voices_success = False
             return
 
@@ -111,14 +121,22 @@ class PreDownloadWorker(QThread):
                 return
             filename = f"voices/{voice}.pt"
             if try_to_load_from_cache(repo_id=self._repo_id, filename=filename):
-                self.progress.emit("voice", "installed", f"{idx}/{len(voice_list)}: {voice} already present")
+                self.progress.emit(
+                    "voice",
+                    "installed",
+                    f"{idx}/{len(voice_list)}: {voice} already present",
+                )
                 continue
-            self.progress.emit("voice", "downloading", f"{idx}/{len(voice_list)}: {voice}...")
+            self.progress.emit(
+                "voice", "downloading", f"{idx}/{len(voice_list)}: {voice}..."
+            )
             try:
                 hf_hub_download(repo_id=self._repo_id, filename=filename)
                 self.progress.emit("voice", "downloaded", f"{voice} downloaded")
             except Exception as exc:
-                self.progress.emit("voice", "warning", f"could not download {voice}: {exc}")
+                self.progress.emit(
+                    "voice", "warning", f"could not download {voice}: {exc}"
+                )
                 self._voices_success = False
 
     # Kokoro model
@@ -127,7 +145,9 @@ class PreDownloadWorker(QThread):
         try:
             from huggingface_hub import hf_hub_download, try_to_load_from_cache
         except Exception:
-            self.progress.emit("model", "warning", "huggingface_hub not installed, skipping model...")
+            self.progress.emit(
+                "model", "warning", "huggingface_hub not installed, skipping model..."
+            )
             self._model_success = False
             return
         for fname in self._model_files:
@@ -136,14 +156,18 @@ class PreDownloadWorker(QThread):
                 return
             category = "config" if fname == "config.json" else "model"
             if try_to_load_from_cache(repo_id=self._repo_id, filename=fname):
-                self.progress.emit(category, "installed", f"file {fname} already present")
+                self.progress.emit(
+                    category, "installed", f"file {fname} already present"
+                )
                 continue
             self.progress.emit(category, "downloading", f"file {fname}...")
             try:
                 hf_hub_download(repo_id=self._repo_id, filename=fname)
                 self.progress.emit(category, "downloaded", f"file {fname} downloaded")
             except Exception as exc:
-                self.progress.emit(category, "warning", f"could not download file {fname}: {exc}")
+                self.progress.emit(
+                    category, "warning", f"could not download file {fname}: {exc}"
+                )
                 self._model_success = False
 
     # spaCy models
@@ -158,7 +182,11 @@ class PreDownloadWorker(QThread):
         parent = self.parent()
         models_to_process: List[str] = _unique_sorted_models()
         try:
-            if parent is not None and hasattr(parent, "_spacy_models_missing") and parent._spacy_models_missing:
+            if (
+                parent is not None
+                and hasattr(parent, "_spacy_models_missing")
+                and parent._spacy_models_missing
+            ):
                 models_to_process = list(dict.fromkeys(parent._spacy_models_missing))
         except Exception:
             pass
@@ -167,7 +195,9 @@ class PreDownloadWorker(QThread):
         try:
             import spacy.cli as _spacy_cli
         except Exception:
-            self.progress.emit("spacy", "warning", "spaCy not available, skipping spaCy models...")
+            self.progress.emit(
+                "spacy", "warning", "spaCy not available, skipping spaCy models..."
+            )
             self._spacy_success = False
             return
 
@@ -176,14 +206,24 @@ class PreDownloadWorker(QThread):
                 self._spacy_success = False
                 return
             if _is_package_installed(model_name):
-                self.progress.emit("spacy", "installed", f"{idx}/{len(models_to_process)}: {model_name} already installed")
+                self.progress.emit(
+                    "spacy",
+                    "installed",
+                    f"{idx}/{len(models_to_process)}: {model_name} already installed",
+                )
                 continue
-            self.progress.emit("spacy", "downloading", f"{idx}/{len(models_to_process)}: {model_name}...")
+            self.progress.emit(
+                "spacy",
+                "downloading",
+                f"{idx}/{len(models_to_process)}: {model_name}...",
+            )
             try:
                 _spacy_cli.download(model_name)
                 self.progress.emit("spacy", "downloaded", f"{model_name} downloaded")
             except Exception as exc:
-                self.progress.emit("spacy", "warning", f"could not download {model_name}: {exc}")
+                self.progress.emit(
+                    "spacy", "warning", f"could not download {model_name}: {exc}"
+                )
                 self._spacy_success = False
 
 
@@ -271,7 +311,9 @@ class PreDownloadDialog(QDialog):
 
         layout.addLayout(status_layout)
 
-        layout.addItem(QSpacerItem(0, 20, QSizePolicy.Policy.Minimum, QSizePolicy.Policy.Fixed))
+        layout.addItem(
+            QSpacerItem(0, 20, QSizePolicy.Policy.Minimum, QSizePolicy.Policy.Fixed)
+        )
 
         # Buttons
         button_row = QHBoxLayout()
@@ -339,7 +381,12 @@ class PreDownloadDialog(QDialog):
         # These are initialized in __init__ to keep consistent object state
 
         # Set checking visual state
-        for lbl in (self.voices_status, self.model_status, self.config_status, self.spacy_status):
+        for lbl in (
+            self.voices_status,
+            self.model_status,
+            self.config_status,
+            self.spacy_status,
+        ):
             lbl.setStyleSheet(f"color: {COLORS['ORANGE']};")
 
         self.spacy_status.setText(self.SPACY_PREFIX + "⏳ Checking...")
@@ -356,7 +403,9 @@ class PreDownloadDialog(QDialog):
         checked = len(self._spacy_models_checked)
         missing_count = len(self._spacy_models_missing)
         if missing_count:
-            self.spacy_status.setText(f"{self.SPACY_PREFIX}{checked} checked, {missing_count} missing...")
+            self.spacy_status.setText(
+                f"{self.SPACY_PREFIX}{checked} checked, {missing_count} missing..."
+            )
         else:
             self.spacy_status.setText(f"{self.SPACY_PREFIX}{checked} checked...")
 
@@ -366,7 +415,9 @@ class PreDownloadDialog(QDialog):
         else:
             self.has_missing = True
             if missing:
-                self._set_status("voice", f"✗ Missing {len(missing)} voices", COLORS["RED"])
+                self._set_status(
+                    "voice", f"✗ Missing {len(missing)} voices", COLORS["RED"]
+                )
             else:
                 self._set_status("voice", "✗ Not downloaded", COLORS["RED"])
 
@@ -390,7 +441,9 @@ class PreDownloadDialog(QDialog):
         else:
             self.has_missing = True
             if missing:
-                self._set_status("spacy", f"✗ Missing {len(missing)} model(s)", COLORS["RED"])
+                self._set_status(
+                    "spacy", f"✗ Missing {len(missing)} model(s)", COLORS["RED"]
+                )
             else:
                 self._set_status("spacy", "✗ Not downloaded", COLORS["RED"])
         self.download_btn.setEnabled(self.has_missing)
@@ -408,8 +461,11 @@ class PreDownloadDialog(QDialog):
         missing = []
         try:
             from huggingface_hub import try_to_load_from_cache
+
             for voice in VOICES_INTERNAL:
-                if not try_to_load_from_cache(repo_id="hexgrad/Kokoro-82M", filename=f"voices/{voice}.pt"):
+                if not try_to_load_from_cache(
+                    repo_id="hexgrad/Kokoro-82M", filename=f"voices/{voice}.pt"
+                ):
                     missing.append(voice)
         except Exception:
             # If HF missing, report all as missing
@@ -419,14 +475,26 @@ class PreDownloadDialog(QDialog):
     def _check_kokoro_model(self) -> bool:
         try:
             from huggingface_hub import try_to_load_from_cache
-            return try_to_load_from_cache(repo_id="hexgrad/Kokoro-82M", filename="kokoro-v1_0.pth") is not None
+
+            return (
+                try_to_load_from_cache(
+                    repo_id="hexgrad/Kokoro-82M", filename="kokoro-v1_0.pth"
+                )
+                is not None
+            )
         except Exception:
             return False
 
     def _check_kokoro_config(self) -> bool:
         try:
             from huggingface_hub import try_to_load_from_cache
-            return try_to_load_from_cache(repo_id="hexgrad/Kokoro-82M", filename="config.json") is not None
+
+            return (
+                try_to_load_from_cache(
+                    repo_id="hexgrad/Kokoro-82M", filename="config.json"
+                )
+                is not None
+            )
         except Exception:
             return False
 
diff --git a/abogen/spacy_utils.py b/abogen/spacy_utils.py
index 78f4750..6a18c6b 100644
--- a/abogen/spacy_utils.py
+++ b/abogen/spacy_utils.py
@@ -16,7 +16,7 @@ SPACY_MODELS = {
     "p": "pt_core_news_sm",  # Brazilian Portuguese
     "z": "zh_core_web_sm",  # Mandarin Chinese
     "j": "ja_core_news_sm",  # Japanese
-    "h": "xx_sent_ud_sm",   # Hindi (multi-language model)
+    "h": "xx_sent_ud_sm",  # Hindi (multi-language model)
 }
 
 
@@ -26,6 +26,7 @@ def _load_spacy():
     if _spacy is None:
         try:
             import spacy
+
             _spacy = spacy
         except ImportError:
             return None
@@ -36,14 +37,15 @@ def get_spacy_model(lang_code, log_callback=None):
     """
     Get or load a spaCy model for the given language code.
     Downloads the model automatically if not available.
-    
+
     Args:
         lang_code: Language code (a, b, e, f, etc.)
         log_callback: Optional function to log messages
-        
+
     Returns:
         Loaded spaCy model or None if unavailable
     """
+
     def log(msg, is_error=False):
         # Prefer GUI log callback when provided to avoid spamming stdout.
         if log_callback:
@@ -55,27 +57,30 @@ def get_spacy_model(lang_code, log_callback=None):
                 print(msg)
         else:
             print(msg)
-    
+
     # Check if model is cached
     if lang_code in _nlp_cache:
         return _nlp_cache[lang_code]
-    
+
     # Check if language is supported
     model_name = SPACY_MODELS.get(lang_code)
     if not model_name:
         log(f"\nspaCy: No model mapping for language '{lang_code}'...")
         return None
-    
+
     # Lazy load spaCy
     spacy = _load_spacy()
     if spacy is None:
         log("\nspaCy: Module not installed, falling back to default segmentation...")
         return None
-    
+
     # Try to load the model
     try:
         log(f"\nLoading spaCy model '{model_name}'...")
-        nlp = spacy.load(model_name, disable=["ner", "parser", "tagger", "lemmatizer", "attribute_ruler"])
+        nlp = spacy.load(
+            model_name,
+            disable=["ner", "parser", "tagger", "lemmatizer", "attribute_ruler"],
+        )
         # Enable sentence segmentation only
         if "sentencizer" not in nlp.pipe_names:
             nlp.add_pipe("sentencizer")
@@ -86,16 +91,23 @@ def get_spacy_model(lang_code, log_callback=None):
         log(f"\nspaCy: Downloading model '{model_name}'...")
         try:
             from spacy.cli import download
+
             download(model_name)
             # Retry loading
-            nlp = spacy.load(model_name, disable=["ner", "parser", "tagger", "lemmatizer", "attribute_ruler"])
+            nlp = spacy.load(
+                model_name,
+                disable=["ner", "parser", "tagger", "lemmatizer", "attribute_ruler"],
+            )
             if "sentencizer" not in nlp.pipe_names:
                 nlp.add_pipe("sentencizer")
             _nlp_cache[lang_code] = nlp
             log(f"spaCy model '{model_name}' downloaded and loaded")
             return nlp
         except Exception as e:
-            log(f"\nspaCy: Failed to download model '{model_name}': {e}...", is_error=True)
+            log(
+                f"\nspaCy: Failed to download model '{model_name}': {e}...",
+                is_error=True,
+            )
             return None
     except Exception as e:
         log(f"\nspaCy: Error loading model '{model_name}': {e}...", is_error=True)
@@ -105,19 +117,19 @@ def get_spacy_model(lang_code, log_callback=None):
 def segment_sentences(text, lang_code, log_callback=None):
     """
     Segment text into sentences using spaCy.
-    
+
     Args:
         text: Text to segment
         lang_code: Language code
         log_callback: Optional function to log messages
-        
+
     Returns:
         List of sentence strings, or None if spaCy unavailable
     """
     nlp = get_spacy_model(lang_code, log_callback)
     if nlp is None:
         return None
-    
+
     # Ensure spaCy can handle large texts by adjusting max_length if necessary
     try:
         text_len = len(text or "")