refactor: extract synthesize_text() domain function (#2)

Combines TTSContext.normalize() + run_tts_segment_loop() into a single
domain function. Both UIs call synthesize_text() instead of inlining
normalize → TTS loop. UI-specific concerns (provider resolution,
progress display, cancellation) stay in the UI layer.

Tests: 1253 passed

abogen/domain/conversion_engine.py

@@ -11,8 +11,8 @@ The core pattern is identical across both UIs:
 After the loop, the caller processes accumulated subtitle tokens.
 
 This module provides ``run_tts_segment_loop`` which encapsulates that
-iteration, while leaving UI-specific concerns (progress display, subtitle
-processing strategy) to the caller via callbacks.
+iteration, and ``synthesize_text`` which adds normalization on top —
+the single entry point both UIs should call for text-to-speech.
 """
 
 from __future__ import annotations
@@ -23,6 +23,7 @@ from typing import Any, Callable, List, Optional, Protocol
 
 from abogen.domain.audio_sink import AudioSink
 from abogen.domain.conversion_pipeline import tts_segments
+from abogen.domain.normalization import TTSContext
 from abogen.domain.progress import calc_etr_str
 from abogen.domain.subtitle_generation import process_subtitle_tokens
 
@@ -188,3 +189,49 @@ def process_and_write_subtitles(
     )
     for start, end, text in new_entries:
         subtitle_writer.write_entry(start=start, end=end, text=text)
+
+
+def synthesize_text(
+    *,
+    text: str,
+    tts_context: TTSContext,
+    backend: Any,
+    voice: Any,
+    speed: float,
+    stats: SegmentStats,
+    check_cancel: CancelChecker,
+    on_progress: Callable[[int, str], None],
+    chapter_sink: Optional[AudioSink] = None,
+    audio_sink: Optional[AudioSink] = None,
+    preview_callback: Optional[Callable[[str], None]] = None,
+    on_segment: Optional[Callable[[SegmentInfo], None]] = None,
+    subtitle_mode: str = "Disabled",
+    max_subtitle_words: int = 5,
+    lang_code: str = "a",
+    use_spacy_segmentation: bool = False,
+    split_pattern_override: Optional[str] = None,
+) -> tuple[int, list]:
+    """Normalize text and run TTS — the single entry point for both UIs.
+
+    Combines TTSContext.normalize() + run_tts_segment_loop() into one call.
+    UI-specific concerns (provider resolution, progress display) stay in the UI.
+    """
+    normalized = tts_context.normalize(text)
+    return run_tts_segment_loop(
+        text=normalized,
+        backend=backend,
+        voice=voice,
+        speed=speed,
+        split_pattern=split_pattern_override or tts_context.split_pattern,
+        stats=stats,
+        check_cancel=check_cancel,
+        on_progress=on_progress,
+        chapter_sink=chapter_sink,
+        audio_sink=audio_sink,
+        preview_callback=preview_callback,
+        on_segment=on_segment,
+        subtitle_mode=subtitle_mode,
+        max_subtitle_words=max_subtitle_words,
+        lang_code=lang_code,
+        use_spacy_segmentation=use_spacy_segmentation,
+    )

abogen/pyqt/conversion.py

@@ -36,7 +36,7 @@ from abogen.domain.output_paths import (
 )
 from abogen.domain.audio_helpers import build_ffmpeg_command, to_float32
 from abogen.domain.audio_sink import AudioSink, open_audio_sink
-from abogen.domain.conversion_engine import run_tts_segment_loop, SegmentStats, SegmentInfo
+from abogen.domain.conversion_engine import synthesize_text, SegmentStats, SegmentInfo
 from abogen.domain.intro_outro import resolve_intro, resolve_outro
 from abogen.domain.audio_buffer import (
     create_silence,
@@ -982,14 +982,6 @@ class ConversionThread(QThread):
                         print("Using split pattern: (unprintable)")
 
                     for text_segment in text_segments:
-                        # Normalize text before TTS
-                        try:
-                            text_segment = self._tts_context.normalize(text_segment)
-                        except Exception as exc:
-                            self.log_updated.emit(
-                                (f"Warning: Text normalization failed: {exc}", "orange")
-                            )
-
                         def _qt_check_cancel() -> bool:
                             if self.cancel_requested:
                                 sink_stack.close()
@@ -1049,19 +1041,25 @@ class ConversionThread(QThread):
                             total_characters=self.total_char_count,
                         )
 
-                        run_tts_segment_loop(
-                            text=text_segment,
-                            backend=self.backend,
-                            voice=loaded_voice,
-                            speed=self.speed,
-                            split_pattern=active_split_pattern,
-                            stats=stats,
-                            check_cancel=_qt_check_cancel,
-                            on_progress=_qt_on_progress,
-                            chapter_sink=chapter_sink,
-                            audio_sink=merged_sink if merge_chapters_at_end else None,
-                            on_segment=_qt_on_segment,
-                        )
+                        try:
+                            synthesize_text(
+                                text=text_segment,
+                                tts_context=self._tts_context,
+                                backend=self.backend,
+                                voice=loaded_voice,
+                                speed=self.speed,
+                                stats=stats,
+                                check_cancel=_qt_check_cancel,
+                                on_progress=_qt_on_progress,
+                                chapter_sink=chapter_sink,
+                                audio_sink=merged_sink if merge_chapters_at_end else None,
+                                on_segment=_qt_on_segment,
+                                split_pattern_override=active_split_pattern,
+                            )
+                        except Exception as exc:
+                            self.log_updated.emit(
+                                (f"Warning: TTS failed: {exc}", "orange")
+                            )
 
                         self.processed_char_count = stats.processed_chars
                         current_time = stats.current_time

abogen/webui/conversion_runner.py

@@ -32,7 +32,6 @@ from abogen.utils import (
     get_user_output_path,
 )
 from abogen.voice_profiles import load_profiles, normalize_profile_entry
-from abogen.llm_client import LLMClientError
 from abogen.infrastructure.subtitle_writer import make_subtitle_writer
 from abogen.domain.chapter_titles import (
     simplify_heading_text as _simplify_heading_text,
@@ -118,7 +117,7 @@ from abogen.domain.audio_buffer import (
 )
 from abogen.domain.audio_sink import AudioSink, open_audio_sink
 from abogen.domain.pipeline_factory import PipelinePool
-from abogen.domain.conversion_engine import run_tts_segment_loop, process_and_write_subtitles, SegmentStats
+from abogen.domain.conversion_engine import synthesize_text, process_and_write_subtitles, SegmentStats
 from abogen.domain.voice_loader import VoiceCache, resolve_voice
 from abogen.domain.voice_utils import resolve_voice_target as _resolve_voice_target
 
@@ -422,15 +421,7 @@ def run_conversion_job(job: Job) -> None:
             supertonic_steps_override: Optional[int] = None,
         ) -> int:
             nonlocal processed_chars, current_time
-            if split_pattern is None:
-                split_pattern = tts_context.split_pattern
             source_text = str(text or "")
-            try:
-                normalized = tts_context.normalize(source_text)
-            except LLMClientError as exc:
-                job.add_log(f"LLM normalization failed: {exc}", level="error")
-                raise
-            local_segments = 0
 
             provider = str(tts_provider or getattr(job, "tts_provider", "kokoro") or "kokoro").strip().lower() or "kokoro"
             if provider == "supertonic":
@@ -467,12 +458,12 @@ def run_conversion_job(job: Job) -> None:
                 def _preview(text: str) -> None:
                     job.add_log(f"{prefix}{stats.processed_chars:,}/{job.total_characters or '—'}: {text[:80]}")
 
-                local_segments, accumulated_tokens = run_tts_segment_loop(
-                    text=normalized,
+                local_segments, accumulated_tokens = synthesize_text(
+                    text=source_text,
+                    tts_context=tts_context,
                     backend=backend,
                     voice=resolved_voice,
                     speed=effective_speed,
-                    split_pattern=split_pattern,
                     stats=stats,
                     check_cancel=canceller,
                     on_progress=_on_progress,