refactor: SynthParams dataclass for synthesize_text

- Frozen dataclass in domain/conversion_engine.py with common params
- synthesize_text now takes params=SynthParams + unique kwargs
- Executor, PyQt legacy, WebUI legacy, and tests updated
- Adding new common params now only requires changing the dataclass

abogen/application/conversion_executor.py

@@ -29,6 +29,7 @@ from abogen.application.conversion_result import ConversionResult
 from abogen.domain.audio_sink import open_audio_sink
 from abogen.domain.conversion_engine import (
     SegmentStats,
+    SynthParams,
     process_and_write_subtitles,
     synthesize_text,
 )
@@ -138,6 +139,18 @@ def execute_conversion(
 
         effective_subtitle_mode = request.subtitle_mode if subtitle_writer else "Disabled"
 
+        synth = SynthParams(
+            tts_context=tts_context,
+            stats=stats,
+            check_cancel=check_cancelled,
+            on_progress=lambda pct, etr: events.progress(pct, etr),
+            audio_sink=audio_sink,
+            subtitle_mode=effective_subtitle_mode,
+            max_subtitle_words=request.max_subtitle_words,
+            lang_code=request.language,
+            use_spacy_segmentation=use_spacy,
+        )
+
         # Chapter directory
         chapter_dir = None
         if request.save_chapters_separately and len(plan.chapters) > 1:
@@ -154,20 +167,12 @@ def execute_conversion(
             intro_backend = pipeline_provider.get(intro_provider, request.language, request.use_gpu)
             synthesize_text(
                 text=plan.intro.text,
-                tts_context=tts_context,
+                params=synth,
                 backend=intro_backend,
                 voice=intro_voice,
                 speed=intro_speed or request.speed,
-                stats=stats,
-                check_cancel=check_cancelled,
-                on_progress=lambda pct, etr: events.progress(pct, etr),
                 chapter_sink=None,
-                audio_sink=audio_sink,
                 preview_callback=lambda text: events.log(f"  {text[:80]}"),
-                subtitle_mode=effective_subtitle_mode,
-                max_subtitle_words=request.max_subtitle_words,
-                lang_code=request.language,
-                use_spacy_segmentation=use_spacy,
             )
             intro_emitted = True
             events.log("Intro synthesized.")
@@ -209,20 +214,12 @@ def execute_conversion(
                 intro_backend = pipeline_provider.get(intro_provider, request.language, request.use_gpu)
                 synthesize_text(
                     text=plan.intro.text,
-                    tts_context=tts_context,
+                    params=synth,
                     backend=intro_backend,
                     voice=intro_voice,
                     speed=intro_speed or request.speed,
-                    stats=stats,
-                    check_cancel=check_cancelled,
-                    on_progress=lambda pct, etr: events.progress(pct, etr),
                     chapter_sink=chapter_sink,
-                    audio_sink=audio_sink,
                     preview_callback=lambda text: events.log(f"  Intro: {text[:80]}"),
-                    subtitle_mode=effective_subtitle_mode,
-                    max_subtitle_words=request.max_subtitle_words,
-                    lang_code=request.language,
-                    use_spacy_segmentation=use_spacy,
                 )
                 intro_emitted = True
                 if request.chapter_intro_delay > 0:
@@ -239,20 +236,12 @@ def execute_conversion(
                 if heading_text:
                     synthesize_text(
                         text=heading_text,
-                        tts_context=tts_context,
+                        params=synth,
                         backend=chapter_backend,
                         voice=chapter_voice,
                         speed=chapter_speed or request.speed,
-                        stats=stats,
-                        check_cancel=check_cancelled,
-                        on_progress=lambda pct, etr: events.progress(pct, etr),
                         chapter_sink=chapter_sink,
-                        audio_sink=audio_sink,
                         preview_callback=lambda text: events.log(f"  Title: {text[:80]}"),
-                        subtitle_mode=effective_subtitle_mode,
-                        max_subtitle_words=request.max_subtitle_words,
-                        lang_code=request.language,
-                        use_spacy_segmentation=use_spacy,
                     )
                     if request.chapter_intro_delay > 0:
                         _append_silence(
@@ -282,20 +271,12 @@ def execute_conversion(
                 seg_start_time = stats.current_time
                 local_segments, accumulated_tokens = synthesize_text(
                     text=segment.text,
-                    tts_context=tts_context,
+                    params=synth,
                     backend=seg_backend,
                     voice=seg_voice,
                     speed=seg_speed or request.speed,
-                    stats=stats,
-                    check_cancel=check_cancelled,
-                    on_progress=lambda pct, etr: events.progress(pct, etr),
                     chapter_sink=chapter_sink,
-                    audio_sink=audio_sink,
                     preview_callback=lambda text: events.log(f"  {text[:80]}"),
-                    subtitle_mode=effective_subtitle_mode,
-                    max_subtitle_words=request.max_subtitle_words,
-                    lang_code=request.language,
-                    use_spacy_segmentation=use_spacy,
                 )
 
                 # Process subtitles
@@ -366,20 +347,12 @@ def execute_conversion(
 
             synthesize_text(
                 text=plan.outro.text,
-                tts_context=tts_context,
+                params=synth,
                 backend=outro_backend,
                 voice=outro_voice,
                 speed=outro_speed or request.speed,
-                stats=stats,
-                check_cancel=check_cancelled,
-                on_progress=lambda pct, etr: events.progress(pct, etr),
                 chapter_sink=None,
-                audio_sink=audio_sink,
                 preview_callback=lambda text: events.log(f"  {text[:80]}"),
-                subtitle_mode=effective_subtitle_mode,
-                max_subtitle_words=request.max_subtitle_words,
-                lang_code=request.language,
-                use_spacy_segmentation=use_spacy,
             )
             events.log("Outro synthesized.")
 

abogen/domain/conversion_engine.py

@@ -191,24 +191,34 @@ def process_and_write_subtitles(
         subtitle_writer.write_entry(start=start, end=end, text=text)
 
 
+@dataclass(frozen=True)
+class SynthParams:
+    """Common parameters for synthesize_text calls.
+
+    Packed once by the executor to avoid repeating identical kwargs.
+    When adding new common params, change only this dataclass.
+    """
+    tts_context: TTSContext
+    stats: SegmentStats
+    check_cancel: CancelChecker
+    on_progress: Callable[[int, str], None]
+    audio_sink: Optional[AudioSink] = None
+    subtitle_mode: str = "Disabled"
+    max_subtitle_words: int = 50
+    lang_code: str = "a"
+    use_spacy_segmentation: bool = False
+
+
 def synthesize_text(
     *,
     text: str,
-    tts_context: TTSContext,
+    params: SynthParams,
     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 = 50,
-    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.
@@ -216,22 +226,22 @@ def synthesize_text(
     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)
+    normalized = params.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,
+        split_pattern=split_pattern_override or params.tts_context.split_pattern,
-        stats=stats,
+        stats=params.stats,
-        check_cancel=check_cancel,
+        check_cancel=params.check_cancel,
-        on_progress=on_progress,
+        on_progress=params.on_progress,
         chapter_sink=chapter_sink,
-        audio_sink=audio_sink,
+        audio_sink=params.audio_sink,
         preview_callback=preview_callback,
         on_segment=on_segment,
-        subtitle_mode=subtitle_mode,
+        subtitle_mode=params.subtitle_mode,
-        max_subtitle_words=max_subtitle_words,
+        max_subtitle_words=params.max_subtitle_words,
-        lang_code=lang_code,
+        lang_code=params.lang_code,
-        use_spacy_segmentation=use_spacy_segmentation,
+        use_spacy_segmentation=params.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 synthesize_text, SegmentStats, SegmentInfo
+from abogen.domain.conversion_engine import synthesize_text, SynthParams, SegmentStats, SegmentInfo
 from abogen.domain.intro_outro import resolve_intro, resolve_outro
 from abogen.domain.audio_buffer import (
     create_silence,
@@ -1016,18 +1016,26 @@ class ConversionThread(QThread):
                             total_characters=self.total_char_count,
                         )
 
+                        synth_params = SynthParams(
+                            tts_context=self._tts_context,
+                            stats=stats,
+                            check_cancel=_qt_check_cancel,
+                            on_progress=_qt_on_progress,
+                            audio_sink=merged_sink if merge_chapters_at_end else None,
+                            subtitle_mode=self.subtitle_mode,
+                            max_subtitle_words=self.max_subtitle_words,
+                            lang_code=self.lang_code,
+                            use_spacy_segmentation=getattr(self, "use_spacy_segmentation", False),
+                        )
+
                         try:
                             synthesize_text(
                                 text=text_segment,
-                                tts_context=self._tts_context,
+                                params=synth_params,
                                 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,
                             )

abogen/webui/conversion_runner.py

@@ -117,7 +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 synthesize_text, process_and_write_subtitles, SegmentStats
+from abogen.domain.conversion_engine import synthesize_text, SynthParams, 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
 
@@ -462,23 +462,27 @@ 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 = synthesize_text(
+                synth_params = SynthParams(
-                    text=source_text,
                     tts_context=tts_context,
-                    backend=backend,
-                    voice=resolved_voice,
-                    speed=effective_speed,
                     stats=stats,
                     check_cancel=canceller,
                     on_progress=_on_progress,
-                    chapter_sink=chapter_sink,
                     audio_sink=audio_sink,
-                    preview_callback=_preview,
                     subtitle_mode=job.subtitle_mode if (subtitle_writer and audio_sink) else "Disabled",
                     max_subtitle_words=job.max_subtitle_words,
                     lang_code=job.language,
                     use_spacy_segmentation=job.subtitle_mode not in ("Disabled", "Line"),
                 )
+
+                local_segments, accumulated_tokens = synthesize_text(
+                    text=source_text,
+                    params=synth_params,
+                    backend=backend,
+                    voice=resolved_voice,
+                    speed=effective_speed,
+                    chapter_sink=chapter_sink,
+                    preview_callback=_preview,
+                )
                 current_time = stats.current_time
 
                 if subtitle_writer and audio_sink and accumulated_tokens:

tests/test_conversion_executor.py

@@ -16,6 +16,7 @@ from typing import Any
 
 from abogen.domain.conversion_engine import (
     synthesize_text,
+    SynthParams,
     run_tts_segment_loop,
     process_and_write_subtitles,
     SegmentStats,
@@ -133,18 +134,22 @@ class TestSynthesizeText:
         def on_progress(pct, etr):
             progress_calls.append((pct, etr))
 
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="Hello world.",
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel,
             on_progress=on_progress,
             audio_sink=sink,
         )
 
+        segments, tokens = synthesize_text(
+            text="Hello world.",
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
+        )
+
         assert segments >= 1
         assert len(sink.written) >= 1
         assert len(progress_calls) >= 1
@@ -159,17 +164,21 @@ class TestSynthesizeText:
         def on_progress(pct, etr):
             progress_calls.append((pct, etr))
 
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="Hello world.",
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel,
             on_progress=on_progress,
         )
 
+        segments, tokens = synthesize_text(
+            text="Hello world.",
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
+        )
+
         # Should stop early due to cancellation
         assert segments == 0
 
@@ -184,19 +193,23 @@ class TestSynthesizeText:
         def on_progress(pct, etr):
             pass
 
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="Hello world.",
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel,
             on_progress=on_progress,
-            chapter_sink=chapter_sink,
             audio_sink=merged_sink,
         )
 
+        segments, tokens = synthesize_text(
+            text="Hello world.",
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
+            chapter_sink=chapter_sink,
+        )
+
         # Both sinks should receive audio
         assert len(chapter_sink.written) >= 1
         assert len(merged_sink.written) >= 1
@@ -210,15 +223,19 @@ class TestSynthesizeText:
         def on_progress(pct, etr):
             pass
 
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="Hello world.",
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel,
             on_progress=on_progress,
+        )
+
+        segments, tokens = synthesize_text(
+            text="Hello world.",
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
             split_pattern_override=r"\n+",
         )
 
@@ -323,16 +340,11 @@ class TestFullPipeline:
             progress_calls.append((pct, etr))
 
         # Simulate full pipeline: synthesize → subtitles → finalize
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="This is a test sentence. Another sentence here.",
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel,
             on_progress=on_progress,
-            chapter_sink=chapter_sink,
             audio_sink=merged_sink,
             subtitle_mode="Sentence",
             max_subtitle_words=5,
@@ -340,6 +352,15 @@ class TestFullPipeline:
             use_spacy_segmentation=False,
         )
 
+        segments, tokens = synthesize_text(
+            text="This is a test sentence. Another sentence here.",
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
+            chapter_sink=chapter_sink,
+        )
+
         # Process accumulated tokens
         process_and_write_subtitles(
             tokens,
@@ -373,16 +394,20 @@ class TestFullPipeline:
         def on_progress(pct, etr):
             progress_calls.append((pct, etr))
 
-        segments, tokens = synthesize_text(
+        params = SynthParams(
-            text="Hello world. " * 100,
             tts_context=tts_ctx,
-            backend=backend,
-            voice="M1",
-            speed=1.0,
             stats=stats,
             check_cancel=cancel_fn,
             on_progress=on_progress,
         )
 
+        segments, tokens = synthesize_text(
+            text="Hello world. " * 100,
+            params=params,
+            backend=backend,
+            voice="M1",
+            speed=1.0,
+        )
+
         # Should have stopped before processing all text
         assert segments <= 4