feat: smart chunking to avoid chunk boundaries mid-sentence

1 files changed, 25 insertions, 11 deletions

diff --git a/app/converter/converter.py b/app/converter/converter.py
index 2b849a2..f8815d8 100644
--- a/app/converter/converter.py
+++ b/app/converter/converter.py
@@ -251,11 +251,11 @@ def chunk_clamp_needed(entry) -> bool:
 def chunk_clamp_message(entry) -> List[str]:
     """The popup text for a chunk_words-capped ENTRY (short lines)."""
     return [
-        f"{entry.label} can narrate at most ~{entry.chunk_words} words "
-        "per request: the server caps",
-        "each request's prompt plus generation at a fixed window. "
-        "Longer sub-chunks",
-        "may cut off mid-sentence.",
+        f"{entry.label} narrates best at ~{entry.chunk_words} words "
+        "per request on this server:",
+        "each request's prompt plus generation must fit a fixed "
+        "window, so longer",
+        "sub-chunks may cut off mid-sentence.",
     ]
 
 
@@ -305,6 +305,9 @@ class AudiobookConverter:
     # Class-level default so a partially-constructed instance (tests build
     # these with __new__) behaves like a plain console run.
     _progress = None
+    # Same for the per-run chunk override: without __init__ there is no
+    # clamp, so chunking follows the config.CHUNK_SIZE setting.
+    chunk_size = None
 
     def __init__(self, voice_mode: str = VOICE_MODE_CUSTOM, voice_clone_ref_audio: Optional[str] = None,
                  voice_clone_ref_text: Optional[str] = None, skip_transcription: bool = False,
@@ -340,6 +343,12 @@ class AudiobookConverter:
         self.backend = backend
         self.voice = voice
         self.debug = bool(debug)
+        # Per-run chunk-word override (the pre-flight popup's clamp for
+        # models whose engine caps one request below a full sub-chunk,
+        # SGLang-Omni's Higgs): caps the chapter chunks themselves so
+        # progress and debug dumps span one generation request each.
+        # None follows the config.CHUNK_SIZE setting.
+        self.chunk_size = chunk_size
         # The run's model selection (audio.cpp: a server entry id, sglomni:
         # the resolved catalog key, None elsewhere) — the startup banner
         # reports it.
@@ -404,10 +413,9 @@ class AudiobookConverter:
                         "catalog key for --model (see the backend docs).")
             model_id = entry.key
             self.model_id = model_id
-            # CHUNK_SIZE carries a per-run override (the pre-flight chunk
-            # popup's clamp for models whose engine caps one request below
-            # a full sub-chunk); None follows the config.CHUNK_SIZE setting.
-            self.chunk_size = chunk_size
+            # The catalog/request shape is resolved below; the per-run
+            # chunk override (self.chunk_size) was recorded above and
+            # reaches the client here.
             self.tts = SgOmniTTSClient(
                 chunks_dir=CHUNKS_FOLDER, model=model_id, voice=voice,
                 ref_audio=voice_clone_ref_audio,
@@ -839,8 +847,14 @@ class AudiobookConverter:
         return results
 
     def _chapter_chunks(self, text: str) -> List[str]:
-        """Split chapter text into CHUNK_SIZE-word TTS requests."""
-        return chunking.split_into_chunks(text)
+        """Split chapter text into word-capped TTS request chunks.
+
+        Each chunk is one progress unit; when the pre-flight popup set
+        a per-run clamp (models whose engine caps one request below
+        CHUNK_SIZE), it caps these chunks too so a chunk is never
+        wider than one generation request.
+        """
+        return chunking.split_into_chunks(text, max_words=self.chunk_size)
 
     def _convert_text(self, text: str, output_path: Path, start_time: float,
                       speed: Optional[float] = None,