fix(converter): make m4b a single file with embedded chapters

1 files changed, 10 insertions, 6 deletions

diff --git a/converter/converter.py b/converter/converter.py
index ce2c351..f63a412 100644
--- a/converter/converter.py
+++ b/converter/converter.py
@@ -99,10 +99,14 @@ class AudiobookConverter:
                 return False
 
             stem = output_name or file_path.stem
-            embed_chapters = (self.output_format == "m4b" and self.single_file
-                              and len(sections) > 1)
-            if embed_chapters:
-                return self._convert_single_m4b_with_chapters(sections, stem, start_time)
+
+            # m4b is always a single file; multi-chapter books get embedded
+            # chapter markers so listeners can skip between chapters.
+            if self.output_format == "m4b":
+                if len(sections) > 1:
+                    return self._convert_m4b_with_chapters(sections, stem, start_time)
+                output_path = config.AUDIOBOOKS_FOLDER / f"{stem}.{self.output_format}"
+                return self._convert_text(sections[0].text, output_path, start_time)
 
             if self.single_file or len(sections) == 1:
                 text = "\n\n".join(section.text for section in sections)
@@ -124,7 +128,7 @@ class AudiobookConverter:
             # Always cleanup, even on failure or interrupt
             audio.cleanup_chunks()
 
-    def _convert_single_m4b_with_chapters(self, sections, stem: str, start_time: float) -> bool:
+    def _convert_m4b_with_chapters(self, sections, stem: str, start_time: float) -> bool:
         """Convert each chapter to audio, then assemble a single m4b with
         embedded chapter markers."""
         chapter_files = []
@@ -250,7 +254,7 @@ class AudiobookConverter:
             print(f"Reference audio: {Path(self.voice_clone_ref_audio).name}")
             print(f"Language: {config.VOICE_CLONE_LANGUAGE}")
         print(f"Output format: {self.output_format}")
-        if self.single_file:
+        if self.single_file and self.output_format == "mp3":
             print("Chapter mode: single file (--single-file)")
         if abs(self.speed - 1.0) >= 1e-6:
             print(f"Playback speed: {self.speed:g}x")