fix: handle broken pipe and filter graph failures in playback loop

Co-authored-by: aider (gemini/gemini-3.1-pro-preview) <aider@aider.chat>

main.py

@@ -75,19 +75,24 @@ def playback_thread(file_path, state):
                     graph = build_graph(frame)
                 except Exception as e:
                     print(f"Filter graph error: {e}", file=sys.stderr)
-                    break
+                    graph = "FAILED"
                     
-            try:
-                graph.push(frame)
-            except av.AVError:
-                continue
-                
-            while True:
+            if graph == "FAILED":
+                frames_to_process = [frame]
+            else:
                 try:
-                    filtered_frame = graph.pull()
-                except (av.AVError, BlockingIOError):
-                    break
+                    graph.push(frame)
+                except av.AVError:
+                    continue
                     
+                frames_to_process = []
+                while True:
+                    try:
+                        frames_to_process.append(graph.pull())
+                    except (av.AVError, BlockingIOError):
+                        break
+                        
+            for filtered_frame in frames_to_process:
                 resampled_frames = resampler.resample(filtered_frame)
                 for r_frame in resampled_frames:
                     arr = r_frame.to_ndarray()
@@ -98,7 +103,11 @@ def playback_thread(file_path, state):
                         arr = arr.astype(np.float32) * multiplier
                         arr = np.clip(arr, -32768, 32767).astype(np.int16)
                         
-                    fifo.write(arr.tobytes())
+                    try:
+                        fifo.write(arr.tobytes())
+                    except BrokenPipeError:
+                        state.running = False
+                        return
 
 def handle_ipc_client(conn, state):
     buffer = ""
@@ -199,6 +208,9 @@ def main():
     
     try:
         playback_thread(args.file, state)
+        # Keep the main thread alive until Navidrome explicitly sends 'quit'
+        while state.running:
+            time.sleep(0.1)
     except KeyboardInterrupt:
         pass
     finally: