Fix lock contention: get_boot_status reads without lock, phox_chat checks minimal

app.py

@@ -273,8 +273,11 @@ def stop_phoenix():
 
 def get_boot_status():
     """Return current boot status for the UI."""
-    with _state_lock:
+    # Read without lock to avoid contention with boot_phoenix thread
+    try:
         return dict(_boot_status)
+    except Exception:
+        return {"ready": False, "phase": "error", "message": "Status unavailable"}
 
 
 def phox_chat(message, history):
@@ -283,8 +286,9 @@ def phox_chat(message, history):
         return "Engine not initialized. Please wait for startup."
 
     with _state_lock:
-        if _phoenix_proc is None or _phoenix_proc.poll() is not None:
-            return "Phoenix is not running. Please click 'Start Engine' first."
+        phoenix_running = _phoenix_proc is not None and _phoenix_proc.poll() is None
+    if not phoenix_running:
+        return "Phoenix is not running. Please click 'Start Engine' first."
 
     if _tokenizer is None:
         return "Tokenizer not loaded."