UCI engine makes LucasChess hangs on Windows. I have a simple fix.

[iandevpro]

Hi!

Thanks a lot for publishing maia-3!
I tried to use on Windows with LucasChess app, which has possibility to add UCI engines.

1. I installed engine with "python -m pip install .", it created a set of .exe files.
2. Configured LucasChess to use one of the engines C:\Python\Scripts\maia3-5m.exe
3. LucasChess hangs when starting game

I had a suspicion, that on Windows stderr is wrapped to go to stdout and LucasChess is confused to parse non-UCI messages like warning, etc.
I commented them out, did again "python -m pip install ." - and it worked!

Here is a simple fix below.

Thanks,
Ian

--- uci.py.orig 2026-05-27 20:27:59.225321200 -0700
+++ uci.py      2026-06-02 21:57:16.078947400 -0700
@@ -149,12 +149,12 @@
     renamed = {k.replace("smolgen", "gab"): v for k, v in state_dict.items()}

     missing, unexpected = model.load_state_dict(renamed, strict=False)
-    if missing:
-        print(f"warning: missing keys: {missing[:5]}{'...' if len(missing) > 5 else ''}",
-              file=sys.stderr, flush=True)
-    if unexpected:
-        print(f"warning: unexpected keys: {unexpected[:5]}{'...' if len(unexpected) > 5 else ''}",
-              file=sys.stderr, flush=True)
+#    if missing:
+#        print(f"warning: missing keys: {missing[:5]}{'...' if len(missing) > 5 else ''}",
+#              file=sys.stderr, flush=True)
+#    if unexpected:
+#        print(f"warning: unexpected keys: {unexpected[:5]}{'...' if len(unexpected) > 5 else ''}",
+#               file=sys.stderr, flush=True)

     model.eval()
     return model
@@ -244,7 +244,7 @@
             spec = getattr(self.cfg, "model_spec", None)
             if spec is None:
                 raise RuntimeError("No model or checkpoint was configured.")
-            print(f"resolving Maia3 checkpoint for {spec.display_name}", file=sys.stderr, flush=True)
+            # print(f"resolving Maia3 checkpoint for {spec.display_name}", file=sys.stderr, flush=True)
             self.cfg.checkpoint_path = resolve_checkpoint_path(
                 spec,
                 checkpoint_filename=self.cfg.checkpoint_filename,
@@ -255,9 +255,9 @@
                 token=self.cfg.hf_token,
             )

-        print(f"loading Maia3 checkpoint {self.cfg.checkpoint_path}", file=sys.stderr, flush=True)
+        # print(f"loading Maia3 checkpoint {self.cfg.checkpoint_path}", file=sys.stderr, flush=True)
         self.model = load_model(self.cfg)
-        print("Maia3 ready", file=sys.stderr, flush=True)
+        # print("Maia3 ready", file=sys.stderr, flush=True)

     def _reset_history(self):
         self.history.clear()