Update app.py

app.py

@@ -467,7 +467,9 @@ def _install_workspace_shim_v3(cwd_for_train: str, module_default: str = "rtdetr
     The shim ensures kwargs['cfg'] is a dict, then guarantees cfg['_pymodule'] is a *module object*.
     """
     sc_path = os.path.join(cwd_for_train, "sitecustomize.py")
-    code = textwrap.dedent(f"""
+
+    # NOTE: Not an f-string. Escape literal braces with {{ }} and only format {module_default}.
+    code = textwrap.dedent("""\
         import os, importlib, types
         try:
             mod_default = os.environ.get("RTDETR_PYMODULE", "{module_default}") or "{module_default}"
@@ -503,15 +505,17 @@ def _install_workspace_shim_v3(cwd_for_train: str, module_default: str = "rtdetr
             def create(name, **kwargs):
                 cfg = kwargs.get("cfg")
                 if not isinstance(cfg, dict):
-                    cfg = {} if cfg is None else dict(cfg)
+                    cfg = {{}} if cfg is None else dict(cfg)
                     kwargs["cfg"] = cfg
                 _ensure_pymodule_object(cfg)
                 return _orig_create(name, **kwargs)
 
             ws_mod.create = create
         except Exception:
+            # never block training if shim fails
             pass
-    """)
+    """).format(module_default=module_default)
+
     with open(sc_path, "w", encoding="utf-8") as f:
         f.write(code)
     return sc_path