Add auto GPU->CPU conversion at interpreter level

Convert GPU frames/CuPy arrays to numpy before calling primitives.
This fixes all CPU primitives without modifying each one individually.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

streaming/stream_sexp_generic.py

@@ -102,8 +102,17 @@ class StreamInterpreter:
         self.errors.append(msg)
         print(f"ERROR: {msg}", file=sys.stderr)
 
-        import random
-        self.rng = random.Random(self.config.get('seed', 42))
+    def _maybe_to_numpy(self, val):
+        """Convert GPU frames/CuPy arrays to numpy for CPU primitives."""
+        if val is None:
+            return val
+        # Handle GPUFrame objects (have .cpu property)
+        if hasattr(val, 'cpu'):
+            return val.cpu
+        # Handle CuPy arrays (have .get() method)
+        if hasattr(val, 'get') and callable(val.get):
+            return val.get()
+        return val
 
     def _load_config_file(self, config_path):
         """Load a config file and process its definitions."""
@@ -773,10 +782,10 @@ class StreamInterpreter:
                 if isinstance(args[i], Keyword):
                     k = args[i].name
                     v = self._eval(args[i + 1], env) if i + 1 < len(args) else None
-                    kwargs[k] = v
+                    kwargs[k] = self._maybe_to_numpy(v)
                     i += 2
                 else:
-                    evaluated_args.append(self._eval(args[i], env))
+                    evaluated_args.append(self._maybe_to_numpy(self._eval(args[i], env)))
                     i += 1
             try:
                 if kwargs: