chore: address comments

Author: ryanking13

packages/runtime-sdk/src/workers/_workers.py

@@ -392,14 +392,18 @@ def _get_js_body(body):
     "Response",
 }
 
+# JS built-in types that should NOT be wrapped in _BindingWrapper.
+# These have their own Python-side semantics (e.g. passed directly to Response())
+# and wrapping them breaks property access like `.constructor.name`.
+_JS_PASSTHROUGH_TYPES = RESPONSE_ACCEPTED_TYPES | {
+    "Headers",
+}
 
-def _is_response_accepted_type(obj) -> bool:
-    """
-    Check if the given object is an accepted type for a Response body.
-    """
+
+def _get_js_constructor_name(obj) -> str | None:
     if hasattr(obj, "constructor"):
-        return obj.constructor.name in RESPONSE_ACCEPTED_TYPES
-    return False
+        return obj.constructor.name
+    return None
 
 
 class Response(FetchResponse):
@@ -423,11 +427,9 @@ def __init__(
         https://developer.mozilla.org/en-US/docs/Web/API/Response/Response.
         """
         # Verify passed in types.
-        if hasattr(body, "constructor"):
-            if not _is_response_accepted_type(body):
-                raise TypeError(
-                    f"Unsupported type in Response: {body.constructor.name}"
-                )
+        js_type = _get_js_constructor_name(body)
+        if js_type not in RESPONSE_ACCEPTED_TYPES:
+                raise TypeError(f"Unsupported type in Response: {js_type}")
         elif not isinstance(body, str | FormData | bytes) and body is not None:
             raise TypeError(f"Unsupported type in Response: {type(body).__name__}")
 
@@ -1123,18 +1125,18 @@ def _should_wrap_nested_attribute(self, jsobj) -> bool:
         if not isinstance(jsobj, JsProxy):
             return False
 
-        return not _is_response_accepted_type(jsobj)
+        # TODO: This allowlist approach is a workaround. The long-term fix is to
+        # add dedicated Python wrappers for these types in python_from_rpc so they
+        # never reach _BindingWrapper in the first place.
+        js_type = _get_js_constructor_name(jsobj)
+        return js_type not in _JS_PASSTHROUGH_TYPES
 
     def _convert_result(self, result):
         converted = python_from_rpc(result)
 
         # After python_from_rpc, some objects may still be JsProxy objects.
-        # For now, we wrap all of them except the ones that are already accepted as responses
-        # with the _BindingWrapper (or a subclass of it)
-        # so that accessing attributes on them will be properly converted.
-
-        # TODO: This is a bit of a hack. We should revisit when there are more
-        # bindings to support with different return types.
+        # We need to wrap them with _BindingWrapper (or a subclass of it) again
+        # to ensure that accessing attributes on them will be properly converted.
         if self._should_wrap_nested_attribute(converted):
             return self.__class__(converted)
         if isinstance(converted, list):