diff --git a/shared/sx/async_eval.py b/shared/sx/async_eval.py
index 9c25fbf..49f4d1f 100644
--- a/shared/sx/async_eval.py
+++ b/shared/sx/async_eval.py
@@ -1253,15 +1253,25 @@ async def _aser_call(
                         extra_class = val.class_name
                     else:
                         parts.append(f":{arg.name}")
-                        # Plain list (e.g. from map) → wrap as fragment to
-                        # avoid ambiguity with function application on re-parse
+                        # Plain list → serialize for the client.
+                        # Rendered items (SxExpr) → wrap in (<> ...) fragment.
+                        # Data items (dicts, strings, numbers) → (list ...)
+                        # so the client gets an iterable array, not a
+                        # DocumentFragment that breaks map/filter.
                         if isinstance(val, list):
-                            items = [serialize(v) for v in val
-                                     if v is not NIL and v is not None]
-                            parts.append(
-                                "(<> " + " ".join(items) + ")" if items
-                                else "nil"
-                            )
+                            live = [v for v in val
+                                    if v is not NIL and v is not None]
+                            items = [serialize(v) for v in live]
+                            if not items:
+                                parts.append("nil")
+                            elif any(isinstance(v, SxExpr) for v in live):
+                                parts.append(
+                                    "(<> " + " ".join(items) + ")"
+                                )
+                            else:
+                                parts.append(
+                                    "(list " + " ".join(items) + ")"
+                                )
                         else:
                             parts.append(serialize(val))
                 i += 2
diff --git a/shared/sx/helpers.py b/shared/sx/helpers.py
index 84982de..cfe5a5d 100644
--- a/shared/sx/helpers.py
+++ b/shared/sx/helpers.py
@@ -404,13 +404,22 @@ def sx_call(component_name: str, **kwargs: Any) -> str:
 
     Values are serialized: strings are quoted, None becomes nil,
     bools become true/false, numbers stay as-is.
+    List values use ``(list ...)`` so the client gets an iterable array
+    rather than a rendered fragment.
     """
-    from .parser import serialize
+    from .parser import serialize, SxExpr
     name = component_name if component_name.startswith("~") else f"~{component_name}"
     parts = [name]
     for key, val in kwargs.items():
         parts.append(f":{key.replace('_', '-')}")
-        parts.append(serialize(val))
+        if isinstance(val, list):
+            items = [serialize(v) for v in val if v is not None]
+            if not items:
+                parts.append("nil")
+            else:
+                parts.append("(list " + " ".join(items) + ")")
+        else:
+            parts.append(serialize(val))
     return "(" + " ".join(parts) + ")"