diff --git a/pageindex/cloud_api.py b/pageindex/cloud_api.py
index a4b1039..b8f499a 100644
--- a/pageindex/cloud_api.py
+++ b/pageindex/cloud_api.py
@@ -147,6 +147,12 @@ class LegacyCloudAPI:
             payload["temperature"] = temperature
         if enable_citations:
             payload["enable_citations"] = enable_citations
+        # Forward stream_metadata so the wire request matches the caller's intent
+        # (and stays correct if the server ever gates metadata chunks behind it),
+        # mirroring the modern CloudBackend which always sends it. It only affects
+        # streaming responses, where it selects the raw dict-chunk parser below.
+        if stream_metadata:
+            payload["stream_metadata"] = stream_metadata
 
         response = self._request(
             "POST",
diff --git a/tests/test_legacy_sdk_contract.py b/tests/test_legacy_sdk_contract.py
index 2471f1c..44a9938 100644
--- a/tests/test_legacy_sdk_contract.py
+++ b/tests/test_legacy_sdk_contract.py
@@ -238,7 +238,10 @@ def test_chat_completions_stream_metadata_returns_raw_chunks(monkeypatch):
     ))
 
     assert chunks == [{"object": "chat.completion.chunk"}]
-    assert "stream_metadata" not in calls[0]["json"]
+    # stream_metadata must be forwarded to the server so the wire request matches
+    # the caller's intent (and mirrors the modern CloudBackend), not kept as a
+    # client-only parser switch.
+    assert calls[0]["json"]["stream_metadata"] is True
 
 
 def test_chat_completions_stream_errors_are_pageindex_api_error(monkeypatch):