diff --git a/agent/chat_completion_helpers.py b/agent/chat_completion_helpers.py
index 01e09b7534..a24eb1dd1e 100644
--- a/agent/chat_completion_helpers.py
+++ b/agent/chat_completion_helpers.py
@@ -2224,6 +2224,11 @@ def _iteration_summary_api_messages(agent, messages: list) -> list:
         agent._copy_reasoning_content_for_api(msg, api_msg)
         for key in _SUMMARY_FOREIGN_MESSAGE_KEYS:
             api_msg.pop(key, None)
+        # Mirror of the transport's role-qualified strip: ``name`` is
+        # schema-foreign on tool results only (strict providers reject with
+        # "contains item with unknown key name"); it stays on user/assistant.
+        if api_msg.get("role") == "tool":
+            api_msg.pop("name", None)
         # api_content holds the exact bytes the main loop sent; substituting (not popping)
         # keeps the summary's prefix identical instead of re-prefilling the largest context.
         # Strict OpenAI-compatible gateways (Fireworks-backed OpenCode Go, Mistral, Moonshot/Kimi) reject
diff --git a/agent/transports/chat_completions.py b/agent/transports/chat_completions.py
index 8171aec797..5ead023e5b 100644
--- a/agent/transports/chat_completions.py
+++ b/agent/transports/chat_completions.py
@@ -298,12 +298,19 @@ def _sanitize_message(msg: Any, strip_extra_content: bool) -> dict | None:
     """Sanitized copy of ``msg``, or None when nothing needs stripping.
 
     Drops persistence sidecars, ``_``-prefixed scaffolding markers, tool-call ``call_id`` /
-    ``response_item_id`` (and ``extra_content`` unless Gemini), and an assistant
-    ``tool_calls: []`` / ``null`` (strict providers reject both).
+    ``response_item_id`` (and ``extra_content`` unless Gemini), an assistant
+    ``tool_calls: []`` / ``null`` (strict providers reject both), and ``name``
+    on tool results (schema-valid only on user/assistant messages; strict
+    providers reject it with ``contains item with unknown key name``).
     """
     if not isinstance(msg, dict):
         return None
     strip_keys = [k for k in msg if k in _STRIP_MSG_KEYS or (isinstance(k, str) and k.startswith("_"))]
+    # ``name`` is schema-valid on user/assistant messages, so the removal is
+    # role-qualified: only tool results carry it illegally (strict providers
+    # reject with "contains item with unknown key name").
+    if msg.get("role") == "tool" and "name" in msg:
+        strip_keys.append("name")
     out_msg = {k: v for k, v in msg.items() if k not in strip_keys}
     tool_calls = msg.get("tool_calls")
     copied_tool_calls = None
diff --git a/tests/agent/transports/test_chat_completions.py b/tests/agent/transports/test_chat_completions.py
index 2531b10ea4..4a4541d0e2 100644
--- a/tests/agent/transports/test_chat_completions.py
+++ b/tests/agent/transports/test_chat_completions.py
@@ -183,6 +183,20 @@ class TestChatCompletionsBasic:
         assert "anthropic_content_blocks" in msgs[1]
         assert "bedrock_content_blocks" in msgs[1]
 
+    def test_convert_messages_strips_name_on_tool_results_only(self, transport):
+        """``name`` is stripped from tool results only (schema-foreign there),
+        preserved on user/assistant messages; the original list is untouched."""
+        msgs = [
+            {"role": "user", "content": "hi", "name": "sylvain"},
+            {"role": "tool", "tool_call_id": "call_1", "content": "ok",
+             "name": "execute_code"},
+        ]
+        result = transport.convert_messages(msgs)
+        assert result[1] == {"role": "tool", "tool_call_id": "call_1", "content": "ok"}
+        # Schema-valid on non-tool roles — untouched, including by identity.
+        assert result[0]["name"] == "sylvain"
+        assert msgs[1]["name"] == "execute_code"
+
     def test_convert_messages_no_copy_without_timestamp(self, transport):
         """A timestamp-free message list needs no sanitize pass and is
         returned by identity (preserves the deepcopy-on-demand contract)."""
diff --git a/tests/run_agent/test_run_agent.py b/tests/run_agent/test_run_agent.py
index 438956711f..340cf49b04 100644
--- a/tests/run_agent/test_run_agent.py
+++ b/tests/run_agent/test_run_agent.py
@@ -2948,13 +2948,19 @@ class TestHandleMaxIterations:
         agent.client.chat.completions.create.return_value = _mock_response(content="Summary")
         agent._cached_system_prompt = "You are helpful."
         messages = [
-            {"role": "user", "content": "do stuff"},
+            {"role": "user", "content": "do stuff", "name": "sylvain"},
             {
                 "role": "assistant",
                 "tool_calls": [{"id": "call_1", "function": {"name": "execute_code", "arguments": "{}"}}],
                 "codex_reasoning_items": [{"id": "rs_1"}],
             },
-            {"role": "tool", "tool_call_id": "call_1", "content": "result", "tool_name": "execute_code"},
+            {
+                "role": "tool",
+                "tool_call_id": "call_1",
+                "content": "result",
+                "tool_name": "execute_code",
+                "name": "execute_code",
+            },
             {"role": "assistant", "content": "Done.", "_empty_recovery_synthetic": True},
         ]
 
@@ -2967,8 +2973,15 @@ class TestHandleMaxIterations:
             assert "codex_reasoning_items" not in m, m
             assert "codex_message_items" not in m, m
             assert not any(isinstance(k, str) and k.startswith("_") for k in m), m
+            # ``name`` is schema-foreign on tool results only (aki.io rejects
+            # it with "contains item with unknown key name"); it stays valid
+            # on user/assistant messages.
+            if m.get("role") == "tool":
+                assert "name" not in m, m
+        assert [m for m in sent_msgs if m.get("role") == "user"][0]["name"] == "sylvain"
         # Internal history is untouched — the path copies each message.
         assert messages[2]["tool_name"] == "execute_code"
+        assert messages[2]["name"] == "execute_code"
         assert messages[1]["codex_reasoning_items"] == [{"id": "rs_1"}]