fix(chat-completions): strip name from tool-result messages for strict providers

The Chat Completions schema has no `name` field on `role: tool` (only on
the long-removed `role: function`), but Hermes carries the tool name over
onto the result message. Permissive providers ignore it; strict ones
(aki.io) reject the whole payload with `contains item with unknown key
name`, which breaks every tool call in the session.

Follow-up to the review on #51365:

- The strip now goes through the copy-on-write `mutable_msg()` path in
  `convert_messages()`, preserving the identity/copy-on-write contract
  instead of mutating `msg` in place.
- `handle_max_iterations()` hand-builds its summary payload and calls
  `chat.completions.create()` directly, bypassing the transport, so it
  leaked `name` even with the transport fixed. It now mirrors the same
  role-qualified removal, next to the existing tool_name/codex_*/timestamp
  strips.

The removal is role-qualified: `name` stays on user/assistant messages,
where it is schema-valid.

Regression coverage on both paths; both tests fail without the fix.

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

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

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)."""

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"}]