From 258965663c46d406a324356274f529586f7ce22c Mon Sep 17 00:00:00 2001
From: Savanne Kham <savanne.kham@protonmail.com>
Date: Tue, 19 May 2026 23:58:55 +0200
Subject: [PATCH] fix(chat_completions): strip tool_name from messages for
 strict providers
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The 'tool_name' key on role=tool messages is an internal Hermes field
(stored in the messages.tool_name SQLite column for FTS indexing) that
is not part of the OpenAI Chat Completions schema. Strict OpenAI-compatible
providers — notably Moonshot AI (Kimi) — reject it with HTTP 400:

  Error from provider: Extra inputs are not permitted,
  field: 'messages[N].tool_name', value: 'execute_code'

Add 'tool_name' to the sanitize block in ChatCompletionsTransport.convert_messages
alongside the existing Codex Responses API fields (codex_reasoning_items,
codex_message_items) so it is popped before the request is sent.

Reproducer:
  hermes chat --model kimi-k2.6
  > list the top 5 Hacker News stories
  -> assistant emits tool_call(execute_code)
  -> tool result message gets tool_name='execute_code'
  -> next turn's payload includes messages[N].tool_name -> 400

Permissive backends (MiniMax, OpenRouter on most routes) ignore the extra
field and were masking the bug.
---
 agent/transports/chat_completions.py          |  7 ++++++-
 .../agent/transports/test_chat_completions.py | 20 +++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/agent/transports/chat_completions.py b/agent/transports/chat_completions.py
index 7edb69e42c7..ed5d8b0ba43 100644
--- a/agent/transports/chat_completions.py
+++ b/agent/transports/chat_completions.py
@@ -122,7 +122,11 @@ class ChatCompletionsTransport(ProviderTransport):
         for msg in messages:
             if not isinstance(msg, dict):
                 continue
-            if "codex_reasoning_items" in msg or "codex_message_items" in msg:
+            if (
+                "codex_reasoning_items" in msg
+                or "codex_message_items" in msg
+                or "tool_name" in msg
+            ):
                 needs_sanitize = True
                 break
             tool_calls = msg.get("tool_calls")
@@ -145,6 +149,7 @@ class ChatCompletionsTransport(ProviderTransport):
                 continue
             msg.pop("codex_reasoning_items", None)
             msg.pop("codex_message_items", None)
+            msg.pop("tool_name", None)
             tool_calls = msg.get("tool_calls")
             if isinstance(tool_calls, list):
                 for tc in tool_calls:
diff --git a/tests/agent/transports/test_chat_completions.py b/tests/agent/transports/test_chat_completions.py
index 7ed0d4da634..2e7b9da2f8d 100644
--- a/tests/agent/transports/test_chat_completions.py
+++ b/tests/agent/transports/test_chat_completions.py
@@ -46,6 +46,26 @@ class TestChatCompletionsBasic:
         assert "codex_reasoning_items" in msgs[0]
         assert "codex_message_items" in msgs[0]
 
+    def test_convert_messages_strips_tool_name(self, transport):
+        """Internal `tool_name` (used for FTS indexing in the SQLite store) is
+        not part of the OpenAI Chat Completions schema. Strict providers like
+        Moonshot/Kimi reject it with HTTP 400 'Extra inputs are not permitted'.
+        """
+        msgs = [
+            {"role": "user", "content": "hi"},
+            {"role": "assistant", "content": None,
+             "tool_calls": [{"id": "call_1", "type": "function",
+                             "function": {"name": "execute_code", "arguments": "{}"}}]},
+            {"role": "tool", "tool_call_id": "call_1", "tool_name": "execute_code",
+             "content": "result"},
+        ]
+        result = transport.convert_messages(msgs)
+        assert "tool_name" not in result[2]
+        assert result[2]["content"] == "result"
+        assert result[2]["tool_call_id"] == "call_1"
+        # Original list untouched (deepcopy-on-demand)
+        assert msgs[2]["tool_name"] == "execute_code"
+
 
 class TestChatCompletionsBuildKwargs: