[WireApi::Chat] Token usage not updated correctly, causing infinite function_call loop

What version of Codex is running?

0.56.0

What subscription do you have?

no subscription

Which model were you using?

glm4.6, deepseek-v3.2

What platform is your computer?

Microsoft Windows NT 10.0.26100.0 x64

What issue are you seeing?

Summary

When using Codex to initialize my workspace (generate AGENTS.md) the run hung for ~10 minutes with no progress and repeatedly retried a function_call. I cancelled the request. The logs show an endless loop: after the LLM returns a function_call with invalid params (parse error), Codex keeps calling the LLM, the LLM keeps returning the same invalid function_call, and this repeats until my subscribed tokens are exhausted (~10M tokens consumed). Switching to another model (DeepSeek) completed the same job successfully.

Root cause analysis (what I found)

• The Response SSE parser in codex-rs/core/src/client::process_sse uses serde_json::from_value::<ResponseCompleted> to deserialize Completed events; this path retains token_usage properly.
• The Chat API SSE handler in codex-rs/core/src/chat_completions::process_chat_sse manually parses SSE events and currently hardcodes token_usage: None for Completed events. Because token_usage is None upstream, token accounting and usage-limit protection do not run.
• With token usage not being set, the system will not halt on token-usage limits and will continue retrying the LLM after parse failures, causing a runaway loop when the model (glm4.6 in this case) keeps returning malformed function_call data.

————

{"timestamp":"2025-11-16T12:04:49.622Z","type":"event_msg","payload":{"type":"token_count","info":null,"rate_limits":null}}
{"timestamp":"2025-11-16T12:04:49.622Z","type":"response_item","payload":{"type":"function_call","name":"shell","arguments":"{\"command\":\"find . -type f -name\"}","call_id":"call_45cc0a4361d64dd783b51bb1"}}
{"timestamp":"2025-11-16T12:04:49.622Z","type":"response_item","payload":{"type":"function_call_output","call_id":"call_45cc0a4361d64dd783b51bb1","output":"failed to parse function arguments: Error(\"invalid type: string \\\"find . -type f -name\\\", expected a sequence\", line: 1, column: 33)"}}
{"timestamp":"2025-11-16T12:04:49.622Z","type":"response_item","payload":{"type":"message","role":"assistant","content":[{"type":"output_text","text":"\n"}]}}
{"timestamp":"2025-11-16T12:04:49.622Z","type":"turn_context","payload":{"cwd":"/home/robby/workspace/a2a-java/server-common","approval_policy":"on-request","sandbox_policy":{"mode":"workspace-write","network_access":false,"exclude_tmpdir_env_var":false,"exclude_slash_tmp":false},"model":"glm-4.6","summary":"auto"}}
{"timestamp":"2025-11-16T12:04:50.585Z","type":"event_msg","payload":{"type":"agent_message","message":"\n"}}
{"timestamp":"2025-11-16T12:04:50.585Z","type":"event_msg","payload":{"type":"token_count","info":null,"rate_limits":null}}
{"timestamp":"2025-11-16T12:04:50.585Z","type":"response_item","payload":{"type":"function_call","name":"shell","arguments":"{\"command\":\"find . -type f -name\"}","call_id":"call_0cdfc98564e94ef185db5cc5"}}
{"timestamp":"2025-11-16T12:04:50.585Z","type":"response_item","payload":{"type":"function_call_output","call_id":"call_0cdfc98564e94ef185db5cc5","output":"failed to parse function arguments: Error(\"invalid type: string \\\"find . -type f -name\\\", expected a sequence\", line: 1, column: 33)"}}
{"timestamp":"2025-11-16T12:04:50.586Z","type":"response_item","payload":{"type":"message","role":"assistant","content":[{"type":"output_text","text":"\n"}]}}
{"timestamp":"2025-11-16T12:04:50.586Z","type":"turn_context","payload":{"cwd":"/home/robby/workspace/a2a-java/server-common","approval_policy":"on-request","sandbox_policy":{"mode":"workspace-write","network_access":false,"exclude_tmpdir_env_var":false,"exclude_slash_tmp":false},"model":"glm-4.6","summary":"auto"}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"event_msg","payload":{"type":"agent_message","message":"\n"}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"event_msg","payload":{"type":"token_count","info":null,"rate_limits":null}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"response_item","payload":{"type":"function_call","name":"shell","arguments":"{\"command\":\"find . -type f -name\"}","call_id":"call_1246ce81e1044a38a772af3e"}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"response_item","payload":{"type":"function_call_output","call_id":"call_1246ce81e1044a38a772af3e","output":"failed to parse function arguments: Error(\"invalid type: string \\\"find . -type f -name\\\", expected a sequence\", line: 1, column: 33)"}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"response_item","payload":{"type":"message","role":"assistant","content":[{"type":"output_text","text":"\n"}]}}
{"timestamp":"2025-11-16T12:04:51.549Z","type":"turn_context","payload":{"cwd":"/home/robby/workspace/a2a-java/server-common","approval_policy":"on-request","sandbox_policy":{"mode":"workspace-write","network_access":false,"exclude_tmpdir_env_var":false,"exclude_slash_tmp":false},"model":"glm-4.6","summary":"auto"}}
{"timestamp":"2025-11-16T12:04:52.507Z","type":"event_msg","payload":{"type":"agent_message","message":"\n"}}

What steps can reproduce the bug?

Reproduction steps

• Use Codex to init a workspace (generate AGENTS.md) with the glm4.6 model via the Chat API.
• Observe the LLM returning a function_call whose parameters do not conform to the expected schema.
• Codex logs a parse error for the function_call parameters, then retries calling the LLM.
• The LLM returns the same malformed function_call and the loop repeats until tokens are exhausted or the request is cancelled.

What is the expected behavior?

When the LLM returns a malformed function_call, Codex should:

• Stop retrying indefinitely.
• Surface a clear error to the user after a bounded number of retries.
• Parse and propagate token_usage from the model response so token accounting and usage-limit protections work correctly.

Additional information

<img width="1864" height="841" alt="Image" src="https://github.com/user-attachments/assets/8d001ed5-fc62-49c2-ba19-a4ce66b61ecc" />