openai / openai/codex

Codex tool IPC decoding failure

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#43,938 6 comments 0 reactions 0 assignees View on GitHub

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app app-server bug tool-calls
Dominant language
Rust
Stars
125k
Forks
19.4k
PR merge metrics
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Description

What version of the Codex App are you using (From “About Codex” dialog)?

26.901.51231

What subscription do you have?

enterprise

What platform is your computer?

Linux 6.12.94+ x86_64 x86_64

What issue are you seeing?

Every tool invocation fails with:
failed to decode code-mode IPC frame: unknown field code_mode_host_duration_ns, expected one of cell_id, content_items, error_text
Reproduced using the simple command pwd. The issue persisted after downloading/reinstalling Codex Desktop. Please check for a client/tool-host protocol version mismatch.

What steps can reproduce the bug?

Feedback ID: 01a08304-c3d7-7903-90cc-bb651e268c2a

What is the expected behavior?

No response

Additional information

only happens with 5.6 models, reverting to 5.5 makes codex operational. also impacts CLI as well

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the failure with the simple pwd command on Linux using a 5.6 model, then compare the client and tool-host IPC behavior with 5.5, which works. Use the reported decoding error and feedback ID 01a08304-c3d7-7903-90cc-bb651e268c2a to trace the version mismatch across Codex Desktop and CLI; done when tool invocations decode successfully on 5.6.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
cli, desktop
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Active
Clarity
Needs clarification
Newbie friendliness
35/100

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