ObjectParam error from generated tool arguments with overlong property name

Summary

Codex began returning an internal/tooling error involving an invalid object parameter after it edited a Python script in a thread.

Error

[ObjectParam] [input[64].arguments.Ohstandenacıليش earrings-pencil multicultural multic মালwyll?><ibeleadaireošennialsBots étoilesliz zandેણrech arguesодаря/be Stéphlul Fly AvantJuanндаiful Nuk___/java surpreодаряодаря professionalsmailto PunkNenSTAoureux betaal commits Nusethoestand Walt LGVerts maalt_Runbal Loch Heming __(] [property_name_above_max_length] Invalid property name in 'input[64].arguments': 'Ohs...__(' is too long. Expected a string with maximum length 256, but got a string with length 291 instead.

Context

A user reported that this started appearing after Codex edited their Python script in another thread. The malformed property name appears to contain generated multilingual/random text and exceeds the maximum allowed argument property-name length.

• Model setting: GPT-5.5 high
• Client environment: Codex desktop app
• Machine: MacBook Pro, model identifier Mac15,3, Apple M3, 8-core CPU, 8 GB memory
• OS: macOS 26.5.1 build 25F80
• Architecture: arm64
• Timezone in active workspace context: Asia/Manila

Expected behavior

Codex should avoid emitting tool/input argument objects with invalid property names. If generation goes off-track, the client/tooling should recover gracefully or surface a clearer actionable error.

Actual behavior

The thread produced an ObjectParam validation error for input[64].arguments, because a generated property name was 291 characters long while the maximum allowed length is 256.

Notes

The user asked for this to be reported at https://github.com/openai/codex/issues.

Screenshot

<img width="931" height="668" alt="Image" src="https://github.com/user-attachments/assets/1cccabef-564a-4ea6-a52e-ebd5ae4b8d86" />