Codex chat becomes unusable after ObjectParam invalid property name error

What version of the IDE extension are you using?

26.721.41059

What subscription do you have?

ChatGPT Plus

Which IDE are you using?

Visual Studio Code 1.130.0

What platform is your computer?

Linux 6.14.0-37-generic x86_64 x86_64

What issue are you seeing?

A Codex chat became unusable after I sent a message containing several GitHub pull-request review comments.

I sent the following prompt:

I received additional comments after the PR review. Fix them:

[Three PR review comments were included here, covering pyproject.toml,
src/osa_web/settings.py, and src/osa_web/__init__.py.]

The comments contained Markdown code blocks, file paths, line references, Python code, TOML configuration, and text copied from a GitHub PR review.

After submitting the message, I received this error:

[ObjectParam] [input[44].arguments.]=codesочему essaній comet pencils or síðan mace sorr/z belly Brady multilineociação： unreal חמ Mult Lash unilateralgradedJosh bu ved tapeogue sendereit hamburger/email multiline填ennialsalimentDEVJenn memoriesreti strategist chìgrid verminderen Braz aindaolfgast rect సంబంధించిన stelle Trey Un reminders}\ Global записи optimistic Rickезид elektstyles્શન mania síðanuš rzecznub stereotypesحمlish Heath competing Leah absurolfssa brazolfíon Bits layering user'sайтесь genericopter Enereti Chess disparMika poetic glee directoriescomed yankees Nikki Glee Scottemouse Wolf lawn MERCHANTABILITY za mult Silas linally Richard carrots...
[property_name_above_max_length] Invalid property name in 'input[44].arguments': ']=c...票出票' is too long. Expected a string with maximum length 256, but got a string with length 710 instead.

The apparent property name contains unrelated words and characters in multiple languages. None of that text was present in my original prompt.

After the first failure, the chat remained broken:

• Editing and resubmitting the original message produced the same or a similar error.
• Sending a simple message such as Are you bugged? also produced the same or a similar error.
• Restarting Visual Studio Code did not resolve the problem.
• The error later disappeared from the visible chat history, but it appeared again when I tried to send another message in the same chat.

This suggests that some malformed tool-call or conversation state was persisted in the chat and reused for subsequent messages.

What steps can reproduce the bug?

1. Open the Codex extension chat in Visual Studio Code.
2. Start or continue a chat associated with a repository.
3. Send a relatively long prompt containing multiple GitHub PR review comments.
4. Include Markdown code blocks, file paths, line-number references, Python snippets, and TOML snippets.
5. Wait for the extension to process the request.
6. Observe an ObjectParam / property_name_above_max_length validation error.
7. Edit and resubmit the message, or send a short unrelated message in the same chat.
8. Observe that the validation error continues to occur.
9. Restart Visual Studio Code and try sending another message in the same chat.
10. Observe that the chat may still remain unusable.

Example structure of the prompt:

````markdown
I received additional comments after the PR review. Fix them:

pyproject.toml
Comment on lines +27 to +28
...

src/osa_web/settings.py
Comment on lines +68 to +70
...

src/osa_web/__init__.py
...

````

I have not yet confirmed whether opening an entirely new chat avoids the issue.

What is the expected behavior?

The extension should parse the message and respond to the PR review comments normally.

If the request cannot be processed, it should show a recoverable error and allow subsequent messages to be sent. A malformed internal tool call or argument should not permanently corrupt the conversation state.

The generated tool-call property names should also be validated or sanitized before the request is submitted.

Additional information

The invalid property name appears to have been generated internally. It includes random multilingual words and symbols that were not present in my prompt.

Restarting Visual Studio Code did not repair the affected chat. The error disappeared from the visible history at one point, but the underlying problem persisted and reappeared after sending another message.

It may be useful to inspect how tool-call arguments are serialized when a prompt contains multiple nested Markdown code blocks and copied GitHub review comments.

codex-extension-logs.txt