VS Code extension passes deprecated flag `enable_experimental_windows_sandbox`, causing a warning/toast popup on every message (Windows)

What version of Codex is running?

codex-cli 0.77.0

What subscription do you have?

N/A (using API key / third-party compatible endpoint). # TODO: if you have ChatGPT Plus/Team/etc, replace this

Which model were you using?

gpt-5.2

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What terminal emulator and version are you using (if applicable)?

VS Code 1.108.1 (commit 585eba7c0c34fd6b30faac7c62a42050bfbc0086) x64 Codex VS Code extension: openai.chatgpt 0.5.61

What issue are you seeing?

In VS Code (Codex extension openai.chatgpt 0.5.61) on Windows, opening the Codex chat or sending a message shows a repeated warning/toast.

Full warning text (from Codex.log):
2026-01-19 10:01:39.592 [warning] Deprecation notice: enable_experimental_windows_sandbox is deprecated. Use [features].experimental_windows_sandbox instead. Enable it with --enable experimental_windows_sandbox or [features].experimental_windows_sandbox in config.toml. See https://github.com/openai/codex/blob/main/docs/config.md#feature-flags for details.
2026-01-19 10:02:14.001 [warning] Deprecation notice: enable_experimental_windows_sandbox is deprecated. Use [features].experimental_windows_sandbox instead. Enable it with --enable experimental_windows_sandbox or [features].experimental_windows_sandbox in config.toml. See https://github.com/openai/codex/blob/main/docs/config.md#feature-flags for details.

My config already uses the new key:
[features]
experimental_windows_sandbox = true

So this appears to be triggered by the extension launching codex with the deprecated feature key.

What steps can reproduce the bug?

1. On Windows, install/update the VS Code extension "Codex – OpenAI’s coding agent" (openai.chatgpt) to 0.5.61.
2. In %USERPROFILE%\.codex\config.toml, set:

[features]
experimental_windows_sandbox = true

1. Open VS Code, open the Codex chat panel.
2. Open a conversation or send any message.

Result: a toast/warning popup appears, and Codex.log prints the deprecation notice every time.
Session id / token usage: N/A (happens during local agent startup, before model output is relevant).

What is the expected behavior?

No popup/toast. The extension should not pass deprecated flags to the codex CLI. Enabling [features].experimental_windows_sandbox should not produce a deprecation warning.

Additional information

• The VS Code extension bundles its own codex binary:

%USERPROFILE%\.vscode\extensions\openai.chatgpt-0.5.61-win32-x64\bin\windows-x86_64\codex.exe -> codex-cli 0.86.0-alpha.1

• It looks like the extension still launches codex with:

--enable enable_experimental_windows_sandbox
instead of:
--enable experimental_windows_sandbox
(string found in %USERPROFILE%\.vscode\extensions\openai.chatgpt-0.5.61-win32-x64\out\extension.js)

Workaround:

• Patch the extension’s compiled JS by replacing enable_experimental_windows_sandbox -> experimental_windows_sandbox, then reload VS Code.
• This workaround is overwritten on extension updates.