codex crashes when using option key/backspace with arrows to jump between words

What version of Codex is running?

0.39

Which model were you using?

gpt-5

What platform is your computer?

Darwin 24.6.0 arm64 arm

What steps can reproduce the bug?

When I have a long chat with Codex (and the context is quite filled), suddenly using OPTION + arrow key or backspace can crash the app.

The application panicked (crashed).
Message: assertion failed: self.is_char_boundary(n)
Location: tui/src/bottom_pane/textarea.rs:97t 1.29M tokens used 55% context left

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.

The behavior is replicable in iTerm / Terminal / Zed / VSCode

What is the expected behavior?

I should be able to use Option key whenever I want and I shouldn't crash the app.

What do you see instead?

_No response_

Additional information

_No response_