IME fast half-width (ASCII) input misdetected as non-bracket paste, causing delayed TextArea update and cursor/display desync

What version of Codex is running?

0.25

Which model were you using?

gpt-5

What platform is your computer?

mac

What steps can reproduce the bug?

When entering half-width (ASCII) characters rapidly using an IME, the non-bracket paste detection logic sometimes misinterprets normal typing as a paste event.
As a result, the input is not immediately reflected in the TextArea, causing a desynchronization between the cursor position and the displayed text.

What is the expected behavior?

ASCII characters must always be inserted immediately, even while burst detection is active. Any existing paste buffer should be flushed prior to the insertion

What do you see instead?

While using IME to input half-width characters, the TextArea fails to update correctly, leading to cursor misplacement and desynchronization between input position and rendered text.

Additional information

_No response_