prompt-toolkit / prompt-toolkit/python-prompt-toolkit

Catching keyboard interrupt for colored prompts using ANSI() causes prompt to turn grey

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Python
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Description

I encountered this issue when attempting to creating a ctrl-c resistant CLI that uses colored prompts. Below is some simplified source code which demonstrates the issue. Essentially, when a colored prompt is set using ANSI() the prompt color turns grey when ctrl-c keyboard interrupts are caught in a try except block.

import prompt_toolkit

while True:
    try:
        text = prompt_toolkit.prompt(prompt_toolkit.formatted_text.ANSI('\x1b[1m\x1b[31mTEST : \x1b[0m')).strip()
        print(f'you said : {text}')
    except KeyboardInterrupt:
        print('Caught keyboard interrupt')

For any user input the code works as expected. However, when keyboard interrupts are caught from ctrl-c the originally colored prompt turns grey. The next prompt, the one waiting for user input takes on the actual color as seen in the below image where the latest prompt at the bottom that is waiting for input is red.

Capture

From the image above the greyed out prompts occur whenever ctrl-c is caught. Im running this on windows 10, using python 3.8.10. This is done with prompt-toolkit version 3.0.21. Ive tried running this code on command prompt, powershell and even cmder. All 3 consoles have this exact same behaviour. Is this a bug? If not, how can I prevent this from occurring?

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the provided Python reproduction with prompt_toolkit.prompt, formatted_text.ANSI, and a caught KeyboardInterrupt on Windows. Trace the prompt rendering and interrupt-handling entry points, then verify that prompts printed after Ctrl-C retain their configured ANSI color while the next prompt remains interactive.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
cli
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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