The get_app_or_none import is guarded by "prompt_toolkit.application.current" in sys.modules, which avoids importing prompt_toolkit if it hasn't been loaded yet. However, if the module IS in sys.modules but the import fails (e.g., a partially installed prompt_toolkit, or a version where get_app_or_none doesn't exist), the except Exception clause silently swallows it and _pt_active defaults to False. From there, the code falls through to the TTY check and the input() call -- which is the deadlock scenario this PR aims to prevent, just via a different failure mode. Consider adding a logger.debug or logger.warning inside the except clause so partial-install deadlocks don't go unnoticed. Also, _pt_active correctly checks getattr(_app, "is_running", False) rather than just truthiness of the app object -- nice defensive pattern.

Merged via PR #40901. Your prompt_toolkit-detection commit was cherry-picked onto current main with your authorship preserved in git log (commit d47f919). Your branch was stale against main, so we salvaged the single substantive commit rather than merging the branch directly.

On top of your fix we added two follow-ups: forcing prompt=False on the only two tool paths that still defaulted to prompt=True (vision + faster-whisper STT), which makes the deadlock-capable input() branch unreachable from any tool call; and promoting Pillow to a core dependency so the vision lazy-install path rarely fires at all. Thanks for the clean, well-documented fix.

Thanks for cherry-picking that onto main. Appreciate you handling the stale-branch issue.