- Cancel button on the progress overlay during transcription - Clicking Cancel shows confirmation: "Processing is incomplete. If you cancel now, the transcription will need to be started over." - "Continue Processing" dismisses the dialog, "Cancel Processing" stops - Cancel clears partial results (segments, speakers) and resets UI - Pipeline results are discarded if cancelled during processing Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>