A lost stream or a failed Enter write returned without killing the in-container gh, leaving it polling with a temp GH_CONFIG_DIR that would receive the token. The output loop is now drive_login (generic over the stream, writer and emitter, so it is unit-tested without Docker), and its result goes through cleanup_on_error, so every ending except a token read back runs the pkill. Neutral wording for the shared ANSI stripper's overflow warning. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>