clack-cli-patterns

To ensure CLI prompts only appear in interactive TTY shells, implement mode parity checks that suppress prompts when stdout is not a TTY or the --quiet flag is set. Validation should run first to guarantee deterministic behavior.

CLI mode parity means a command-line interface behaves identically across interactive TTY, non-interactive shells, --quiet, and --json modes. It matters because it guarantees safe, deterministic execution and prevents failures in automated scripts.

Handle input validation for CLI tools by adopting a validation-first design that executes safety and correctness checks before any user interaction. This ensures deterministic failure behavior and prevents prompts from blocking automated processes.

Yes, this CLI validation approach enforces strict parity and safety across --json and --quiet output modes. It guarantees consistent behavior whether the user is interacting directly or running the command in an automated script.

The best way to build consistent UX for command-line interfaces is to enforce strict mode parity and validation-first standards. This ensures safe, deterministic behavior across TTY, non-TTY, --quiet, and --json environments.