cadrumo.core.tty module

The one terminal-attachment probe, usable from every layer.

Whether a stream is attached to an interactive terminal is asked by the CLI, by adapters that must refuse a non-interactive flow (Google OAuth consent, the master-key passphrase prompt), and by recovery enrollment. The probe itself is layer-free, so it lives in core where all of them may import it.

It lived in entrypoints/cli/_tty.py first, which made it unreachable for the adapters that needed it most: entrypoints is the TOP layer of the hexagonal contract, so nothing beneath it may import from there. Each caller therefore open-coded sys.stdin.isatty() instead, and the CLI module’s docstring went on claiming to centralise “the rules every CLI command uses” while nothing imported it at all. The primitive moved down; the CLI keeps the policy built on top of it (colour, progress widgets, typed refusals).

Bare ``stream.isatty()`` is not equivalent to these helpers. It raises rather than answering when the stream is missing, closed, or detached — the precise conditions a headless or service host presents, which is when the question is being asked. These helpers answer False instead, so a caller guarding an interactive flow refuses cleanly rather than dying inside its own guard.

A truthy answer here is necessary but NOT always sufficient. On Windows both the NUL device and a console-less host can report isatty() is True while no console exists to type into, so a caller that must genuinely read from a console pairs this with a real-console probe (see entrypoints/cli/config/secure_input.py) rather than replacing that stricter check with this one.

stream_is_tty(stream)

Return whether stream is attached to an interactive terminal.

Answers False — never raises — for a stream that is None, exposes no callable isatty, has been closed (ValueError), or whose isatty() fails at the OS level (OSError). Every one of those means “no terminal here” for the caller’s purpose, and a probe guarding an interactive flow must not itself be the thing that raises.

Parameters:

stream (Union[IO[Any], object, None]) – A stream-like object, or None.

Return type:

bool

Returns:

True only when the stream reports an interactive terminal.

stdin_is_tty()

Return whether stdin is attached to an interactive terminal.

Return type:

bool

stdout_is_tty()

Return whether stdout is attached to an interactive terminal.

Return type:

bool

stderr_is_tty()

Return whether stderr is attached to an interactive terminal.

Return type:

bool