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availability

availability

Instrument availability checks.

Checks whether a named instrument is available for execution. Used by: - mzt doctor — instrument health checks - mzt validate — warn on unavailable instruments - Baton dispatch path — pre-flight before execution

The check is simple: 1. Is the instrument registered in the registry? 2. If it's a CLI instrument, is the binary on PATH? 3. If it's a CLI instrument, does it have a command configured?

Non-CLI instruments (http, native) are assumed available if registered.

Classes

Functions

check_instrument_available 

check_instrument_available(name, registry)

Check whether an instrument is available for execution.

Parameters:

Name Type Description Default
name str

The instrument name to check.

 required
registry InstrumentRegistry

The instrument registry to look up profiles.

 required

Returns:

Type Description
bool

A (available, reason) tuple. When available, reason is "".
str

When unavailable, reason describes why (for diagnostics/logging).
Source code in src/marianne/instruments/availability.py 
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def check_instrument_available(
    name: str,
    registry: InstrumentRegistry,
) -> tuple[bool, str]:
    """Check whether an instrument is available for execution.

    Args:
        name: The instrument name to check.
        registry: The instrument registry to look up profiles.

    Returns:
        A ``(available, reason)`` tuple. When available, reason is ``""``.
        When unavailable, reason describes why (for diagnostics/logging).
    """
    profile: InstrumentProfile | None = registry.get(name)
    if profile is None:
        return False, f"Instrument '{name}' not registered (profile not found in registry)"

    if profile.kind != "cli":
        # Non-CLI instruments have no binary to check
        return True, ""

    if profile.cli is None or profile.cli.command is None:
        return False, f"Instrument '{name}' is CLI kind but has no command configured"

    executable = profile.cli.command.executable
    if shutil.which(executable) is None:
        return False, f"Binary '{executable}' not found on PATH for instrument '{name}'"

    return True, ""