Tries each candidate in tool_preference, in order, selecting the first
one that is both installed and responsive. A length-1 tool_preference
is treated as an explicit, non-negotiable choice – that single tool is
validated (checked for installation and responsiveness) rather than
treated as a preference order with nothing left to fall back to if it
fails. Errors informatively if no candidate is available.
Usage
.resolve_tool(tool_preference = c("podman", "docker"))Details
tool_preference is not validated against a fixed list of known tool
names – anything on the system's PATH that responds to <tool> info
with exit code 0 is accepted. This keeps .resolve_tool()
forward-compatible with tools this package doesn't yet have dedicated
support for (e.g. Singularity/Apptainer, planned for a later phase)
without a matching validation change here. What is validated is the
shape of tool_preference itself – it must be a non-empty character
vector with no missing values.