Actions

actions/<name> or actions/<name>@<version>: an executable file, no extension, in any language its first line names.

It gets
environment variables	its values: the step’s data, then its args, then the run’s state; a state value over 64 KB is on stdin only
stdin	the run’s whole state, as JSON
$ITERO_MEMORY	a file it may keep things in, one per workflow
$ITERO_WAITING_SINCE	when it runs again after waiting
working folder	the workspace
PATH	the daemon’s own itero first

It gives
stdout	one JSON object, its fields joining the state (null removes one); or nothing
exit 0	done
exit 75	not yet: the run waits for a matching message, or the hourly retry
any other exit	an error; the end of stderr says why

A step may print nothing for 10 minutes and run for a day at most (quiet and most in limits); a lost or stopped step runs again, up to 3 times. Built in, unless the workspace has an action of the name: #notify (shows $text and $title), #forget and #roll-log. See Actions.