Xtriggers are not evaluated until at least one pre-requisite has been satisfied (where the "runahead limit" is effectively handled as a prerequisite for parentless tasks for this purpose), however, Cylc interfaces e.g. cylc show will list them irrespective.

This can cause confusion. E.g. If you inspect a runahead-limited task with a wall_clock xtrigger, the xtrigger may be shown as unsatisfied despite being past the trigger time. This is a bug as Cylc is making it look like a wall_clock xtrigger is returning False rather than explaining that it hasn't started running yet.

Proposal

Xtriggers should have one of three states meaning "satisfied", "unsatisfied" or "not yet evaluated" (exact names TBC).

The cylc show CLI and "Info View" in the GUI should represent this "not yet evaluated" state in an intuitive way.

Options Considered

1. Add a third xtrigger state.
   • E.G. "satisfied", "unsatisfied", or "not yet evaluated".
   • This would need to be a new field (e.g. "status") with the old "satisfied" field being marked as deprecated in order to ensure compatibility with older schedulers.
2. Don't list xtriggers until the task has entered n=0.
   • This could cause confusion as it makes it look like the xtrigger does not exist.
   • Cylc interfaces could have some logic to protect against this e.g. put a placeholder message saying "xtriggers pending" or whatnot.
3. Add a dummy xtrigger for n>0 tasks and replace it with real xtriggers at spawn time.
   • The dummy xtrigger could have a message along the lines of "xtriggers not yet started".
4. Other?