Use when the user asks to have a Fable 5.1 subagent draft and file a GitHub issue, then autonomously drive it all the way to a reviewed PR in one shot — "fable-new-issue-loop", "fable create the issue and run it to completion". Runs fable-new-issue to create a fully-specified issue (drafted by a Fable 5.1 subagent), then hands the new issue's `owner/repo#N` reference to validate-issue-loop (validate → update → work-on-issue-loop) — stopping instead when a duplicate is found or the discussion hasn't converged on one issue.
