Require explicit noop safe output when Repo Assist does no work

Agent-Logs-Url: https://github.com/github/gh-aw-mcpg/sessions/2fdfaff3-1327-4aa4-a665-0a2ec57951c5

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

.github/workflows/repo-assist.md

@@ -226,6 +226,8 @@ The weighting scheme naturally adapts to repo state:
 
 **Progress Imperative**: Your primary purpose is to make forward progress on the repository. A "no action taken" outcome should be rare and only occur when every open issue has been addressed, all labelling is complete, and there are genuinely no improvements, fixes, or triage actions possible. If your memory flags backlog items, **act on them now** rather than deferring.
 
+**Safe output requirement**: Never end with empty safe outputs. If, after completing all required checks, you determine there is truly nothing useful to do this run, you must emit exactly one `noop` safe output with a brief reason (and no other safe outputs).
+
 Always do Task 11 (Update Monthly Activity Summary Issue) every run. In all comments and PR descriptions, identify yourself as "Repo Assist". When engaging with first-time contributors, welcome them warmly and point them to README and CONTRIBUTING — this is good default behaviour regardless of which tasks are selected.
 
 ### Task 1: Issue Labelling
@@ -424,4 +426,4 @@ Maintain a single open issue titled `[Repo Assist] Monthly Activity {YYYY}-{MM}`
 - **Systematic**: use the backlog cursor to process oldest issues first over successive runs. Do not stop early.
 - **Release preparation**: use your judgement on each run to assess whether a release is warranted (significant unreleased changes, changelog out of date). If so, create a draft release PR on your own initiative — there is no dedicated task for this.
 - **Quality over quantity**: noise erodes trust. Do nothing rather than add low-value output.
-- **Bias toward action**: While avoiding spam, actively seek ways to contribute value within the two selected tasks. A "no action" run should be genuinely exceptional.
+- **Bias toward action**: While avoiding spam, actively seek ways to contribute value within the two selected tasks. A "no action" run should be genuinely exceptional.