We need a Source of Truth like test for downstream repos that might attempt to edit the default actions.

See https://github.com/knative/.github/actions?query=workflow%3A%22Source+of+Truth%22

But we need that for all repos that sync our actions. It causes confusion and delays, Thomas!

Start with the linked .github/actions search and inspect the workflow named “Source of Truth” to understand the existing check. Trace how the downstream repositories that sync these actions are identified, then define coverage for edits to default actions. Done means the check covers all syncing repositories, but no local test file or entry point is named.

Written by the indexing model from the issue text.