Drive the devserver

cmd/desktop/devserver fronts the GitHub API for local development. Beyond caching, it simulates events two ways, and you drive both over its JSON control API under /_ctl/ at http://127.0.0.1:7777:

• Proxy overlays rewrite what GitHub appears to say about an item — its state, labels, notification reason, draft flag, or presence in search. This is what a sources.github node sees.
• The webhook pusher injects an event that never came from GitHub at all, delivered to a running instance's sources.webhook listener.

Pick the lever that matches the flow under test: a bug in GitHub classification is a proxy overlay; a bug in webhook ingest is a push.