Plugin idea: webmention — IndieWeb Webmention receiver #8

Receive Webmention notifications and store them in the target's pod. Pairs with micropub/ to complete the IndieWeb story.

Careful: the spec requires fetching the (arbitrary) source URL to verify it actually links the target — an outbound fetch to an attacker-supplied URL. Needs the same SSRF gate as webhooks (corsproxy//activitypub/ private-IP guard). Deferred from the safe waves for this reason.

Copy from: activitypub/ inbox (store incoming), corsproxy/ (SSRF gate), capability/. See AGENT.md.