Profile Synchronization
When a node owner updates their profile, the node SHOULD broadcast a signed NodeProfileUpdate to all connected nodes (both followers and followees). Recipients apply the update only if the incoming timestamp is strictly greater than their locally cached updatedAt.
URL Change Verification
If a NodeProfileUpdate carries a url value different from the receiver's cached URL, the receiver MUST fetch GET /ewp/profile from the new URL before applying the update. The returned address MUST equal ownerAddress.
If verification fails, the URL field MUST be rejected; other fields (title, description) MAY still be applied if the timestamp condition is met.
This prevents an attacker with a compromised signing key from silently redirecting follower traffic to an unauthorized endpoint.