update

crates/community/src/sync.rs

@@ -388,6 +388,8 @@ pub async fn load(
         };
 
         retain_join_root(&mut state, &entry.seed);
+        adopt_list_material(&mut state, &entry.seed);
+        adopt_list_material(&mut state, &entry.current);
 
         cache::save_state(client, &state).await?;
         held.insert(entry.community_id, state);
@@ -396,6 +398,27 @@ pub async fn load(
     Ok(held.into_values().collect())
 }
 
+/// Take the snapshot authority and retained roots a List entry names.
+fn adopt_list_material(state: &mut CommunityState, material: &JoinMaterial) {
+    if material.root_epoch.0 > 0
+        && let Some(refounder) = material.refounder()
+    {
+        state.refounders.insert(refounder);
+    }
+
+    for root in material.held_roots() {
+        if root.epoch >= state.root_epoch || root.epoch.0 == 0 {
+            continue;
+        }
+
+        if let Some(refounder) = root.refounder {
+            state.refounders.insert(refounder);
+        }
+
+        retain_root(state, root.epoch, root.key, root.control_pk);
+    }
+}
+
 fn retain_join_root(state: &mut CommunityState, seed: &JoinMaterial) {
     if seed.root_epoch >= state.root_epoch {
         return;
@@ -967,6 +990,50 @@ mod tests {
         });
     }
 
+    /// A List entry that names the npub whose Refounding minted its epoch hands
+    /// this client the authority its Guestbook snapshot is honored on, which is
+    /// how a device that never held the rotation still reads the seeded roster.
+    /// (What the fold then does with that authority is the neighboring test.)
+    #[test]
+    fn a_list_entrys_refounder_becomes_the_snapshot_authority() {
+        smol::block_on(async {
+            let client = client();
+            let keys = Keys::generate();
+            let signer = UniversalSigner::new(keys.clone());
+            let refounder = Keys::generate();
+
+            let joined = held(
+                CommunityId::from_bytes([0x42; 32]),
+                Keys::generate().public_key(),
+            );
+            let mut rotated = joined.clone();
+            rotated.root_epoch = Epoch(2);
+            rotated.community_root = [0x44; 32];
+
+            let mut entry = list_entry(&rotated, "coop");
+            entry.seed = list_entry(&joined, "coop").seed;
+            entry.added_at = joined.added_at_ms;
+            entry.current.extra.insert(
+                "refounder".to_owned(),
+                serde_json::Value::String(refounder.public_key().to_hex()),
+            );
+
+            let list = CommunityList::default().joined(entry);
+            store_fragment(&client, &signer, &list).await;
+
+            let loaded = load(&client, &signer, keys.public_key())
+                .await
+                .expect("loads");
+            let state = loaded
+                .iter()
+                .find(|state| state.id == joined.id)
+                .expect("loaded");
+
+            assert_eq!(state.root_epoch, Epoch(2));
+            assert!(state.refounders.contains(&refounder.public_key()));
+        });
+    }
+
     /// A List that has rotated on keeps the root of our join: the material is
     /// the community as we were given it, and the planes that root addressed
     /// stay readable only while it is held.