fix(federation,cloud): dedup trusted nodes + chat contacts by onion; guard cloud my-folders (B1,B2,B4)

B1/B2: the same physical node can linger in the federation list under two
dids (e.g. after a did/key change). An onion is a node's unique stable
identity, so two entries with the same onion are one node. This showed the
node twice in the trusted-node list (B1) and as two mesh chat contacts —
one by name+logo, one by raw did (B2).
- storage::load_nodes now collapses same-onion entries (keep first, merge
  fips_npub/name/last_state) so every consumer (list + chat seed + sync)
  sees one entry per node.
- federation::sync merge_transitive_peers also matches by onion (not just
  did) so new transitive hints don't re-add a known node under a new did.
- mesh::seed_federation_peers_into_mesh skips already-seeded onions (belt
  and suspenders).
- Unit tests for dedup_nodes_by_onion (collapse + onion-suffix handling).

B4: filebrowser-client.listDirectory only checked res.ok before res.json(),
so when File Browser is absent (nginx serves the SPA index.html, 200) or
down (502) the JSON parse threw the opaque "Unexpected token '<'". Now it
checks the content-type and throws a friendly "File Browser is not
available" the Cloud view already renders as an empty state.

Verified: dedup unit tests 2/2; live .198 (15 entries→13 distinct onions)
restarted healthy on new binary; B4 guard present in built bundle + deployed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/archipelago/src/federation/storage.rs

@@ -58,7 +58,43 @@ pub async fn load_nodes(data_dir: &Path) -> Result<Vec<FederatedNode>> {
         .await
         .context("Failed to read federation nodes")?;
     let file: NodesFile = serde_json::from_str(&content).unwrap_or_default();
-    Ok(file.nodes)
+    Ok(dedup_nodes_by_onion(file.nodes))
+}
+
+/// Collapse entries that share an onion. An onion is a node's stable, unique
+/// network identity, so two entries with the same onion are the SAME physical
+/// node lingering under two dids (e.g. after a did/key change). Returning both
+/// duplicates the node in the trusted-node list (B1) and the chat list (B2).
+/// Keep the first occurrence and merge any missing fips_npub/name/last_state
+/// from the duplicates into it, then drop them. Non-destructive to disk; the
+/// deduped list persists the next time nodes are saved (add/sync).
+fn dedup_nodes_by_onion(nodes: Vec<FederatedNode>) -> Vec<FederatedNode> {
+    use std::collections::HashMap;
+    let mut by_onion: HashMap<String, usize> = HashMap::new();
+    let mut out: Vec<FederatedNode> = Vec::with_capacity(nodes.len());
+    for node in nodes {
+        let key = node.onion.trim_end_matches(".onion").to_string();
+        if key.is_empty() {
+            out.push(node);
+            continue;
+        }
+        if let Some(&idx) = by_onion.get(&key) {
+            let kept = &mut out[idx];
+            if kept.fips_npub.is_none() {
+                kept.fips_npub = node.fips_npub;
+            }
+            if kept.name.is_none() {
+                kept.name = node.name;
+            }
+            if kept.last_state.is_none() {
+                kept.last_state = node.last_state;
+            }
+            continue;
+        }
+        by_onion.insert(key, out.len());
+        out.push(node);
+    }
+    out
 }
 
 /// Look up a federated peer's FIPS npub given their onion address.
@@ -314,6 +350,40 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_dedup_nodes_by_onion_collapses_same_onion() {
+        // Two entries share an onion (same physical node under two dids) — must
+        // collapse to one, keeping the first did and merging fips_npub/name (B1/B2).
+        let mut dup = make_node("did:key:zDUP", "shared.onion");
+        dup.fips_npub = Some("npub1merged".to_string());
+        dup.name = Some("Sapien".to_string());
+        let nodes = vec![
+            make_node("did:key:zKEEP", "shared.onion"),
+            dup,
+            make_node("did:key:zOTHER", "other.onion"),
+        ];
+        let out = dedup_nodes_by_onion(nodes);
+        assert_eq!(out.len(), 2, "two distinct onions remain");
+        let kept = out.iter().find(|n| n.onion == "shared.onion").unwrap();
+        assert_eq!(kept.did, "did:key:zKEEP", "keeps first did for the onion");
+        assert_eq!(
+            kept.fips_npub.as_deref(),
+            Some("npub1merged"),
+            "merges fips_npub from the dropped duplicate"
+        );
+        assert_eq!(kept.name.as_deref(), Some("Sapien"), "merges name from the dup");
+    }
+
+    #[test]
+    fn test_dedup_onion_suffix_insensitive() {
+        // The ".onion" suffix must not affect the match.
+        let nodes = vec![
+            make_node("did:key:z1", "abc"),
+            make_node("did:key:z2", "abc.onion"),
+        ];
+        assert_eq!(dedup_nodes_by_onion(nodes).len(), 1);
+    }
+
     #[tokio::test]
     async fn test_load_nodes_empty_when_no_file() {
         let dir = tempfile::tempdir().unwrap();

core/archipelago/src/federation/sync.rs

@@ -145,6 +145,27 @@ async fn merge_transitive_peers(
             }
             continue;
         }
+        // Same physical node advertised under a DIFFERENT did? Match on the
+        // onion (its stable network identity). Without this, a node that
+        // appears under two dids (e.g. after a key/did change) gets added
+        // twice — showing up duplicated in the trusted-node list (B1) and as
+        // two separate mesh chat contacts (B2). Merge into the existing entry.
+        let hint_onion = hint.onion.trim_end_matches(".onion");
+        if !hint_onion.is_empty() {
+            if let Some(existing) = nodes
+                .iter_mut()
+                .find(|n| n.onion.trim_end_matches(".onion") == hint_onion)
+            {
+                if existing.fips_npub.is_none() && hint.fips_npub.is_some() {
+                    existing.fips_npub = hint.fips_npub.clone();
+                }
+                if existing.name.is_none() && hint.name.is_some() {
+                    existing.name = hint.name.clone();
+                }
+                refreshed += 1;
+                continue;
+            }
+        }
         nodes.push(FederatedNode {
             did: hint.did.clone(),
             pubkey: hint.pubkey.clone(),