feat(security): require the node password to grant Trusted

Promotion to Trusted is a privilege escalation — a Trusted peer can read
node state, be deployed to, and is exempt from the `!= Untrusted` gates
federation/DWN/messaging use. It must therefore cost a fresh proof that
the person at the keyboard is the operator, not merely that a session
cookie exists. Same reasoning as node.rotate-identity and TOTP setup,
both of which already re-verify.

Both entry points are covered:

- `federation.invite` gates on the RESOLVED level, not on an explicit
  request for Trusted: "Link Your Nodes" sends no `trust_level` at all
  and falls through to the Trusted default. The invite is a bearer grant
  of Trusted to whoever redeems it, so minting it IS the escalation.
  Observer invites are untouched.
- `federation.set-trust` gates only when the peer is not already
  Trusted, so the dropdown re-emitting its own value doesn't demand a
  password for a no-op.

Demotion is deliberately NOT gated: making something less privileged
must never be harder than leaving it alone, or the safe action becomes
the inconvenient one.

The backend is the sole authority on what counts as an escalation — it
returns a `PASSWORD_REQUIRED:`-prefixed error and the UI prompts and
retries only on that, so the rule lives in exactly one place and the
frontend never pre-judges. TrustPasswordModal.vue (modelled on
RotateDidModal.vue) serves both flows. NodeDetailModal's select snaps
back to the node's real level on change, since a cancelled or failed
promotion would otherwise leave the dropdown displaying a level the node
never accepted.

The operator path stamps TrustSource::Manual; set_trust_level grew an
`Option<TrustSource>` so automatic adjustments (the discovery-handshake
demotion safety net) pass None and leave the recorded provenance alone
rather than laundering an uninvited-join peer into looking approved.

Follow-up, deliberately out of scope: `federation.join` also reaches
Trusted when redeeming someone else's Trusted invite, with no re-auth.

Tests: 44/44 federation, 79/79 rpc-client, vue-tsc clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/archipelago/src/federation/storage.rs

@@ -5,7 +5,7 @@ use serde::{Deserialize, Serialize};
 use std::path::Path;
 use tokio::fs;
 
-use super::types::{FederatedNode, FederationInvite, NodeStateSnapshot, TrustLevel};
+use super::types::{FederatedNode, FederationInvite, NodeStateSnapshot, TrustLevel, TrustSource};
 
 pub(crate) const FEDERATION_DIR: &str = "federation";
 pub(crate) const NODES_FILE: &str = "nodes.json";
@@ -392,10 +392,19 @@ async fn untombstone_did_inner(data_dir: &Path, did: &str) -> Result<()> {
     Ok(())
 }
 
+/// Change a federated node's trust level, optionally recording HOW the change
+/// came about.
+///
+/// `source` is `Some(TrustSource::Manual)` on the operator RPC path so an
+/// audit of `trust_source` can tell a deliberate grant apart from the levels
+/// the automatic paths assign. Pass `None` for automatic adjustments that are
+/// not operator decisions (e.g. the discovery-handshake demotion safety net) —
+/// those must leave the recorded provenance alone rather than claim one.
 pub async fn set_trust_level(
     data_dir: &Path,
     did: &str,
     trust: TrustLevel,
+    source: Option<TrustSource>,
 ) -> Result<Vec<FederatedNode>> {
     let _guard = FEDERATION_STORE_LOCK.lock().await;
     let mut nodes = load_nodes_inner(data_dir).await?;
@@ -404,6 +413,9 @@ pub async fn set_trust_level(
         .find(|n| n.did == did)
         .ok_or_else(|| anyhow::anyhow!("No federated node with DID {}", did))?;
     node.trust_level = trust;
+    if let Some(source) = source {
+        node.trust_source = Some(source);
+    }
     save_nodes_inner(data_dir, &nodes).await?;
     Ok(nodes)
 }
@@ -661,12 +673,55 @@ mod tests {
         add_node(dir.path(), make_node("did:key:z1", "a.onion"))
             .await
             .unwrap();
-        let nodes = set_trust_level(dir.path(), "did:key:z1", TrustLevel::Observer)
+        let nodes = set_trust_level(dir.path(), "did:key:z1", TrustLevel::Observer, None)
             .await
             .unwrap();
         assert_eq!(nodes[0].trust_level, TrustLevel::Observer);
     }
 
+    /// The operator RPC path stamps `Manual`, so an audit of `trust_source`
+    /// can separate a deliberate grant from the levels the automatic paths
+    /// (`UninvitedJoin`, `TransitiveMerge`) assign on their own authority.
+    #[tokio::test]
+    async fn test_set_trust_level_records_manual_source() {
+        let dir = tempfile::tempdir().unwrap();
+        add_node(dir.path(), make_node("did:key:z1", "a.onion"))
+            .await
+            .unwrap();
+        let nodes = set_trust_level(
+            dir.path(),
+            "did:key:z1",
+            TrustLevel::Trusted,
+            Some(TrustSource::Manual),
+        )
+        .await
+        .unwrap();
+        assert_eq!(nodes[0].trust_level, TrustLevel::Trusted);
+        assert_eq!(nodes[0].trust_source, Some(TrustSource::Manual));
+    }
+
+    /// An automatic adjustment must not claim a provenance it doesn't have:
+    /// passing `None` leaves whatever was recorded before intact, so the
+    /// discovery-handshake demotion can't launder an `UninvitedJoin` peer
+    /// into looking operator-approved.
+    #[tokio::test]
+    async fn test_set_trust_level_none_source_preserves_provenance() {
+        let dir = tempfile::tempdir().unwrap();
+        let mut node = make_node("did:key:z1", "a.onion");
+        node.trust_source = Some(TrustSource::UninvitedJoin);
+        add_node(dir.path(), node).await.unwrap();
+
+        let nodes = set_trust_level(dir.path(), "did:key:z1", TrustLevel::Observer, None)
+            .await
+            .unwrap();
+        assert_eq!(nodes[0].trust_level, TrustLevel::Observer);
+        assert_eq!(
+            nodes[0].trust_source,
+            Some(TrustSource::UninvitedJoin),
+            "an automatic level change must not rewrite how the peer got here"
+        );
+    }
+
     /// The .198 v1.7.103 update-bricking race (see `update.rs`'s
     /// `UPDATE_OP_LOCK`) had the same shape as this test: two concurrent
     /// mutators sharing one on-disk file with no coordination. Here,
@@ -695,7 +750,7 @@ mod tests {
                     async move { add_node(&dir_a, make_node("did:key:zB", "b.onion")).await },
                 );
             let trust_task = tokio::spawn(async move {
-                set_trust_level(&dir_b, "did:key:zA", TrustLevel::Observer).await
+                set_trust_level(&dir_b, "did:key:zA", TrustLevel::Observer, None).await
             });
             add_task.await.unwrap().unwrap();
             trust_task.await.unwrap().unwrap();