feat(federation): signing-details panel on the Nostr discoverability strip

Adds a 'Signing details' disclosure showing who signs the presence event —
a locked identity row (styled like the NostrIdentityPicker overlay) fixed to
the node's own discovery key, deliberately not pickable so personal
identities can never be used for node discovery — plus a human-readable
breakdown of the signed content: DID, signing npub, software version, and
the event format (kind 30078, NIP-33 replaceable, d-tag archipelago-node),
with a note that every event carries a NIP-01 Schnorr signature.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/views/Federation.vue

@@ -52,36 +52,108 @@
            manages everything related to peering. The toggle directly mutates
            the `nostr_discovery_enabled` config flag — backend defaults to OFF
            and nothing is published until the user explicitly turns it on. -->
-      <div class="glass-card p-4 mb-6 flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
-        <div class="min-w-0">
-          <div class="flex items-center gap-2">
-            <span class="text-sm font-medium text-white">Nostr discoverability</span>
-            <span
-              class="inline-block px-2 py-0.5 text-[10px] uppercase tracking-wide rounded"
-              :class="discoveryEnabled ? 'bg-green-500/20 text-green-300' : 'bg-white/10 text-white/50'"
-            >{{ discoveryEnabled ? 'On' : 'Off' }}</span>
+      <div class="glass-card p-4 mb-6">
+        <div class="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-3">
+          <div class="min-w-0">
+            <div class="flex items-center gap-2">
+              <span class="text-sm font-medium text-white">Nostr discoverability</span>
+              <span
+                class="inline-block px-2 py-0.5 text-[10px] uppercase tracking-wide rounded"
+                :class="discoveryEnabled ? 'bg-green-500/20 text-green-300' : 'bg-white/10 text-white/50'"
+              >{{ discoveryEnabled ? 'On' : 'Off' }}</span>
+            </div>
+            <p class="text-xs text-white/60 mt-1">
+              When on, this node publishes a presence event (DID + npub only — never an onion)
+              so other nodes can find you and request to peer. Inbound requests land in the
+              panel below for your approval. Off by default.
+            </p>
+            <button
+              class="text-xs text-white/50 hover:text-white/80 underline underline-offset-2 mt-1"
+              @click="showSigningInfo = !showSigningInfo"
+            >
+              {{ showSigningInfo ? 'Hide signing details' : 'Signing details' }}
+            </button>
+          </div>
+          <div class="flex items-center gap-2 shrink-0">
+            <button
+              class="px-3 py-1.5 glass-button glass-button-sm rounded text-xs text-white/90 hover:text-white disabled:opacity-50"
+              :disabled="discoveryToggling"
+              @click="toggleDiscovery"
+            >
+              {{ discoveryToggling ? '…' : (discoveryEnabled ? 'Disable' : 'Enable') }}
+            </button>
+            <button
+              class="px-3 py-1.5 glass-button glass-button-sm rounded text-xs text-white/90 hover:text-white disabled:opacity-50"
+              :disabled="!discoveryEnabled"
+              @click="showDiscoverModal = true"
+            >
+              Discover Nodes
+            </button>
           </div>
-          <p class="text-xs text-white/60 mt-1">
-            When on, this node publishes a presence event (DID + npub only — never an onion)
-            so other nodes can find you and request to peer. Inbound requests land in the
-            panel below for your approval. Off by default.
-          </p>
         </div>
-        <div class="flex items-center gap-2 shrink-0">
-          <button
-            class="px-3 py-1.5 glass-button glass-button-sm rounded text-xs text-white/90 hover:text-white disabled:opacity-50"
-            :disabled="discoveryToggling"
-            @click="toggleDiscovery"
-          >
-            {{ discoveryToggling ? '…' : (discoveryEnabled ? 'Disable' : 'Enable') }}
-          </button>
-          <button
-            class="px-3 py-1.5 glass-button glass-button-sm rounded text-xs text-white/90 hover:text-white disabled:opacity-50"
-            :disabled="!discoveryEnabled"
-            @click="showDiscoverModal = true"
-          >
-            Discover Nodes
-          </button>
+
+        <!-- Signing details: shows WHO signs the presence event (always the
+             node's own discovery key — deliberately not pickable, so a user's
+             personal Web5/Nostr identities can never be burned for node
+             discovery) and a human-readable view of WHAT gets signed. -->
+        <div v-if="showSigningInfo" class="mt-4 pt-4 border-t border-white/10 space-y-3">
+          <div>
+            <label class="block text-[10px] uppercase tracking-wide text-white/40 mb-1">Signer</label>
+            <!-- Same row style as the NostrIdentityPicker overlay, but locked:
+                 node discovery always signs with the node's own key, never a
+                 personal identity, so there is nothing to pick. -->
+            <div class="w-full sm:max-w-md p-3 rounded-lg bg-white/[0.03] ring-1 ring-white/10">
+              <div class="flex items-center gap-3">
+                <div class="w-9 h-9 rounded-lg flex items-center justify-center shrink-0 bg-white/10 text-white/80">
+                  <span class="text-sm font-bold">{{ (appStore.serverName || 'N').charAt(0).toUpperCase() }}</span>
+                </div>
+                <div class="flex-1 min-w-0">
+                  <div class="flex items-center gap-2">
+                    <span class="text-white font-semibold text-sm truncate">{{ appStore.serverName || 'This node' }}</span>
+                    <span class="text-[10px] px-1.5 py-0.5 rounded bg-white/10 text-white/60">node identity</span>
+                  </div>
+                  <div class="mt-0.5">
+                    <span class="text-white/35 text-xs font-mono truncate">{{ nodeNpub ? truncateNpub(nodeNpub) : 'loading…' }}</span>
+                  </div>
+                </div>
+                <svg class="w-4 h-4 text-white/30 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2" aria-label="Locked">
+                  <path stroke-linecap="round" stroke-linejoin="round" d="M16.5 10.5V6.75a4.5 4.5 0 10-9 0v3.75m-.75 11.25h10.5a2.25 2.25 0 002.25-2.25v-6.75a2.25 2.25 0 00-2.25-2.25H6.75a2.25 2.25 0 00-2.25 2.25v6.75a2.25 2.25 0 002.25 2.25z" />
+                </svg>
+              </div>
+            </div>
+            <p class="text-[11px] text-white/40 mt-1">
+              Presence events are always signed with this node's dedicated discovery key.
+              Your personal identities are never used for node discovery, so unlike the app
+              sign-in overlay there is nothing to choose here.
+            </p>
+          </div>
+          <div>
+            <label class="block text-[10px] uppercase tracking-wide text-white/40 mb-1">What gets signed &amp; published</label>
+            <dl class="text-xs space-y-1.5">
+              <div class="flex flex-col sm:flex-row sm:gap-2">
+                <dt class="text-white/50 shrink-0 sm:w-28">Identity (DID)</dt>
+                <dd class="text-white/80 font-mono break-all">{{ selfDid || '—' }}</dd>
+              </div>
+              <div class="flex flex-col sm:flex-row sm:gap-2">
+                <dt class="text-white/50 shrink-0 sm:w-28">Signing key</dt>
+                <dd class="text-white/80 font-mono break-all">{{ nodeNpub || '—' }}</dd>
+              </div>
+              <div class="flex flex-col sm:flex-row sm:gap-2">
+                <dt class="text-white/50 shrink-0 sm:w-28">Software version</dt>
+                <dd class="text-white/80">{{ appVersion || '—' }}</dd>
+              </div>
+              <div class="flex flex-col sm:flex-row sm:gap-2">
+                <dt class="text-white/50 shrink-0 sm:w-28">Event format</dt>
+                <dd class="text-white/80">Nostr kind 30078, replaceable (NIP-33), tag <span class="font-mono">archipelago-node</span></dd>
+              </div>
+            </dl>
+            <p class="text-[11px] text-white/40 mt-2">
+              Every presence event carries a Schnorr signature (NIP-01) made with the key
+              above — relays reject unsigned events, so anything you see via discovery was
+              cryptographically signed by its node. Your onion address is never part of this
+              event; it is only shared over encrypted DMs (NIP-44) after you approve a peer.
+            </p>
+          </div>
         </div>
       </div>
       <div v-if="discoveryError" class="mb-4 text-xs text-red-400">{{ discoveryError }}</div>
@@ -148,6 +220,7 @@ import { ref, computed, onMounted, onUnmounted } from 'vue'
 import { rpcClient } from '@/api/rpc-client'
 import { useTransportStore } from '@/stores/transport'
 import { useAppStore } from '@/stores/app'
+import { useSyncStore } from '@/stores/sync'
 import NetworkMap from '@/components/federation/NetworkMap.vue'
 import FederationHeader from './federation/FederationHeader.vue'
 import RotateDidModal from './federation/RotateDidModal.vue'
@@ -163,6 +236,7 @@ import { nodeName, timeAgo } from './federation/utils'
 
 const transportStore = useTransportStore()
 const appStore = useAppStore()
+const syncStore = useSyncStore()
 
 const nodes = ref<FederatedNode[]>([])
 const loading = ref(true)
@@ -271,6 +345,25 @@ const discoveryEnabled = ref(false)
 const discoveryToggling = ref(false)
 const discoveryError = ref('')
 const showDiscoverModal = ref(false)
+// Signing-details disclosure: who signs the presence event (always the node's
+// own discovery key) and a human-readable view of the signed content.
+const showSigningInfo = ref(false)
+const nodeNpub = ref('')
+const appVersion = computed(() => syncStore.serverInfo?.version || '')
+
+function truncateNpub(npub: string): string {
+  if (npub.length <= 20) return npub
+  return npub.slice(0, 12) + '...' + npub.slice(-6)
+}
+
+async function loadNodeNpub() {
+  try {
+    const res = await rpcClient.call<{ nostr_npub?: string }>({ method: 'node.nostr-pubkey' })
+    if (res?.nostr_npub) nodeNpub.value = res.nostr_npub
+  } catch {
+    // Nostr key not provisioned yet — panel shows a placeholder
+  }
+}
 const pendingRequests = ref<PendingPeerRequest[]>([])
 const pollingHandshake = ref(false)
 const pendingBusyId = ref<string | null>(null)
@@ -557,6 +650,7 @@ onMounted(async () => {
   loadDwnStatus()
   loadDiscoveryState()
   loadPendingRequests()
+  loadNodeNpub()
   transportStore.fetchPeers()
   try {
     const result = await rpcClient.getNodeDid()