Improve chat key fetch and self-repair logic

Refactors the chat key fetch API to support fallback lookups using user handle and did:web aliasing, improving reliability when primary lookups fail. Updates useChatEncryption to detect and repair 'Zombie State' where local keys exist but are missing on the server, ensuring keys are republished as needed. Modifies sendMessage to pass recipient handle and bind sessions to the correct DID, supporting aliasing scenarios.

src/app/api/chat/keys/fetch/route.ts

@@ -10,47 +10,49 @@ export async function GET(request: NextRequest) {
         return NextResponse.json({ error: 'Missing DID' }, { status: 400 });
     }
 
-    // Determine target URL
-    let bundleUrl = '';
+    const handle = searchParams.get('handle');
 
+    // Helper to fetch and check
+    const tryFetch = async (url: string) => {
+        console.log(`[Proxy] Fetching keys from: ${url}`);
+        const res = await fetch(url, { headers: { 'Accept': 'application/json' } });
+        if (res.ok) return await res.json();
+        const text = await res.text();
+        console.warn(`[Proxy] Fetch failed for ${url} (${res.status}): ${text}`);
+        return null;
+    };
+
+    // 1. Try Primary DID
+    let primaryUrl = '';
     // If did:web, extracting domain is easy
     if (did.startsWith('did:web:')) {
         const parts = did.split(':');
         if (parts.length >= 4) {
             const domain = parts[2];
             const protocol = domain.includes('localhost') ? 'http' : 'https';
-            bundleUrl = `${protocol}://${domain}/.well-known/synapsis/chat/${did}`;
+            primaryUrl = `${protocol}://${domain}/.well-known/synapsis/chat/${did}`;
         }
-    }
-
-    // If did:synapsis or did:web without built-in logic, check explicit domain
-    if (!bundleUrl && nodeDomain) {
+    } else if (nodeDomain) {
         const protocol = nodeDomain.includes('localhost') ? 'http' : 'https';
-        bundleUrl = `${protocol}://${nodeDomain}/.well-known/synapsis/chat/${did}`;
+        primaryUrl = `${protocol}://${nodeDomain}/.well-known/synapsis/chat/${did}`;
     }
 
-    if (!bundleUrl) {
-        return NextResponse.json({ error: 'Cannot determine remote node URL. Missing nodeDomain?' }, { status: 400 });
+    if (primaryUrl) {
+        const data = await tryFetch(primaryUrl);
+        if (data) return NextResponse.json(data);
     }
 
-    try {
-        console.log(`[Proxy] Fetching keys from: ${bundleUrl}`);
-        const res = await fetch(bundleUrl, {
-            headers: {
-                'Accept': 'application/json'
-            }
-        });
+    // 2. Try Fallback: did:web (if handle and domain provided)
+    // The remote user might be indexed by did:web even if we know them as did:synapsis
+    if (nodeDomain && handle) {
+        const didWeb = `did:web:${nodeDomain}:${handle}`;
+        const protocol = nodeDomain.includes('localhost') ? 'http' : 'https';
+        const fallbackUrl = `${protocol}://${nodeDomain}/.well-known/synapsis/chat/${didWeb}`;
 
-        if (!res.ok) {
-            const text = await res.text();
-            console.error(`[Proxy] Remote fetch failed (${res.status}): ${text}`);
-            return NextResponse.json({ error: `Remote error: ${res.status}` }, { status: res.status });
-        }
-
-        const data = await res.json();
-        return NextResponse.json(data);
-    } catch (error: any) {
-        console.error('[Proxy] Fetch error:', error);
-        return NextResponse.json({ error: 'Failed to fetch remote keys' }, { status: 500 });
+        console.log(`[Proxy] Primary failed. Trying fallback: ${didWeb}`);
+        const data = await tryFetch(fallbackUrl);
+        if (data) return NextResponse.json(data);
     }
+
+    return NextResponse.json({ error: 'Remote keys not found (checked primary and fallback)' }, { status: 404 });
 }

src/app/chat/page.tsx

@@ -278,7 +278,7 @@ export default function ChatPage() {
                 if (!did) throw new Error('User not found');
             }
 
-            await sendMessage(did, newMessage, nodeDomain);
+            await sendMessage(did, newMessage, nodeDomain, selectedConversation.participant2.handle);
 
             // Legacy UI expects message reload.
             setNewMessage('');
@@ -306,7 +306,7 @@ export default function ChatPage() {
             }
 
             // Send "Hello" to init session
-            await sendMessage(data.user.did, '👋', data.user.nodeDomain);
+            await sendMessage(data.user.did, '👋', data.user.nodeDomain, data.user.handle);
 
             setShowNewChat(false);
             setNewChatHandle('');