Add remote key fetch proxy and improve chat reliability

Introduces an API route to proxy remote key bundle fetches, improving CORS handling for secure chat. Updates chat UI to handle error states and retries, enhances key/identity synchronization, and refactors message sending to support remote node domains. Also adds CORS preflight support to the .well-known chat route and improves in-memory key store management.

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

@@ -0,0 +1,56 @@
+
+import { NextRequest, NextResponse } from 'next/server';
+
+export async function GET(request: NextRequest) {
+    const searchParams = request.nextUrl.searchParams;
+    const did = searchParams.get('did');
+    const nodeDomain = searchParams.get('nodeDomain');
+
+    if (!did) {
+        return NextResponse.json({ error: 'Missing DID' }, { status: 400 });
+    }
+
+    // Determine target URL
+    let bundleUrl = '';
+
+    // 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/${did}`;
+        }
+    }
+
+    // If did:synapsis or did:web without built-in logic, check explicit domain
+    if (!bundleUrl && nodeDomain) {
+        const protocol = nodeDomain.includes('localhost') ? 'http' : 'https';
+        bundleUrl = `${protocol}://${nodeDomain}/.well-known/synapsis/chat/${did}`;
+    }
+
+    if (!bundleUrl) {
+        return NextResponse.json({ error: 'Cannot determine remote node URL. Missing nodeDomain?' }, { status: 400 });
+    }
+
+    try {
+        console.log(`[Proxy] Fetching keys from: ${bundleUrl}`);
+        const res = await fetch(bundleUrl, {
+            headers: {
+                'Accept': 'application/json'
+            }
+        });
+
+        if (!res.ok) {
+            const text = await res.text();
+            console.error(`[Proxy] Remote fetch failed (${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 });
+    }
+}