Group chat with E2E encryption for both web and CLI clients

Server:
- POST /v1/groups/create — create named group
- POST /v1/groups/:name/join — join group
- GET /v1/groups/:name — get group info + member list
- GET /v1/groups — list all groups
- POST /v1/groups/:name/send — fan-out encrypted messages to members
- Groups stored in sled, members tracked by fingerprint

Web client:
- /gcreate <name> — create group
- /gjoin <name> — join group
- /g <name> — switch to group chat mode
- /glist — list all groups
- /dm — switch back to DM mode
- Group messages encrypted per-member (ECDH + AES-GCM for each)
- Group tag shown on received messages: "sender [groupname]"

CLI TUI client:
- Same commands: /gcreate, /gjoin, /g, /glist, /dm
- Group messages encrypted per-member (X3DH + Double Ratchet for each)
- Automatic X3DH key exchange with new group members on first message
- Sessions established and persisted per-member

Architecture:
- Client-side fan-out encryption: message encrypted N times (once per member)
- Server stores one copy per recipient in their message queue
- Reuses existing 1:1 encryption — no new crypto primitives needed
- Works for groups ≤ 50 members (per DESIGN.md)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

warzone/crates/warzone-server/src/routes/web.rs

@@ -295,7 +295,9 @@ async function pollMessages() {
             const aesKey = await fetchPeerKey(env.from);
             const ct = fromHex(env.ciphertext);
             const text = await aesDecrypt(aesKey, ct);
-            addMsg(formatFP(fromHex(env.from)).slice(0, 19), text, false);
+            const fromLabel = formatFP(fromHex(env.from)).slice(0, 19);
+            const groupTag = env.group ? ' [' + env.group + ']' : '';
+            addMsg(fromLabel + groupTag, text, false);
             continue;
           }
         } catch(e) { /* not JSON, might be CLI bincode */ }
@@ -364,6 +366,8 @@ async function doRecover() {
   }
 }
 
+let currentGroup = null;  // if set, messages go to group
+
 async function enterChat() {
   document.getElementById('setup').classList.remove('active');
   document.getElementById('chat').classList.add('active');
@@ -373,18 +377,103 @@ async function enterChat() {
   await registerKey();
   addSys('Identity loaded: ' + myFingerprint);
   addSys('Key registered with server');
-  addSys('Paste a peer fingerprint above and start chatting');
-  addSys('Commands: /info, /clear, /quit');
+  addSys('DM: paste peer fingerprint above');
+  addSys('Groups: /gcreate <name> · /gjoin <name> · /g <name> · /glist');
+  addSys('Other: /info · /clear · /dm (switch back to DM mode)');
 
-  // Restore saved peer
   const savedPeer = localStorage.getItem('wz-peer');
   if (savedPeer) $peerInput.value = savedPeer;
 
-  // Start polling
   pollTimer = setInterval(pollMessages, 2000);
   $input.focus();
 }
 
+// ── Group helpers ──
+
+async function groupCreate(name) {
+  const resp = await fetch(SERVER + '/v1/groups/create', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ name, creator: normFP(myFingerprint) })
+  });
+  const data = await resp.json();
+  if (data.error) { addSys('Error: ' + data.error); return; }
+  addSys('Group "' + name + '" created. Join with /gjoin ' + name);
+}
+
+async function groupJoin(name) {
+  const resp = await fetch(SERVER + '/v1/groups/' + name + '/join', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ fingerprint: normFP(myFingerprint) })
+  });
+  const data = await resp.json();
+  if (data.error) { addSys('Error: ' + data.error); return; }
+  addSys('Joined group "' + name + '" (' + data.members + ' members)');
+}
+
+async function groupSwitch(name) {
+  const resp = await fetch(SERVER + '/v1/groups/' + name);
+  const data = await resp.json();
+  if (data.error) { addSys('Error: ' + data.error); return; }
+  currentGroup = name;
+  $peerInput.value = '#' + name;
+  addSys('Switched to group "' + name + '" (' + data.count + ' members: ' + data.members.map(m => m.slice(0,8)).join(', ') + ')');
+}
+
+async function groupList() {
+  const resp = await fetch(SERVER + '/v1/groups');
+  const data = await resp.json();
+  if (!data.groups || data.groups.length === 0) { addSys('No groups'); return; }
+  for (const g of data.groups) {
+    addSys('  #' + g.name + ' (' + g.members + ' members)');
+  }
+}
+
+async function sendToGroup(groupName, text) {
+  // Get member list
+  const resp = await fetch(SERVER + '/v1/groups/' + groupName);
+  const data = await resp.json();
+  if (data.error) { addSys('Error: ' + data.error); return; }
+
+  const myFP = normFP(myFingerprint);
+  const members = data.members.filter(m => m !== myFP);
+  if (members.length === 0) { addSys('No other members in group'); return; }
+
+  // Encrypt for each member
+  const messages = [];
+  for (const memberFP of members) {
+    try {
+      const aesKey = await fetchPeerKey(memberFP);
+      const encrypted = await aesEncrypt(aesKey, text);
+      const envelope = JSON.stringify({
+        type: 'web',
+        from: myFP,
+        group: groupName,
+        ciphertext: toHex(encrypted)
+      });
+      messages.push({
+        to: memberFP,
+        message: Array.from(new TextEncoder().encode(envelope))
+      });
+    } catch(e) {
+      addSys('Failed to encrypt for ' + memberFP.slice(0,8) + ': ' + e.message);
+    }
+  }
+
+  if (messages.length === 0) return;
+
+  await fetch(SERVER + '/v1/groups/' + groupName + '/send', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ from: myFP, messages })
+  });
+
+  addMsg(myFingerprint.slice(0, 19) + ' [' + groupName + ']', text, true);
+}
+
+// ── Send handler ──
+
 async function doSend() {
   const text = $input.value.trim();
   $input.value = '';
@@ -395,9 +484,26 @@ async function doSend() {
   if (text === '/info') { addSys('Fingerprint: ' + myFingerprint); return; }
   if (text === '/clear') { $messages.innerHTML = ''; return; }
   if (text === '/quit') { window.close(); return; }
+  if (text === '/glist') { await groupList(); return; }
+  if (text === '/dm') { currentGroup = null; addSys('Switched to DM mode'); $peerInput.value = localStorage.getItem('wz-peer') || ''; return; }
 
+  if (text.startsWith('/gcreate ')) { await groupCreate(text.slice(9).trim()); return; }
+  if (text.startsWith('/gjoin ')) { await groupJoin(text.slice(7).trim()); return; }
+  if (text.startsWith('/g ')) { await groupSwitch(text.slice(3).trim()); return; }
+
+  // Send to group or DM
+  if (currentGroup) {
+    try {
+      await sendToGroup(currentGroup, text);
+    } catch(e) {
+      addSys('Group send failed: ' + e.message);
+    }
+    return;
+  }
+
+  // DM
   const peer = $peerInput.value.trim();
-  if (!peer) { addSys('Set a peer fingerprint first'); return; }
+  if (!peer || peer.startsWith('#')) { addSys('Set a peer fingerprint or use /g <group>'); return; }
   localStorage.setItem('wz-peer', peer);
 
   try {