fix: reactions in browser mode (BrowserAdapter)

- Include mid on the wire in sendChat() so recipients can reference it
- Handle incoming 'reaction' wire message in PeerConn._onControl
- Add PeerConn.sendReaction() to send the reaction wire message
- Handle 'send_reaction' IPC command in BrowserAdapter.send()
- Emit 'reaction' IPC event on receive and on local send
- Use wire mid (not synthetic peer-ts mid) when receiving chat messages

Reactions now work across all combinations: daemon↔daemon,
browser↔browser, and daemon↔browser.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/adapter/browser.ts

@@ -433,9 +433,17 @@ class PeerConn {
         nick: m['nick'] as string || '', caps: m['caps'] || []
       })
     } else if (m['type'] === 'chat') {
+      const ts = (m['ts'] as number) || Date.now()
       this.on('chat', {
         peer: this.peerId, room: m['room'] as string || 'general',
-        text: m['text'] as string, ts: m['ts'] as number || Date.now()
+        text: m['text'] as string, ts,
+        mid: (m['mid'] as string) || `${this.peerId}-${ts}`,
+      })
+    } else if (m['type'] === 'reaction') {
+      this.on('reaction', {
+        peer: this.peerId,
+        mid: m['reaction_mid'] as string,
+        emoji: m['reaction_emoji'] as string,
       })
     } else if (m['type'] === 'pm') {
       this.on('pm', { peer: this.peerId, text: m['text'] as string, ts: m['ts'] as number || Date.now() })
@@ -556,14 +564,18 @@ class PeerConn {
     } catch { /* ignore */ }
   }
 
-  sendChat(room: string, text: string) {
+  sendChat(room: string, text: string, mid: string) {
-    this._dc({ type: 'chat', room, text, ts: Date.now() })
+    this._dc({ type: 'chat', room, text, ts: Date.now(), mid })
   }
 
   sendPm(text: string) {
     this._dc({ type: 'pm', text, ts: Date.now() })
   }
 
+  sendReaction(mid: string, emoji: string) {
+    this._dc({ type: 'reaction', reaction_mid: mid, reaction_emoji: emoji })
+  }
+
   private _dc(obj: object) {
     if (this.dc?.readyState === 'open') this.dc.send(JSON.stringify(obj))
   }
@@ -755,9 +767,17 @@ export class BrowserAdapter {
           public_key: data['peer'] as string, created_at: new Date().toISOString()
         },
       })
+    } else if (event === 'reaction') {
+      this.emit({
+        type: 'reaction',
+        network_id: this.networkId,
+        peer_id: data['peer'] as unknown as import('../types').PeerID,
+        reaction_mid: data['mid'] as string,
+        reaction_emoji: data['emoji'] as string,
+      })
     } else if (event === 'chat') {
       const ts = (data['ts'] as number) || Date.now()
-      const mid = `${data['peer']}-${ts}`
+      const mid = (data['mid'] as string) || `${data['peer']}-${ts}`
       this.emit({
         type: 'message_received',
         network_id: this.networkId,
@@ -910,8 +930,8 @@ export class BrowserAdapter {
           },
         })
       } else {
-        // Broadcast
+        // Broadcast — include mid on the wire so recipients can reference it in reactions
-        this.peers.forEach(p => p.sendChat(room, text))
+        this.peers.forEach(p => p.sendChat(room, text, mid))
         this.emit({
           type: 'message_received',
           network_id: this.networkId,
@@ -924,6 +944,22 @@ export class BrowserAdapter {
       return
     }
 
+    if (msg.type === 'send_reaction') {
+      const mid = msg.reaction_mid
+      const emoji = msg.reaction_emoji
+      if (!mid || !emoji) return
+      this.peers.forEach(p => p.sendReaction(mid, emoji))
+      // Emit locally so the sender sees their own reaction immediately
+      this.emit({
+        type: 'reaction',
+        network_id: this.networkId,
+        peer_id: this.identity.id as unknown as import('../types').PeerID,
+        reaction_mid: mid,
+        reaction_emoji: emoji,
+      })
+      return
+    }
+
     if (msg.type === 'export_identity') {
       if (!msg.passphrase) return
       try {