Update.

src/snek/static/chat-input.js

@@ -47,14 +47,14 @@ class ChatInputComponent extends HTMLElement {
     this.textarea.focus();
   } 
     getAuthors(){
-	const uniqueAuthors = new Set()
-	document.querySelectorAll('div.author').forEach(el=>
-		{
-			uniqueAuthors.add(el.innerText.trim())
-		})
-		
-    return Array.from(uniqueAuthors)
-}
+        let authors = []
+        for (let i = 0; i < this.users.length; i++) {
+            authors.push(this.users[i].username)
+            authors.push(this.users[i].nick)
+        }
+        return authors
+        
+    }
  extractMentions(text) {
   const regex = /@([a-zA-Z0-9_]+)/g;
   const mentions = [];
@@ -136,12 +136,16 @@ levenshteinDistance(a, b) {
     app.rpc.getUser(null).then((user) => {
         this.user=user
     })
+
+
       const me = this;
     this.liveType = this.getAttribute("live-type") === "true";
     this.liveTypeInterval =
       parseInt(this.getAttribute("live-type-interval")) || 3;
     this.channelUid = this.getAttribute("channel");
-    this.messageUid = null;
+    
+    this.users = await app.rpc.getUsers(this.channelUid)
+      this.messageUid = null;
 
     this.classList.add("chat-input");