--- a/src/chat.js	Sun Mar 09 10:55:30 2025 -0600
+++ b/src/chat.js	Sun Mar 09 18:26:49 2025 -0600
@@ -227,7 +227,10 @@
 }
 
 function heartbeat() {
-	ajax(`heartbeat.js?last_update=${lastUpdate}`);
+	let url = `heartbeat.js?last_update=${lastUpdate}`;
+	if( currentChatId )
+		url += `&chat=${currentChatId}`;
+	ajax(url);
 }
 
 setInterval( heartbeat, 10000 );
@@ -372,3 +375,19 @@
 	}
 	openModal(dialog);
 }
+
+function readUpTo(userId,userNameHtml,unread) {
+	let div = document.querySelector(`div[user="${userId}"]`);
+	if( div ) {
+		if( unread == div.getAttribute('unread') )
+			return;
+		div.outerHTML = '';
+	} 
+	console.log('readUpTo');
+	let divs = document.querySelectorAll('div[post]');
+	if( unread >= divs.length )
+		return;
+	div = divs[divs.length - unread - 1];
+	let html = `<div user="${userId}" unread="${unread}">read by ${userNameHtml}</div>`;
+	div.insertAdjacentHTML('beforeend',html);
+}