From 31340fe0a85c9e129758d2d436f3c87b10725b6a Mon Sep 17 00:00:00 2001
From: Jared Miller <jared@smell.flowers>
Date: Sat, 31 Jan 2026 11:06:37 -0500
Subject: [PATCH] Fix async terminal.write() causing garbled dashboard output

The terminal.write() method from @xterm/headless is async - the data
isn't in the buffer yet when we call serializeAsHTML() immediately
after. This caused empty or partially rendered output in the browser.

Now using the callback form of terminal.write(data, callback) to wait
for the write to complete before serializing and broadcasting to SSE
clients. This ensures the terminal buffer is fully updated before we
generate HTML from it.
---
 src/server.ts | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/server.ts b/src/server.ts
index 9c38fad..6f6b495 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -520,20 +520,21 @@ const server = Bun.serve<SessionData>({
             return;
           }
 
-          // Write to terminal emulator (handles all ANSI sequences)
-          termSession.terminal.write(msg.data);
-
           // Store raw ANSI in database
           appendOutput(sessionId, msg.data);
 
-          // Serialize current terminal state as HTML
-          const html = serializeAsHTML(termSession);
+          // Write to terminal emulator (handles all ANSI sequences)
+          // Use callback to wait for write completion before serializing
+          termSession.terminal.write(msg.data, () => {
+            // Serialize current terminal state as HTML
+            const html = serializeAsHTML(termSession);
 
-          // Broadcast to dashboards
-          broadcastSSE({
-            type: "output",
-            session_id: sessionId,
-            data: html,
+            // Broadcast to dashboards
+            broadcastSSE({
+              type: "output",
+              session_id: sessionId,
+              data: html,
+            });
           });
 
           return;