diff --git a/frontend/src/composables/useTerminal.ts b/frontend/src/composables/useTerminal.ts
index 03a0736..2d3407b 100644
--- a/frontend/src/composables/useTerminal.ts
+++ b/frontend/src/composables/useTerminal.ts
@@ -96,9 +96,23 @@ export function useTerminal(sessionId: string): UseTerminalReturn {
     fitAddon.fit();
 
     // Subscribe to SSH output events for this session
-    cleanupEvent = Events.On(`ssh:data:${sessionId}`, (...args: unknown[]) => {
-      // Wails v3 events pass data as arguments
-      const b64data = typeof args[0] === "string" ? args[0] : String(args[0] ?? "");
+    // Wails v3 Events.On callback receives a CustomEvent object with .data property
+    cleanupEvent = Events.On(`ssh:data:${sessionId}`, (event: any) => {
+      // Extract the base64 string from the event
+      // event.data is the first argument passed to app.Event.Emit()
+      let b64data: string;
+      if (typeof event === "string") {
+        b64data = event;
+      } else if (event?.data && typeof event.data === "string") {
+        b64data = event.data;
+      } else if (Array.isArray(event?.data)) {
+        b64data = String(event.data[0] ?? "");
+      } else {
+        // Debug: log the actual shape so we can fix it
+        console.warn("ssh:data unexpected shape:", JSON.stringify(event)?.slice(0, 200));
+        return;
+      }
+
       try {
         const decoded = atob(b64data);
         terminal.write(decoded);