From 53c944e8bcc49b535833754aefee40b03fb77bc7 Mon Sep 17 00:00:00 2001
From: Matt Van Horn <mvanhorn@gmail.com>
Date: Sat, 7 Mar 2026 16:04:17 -0800
Subject: [PATCH] fix(ui): prevent blank screen when prompt template is emptied

Change onChange handler from v || undefined to v ?? "" so empty
strings don't become undefined and crash downstream .trim() calls.

Fixes #191

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 ui/src/components/AgentConfigForm.tsx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ui/src/components/AgentConfigForm.tsx b/ui/src/components/AgentConfigForm.tsx
index 2ea08954..06cf01d4 100644
--- a/ui/src/components/AgentConfigForm.tsx
+++ b/ui/src/components/AgentConfigForm.tsx
@@ -441,7 +441,7 @@ export function AgentConfigForm(props: AgentConfigFormProps) {
                     "promptTemplate",
                     String(config.promptTemplate ?? ""),
                   )}
-                  onChange={(v) => mark("adapterConfig", "promptTemplate", v || undefined)}
+                  onChange={(v) => mark("adapterConfig", "promptTemplate", v ?? "")}
                   placeholder="You are agent {{ agent.name }}. Your role is {{ agent.role }}..."
                   contentClassName="min-h-[88px] text-sm font-mono"
                   imageUploadHandler={async (file) => {