From c424f062633b406638c3c4f11718de044ef871a0 Mon Sep 17 00:00:00 2001
From: SparkEros <kent@sparkeros.com>
Date: Wed, 1 Apr 2026 12:24:15 -0500
Subject: [PATCH] fix: prevent blank screen when clearing Capabilities field

The MarkdownEditor in the agent Configuration tab crashes when the
Capabilities field is fully cleared. The onChange handler converts empty
strings to null via (v || null), but the eff() overlay function then
returns that null to MDXEditor which expects a string, causing an
unhandled React crash and a blank screen.

Add a null-coalescing fallback (?? "") so MDXEditor always receives a
string.

Co-Authored-By: Claude Opus 4.6 (1M context) <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 b9781a05..a0afbdaf 100644
--- a/ui/src/components/AgentConfigForm.tsx
+++ b/ui/src/components/AgentConfigForm.tsx
@@ -515,7 +515,7 @@ export function AgentConfigForm(props: AgentConfigFormProps) {
             </Field>
             <Field label="Capabilities" hint={help.capabilities}>
               <MarkdownEditor
-                value={eff("identity", "capabilities", props.agent.capabilities ?? "")}
+                value={eff("identity", "capabilities", props.agent.capabilities ?? "") ?? ""}
                 onChange={(v) => mark("identity", "capabilities", v || null)}
                 placeholder="Describe what this agent can do..."
                 contentClassName="min-h-[44px] text-sm font-mono"