fix(tui): surface provider error in assistant footer (#34511)

packages/tui/src/routes/session/index.tsx

@@ -1147,15 +1147,32 @@ function AssistantFooter(props: { message: SessionMessageAssistant }) {
     props.message.time.completed ? props.message.time.completed - props.message.time.created : 0,
   )
   return (
-    <box paddingLeft={3}>
+    <>
+      <Show when={props.message.error}>
+        <box
+          border={["left"]}
+          paddingTop={1}
+          paddingBottom={1}
+          paddingLeft={2}
+          backgroundColor={theme.backgroundPanel}
+          customBorderChars={SplitBorder.customBorderChars}
+          borderColor={theme.error}
+        >
+          <text fg={theme.textMuted}>{errorMessage(props.message.error)}</text>
+        </box>
+      </Show>
+      <box paddingLeft={3} marginTop={props.message.error ? 1 : 0}>
         <text>
-        <span style={{ fg: local.agent.color(props.message.agent) }}>{Locale.titlecase(props.message.agent)}</span>
+          <span style={{ fg: props.message.error ? theme.textMuted : local.agent.color(props.message.agent) }}>
+            {Locale.titlecase(props.message.agent)}
+          </span>
           <span style={{ fg: theme.textMuted }}> · {model()}</span>
           <Show when={duration()}>
             <span style={{ fg: theme.textMuted }}> · {Locale.duration(duration())}</span>
           </Show>
         </text>
       </box>
+    </>
   )
 }