fix(desktop): allow selecting configured providers in setup step

Remove strict model validation from provider:set IPC handler that
rejected custom models not in the static registry list (broke OpenRouter
with user-typed models). Add error display to setup page.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/desktop/src/main/ipc/provider.ts

@@ -164,14 +164,6 @@ export function registerProviderIpcHandlers(): void {
         }
       }
 
-      // Validate model if specified
-      if (modelId && !meta.models.includes(modelId)) {
-        return {
-          ok: false,
-          error: `Model "${modelId}" is not available for provider "${providerId}". Available: ${meta.models.join(', ')}`,
-        }
-      }
-
       try {
         const result = agent.setProvider(providerId, modelId)
         console.log(`[IPC] Provider switched to: ${result.provider}, model: ${result.model}`)

apps/desktop/src/renderer/src/pages/onboarding/setup.tsx

@@ -12,7 +12,7 @@ import { useOnboardingStore } from '../../stores/onboarding'
 
 export default function SetupStep() {
   const navigate = useNavigate()
-  const { providers, availableProviders, current, loading, refresh, setProvider } =
+  const { providers, availableProviders, current, loading, error, refresh, setProvider } =
     useProvider()
   const { setProviderConfigured } = useOnboardingStore()
 
@@ -87,6 +87,10 @@ export default function SetupStep() {
             onFocus={setFocusedProvider}
           />
 
+          {error && (
+            <p className="text-sm text-destructive">{error}</p>
+          )}
+
           <div className="flex justify-end">
             <Button
               size="lg"