Fix

apps/sim/app/api/copilot/chat/route.ts

@@ -85,7 +85,7 @@ const ChatMessageSchema = z.object({
   chatId: z.string().optional(),
   workflowId: z.string().optional(),
   workflowName: z.string().optional(),
-  model: z.string().optional().default('claude-opus-4-6'),
+  model: z.string().optional().default('claude-opus-4-5'),
   mode: z.enum(COPILOT_REQUEST_MODES).optional().default('agent'),
   prefetch: z.boolean().optional(),
   createNewChat: z.boolean().optional().default(false),
@@ -238,7 +238,7 @@ export async function POST(req: NextRequest) {
     let currentChat: any = null
     let conversationHistory: any[] = []
     let actualChatId = chatId
-    const selectedModel = model || 'claude-opus-4-6'
+    const selectedModel = model || 'claude-opus-4-5'
 
     if (chatId || createNewChat) {
       const chatResult = await resolveOrCreateChat({

apps/sim/app/api/mcp/copilot/route.ts

@@ -38,7 +38,7 @@ import {
 
 const logger = createLogger('CopilotMcpAPI')
 const mcpRateLimiter = new RateLimiter()
-const DEFAULT_COPILOT_MODEL = 'claude-opus-4-6'
+const DEFAULT_COPILOT_MODEL = 'claude-opus-4-5'
 
 export const dynamic = 'force-dynamic'
 export const runtime = 'nodejs'

apps/sim/app/api/v1/copilot/chat/route.ts

@@ -8,7 +8,7 @@ import { resolveWorkflowIdForUser } from '@/lib/workflows/utils'
 import { authenticateV1Request } from '@/app/api/v1/auth'
 
 const logger = createLogger('CopilotHeadlessAPI')
-const DEFAULT_COPILOT_MODEL = 'claude-opus-4-6'
+const DEFAULT_COPILOT_MODEL = 'claude-opus-4-5'
 
 const RequestSchema = z.object({
   message: z.string().min(1, 'message is required'),

apps/sim/stores/panel/copilot/store.ts

@@ -1042,7 +1042,7 @@ const cachedAutoAllowedTools = readAutoAllowedToolsFromStorage()
 // Initial state (subset required for UI/streaming)
 const initialState = {
   mode: 'build' as const,
-  selectedModel: 'anthropic/claude-opus-4-6' as CopilotStore['selectedModel'],
+  selectedModel: 'anthropic/claude-opus-4-5' as CopilotStore['selectedModel'],
   agentPrefetch: false,
   availableModels: [] as AvailableModel[],
   isLoadingModels: false,
@@ -2381,17 +2381,17 @@ export const useCopilotStore = create<CopilotStore>()(
           (model) => model.id === normalizedSelectedModel
         )
 
-        // Pick the best default: prefer claude-opus-4-6 with provider priority:
+        // Pick the best default: prefer claude-opus-4-5 with provider priority:
         // direct anthropic > bedrock > azure-anthropic > any other.
         let nextSelectedModel = normalizedSelectedModel
         if (!selectedModelExists && normalizedModels.length > 0) {
-          let opus46: AvailableModel | undefined
+          let opus45: AvailableModel | undefined
           for (const prov of MODEL_PROVIDER_PRIORITY) {
-            opus46 = normalizedModels.find((m) => m.id === `${prov}/claude-opus-4-6`)
-            if (opus46) break
+            opus45 = normalizedModels.find((m) => m.id === `${prov}/claude-opus-4-5`)
+            if (opus45) break
           }
-          if (!opus46) opus46 = normalizedModels.find((m) => m.id.endsWith('/claude-opus-4-6'))
-          nextSelectedModel = opus46 ? opus46.id : normalizedModels[0].id
+          if (!opus45) opus45 = normalizedModels.find((m) => m.id.endsWith('/claude-opus-4-5'))
+          nextSelectedModel = opus45 ? opus45.id : normalizedModels[0].id
         }
 
         set({