fix: improve error message when OAuth succeeds but project ID is required (#21070)

packages/cli/src/ui/AppContainer.tsx

@@ -80,6 +80,7 @@ import {
   type ConsentRequestPayload,
   type AgentsDiscoveredPayload,
   ChangeAuthRequestedError,
+  ProjectIdRequiredError,
   CoreToolCallStatus,
   generateSteeringAckMessage,
   buildUserSteeringHintPrompt,
@@ -771,6 +772,12 @@ export const AppContainer = (props: AppContainerProps) => {
           if (e instanceof ChangeAuthRequestedError) {
             return;
           }
+          if (e instanceof ProjectIdRequiredError) {
+            // OAuth succeeded but account setup requires project ID
+            // Show the error message directly without "Failed to authenticate" prefix
+            onAuthError(getErrorMessage(e));
+            return;
+          }
           onAuthError(
             `Failed to authenticate: ${e instanceof Error ? e.message : String(e)}`,
           );