fix: block creation when workspace summaries fail

frontend/src/shell/SteerInput.tsx

@@ -8,7 +8,9 @@ import { getSettings } from "../api/settings";
 import { getWorkspace, listWorkspaces } from "../api/workspaces";
 import { listModels } from "../api/models";
 import { useSessionStore } from "../store/sessionStore";
-import { workspacePolicyGate, workspacePreferences, type WorkspacePreference } from "../workspaces/drafts";
+import {
+  WorkspaceSelectionError, workspacePolicyGate, workspacePreferences, type WorkspacePreference,
+} from "../workspaces/drafts";
 
 const THINKING_LEVELS = ["low", "medium", "high"] as const;
 
@@ -94,7 +96,9 @@ export function SteerInput({
       const payload = error instanceof ApiError
         ? (error.payload as { code?: string; error?: string } | undefined)
         : undefined;
-      const alert = payload?.code === "dwh_unreachable" ? payload.error : undefined;
+      const alert = payload?.code === "dwh_unreachable"
+        ? payload.error
+        : error instanceof WorkspaceSelectionError ? error.message : undefined;
       onSessionCreateFailed?.(alert);
     } finally {
       setBusy(false);
@@ -156,7 +160,7 @@ export function SteerInput({
  */
 export function ComposerFooter() {
   const { data: settings } = useQuery({ queryKey: ["settings"], queryFn: getSettings });
-  const { data: workspaces = [], isLoading: workspacesLoading } = useQuery({
+  const { data: workspaces = [], isLoading: workspacesLoading, isError: workspaceSummariesError } = useQuery({
     queryKey: ["workspaces"], queryFn: listWorkspaces,
   });
   const { data: modelsData } = useQuery({ queryKey: ["models"], queryFn: listModels });
@@ -196,12 +200,14 @@ export function ComposerFooter() {
       workspacePolicyGate.clear();
     } else if (workspacesLoading) {
       workspacePolicyGate.beginSummary(workspace);
+    } else if (workspaceSummariesError) {
+      workspacePolicyGate.rejectSummary(workspace);
     } else if (selectedWorkspace?.revision) {
       workspacePolicyGate.select(workspace);
     } else {
       workspacePolicyGate.allowLegacy(workspace);
     }
-  }, [selectedWorkspace, workspace, workspacesLoading]);
+  }, [selectedWorkspace, workspace, workspaceSummariesError, workspacesLoading]);
 
   useEffect(() => {
     if (!allowedModels?.length) return;