diff --git a/apps/frontend/src/app/pages/AIWorkspacePage.tsx b/apps/frontend/src/app/pages/AIWorkspacePage.tsx
index 0c6a54d..7652382 100644
--- a/apps/frontend/src/app/pages/AIWorkspacePage.tsx
+++ b/apps/frontend/src/app/pages/AIWorkspacePage.tsx
@@ -1,10 +1,11 @@
 import { useNavigate } from 'react-router-dom';
-import { Bot, Send, AlertCircle } from 'lucide-react';
+import { Bot, Send, AlertCircle, Settings } from 'lucide-react';
 import { PageHeader } from '@/shared/components/ui/PageHeader';
 import { PreviewBanner } from '@/shared/components/ui/PreviewBanner';
 import { EmptyState } from '@/shared/components/ui/EmptyState';
 import { DataSourceBadge } from '@/shared/components/ui/DataSourceBadge';
 import { useAIWorkspace } from '@/features/ai/hooks/useAIWorkspace';
+import { getErrorDetail } from '@/shared/services/api';
 import { cn } from '@/shared/utils/cn';
 
 // Kept identical to the `limitation` recorded for this surface in the
@@ -85,12 +86,24 @@ export function AIWorkspacePage() {
             ))
           )}
           {aiWorkspace.loading && <p className="text-xs text-muted-foreground">AI provider is thinking...</p>}
-          {aiWorkspace.error && (
-            <div className="flex items-center gap-2 rounded-lg border border-destructive/50 bg-destructive/5 px-4 py-3">
-              <AlertCircle className="h-4 w-4 text-destructive" />
-              <p className="text-sm text-destructive">{aiWorkspace.error}</p>
-            </div>
-          )}
+          {aiWorkspace.error && (() => {
+            const detail = getErrorDetail(aiWorkspace.error);
+            return (
+              <div className="flex items-start gap-2 rounded-lg border border-destructive/50 bg-destructive/5 px-4 py-3">
+                <AlertCircle className="mt-0.5 h-4 w-4 shrink-0 text-destructive" />
+                <div className="space-y-1">
+                  <p className="text-sm text-destructive">{detail.message}</p>
+                  {detail.details.length > 0 && (
+                    <ul className="list-disc pl-4 text-xs text-destructive/80">
+                      {detail.details.map((d, i) => (
+                        <li key={i}>{d}</li>
+                      ))}
+                    </ul>
+                  )}
+                </div>
+              </div>
+            );
+          })()}
           {aiWorkspace.suggestions.length > 0 && (
             <div className="flex flex-wrap gap-2">
               {aiWorkspace.suggestions.map((suggestion) => (
@@ -102,6 +115,22 @@ export function AIWorkspacePage() {
           )}
         </div>
         <div className="border-t border-border p-4">
+          {aiWorkspace.providerConfigured === false && (
+            <div className="mb-3 flex items-center gap-2 rounded-lg border border-amber-500/40 bg-amber-500/5 px-4 py-2.5 text-sm text-amber-200">
+              <Settings className="h-4 w-4 shrink-0" />
+              <span>
+                No AI provider is configured. Free-form questions cannot run until you save a provider in{' '}
+                <button
+                  type="button"
+                  onClick={() => navigate('/settings')}
+                  className="underline underline-offset-2 hover:text-amber-100"
+                >
+                  Settings
+                </button>
+                .
+              </span>
+            </div>
+          )}
           <form
             className="flex items-center gap-2"
             onSubmit={(event) => {
diff --git a/apps/frontend/src/features/ai/hooks/useAIWorkspace.test.tsx b/apps/frontend/src/features/ai/hooks/useAIWorkspace.test.tsx
index f2f665f..4c56061 100644
--- a/apps/frontend/src/features/ai/hooks/useAIWorkspace.test.tsx
+++ b/apps/frontend/src/features/ai/hooks/useAIWorkspace.test.tsx
@@ -13,6 +13,7 @@ vi.mock('@/shared/feature-state/useRepositoryFeatureStatus', () => ({
 vi.mock('@/shared/services/api', () => ({
   aiService: {
     query: vi.fn(),
+    getConfig: vi.fn().mockResolvedValue({ provider: 'anthropic', hasKey: true }),
   },
   getErrorMessage: vi.fn((error: unknown) => String(error)),
 }));
diff --git a/apps/frontend/src/features/ai/hooks/useAIWorkspace.ts b/apps/frontend/src/features/ai/hooks/useAIWorkspace.ts
index e729312..edd1ddb 100644
--- a/apps/frontend/src/features/ai/hooks/useAIWorkspace.ts
+++ b/apps/frontend/src/features/ai/hooks/useAIWorkspace.ts
@@ -1,4 +1,4 @@
-import { useCallback, useState } from 'react';
+import { useCallback, useEffect, useState } from 'react';
 import { aiService, getErrorMessage } from '@/shared/services/api';
 import type { AiMessage } from '@/shared/services/api/types';
 import { useRepositoryFeatureStatus } from '@/shared/feature-state/useRepositoryFeatureStatus';
@@ -10,6 +10,18 @@ export function useAIWorkspace() {
   const [suggestions, setSuggestions] = useState<string[]>([]);
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
+  const [providerConfigured, setProviderConfigured] = useState<boolean | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+    aiService
+      .getConfig()
+      .then(() => !cancelled && setProviderConfigured(true))
+      .catch(() => !cancelled && setProviderConfigured(false));
+    return () => {
+      cancelled = true;
+    };
+  }, []);
 
   const ask = useCallback(async () => {
     const activeRepository = repositoryFeature.activeRepository;
@@ -50,6 +62,7 @@ export function useAIWorkspace() {
     suggestions,
     loading: repositoryFeature.loading || loading,
     error: repositoryFeature.error || error,
+    providerConfigured,
     ask,
   };
 }
diff --git a/apps/frontend/src/shared/services/api/errors.ts b/apps/frontend/src/shared/services/api/errors.ts
index 901b790..360e8bf 100644
--- a/apps/frontend/src/shared/services/api/errors.ts
+++ b/apps/frontend/src/shared/services/api/errors.ts
@@ -67,13 +67,19 @@ export function isCancelledError(error: unknown): error is CancelledError {
 export function getErrorMessage(error: unknown): string {
   if (isApiError(error)) {
     const backendMessage = getBackendMessage(error.body);
-    if (backendMessage) return backendMessage;
+    const details = getBackendDetails(error.body);
+    if (backendMessage && !details.length) return backendMessage;
+    if (backendMessage && details.length) {
+      return `${backendMessage}\n${details.map((d) => `- ${d}`).join('\n')}`;
+    }
 
     switch (error.status) {
       case 401: return 'Authentication required. Please sign in.';
       case 403: return 'You do not have permission to perform this action.';
       case 404: return 'The requested resource was not found.';
-      case 422: return 'The request data is invalid.';
+      case 422: return details.length
+        ? `The request data is invalid:\n${details.map((d) => `- ${d}`).join('\n')}`
+        : 'The request data is invalid.';
       case 409: return 'The request conflicts with an existing resource.';
       case 429: return 'Too many requests. Please try again later.';
       case 503: return 'Service is temporarily unavailable. Please try again.';
@@ -87,12 +93,42 @@ export function getErrorMessage(error: unknown): string {
   return 'An unknown error occurred.';
 }
 
+/** Structured error for UIs that want to render field-level validation details. */
+export function getErrorDetail(error: unknown): { message: string; details: string[] } {
+  if (isApiError(error)) {
+    const message = getBackendMessage(error.body) ?? getErrorMessage(error);
+    return { message, details: getBackendDetails(error.body) };
+  }
+  return { message: getErrorMessage(error), details: [] };
+}
+
 function getBackendMessage(body: unknown): string | null {
   if (!body || typeof body !== 'object') return null;
   const maybeMessage = (body as { message?: unknown }).message;
   return typeof maybeMessage === 'string' && maybeMessage.trim() ? maybeMessage : null;
 }
 
+function getBackendDetails(body: unknown): string[] {
+  if (!body || typeof body !== 'object') return [];
+  const raw = (body as { details?: unknown }).details;
+  if (Array.isArray(raw)) {
+    return raw
+      .map((item) => {
+        if (typeof item === 'string') return item;
+        if (item && typeof item === 'object') {
+          const loc = (item as { loc?: unknown }).loc;
+          const msg = (item as { msg?: unknown }).msg;
+          const locStr = Array.isArray(loc) ? loc.filter((p) => typeof p === 'string' || typeof p === 'number').join('.') : '';
+          if (typeof msg === 'string') return locStr ? `${locStr}: ${msg}` : msg;
+        }
+        return null;
+      })
+      .filter((d): d is string => Boolean(d));
+  }
+  if (typeof raw === 'string') return [raw];
+  return [];
+}
+
 function getBackendRequestId(body: unknown): string | null {
   if (!body || typeof body !== 'object') return null;
   const maybeRequestId = (body as { request_id?: unknown }).request_id;
diff --git a/apps/frontend/src/shared/services/api/index.ts b/apps/frontend/src/shared/services/api/index.ts
index a92a5ab..4258d2c 100644
--- a/apps/frontend/src/shared/services/api/index.ts
+++ b/apps/frontend/src/shared/services/api/index.ts
@@ -1,7 +1,7 @@
 export { api, configureApiClient, getApiConfig, uploadFile, requestSharedRefresh } from './client';
 export type { RequestConfig, ApiClientConfig, HttpMethod } from './client';
 
-export { ApiError, NetworkError, TimeoutError, CancelledError, isApiError, isNetworkError, isTimeoutError, isCancelledError, getErrorMessage } from './errors';
+export { ApiError, NetworkError, TimeoutError, CancelledError, isApiError, isNetworkError, isTimeoutError, isCancelledError, getErrorMessage, getErrorDetail } from './errors';
 
 export { authService } from './auth';
 export { repositoryService, repositoryIntelligenceService } from './repositories';