fix: surface backend error details instead of raw axios strings

ui/app/providers/page.tsx

@@ -3,6 +3,7 @@
 import { Button } from '@/components/ui/button';
 import { Card, CardContent } from '@/components/ui/card';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { getApiErrorMessage } from '@/lib/api/errors';
 import {
   AdminService,
   ProviderModels,
@@ -139,7 +140,7 @@ export default function ProvidersPage() {
       resetForm();
     },
     onError: (error: Error) => {
-      toast.error(`Failed to create provider: ${error.message}`);
+      toast.error(getApiErrorMessage(error, 'Failed to create provider'));
     },
   });
 
@@ -153,7 +154,7 @@ export default function ProvidersPage() {
       toast.success('Provider updated successfully');
     },
     onError: (error: Error) => {
-      toast.error(`Failed to update provider: ${error.message}`);
+      toast.error(getApiErrorMessage(error, 'Failed to update provider'));
     },
   });
 
@@ -164,7 +165,7 @@ export default function ProvidersPage() {
       toast.success('Provider deleted successfully');
     },
     onError: (error: Error) => {
-      toast.error(`Failed to delete provider: ${error.message}`);
+      toast.error(getApiErrorMessage(error, 'Failed to delete provider'));
     },
   });
 
@@ -183,7 +184,7 @@ export default function ProvidersPage() {
       toast.success('Model deleted successfully');
     },
     onError: (error: Error) => {
-      toast.error(`Failed to delete model: ${error.message}`);
+      toast.error(getApiErrorMessage(error, 'Failed to delete model'));
     },
   });
 
@@ -205,9 +206,7 @@ export default function ProvidersPage() {
         toast.success('Account created, but no API key returned.');
       }
     } catch (error: unknown) {
-      const errorMessage =
-        error instanceof Error ? error.message : 'Unknown error';
-      toast.error(`Failed to create account: ${errorMessage}`);
+      toast.error(getApiErrorMessage(error, 'Failed to create account'));
     } finally {
       setIsCreatingAccount(false);
     }

ui/components/detailed-wallet-balance.tsx

@@ -4,6 +4,7 @@ import { useState } from 'react';
 import { useQuery } from '@tanstack/react-query';
 import { RefreshCw, AlertCircle, Wallet, User, Coins } from 'lucide-react';
 import { WalletService, BalanceDetail } from '@/lib/api/services/wallet';
+import { getApiErrorMessage } from '@/lib/api/errors';
 import {
   Card,
   CardContent,
@@ -191,7 +192,8 @@ export function DetailedWalletBalance({
             <Alert variant='destructive'>
               <AlertCircle className='h-5 w-5' />
               <AlertDescription>
-                Error loading balance: {(error as Error).message}
+                Error loading balance:{' '}
+                {getApiErrorMessage(error, 'Request failed')}
               </AlertDescription>
             </Alert>
           ) : (

ui/components/settings/cli-tokens-settings.tsx

@@ -21,6 +21,7 @@ import { Skeleton } from '@/components/ui/skeleton';
 import { Alert, AlertDescription } from '@/components/ui/alert';
 import { AlertCircle, Copy, Trash2, Check } from 'lucide-react';
 import { toast } from 'sonner';
+import { getApiErrorMessage } from '@/lib/api/errors';
 
 function formatTs(ts: number | null): string {
   if (!ts) return '—';
@@ -44,9 +45,7 @@ export function CliTokensSettings(): React.ReactElement {
       const data = await AdminService.listCliTokens();
       setTokens(data);
     } catch (err: unknown) {
-      const message =
-        err instanceof Error ? err.message : 'Failed to load tokens';
-      setError(message);
+      setError(getApiErrorMessage(err, 'Failed to load tokens'));
     } finally {
       setLoading(false);
     }
@@ -79,9 +78,7 @@ export function CliTokensSettings(): React.ReactElement {
       await loadTokens();
       toast.success('Token created. Copy it now — it will not be shown again.');
     } catch (err: unknown) {
-      const message =
-        err instanceof Error ? err.message : 'Failed to create token';
-      toast.error(message);
+      toast.error(getApiErrorMessage(err, 'Failed to create token'));
     } finally {
       setCreating(false);
     }
@@ -98,9 +95,7 @@ export function CliTokensSettings(): React.ReactElement {
       await loadTokens();
       toast.success('Token revoked');
     } catch (err: unknown) {
-      const message =
-        err instanceof Error ? err.message : 'Failed to revoke token';
-      toast.error(message);
+      toast.error(getApiErrorMessage(err, 'Failed to revoke token'));
     }
   }
 

ui/components/temporary-balances.tsx

@@ -13,6 +13,7 @@ import {
   ChevronRight,
 } from 'lucide-react';
 import { AdminService } from '@/lib/api/services/admin';
+import { getApiErrorMessage } from '@/lib/api/errors';
 import {
   Card,
   CardContent,
@@ -169,7 +170,8 @@ export function TemporaryBalances({
           <Alert variant='destructive'>
             <AlertCircle className='h-5 w-5' />
             <AlertDescription>
-              Error loading API keys: {(error as Error).message}
+              Error loading API keys:{' '}
+              {getApiErrorMessage(error, 'Request failed')}
             </AlertDescription>
           </Alert>
         ) : (

ui/lib/api/errors.ts

@@ -0,0 +1,26 @@
+import { isAxiosError } from 'axios';
+
+/**
+ * Human-readable message for a failed API call. Prefers the backend's
+ * `detail` field; never surfaces raw axios strings like
+ * "Request failed with status code 500".
+ */
+export function getApiErrorMessage(
+  error: unknown,
+  fallback = 'Something went wrong'
+): string {
+  if (isAxiosError(error)) {
+    if (!error.response) {
+      return 'Cannot reach the node. Is it running?';
+    }
+    const detail: unknown = error.response.data?.detail;
+    if (typeof detail === 'string' && detail) {
+      return detail;
+    }
+    return `${fallback} (HTTP ${error.response.status})`;
+  }
+  if (error instanceof Error && error.message) {
+    return error.message;
+  }
+  return fallback;
+}