diff --git a/frontend/src/lib/components/translate/TargetSchemaHint.svelte b/frontend/src/lib/components/translate/TargetSchemaHint.svelte
index 07afb19a..de6fbd06 100644
--- a/frontend/src/lib/components/translate/TargetSchemaHint.svelte
+++ b/frontend/src/lib/components/translate/TargetSchemaHint.svelte
@@ -7,7 +7,7 @@
 <!-- @RELATION BINDS_TO -> [EXT:frontend:api] -->
 <!-- @UX_STATE Idle -> Кнопка активна. Ждём нажатия. -->
 <!-- @UX_STATE Checking -> Спиннер, кнопка disabled. -->
-<!-- @UX_STATE Complete -> Показан результат: все ок / отсутствуют колонки / таблица не найдена. -->
+<!-- @UX_STATE Complete -> Показан результат: все ок / отсутствуют колонки / таблица не найдена / бэкенд недоступен (503/504). -->
 <!-- @UX_STATE Error -> Ошибка соединения. Кнопка активна для повтора. -->
 <!-- @UX_FEEDBACK Цветовой индикатор: зелёный (все ок), жёлтый (не все колонки), красный (таблица не найдена/ошибка). -->
 <!-- @UX_REACTIVITY Props -> $props() для полей конфигурации. -->
@@ -29,16 +29,20 @@
     targetSourceLanguageColumn = null,
   } = $props();
 
-  /** @type {'idle'|'checking'|'complete'|'error'} */
+  /** @type {'idle'|'checking'|'complete'|'complete_error'|'error'} */
   let state = $state('idle');
   let result = $state(null);
   let abortController = $state(null);
   let renderKey = $state(0);
 
+  /** True if result is a backend/network error (503/504/timeout), not a "table not found" */
+  let isTransientError = $derived(state === 'complete' && !result?.table_exists && !!result?.error);
+
   /** CSS-класс body в зависимости от состояния */
   let bodyClass = $derived.by(() => {
     if (state === 'complete' && result?.all_present) return 'px-3 py-2.5 bg-success-light';
     if (state === 'complete' && !result?.all_present && result?.table_exists) return 'px-3 py-2.5 bg-warning-light';
+    if (state === 'complete' && !result?.table_exists && result?.error) return 'px-3 py-2.5 bg-warning-light';
     if (state === 'error' || (state === 'complete' && !result?.table_exists)) return 'px-3 py-2.5 bg-destructive-light';
     return 'px-3 py-2.5';
   });
@@ -134,7 +138,8 @@
 <div class="target-schema-hint mt-3 rounded-lg border text-sm transition-colors"
   class:border-success={state === 'complete' && result?.all_present}
   class:border-warning={state === 'complete' && !result?.all_present && result?.table_exists}
-  class:border-destructive-ring={state === 'error' || (state === 'complete' && !result?.table_exists)}
+  class:border-warning={state === 'complete' && !result?.table_exists && result?.error}
+  class:border-destructive-ring={state === 'error' || (state === 'complete' && !result?.table_exists && !result?.error)}
   class:border-border={state === 'idle' || state === 'checking'}
   role="region"
   aria-label={_('translate.target_schema.region_label') || 'Target Schema Check'}
@@ -143,7 +148,8 @@
   <div class="flex items-center justify-between px-3 py-2 border-b border-border"
     class:bg-success-light={state === 'complete' && result?.all_present}
     class:bg-warning-light={state === 'complete' && !result?.all_present && result?.table_exists}
-    class:bg-destructive-light={state === 'error' || (state === 'complete' && !result?.table_exists)}
+    class:bg-warning-light={state === 'complete' && !result?.table_exists && result?.error}
+    class:bg-destructive-light={state === 'error' || (state === 'complete' && !result?.table_exists && !result?.error)}
     class:bg-surface-muted={state === 'idle' || state === 'checking'}
   >
     <div class="flex items-center gap-2">
@@ -216,12 +222,22 @@
     {:else if state === 'complete' && result}
       {#key renderKey}
         {#if !result.table_exists}
-          <div class="flex items-center gap-2 text-destructive">
-            <svg class="w-4 h-4 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
-              <circle cx="12" cy="12" r="10"/><line x1="15" y1="9" x2="9" y2="15"/><line x1="9" y1="9" x2="15" y2="15"/>
-            </svg>
-            <p class="font-medium">{_('translate.target_schema.table_not_found') || 'Target table not found in the database.'}</p>
-          </div>
+          {#if result.error}
+            <!-- Transient error (503/504/timeout) — backend unavailable, not "table not found" -->
+            <div class="flex items-center gap-2 text-warning">
+              <svg class="w-4 h-4 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+                <path stroke-linecap="round" stroke-linejoin="round" d="M12 9v2m0 4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"/>
+              </svg>
+              <p class="font-medium">{_('translate.target_schema.check_error') || 'Could not verify target table schema.'}</p>
+            </div>
+          {:else}
+            <div class="flex items-center gap-2 text-destructive">
+              <svg class="w-4 h-4 shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+                <circle cx="12" cy="12" r="10"/><line x1="15" y1="9" x2="9" y2="15"/><line x1="9" y1="9" x2="15" y2="15"/>
+              </svg>
+              <p class="font-medium">{_('translate.target_schema.table_not_found') || 'Target table not found in the database.'}</p>
+            </div>
+          {/if}
 
         {:else if result.all_present}
           <div class="flex items-center gap-2 text-success">