Add invalid-request fallback routing

frontend/src/i18n/locales/en.ts

@@ -919,6 +919,11 @@ export default {
         fallbackHint: 'Non-Claude Code requests will use this group. Leave empty to reject directly.',
         noFallback: 'No Fallback (Reject)'
       },
+      invalidRequestFallback: {
+        title: 'Invalid Request Fallback Group',
+        hint: 'Triggered only when upstream explicitly returns prompt too long. Leave empty to disable fallback.',
+        noFallback: 'No Fallback'
+      },
       modelRouting: {
         title: 'Model Routing',
         tooltip: 'Configure specific model requests to be routed to designated accounts. Supports wildcard matching, e.g., claude-opus-* matches all opus models.',

frontend/src/i18n/locales/zh.ts

@@ -995,6 +995,11 @@ export default {
         fallbackHint: '非 Claude Code 请求将使用此分组，留空则直接拒绝',
         noFallback: '不降级（直接拒绝）'
       },
+      invalidRequestFallback: {
+        title: '无效请求兜底分组',
+        hint: '仅当上游明确返回 prompt too long 时才会触发，留空表示不兜底',
+        noFallback: '不兜底'
+      },
       modelRouting: {
         title: '模型路由配置',
         tooltip: '配置特定模型请求优先路由到指定账号。支持通配符匹配，如 claude-opus-* 匹配所有 opus 模型。',

frontend/src/types/index.ts

@@ -269,6 +269,7 @@ export interface Group {
   // Claude Code 客户端限制
   claude_code_only: boolean
   fallback_group_id: number | null
+  fallback_group_id_on_invalid_request: number | null
   // 模型路由配置（仅 anthropic 平台使用）
   model_routing: Record<string, number[]> | null
   model_routing_enabled: boolean
@@ -322,6 +323,7 @@ export interface CreateGroupRequest {
   image_price_4k?: number | null
   claude_code_only?: boolean
   fallback_group_id?: number | null
+  fallback_group_id_on_invalid_request?: number | null
 }
 
 export interface UpdateGroupRequest {
@@ -340,6 +342,7 @@ export interface UpdateGroupRequest {
   image_price_4k?: number | null
   claude_code_only?: boolean
   fallback_group_id?: number | null
+  fallback_group_id_on_invalid_request?: number | null
 }
 
 // ==================== Account & Proxy Types ====================

frontend/src/views/admin/GroupsView.vue

@@ -460,6 +460,20 @@
           </div>
         </div>
 
+        <!-- 无效请求兜底（仅 anthropic/antigravity 平台，且非订阅分组） -->
+        <div
+          v-if="['anthropic', 'antigravity'].includes(createForm.platform) && createForm.subscription_type !== 'subscription'"
+          class="border-t pt-4"
+        >
+          <label class="input-label">{{ t('admin.groups.invalidRequestFallback.title') }}</label>
+          <Select
+            v-model="createForm.fallback_group_id_on_invalid_request"
+            :options="invalidRequestFallbackOptions"
+            :placeholder="t('admin.groups.invalidRequestFallback.noFallback')"
+          />
+          <p class="input-hint">{{ t('admin.groups.invalidRequestFallback.hint') }}</p>
+        </div>
+
         <!-- 模型路由配置（仅 anthropic 平台） -->
         <div v-if="createForm.platform === 'anthropic'" class="border-t pt-4">
           <div class="mb-1.5 flex items-center gap-1">
@@ -904,6 +918,20 @@
           </div>
         </div>
 
+        <!-- 无效请求兜底（仅 anthropic/antigravity 平台，且非订阅分组） -->
+        <div
+          v-if="['anthropic', 'antigravity'].includes(editForm.platform) && editForm.subscription_type !== 'subscription'"
+          class="border-t pt-4"
+        >
+          <label class="input-label">{{ t('admin.groups.invalidRequestFallback.title') }}</label>
+          <Select
+            v-model="editForm.fallback_group_id_on_invalid_request"
+            :options="invalidRequestFallbackOptionsForEdit"
+            :placeholder="t('admin.groups.invalidRequestFallback.noFallback')"
+          />
+          <p class="input-hint">{{ t('admin.groups.invalidRequestFallback.hint') }}</p>
+        </div>
+
         <!-- 模型路由配置（仅 anthropic 平台） -->
         <div v-if="editForm.platform === 'anthropic'" class="border-t pt-4">
           <div class="mb-1.5 flex items-center gap-1">
@@ -1202,6 +1230,44 @@ const fallbackGroupOptionsForEdit = computed(() => {
   return options
 })
 
+// 无效请求兜底分组选项（创建时）- 仅包含 anthropic 平台、非订阅且未配置兜底的分组
+const invalidRequestFallbackOptions = computed(() => {
+  const options: { value: number | null; label: string }[] = [
+    { value: null, label: t('admin.groups.invalidRequestFallback.noFallback') }
+  ]
+  const eligibleGroups = groups.value.filter(
+    (g) =>
+      g.platform === 'anthropic' &&
+      g.status === 'active' &&
+      g.subscription_type !== 'subscription' &&
+      g.fallback_group_id_on_invalid_request === null
+  )
+  eligibleGroups.forEach((g) => {
+    options.push({ value: g.id, label: g.name })
+  })
+  return options
+})
+
+// 无效请求兜底分组选项（编辑时）- 排除自身
+const invalidRequestFallbackOptionsForEdit = computed(() => {
+  const options: { value: number | null; label: string }[] = [
+    { value: null, label: t('admin.groups.invalidRequestFallback.noFallback') }
+  ]
+  const currentId = editingGroup.value?.id
+  const eligibleGroups = groups.value.filter(
+    (g) =>
+      g.platform === 'anthropic' &&
+      g.status === 'active' &&
+      g.subscription_type !== 'subscription' &&
+      g.fallback_group_id_on_invalid_request === null &&
+      g.id !== currentId
+  )
+  eligibleGroups.forEach((g) => {
+    options.push({ value: g.id, label: g.name })
+  })
+  return options
+})
+
 const groups = ref<Group[]>([])
 const loading = ref(false)
 const searchQuery = ref('')
@@ -1243,6 +1309,7 @@ const createForm = reactive({
   // Claude Code 客户端限制（仅 anthropic 平台使用）
   claude_code_only: false,
   fallback_group_id: null as number | null,
+  fallback_group_id_on_invalid_request: null as number | null,
   // 模型路由开关
   model_routing_enabled: false
 })
@@ -1414,6 +1481,7 @@ const editForm = reactive({
   // Claude Code 客户端限制（仅 anthropic 平台使用）
   claude_code_only: false,
   fallback_group_id: null as number | null,
+  fallback_group_id_on_invalid_request: null as number | null,
   // 模型路由开关
   model_routing_enabled: false
 })
@@ -1497,6 +1565,7 @@ const closeCreateModal = () => {
   createForm.image_price_4k = null
   createForm.claude_code_only = false
   createForm.fallback_group_id = null
+  createForm.fallback_group_id_on_invalid_request = null
   createModelRoutingRules.value = []
 }
 
@@ -1546,6 +1615,7 @@ const handleEdit = async (group: Group) => {
   editForm.image_price_4k = group.image_price_4k
   editForm.claude_code_only = group.claude_code_only || false
   editForm.fallback_group_id = group.fallback_group_id
+  editForm.fallback_group_id_on_invalid_request = group.fallback_group_id_on_invalid_request
   editForm.model_routing_enabled = group.model_routing_enabled || false
   // 加载模型路由规则（异步加载账号名称）
   editModelRoutingRules.value = await convertApiFormatToRoutingRules(group.model_routing)
@@ -1571,6 +1641,10 @@ const handleUpdateGroup = async () => {
     const payload = {
       ...editForm,
       fallback_group_id: editForm.fallback_group_id === null ? 0 : editForm.fallback_group_id,
+      fallback_group_id_on_invalid_request:
+        editForm.fallback_group_id_on_invalid_request === null
+          ? 0
+          : editForm.fallback_group_id_on_invalid_request,
       model_routing: convertRoutingRulesToApiFormat(editModelRoutingRules.value)
     }
     await adminAPI.groups.update(editingGroup.value.id, payload)
@@ -1612,6 +1686,16 @@ watch(
     if (newVal === 'subscription') {
       createForm.rate_multiplier = 1.0
       createForm.is_exclusive = true
+      createForm.fallback_group_id_on_invalid_request = null
+    }
+  }
+)
+
+watch(
+  () => createForm.platform,
+  (newVal) => {
+    if (!['anthropic', 'antigravity'].includes(newVal)) {
+      createForm.fallback_group_id_on_invalid_request = null
     }
   }
 )