feat(routing): make routing profiles the sole scheduler policy source

Bootstrap an enabled system-default routing group from the legacy
scheduler config keys on startup, resolve the default ordering config
from that group before falling back to the legacy keys, and stop merging
keep_priority_on_conversion with the legacy flag when a policy is
resolved. Thread the policy-derived ordering config into candidate
preselection so it no longer reads system config independently.

Add per-API-format key priority overrides so a key serving several
formats keeps independent ordering, matching the legacy
global_priority_by_format semantics. Expose keep_priority_on_conversion
in the routing profile editor and read the effective policy in the
model routing preview, monitoring metrics and provider page badge.

frontend/src/views/admin/ProviderManagement.vue

@@ -272,6 +272,8 @@ import {
   type ProviderWithEndpointsSummary,
 } from '@/api/endpoints'
 import { adminApi } from '@/api/admin'
+import { listRoutingGroups } from '@/api/routing-profiles'
+import { normalizeRoutingGroupConfig } from '@/features/routing/utils/routingPolicy'
 import { parseApiError } from '@/utils/errorParser'
 import { useI18n } from '@/i18n'
 
@@ -533,8 +535,18 @@ const maxProviderPriority = computed(() => {
   return priorities.length > 0 ? Math.max(...priorities) : undefined
 })
 
-// 加载优先级模式
+// 加载优先级模式：优先使用启用中的系统默认调度策略，旧的系统配置键仅作兜底
 async function loadPriorityMode(options: { cacheTtlMs?: number } = {}) {
+  try {
+    const groups = await listRoutingGroups()
+    const systemDefault = groups.items.find(group => group.is_system_default && group.enabled)
+    if (systemDefault) {
+      priorityMode.value = normalizeRoutingGroupConfig(systemDefault.config_json).default_policy.priority_mode
+      return
+    }
+  } catch {
+    // 路由策略不可用时继续尝试旧配置
+  }
   try {
     const response = await adminApi.getSystemConfig('provider_priority_mode', {
       cacheTtlMs: options.cacheTtlMs ?? 0,

frontend/src/views/admin/RoutingProfiles.vue

@@ -454,6 +454,23 @@
                   </div>
                 </div>
               </div>
+              <label
+                class="flex items-start gap-3 rounded-lg border border-border/60 px-3 py-2 text-sm"
+                data-testid="keep-priority-on-conversion"
+              >
+                <Switch
+                  :model-value="keepPriorityOnConversion"
+                  :disabled="saving"
+                  aria-label="格式转换时保持优先级"
+                  @update:model-value="updateKeepPriorityOnConversion"
+                />
+                <span class="min-w-0">
+                  <span class="block font-medium">格式转换时保持优先级</span>
+                  <span class="mt-0.5 block text-xs text-muted-foreground">
+                    开启后，需要跨 API 格式转换的候选不会被降级到同格式候选之后。作用于本策略范围内的全部模型；Provider 自身的同名开关仍单独生效。
+                  </span>
+                </span>
+              </label>
             </div>
 
             <RoutingPriorityPolicyEditor
@@ -749,6 +766,7 @@ import {
   Button,
   Card,
   Input,
+  Switch,
   Table,
   TableBody,
   TableCard,
@@ -874,6 +892,9 @@ const firstStepSchedulingMode = computed<RoutingSchedulingMode>(() => {
   }
   return draft.value?.config_json.default_policy.scheduling_mode ?? 'cache_affinity'
 })
+const keepPriorityOnConversion = computed<boolean>(() => (
+  draft.value?.config_json.default_policy.keep_priority_on_conversion ?? false
+))
 const allowedModelsLookLikeLegacyMirror = computed(() => {
   return draft.value
     ? allowedModelsMirrorPerModelPolicies(draft.value.config_json)
@@ -1190,6 +1211,17 @@ function updateFirstStepSchedulingMode(mode: RoutingSchedulingMode): void {
   })
 }
 
+function updateKeepPriorityOnConversion(value: boolean): void {
+  if (!draft.value) return
+  updateDraftConfig({
+    ...draft.value.config_json,
+    default_policy: {
+      ...draft.value.config_json.default_policy,
+      keep_priority_on_conversion: value,
+    },
+  })
+}
+
 function removePerModelPolicy(model: string): void {
   if (!draft.value) return
   if (perModelEditingActive.value && editingDirty.value) {

frontend/src/views/admin/__tests__/RoutingProfiles.allowed-models.spec.ts

@@ -131,11 +131,31 @@ vi.mock('@/components/ui', async () => {
     },
   })
 
+  const Switch = defineComponent({
+    inheritAttrs: false,
+    props: {
+      modelValue: { type: Boolean, default: false },
+      disabled: Boolean,
+    },
+    emits: ['update:modelValue'],
+    setup(props, { attrs, emit }) {
+      return () => h('button', {
+        ...attrs,
+        type: 'button',
+        role: 'switch',
+        'aria-checked': props.modelValue,
+        disabled: props.disabled,
+        onClick: () => emit('update:modelValue', !props.modelValue),
+      })
+    },
+  })
+
   return {
     Badge: wrapper(),
     Button,
     Card: wrapper('section'),
     Input,
+    Switch,
     Table: wrapper('table'),
     TableBody: wrapper('tbody'),
     TableCard: wrapper(),