diff --git a/apps/backend/src/services/cost-center/affiliate-product-service.ts b/apps/backend/src/services/cost-center/affiliate-product-service.ts
index 3ea198d9..067556d4 100644
--- a/apps/backend/src/services/cost-center/affiliate-product-service.ts
+++ b/apps/backend/src/services/cost-center/affiliate-product-service.ts
@@ -1,6 +1,7 @@
 import { query } from '../../db/client.js'
 import type { AdminSession } from '../admin/admin-auth-service.js'
 import type { JsonObject } from '../../types/json.js'
+import { resolvePriceEffectiveFrom } from './cost-center-normalizers.js'
 import { createHttpError } from '../../utils/http.js'
 import { formatShanghaiDate, shiftDate } from '../../utils/finance-date-range.js'
 import { nowIso } from '../../utils/time.js'
@@ -304,11 +305,7 @@ export async function setAdminAffiliateProductPrice(
   }
 
   const now = nowIso()
-  let effectiveFrom = payload.effectiveFrom ? String(payload.effectiveFrom) : now
-  if (payload.retroactive === true || payload.retroactive === 'true') {
-    const today = formatShanghaiDate(new Date())
-    effectiveFrom = shiftDate(today, -30) + 'T00:00:00+08:00'
-  }
+  const effectiveFrom = resolvePriceEffectiveFrom(payload)
   const changeReason = String(payload.changeReason || '配置自动发货采购成本').trim()
 
   const existingResult = await query<{ id: number; amount_fen: number; effective_from: string }>(
diff --git a/apps/backend/src/services/cost-center/cost-center-normalizers.ts b/apps/backend/src/services/cost-center/cost-center-normalizers.ts
index 31449fa1..8a36b358 100644
--- a/apps/backend/src/services/cost-center/cost-center-normalizers.ts
+++ b/apps/backend/src/services/cost-center/cost-center-normalizers.ts
@@ -246,3 +246,32 @@ export function requiredRow<T>(row: T | undefined | null, message: string): T {
   }
   return row
 }
+
+/**
+ * 成本改价的生效时间：只允许当前或未来，不允许追溯。
+ * 历史订单的成本与成交价已固化在快照里，改价不得回写过去。
+ */
+export function resolvePriceEffectiveFrom(payload: Record<string, unknown>): string {
+  if (payload.retroactive === true || payload.retroactive === 'true') {
+    throw createHttpError('成本改价不支持追溯历史订单；历史订单成本已固化', {
+      statusCode: 400,
+      errorCode: 'cost_retroactive_not_allowed',
+    })
+  }
+  const raw = payload.effectiveFrom ?? payload.effective_from
+  if (!raw) return new Date().toISOString()
+  const time = Date.parse(String(raw))
+  if (!Number.isFinite(time)) {
+    throw createHttpError('生效时间格式无效', {
+      statusCode: 400,
+      errorCode: 'cost_effective_from_invalid',
+    })
+  }
+  if (time < Date.now() - 60_000) {
+    throw createHttpError('生效时间不能早于当前时间；历史订单成本已固化', {
+      statusCode: 400,
+      errorCode: 'cost_effective_from_in_past',
+    })
+  }
+  return new Date(time).toISOString()
+}
diff --git a/apps/backend/src/services/cost-center/product-catalog-service.ts b/apps/backend/src/services/cost-center/product-catalog-service.ts
index 47e7f874..c0161286 100644
--- a/apps/backend/src/services/cost-center/product-catalog-service.ts
+++ b/apps/backend/src/services/cost-center/product-catalog-service.ts
@@ -16,6 +16,7 @@ import { nowIso } from '../../utils/time.js'
 import { normalizeMatchText, normalizeSkuSeriesEquivalence } from '../product-match/normalize.js'
 import { resolveSkuNameQuantity } from '../product-match/pricing.js'
 import { setAdminAffiliateProductPrice } from './affiliate-product-service.js'
+import { resolvePriceEffectiveFrom } from './cost-center-normalizers.js'
 import { ensureVoucherRuleForSku } from '../fulfillment/channel-assign-service.js'
 import { syncAdminWorkProductRulePrice } from '../worker-platform/admin-worker-catalog-service.js'
 import {
@@ -1367,11 +1368,7 @@ export async function setAdminProductPrice(
   }
 
   const now = nowIso()
-  let effectiveFrom = payload.effectiveFrom ? String(payload.effectiveFrom) : now
-  if (payload.retroactive === true || payload.retroactive === 'true') {
-    const today = formatShanghaiDate(new Date())
-    effectiveFrom = shiftDate(today, -30) + 'T00:00:00+08:00'
-  }
+  const effectiveFrom = resolvePriceEffectiveFrom(payload)
   const changeReason = String(payload.changeReason || '在商品与成本中心统一调整价格').trim()
 
   // 2. 如果是接单模板商品 (tpl:)
diff --git a/apps/frontend/src/pages/admin/cost-center/AffiliateSkuPanel.tsx b/apps/frontend/src/pages/admin/cost-center/AffiliateSkuPanel.tsx
index 8c1cd347..127e7b8f 100644
--- a/apps/frontend/src/pages/admin/cost-center/AffiliateSkuPanel.tsx
+++ b/apps/frontend/src/pages/admin/cost-center/AffiliateSkuPanel.tsx
@@ -41,7 +41,7 @@ import { useCostCenter } from './CostCenterContext'
 
 interface PriceFormValues {
   priceYuan: number
-  effectiveMode: 'retroactive' | 'now' | 'custom'
+  effectiveMode: 'now' | 'custom'
   customEffectiveDate?: dayjs.Dayjs
   changeReason?: string
 }
@@ -108,7 +108,7 @@ export function AffiliateSkuPanel() {
 
     priceForm.setFieldsValue({
       priceYuan: currentYuan,
-      effectiveMode: 'retroactive',
+      effectiveMode: 'now',
       changeReason: currentYuan ? '上游采购成本调整' : '首次配置自动发货采购成本',
     })
     setPriceModalOpen(true)
@@ -123,15 +123,10 @@ export function AffiliateSkuPanel() {
     }
 
     let effectiveFrom: string | undefined
-    let retroactive = false
-
-    if (values.effectiveMode === 'retroactive') {
-      retroactive = true
-      effectiveFrom = dayjs().subtract(30, 'day').format('YYYY-MM-DDTHH:mm:ss+08:00')
-    } else if (values.effectiveMode === 'now') {
+    if (values.effectiveMode === 'now') {
       effectiveFrom = new Date().toISOString()
     } else if (values.effectiveMode === 'custom' && values.customEffectiveDate) {
-      effectiveFrom = values.customEffectiveDate.startOf('day').toISOString()
+      effectiveFrom = values.customEffectiveDate.toISOString()
     }
 
     setPriceSubmitting(true)
@@ -139,7 +134,6 @@ export function AffiliateSkuPanel() {
       await setAdminAffiliateProductPrice(selectedProduct.id, {
         amountFen,
         effectiveFrom,
-        retroactive,
         changeReason: values.changeReason,
       })
       message.success(`「${selectedProduct.canonicalName}」采购单价已设置为 ¥${values.priceYuan}`)
@@ -379,20 +373,16 @@ export function AffiliateSkuPanel() {
           >
             <Radio.Group>
               <Space direction="vertical">
-                <Radio value="retroactive">
+                <Radio value="now">
                   <Space direction="vertical" size={0}>
-                    <Typography.Text strong>追溯至历史订单 (推荐)</Typography.Text>
+                    <Typography.Text strong>自当前时间立即生效</Typography.Text>
                     <Typography.Text type="secondary" style={{ fontSize: 12 }}>
-                      自近一个月业务起点（30 天前）生效，重算快照后可直接消除近一个月 cost_missing
-                      异常
+                      只影响之后的新订单；历史订单的成本与成交价已固化，不会被本次改价覆盖
                     </Typography.Text>
                   </Space>
                 </Radio>
-                <Radio value="now">
-                  <span>自当前时间立即生效（仅对后续订单生效）</span>
-                </Radio>
                 <Radio value="custom">
-                  <span>指定生效日期</span>
+                  <span>指定生效时间（不能早于当前时间）</span>
                 </Radio>
               </Space>
             </Radio.Group>
diff --git a/apps/frontend/src/pages/admin/cost-center/ProductCatalogPanel.tsx b/apps/frontend/src/pages/admin/cost-center/ProductCatalogPanel.tsx
index 59ed505c..22b072df 100644
--- a/apps/frontend/src/pages/admin/cost-center/ProductCatalogPanel.tsx
+++ b/apps/frontend/src/pages/admin/cost-center/ProductCatalogPanel.tsx
@@ -352,7 +352,7 @@ export function ProductCatalogPanel() {
 
   async function submitProductPrice(values: {
     amountYuan: number | string
-    effectiveScope: 'retroactive' | 'immediate' | 'custom'
+    effectiveScope: 'immediate' | 'custom'
     effectiveFromCustom?: string
     changeReason?: string
     syncOpenOrders?: boolean
@@ -365,12 +365,7 @@ export function ProductCatalogPanel() {
     }
     const amountFen = Math.round(yuan * 100)
     let effectiveFrom: string | undefined
-    let retroactive = false
-
-    if (values.effectiveScope === 'retroactive') {
-      retroactive = true
-      effectiveFrom = dayjs().subtract(30, 'day').format('YYYY-MM-DDTHH:mm:ss+08:00')
-    } else if (values.effectiveScope === 'custom' && values.effectiveFromCustom) {
+    if (values.effectiveScope === 'custom' && values.effectiveFromCustom) {
       effectiveFrom = values.effectiveFromCustom
     }
 
@@ -379,7 +374,6 @@ export function ProductCatalogPanel() {
       const response = await setAdminProductPrice(pricingProduct.id, {
         amountFen,
         effectiveFrom,
-        retroactive,
         changeReason: values.changeReason || '在商品与成本中心统一调整价格',
         syncOpenOrders: values.syncOpenOrders !== false,
       })
@@ -939,19 +933,13 @@ export function ProductCatalogPanel() {
             >
               <Radio.Group style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
                 <Radio value="immediate">
-                  <strong>自当前时间立即生效（推荐，仅对后续订单生效）</strong>
+                  <strong>自当前时间立即生效（推荐）</strong>
                   <div style={{ color: '#64748b', fontSize: 12, marginTop: 2 }}>
-                    保留旧版本历史，自新的价格版本创建时刻起计算后续履约结算
-                  </div>
-                </Radio>
-                <Radio value="retroactive">
-                  <strong>追溯至历史订单</strong>
-                  <div style={{ color: '#64748b', fontSize: 12, marginTop: 2 }}>
-                    自近一个月业务起点（30 天前）生效，直接更新基线并消除近一个月 cost_missing 异常
+                    只影响之后的新订单；历史订单的成本与成交价已固化，不会被改价覆盖
                   </div>
                 </Radio>
                 <Radio value="custom">
-                  <strong>指定生效日期</strong>
+                  <strong>指定生效时间（不能早于当前时间）</strong>
                 </Radio>
               </Radio.Group>
             </Form.Item>
diff --git a/apps/frontend/src/services/admin/cost-center.ts b/apps/frontend/src/services/admin/cost-center.ts
index 96abe88a..4c4149b8 100644
--- a/apps/frontend/src/services/admin/cost-center.ts
+++ b/apps/frontend/src/services/admin/cost-center.ts
@@ -145,7 +145,6 @@ export function setAdminAffiliateProductPrice(
   payload: {
     amountFen: number
     effectiveFrom?: string
-    retroactive?: boolean
     changeReason?: string
   },
 ) {
@@ -486,7 +485,6 @@ export function setAdminProductPrice(
   payload: {
     amountFen: number
     effectiveFrom?: string
-    retroactive?: boolean
     changeReason?: string
     syncOpenOrders?: boolean
   },