diff --git a/apps/backend/src/db/migrations/113_finance_channel_cutover.sql b/apps/backend/src/db/migrations/113_finance_channel_cutover.sql
index ba6abc50..096211ae 100644
--- a/apps/backend/src/db/migrations/113_finance_channel_cutover.sql
+++ b/apps/backend/src/db/migrations/113_finance_channel_cutover.sql
@@ -404,6 +404,19 @@ COMMENT ON TABLE finance_watermarks IS
 
 -- 先沿用旧列名承载渠道值，本迁移末尾统一改名为 channel；
 -- 这里先放宽约束，允许卡券、未分类与归档状态。
+-- 断代前的销售事实仍是旧口径，可能残留 legacy_platform；新约束不允许该值。
+-- 这些事实随后由 finance:cutover-v2 整体清空，这里先归入 archived（未知值归入 unclassified），
+-- 保证约束能加上；否则生产基线 112 会因存量行直接失败。
+UPDATE sales_daily_facts
+SET fulfillment_mode = CASE
+  WHEN fulfillment_mode = 'legacy_platform' THEN 'archived'
+  ELSE 'unclassified'
+END
+WHERE fulfillment_mode NOT IN (
+  'work_order', 'affiliate_dash', 'third_party_voucher',
+  'manual', 'unclassified', 'archived'
+);
+
 ALTER TABLE sales_daily_facts
   DROP CONSTRAINT IF EXISTS chk_sales_daily_facts_fulfillment_mode;
 
diff --git a/apps/backend/src/services/finance/finance-cutover-migration.test.ts b/apps/backend/src/services/finance/finance-cutover-migration.test.ts
new file mode 100644
index 00000000..9645234f
--- /dev/null
+++ b/apps/backend/src/services/finance/finance-cutover-migration.test.ts
@@ -0,0 +1,34 @@
+import assert from 'node:assert/strict'
+import { readFileSync } from 'node:fs'
+import { fileURLToPath } from 'node:url'
+import test from 'node:test'
+
+const migration = readFileSync(
+  fileURLToPath(new URL('../../db/migrations/113_finance_channel_cutover.sql', import.meta.url)),
+  'utf8',
+)
+
+test('113 迁移必须先归一销售事实旧口径，再收紧渠道约束', () => {
+  const updateIndex = migration.indexOf('UPDATE sales_daily_facts')
+  const constraintIndex = migration.indexOf('ADD CONSTRAINT chk_sales_daily_facts_fulfillment_mode')
+  assert.ok(updateIndex > 0, '缺少 sales_daily_facts 旧口径归一')
+  assert.ok(constraintIndex > updateIndex, '必须先归一数据，再加新约束')
+  assert.ok(
+    migration.includes("WHEN fulfillment_mode = 'legacy_platform' THEN 'archived'"),
+    'legacy_platform 必须归入 archived',
+  )
+  assert.ok(
+    migration.includes("ELSE 'unclassified'"),
+    '其它未知旧值必须归入 unclassified，避免约束因脏数据失败',
+  )
+  for (const channel of [
+    'work_order',
+    'affiliate_dash',
+    'third_party_voucher',
+    'manual',
+    'unclassified',
+    'archived',
+  ]) {
+    assert.ok(migration.includes(`'${channel}'`), `新约束必须允许 ${channel}`)
+  }
+})