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 096211ae..cef64f11 100644
--- a/apps/backend/src/db/migrations/113_finance_channel_cutover.sql
+++ b/apps/backend/src/db/migrations/113_finance_channel_cutover.sql
@@ -338,10 +338,12 @@ ALTER TABLE cost_exceptions
   ADD COLUMN IF NOT EXISTS last_seen_at TIMESTAMPTZ;
 
 -- 存量行（断代脚本会整体清空）给一个可用的 scope_key，避免 NOT NULL 失败。
+-- 旧行可能同 reason + subject_id 但 subject_type 不同，末尾拼 id 保证唯一，
+-- 否则下面的 uq_cost_exceptions_scope_open 会因重复键失败。
 UPDATE cost_exceptions
 SET scope_key = COALESCE(
       NULLIF(scope_key, ''),
-      reason || '|' || COALESCE(order_item_id::text, subject_id::text)
+      reason || '|' || COALESCE(order_item_id::text, subject_id::text) || '|legacy:' || id
     ),
     first_seen_at = COALESCE(first_seen_at, created_at),
     last_seen_at = COALESCE(last_seen_at, created_at)
@@ -405,8 +407,11 @@ 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。
+-- 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）。
+-- 必须先删除旧约束再改值：旧约束只允许四值，写 archived 会被它自己拦下。
+ALTER TABLE sales_daily_facts
+  DROP CONSTRAINT IF EXISTS chk_sales_daily_facts_fulfillment_mode;
+
 UPDATE sales_daily_facts
 SET fulfillment_mode = CASE
   WHEN fulfillment_mode = 'legacy_platform' THEN 'archived'
@@ -417,9 +422,6 @@ WHERE fulfillment_mode NOT IN (
   'manual', 'unclassified', 'archived'
 );
 
-ALTER TABLE sales_daily_facts
-  DROP CONSTRAINT IF EXISTS chk_sales_daily_facts_fulfillment_mode;
-
 ALTER TABLE sales_daily_facts
   ADD CONSTRAINT chk_sales_daily_facts_fulfillment_mode
   CHECK (
diff --git a/apps/backend/src/services/finance/finance-cutover-migration.test.ts b/apps/backend/src/services/finance/finance-cutover-migration.test.ts
index 9645234f..b9f11b8d 100644
--- a/apps/backend/src/services/finance/finance-cutover-migration.test.ts
+++ b/apps/backend/src/services/finance/finance-cutover-migration.test.ts
@@ -8,10 +8,14 @@ const migration = readFileSync(
   'utf8',
 )
 
-test('113 迁移必须先归一销售事实旧口径，再收紧渠道约束', () => {
+test('113 迁移必须先删旧约束、再归一销售事实，最后加新约束', () => {
+  const dropIndex = migration.indexOf(
+    'DROP CONSTRAINT IF EXISTS chk_sales_daily_facts_fulfillment_mode',
+  )
   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(dropIndex > 0, '缺少旧渠道约束的删除')
+  assert.ok(updateIndex > dropIndex, '必须先删旧约束再归一；否则 archived 会被旧约束拒绝')
   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'"),
@@ -32,3 +36,10 @@ test('113 迁移必须先归一销售事实旧口径，再收紧渠道约束', (
     assert.ok(migration.includes(`'${channel}'`), `新约束必须允许 ${channel}`)
   }
 })
+
+test('113 迁移的异常表旧行 scope_key 必须保证唯一', () => {
+  assert.ok(
+    migration.includes("'|legacy:' || id"),
+    '旧异常行 scope_key 必须拼 id，避免同 reason + subject_id 撞唯一索引',
+  )
+})