diff --git a/apps/backend/src/services/cost-center/cost-center.test.ts b/apps/backend/src/services/cost-center/cost-center.test.ts
index 728cdbaa..832575d7 100644
--- a/apps/backend/src/services/cost-center/cost-center.test.ts
+++ b/apps/backend/src/services/cost-center/cost-center.test.ts
@@ -272,3 +272,20 @@ test('mapping lookup follows specificity and concrete-shop priority', () => {
     50,
   )
 })
+
+/**
+ * 2026-10-29 生产：改「接单模板」商品价格 500。
+ *
+ * PostgreSQL 报 `inconsistent types deduced for parameter $1`（integer versus bigint）：
+ * 同一个 $1 在 `reward_amount = $1` 处按 bigint 推断，在 `CASE ... THEN $1 ELSE 0`
+ * 处又因为 `0` 是 integer 被推断成 integer。node-pg 不发送参数类型，必须显式转换。
+ */
+test('接单模板改价 SQL 的参数必须显式指定 bigint', async () => {
+  const { readFile } = await import('node:fs/promises')
+  const source = await readFile(new URL('./product-catalog-service.ts', import.meta.url), 'utf8')
+  assert.ok(
+    source.includes(
+      'unit_price_fen = CASE WHEN unit_price_fen > 0 THEN $1::bigint ELSE 0::bigint END',
+    ),
+  )
+})
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 1f8e5577..cca1d79f 100644
--- a/apps/backend/src/services/cost-center/product-catalog-service.ts
+++ b/apps/backend/src/services/cost-center/product-catalog-service.ts
@@ -1471,8 +1471,8 @@ export async function setAdminProductPrice(
     if (rule) {
       await query(
         `UPDATE work_product_rules
-         SET reward_amount = $1,
-             unit_price_fen = CASE WHEN unit_price_fen > 0 THEN $1 ELSE 0 END,
+         SET reward_amount = $1::bigint,
+             unit_price_fen = CASE WHEN unit_price_fen > 0 THEN $1::bigint ELSE 0::bigint END,
              cost_item_id = $2,
              updated_at = $3
          WHERE id = $4`,