diff --git a/app/core/rewards.py b/app/core/rewards.py
index 842f0ae..f0bc598 100644
--- a/app/core/rewards.py
+++ b/app/core/rewards.py
@@ -26,6 +26,16 @@ SIGNIN_REWARDS: tuple[int, ...] = (
 SIGNIN_CYCLE_LEN: int = len(SIGNIN_REWARDS)
 
 
+# ===== 信息流广告「按会话聚合」的 biz_type =====
+# 比价 / 领券等候期看的信息流广告,每条各写一条 coin_transaction;这两类在「金币变动记录」
+# 里按 trace_id 聚合成一条展示(见 repositories/wallet.list_coin_transactions)。其余类型
+# (reward_video / guide_video / 通用 feed_ad_reward / signin / task_* 等)不聚合。
+FEED_AD_SESSION_BIZ_TYPES: tuple[str, str] = (
+    "feed_ad_reward_comparison",
+    "feed_ad_reward_coupon",
+)
+
+
 def signin_reward(cycle_day: int) -> int:
     """cycle_day 取值 1..SIGNIN_CYCLE_LEN。"""
     return SIGNIN_REWARDS[cycle_day - 1]
diff --git a/app/models/wallet.py b/app/models/wallet.py
index dcdff4a..f5c22b1 100644
--- a/app/models/wallet.py
+++ b/app/models/wallet.py
@@ -84,6 +84,9 @@ class CoinTransaction(Base):
     # 关联业务 id(签到日期、任务 key 等),可空
     ref_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
     remark: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    # 会话键:仅比价/领券信息流发奖(feed_ad_reward_comparison/coupon)时写入本场 trace_id,
+    # 金币记录列表据此把一次比价/领券的多条广告金币聚合成一条。其余类型 = NULL。
+    trace_id: Mapped[str | None] = mapped_column(String(64), index=True, nullable=True)
 
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), server_default=func.now(), index=True, nullable=False
diff --git a/app/repositories/wallet.py b/app/repositories/wallet.py
index fbaebbb..cd17981 100644
--- a/app/repositories/wallet.py
+++ b/app/repositories/wallet.py
@@ -170,6 +170,7 @@ def grant_coins(
     biz_type: str,
     ref_id: str | None = None,
     remark: str | None = None,
+    trace_id: str | None = None,
 ) -> tuple[CoinAccount, CoinTransaction]:
     """金币变动入口(正数入账 / 负数出账)。更新余额 + 写流水,不 commit。
 
@@ -189,6 +190,7 @@ def grant_coins(
         biz_type=biz_type,
         ref_id=ref_id,
         remark=remark,
+        trace_id=trace_id,
         created_at=datetime.now(rewards.CN_TZ).replace(tzinfo=None),  # 存北京 wall-clock(客户端原样切片显示)
     )
     db.add(txn)
diff --git a/tests/test_welfare.py b/tests/test_welfare.py
index bd99334..d9024d8 100644
--- a/tests/test_welfare.py
+++ b/tests/test_welfare.py
@@ -384,3 +384,22 @@ def test_endpoints_require_auth(client) -> None:
     assert client.get("/api/v1/savings/summary").status_code == 401
     assert client.get("/api/v1/savings/battle").status_code == 401
     assert client.get("/api/v1/savings/records").status_code == 401
+
+
+def test_grant_coins_persists_trace_id(client) -> None:
+    """grant_coins 传 trace_id 落库;不传则为 None。"""
+    phone = "13800002001"
+    _login(client, phone)
+    with SessionLocal() as db:
+        user = get_user_by_phone(db, phone)
+        assert user is not None
+        _, txn1 = crud_wallet.grant_coins(
+            db, user.id, 5, biz_type="feed_ad_reward_comparison",
+            ref_id="evt1", remark="比价奖励", trace_id="trace-A",
+        )
+        _, txn2 = crud_wallet.grant_coins(
+            db, user.id, 30, biz_type="signin", remark="每日签到奖励",
+        )
+        db.commit()
+        assert txn1.trace_id == "trace-A"
+        assert txn2.trace_id is None