diff --git a/tests/test_inactivity_reset.py b/tests/test_inactivity_reset.py
index 053ef96..5499ae1 100644
--- a/tests/test_inactivity_reset.py
+++ b/tests/test_inactivity_reset.py
@@ -3,7 +3,8 @@ from __future__ import annotations
 
 from datetime import date, datetime, timedelta, timezone
 
-from sqlalchemy import select
+import pytest
+from sqlalchemy import delete, select, update
 
 from app.db.session import SessionLocal
 from app.models.inactivity import InactivityNotificationLog, InactivityResetLog
@@ -63,6 +64,24 @@ from app.repositories import wallet as wallet_repo
 _PHONE_SEQ = [0]
 
 
+@pytest.fixture(autouse=True)
+def _isolate_inactivity_state():
+    """本文件的测试都做全表扫描 + 全局计数,而 SQLite 测试库 session 级共享、无逐用例回滚
+    (commit 后的 rollback 是 no-op),故先把可能泄漏的余额清零 + 清掉活跃事件/审计行,
+    保证每个用例干净起步。不删 User(零余额用户不会被扫描选中,避免跨文件/外键影响)。"""
+    db = SessionLocal()
+    try:
+        db.execute(update(CoinAccount).values(
+            coin_balance=0, cash_balance_cents=0, invite_cash_balance_cents=0))
+        for model in (AnalyticsEvent, CouponPromptEngagement,
+                      InactivityResetLog, InactivityNotificationLog):
+            db.execute(delete(model))
+        db.commit()
+    finally:
+        db.close()
+    yield
+
+
 def _new_user(db, *, created_at, coin=0, cash=0, invite=0) -> int:
     """直接建一个 User + CoinAccount,created_at 可控。返回 user_id。"""
     _PHONE_SEQ[0] += 1
@@ -130,17 +149,12 @@ def test_log_notifier_returns_placeholder(caplog) -> None:
 
 
 def test_run_reset_clears_three_buckets_and_writes_audit_and_flows() -> None:
-    from sqlalchemy import select, update
+    from sqlalchemy import select
     from app.models.wallet import CoinAccount, CoinTransaction, CashTransaction, InviteCashTransaction
     from app.repositories import inactivity
 
     db = SessionLocal()
     try:
-        # 清掉前序测试遗留的余额(session-scoped DB,前测 commit 后 rollback 是 no-op)
-        db.execute(update(CoinAccount).values(coin_balance=0, cash_balance_cents=0,
-                                              invite_cash_balance_cents=0))
-        db.commit()
-
         today = date(2026, 2, 1)
         # 末次活跃 = created_at 基线 = 1/10(距 today 22 天 → 应清)
         old = _new_user(db, created_at=datetime(2026, 1, 10, tzinfo=timezone.utc),