fix: bugs-04

backend/tests/test_rules.py

@@ -8,7 +8,7 @@ import pytest
 from app.models.transaction import Direction
 from app.models.evidence_image import SourceApp
 from app.rules.dedup_rules import is_duplicate_pair
-from app.rules.transit_rules import is_self_transfer
+from app.rules.transit_rules import is_self_transfer, is_fee_tolerant_transit_pair
 from app.rules.assessment_rules import classify_transaction
 
 
@@ -79,6 +79,32 @@ class TestTransitRules:
         tx = _make_tx(counterparty_name="李*华", remark="投资款")
         assert not is_self_transfer(tx, [])
 
+    def test_fee_tolerant_pair_match(self):
+        out_tx = _make_tx(
+            direction=Direction.out,
+            amount=10000,
+            trade_time=datetime(2026, 3, 8, 10, 0, tzinfo=timezone.utc),
+        )
+        in_tx = _make_tx(
+            direction=Direction.in_,
+            amount=9850,  # 1.5% diff
+            trade_time=datetime(2026, 3, 8, 10, 1, 30, tzinfo=timezone.utc),
+        )
+        assert is_fee_tolerant_transit_pair(out_tx, in_tx)
+
+    def test_fee_tolerant_pair_time_window_exceeded(self):
+        out_tx = _make_tx(
+            direction=Direction.out,
+            amount=10000,
+            trade_time=datetime(2026, 3, 8, 10, 0, tzinfo=timezone.utc),
+        )
+        in_tx = _make_tx(
+            direction=Direction.in_,
+            amount=9900,
+            trade_time=datetime(2026, 3, 8, 10, 3, 1, tzinfo=timezone.utc),
+        )
+        assert not is_fee_tolerant_transit_pair(out_tx, in_tx)
+
 
 class TestAssessmentRules:
     def test_transit_classified_as_low(self):