#!/bin/bash
set -uxo pipefail
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
cd /workspace
git config --global --add safe.directory /workspace
mkdir -p /logs/verifier
git checkout 84cdbdc97389f41a748c72e57b83f9fe89ec12d4 -- tests/test_gains.py || true
git apply --verbose --reject - <<'EOF_R2E_TEST_PATCH'
diff --git a/tests/test_gains.py b/tests/test_gains.py
index 49d65e1..0685a83 100644
--- a/tests/test_gains.py
+++ b/tests/test_gains.py
@@ -140,6 +140,104 @@ class TestGainsClass:
         with pytest.raises(GainsError):
             FIFOUnits(test_fund, transactions)
 
+    def test_stamp_duty_split_lot_does_not_exceed_paid(self):
+        """When a single purchase lot is consumed across multiple
+        disposals, the sum of stamp duty allocated across those
+        disposals must not exceed the original stamp paid.
+
+        Regression guard for the FIFOUnits.sell bug where a
+        partially-consumed lot was re-queued with the FULL original
+        purchase_tax (instead of the unallocated remainder), causing
+        the per-disposal proportional allocation to re-claim the
+        same stamp on every subsequent disposal from the same lot.
+        Worked example with this 3-way 100/100/100 split of a
+        300-unit lot with ₹1.25 stamp:
+
+        - Disposal 1: round(1.25 × 100/300, 2) = 0.42 (lot re-queued
+          with remainder 0.83)
+        - Disposal 2: round(0.83 × 100/200, 2) = 0.42 (lot re-queued
+          with remainder 0.41)
+        - Disposal 3: round(0.41 × 100/100, 2) = 0.41
+        - Total claimed = 1.25 = exactly stamp paid ✓
+
+        Under the pre-fix code the lot was re-queued with the full
+        1.25 each time, producing a total of ~2.29 — an 84% over-
+        claim that grows worse with split depth.
+        """
+        fund = Fund("Split-Lot Fund", "SL", "INF000SL0001", "EQUITY")
+        purchase_dt = date(2020, 1, 1)
+        transactions = [
+            TransactionData(
+                date=purchase_dt,
+                description="Purchase",
+                amount=Decimal("3000.00"),
+                units=Decimal("300.000"),
+                nav=Decimal("10.000"),
+                balance=Decimal("300.000"),
+                type=TransactionType.PURCHASE,
+                dividend_rate=None,
+            ),
+            TransactionData(
+                date=purchase_dt,
+                description="*** Stamp Duty ***",
+                amount=Decimal("1.25"),
+                units=None,
+                nav=None,
+                balance=None,
+                type=TransactionType.STAMP_DUTY_TAX,
+                dividend_rate=None,
+            ),
+            # Three 100-unit redemptions on distinct dates (held > 1yr,
+            # so they're LTCG; specific dates don't matter for the
+            # stamp-allocation invariant).
+            TransactionData(
+                date=date(2022, 1, 1),
+                description="Redemption",
+                amount=Decimal("-2000.00"),
+                units=Decimal("-100.000"),
+                nav=Decimal("20.000"),
+                balance=Decimal("200.000"),
+                type=TransactionType.REDEMPTION,
+                dividend_rate=None,
+            ),
+            TransactionData(
+                date=date(2022, 2, 1),
+                description="Redemption",
+                amount=Decimal("-2000.00"),
+                units=Decimal("-100.000"),
+                nav=Decimal("20.000"),
+                balance=Decimal("100.000"),
+                type=TransactionType.REDEMPTION,
+                dividend_rate=None,
+            ),
+            TransactionData(
+                date=date(2022, 3, 1),
+                description="Redemption",
+                amount=Decimal("-2000.00"),
+                units=Decimal("-100.000"),
+                nav=Decimal("20.000"),
+                balance=Decimal("0.000"),
+                type=TransactionType.REDEMPTION,
+                dividend_rate=None,
+            ),
+        ]
+        fifo = FIFOUnits(fund, transactions)
+
+        # Three disposals, three gain entries.
+        assert len(fifo.gains) == 3
+
+        total_stamp = sum((ge.stamp_duty for ge in fifo.gains), Decimal("0"))
+
+        # Section 48 invariant: deductible transfer expense ≤ paid.
+        assert total_stamp <= Decimal("1.25"), (
+            f"Total stamp claimed ({total_stamp}) exceeds stamp paid (1.25); "
+            f"per-disposal stamps were {[ge.stamp_duty for ge in fifo.gains]}"
+        )
+        # Stronger: with the remainder-aware re-queue the rounding
+        # residual gets absorbed into the final disposal, so the
+        # total equals the paid stamp exactly.
+        assert total_stamp == Decimal("1.25")
+
 
 def _ltcg_entry(fy, fund, purchase_date, sale_date, units="100.000"):
     """Build a minimal LTCG GainEntry (EQUITY, held > 1yr) for the

EOF_R2E_TEST_PATCH
R2E_APPLY_RC=$?
if [ "$R2E_APPLY_RC" -ne 0 ]; then
  echo "0.000000" > /logs/verifier/reward.txt
  printf '%s' '{"reward": 0.0, "resolved": false, "parse_status": "test_patch_apply_failed"}' > /logs/verifier/reward-details.json
  echo "R2E: test_patch failed to apply (rc=$R2E_APPLY_RC) — failing closed" >&2
  exit 0
fi
( python -m pytest -v tests/test_gains.py ) > /logs/verifier/test_output.log 2>&1
TEST_EXIT_CODE=$?
cat /logs/verifier/test_output.log
python3 "$SCRIPT_DIR/verifier.py" --log /logs/verifier/test_output.log --f2p "$SCRIPT_DIR/f2p.json" --p2p "$SCRIPT_DIR/p2p.json" --test-cmds 'python -m pytest -v tests/test_gains.py' --exit-code "$TEST_EXIT_CODE" --out-dir /logs/verifier || { [ "$TEST_EXIT_CODE" -eq 0 ] && echo "1.0" > /logs/verifier/reward.txt || echo "0.0" > /logs/verifier/reward.txt; }
git checkout 84cdbdc97389f41a748c72e57b83f9fe89ec12d4 -- tests/test_gains.py || true
exit 0