fix: address account valuation review findings

tests/test_account_valuation_edge_contracts.py

@@ -0,0 +1,93 @@
+from jarca_ledger_mcp import service
+
+
+def test_loan_balance_requires_representative_liability_definition(tmp_path):
+    path = str(tmp_path / "ledger.sqlite3")
+    bank = service.create_ledger_account("은행", type="bank", db_path=path)["account"]["id"]
+    loan = service.create_ledger_account("대출", type="loan", db_path=path)["account"]["id"]
+
+    missing_definition = service.register_account_valuation(
+        loan,
+        "2026-06-30",
+        100,
+        valuation_kind="balance",
+        verification_status="verified",
+        db_path=path,
+    )
+    assert missing_definition["success"] is False
+    assert missing_definition["error_code"] == "validation_error"
+    assert service.list_account_valuations(loan, db_path=path)["count"] == 0
+
+    ordinary_balance = service.register_account_valuation(
+        bank,
+        "2026-06-30",
+        100,
+        valuation_kind="balance",
+        verification_status="verified",
+        db_path=path,
+    )
+    defined_loan_balance = service.register_account_valuation(
+        loan,
+        "2026-06-30",
+        100,
+        valuation_kind="balance",
+        representative_liability_definition="principal_only",
+        verification_status="verified",
+        db_path=path,
+    )
+    assert ordinary_balance["success"] is True
+    assert defined_loan_balance["success"] is True
+
+
+def test_correction_replays_by_evidence_and_conflicts_on_changed_payload(tmp_path):
+    path = str(tmp_path / "ledger.sqlite3")
+    account = service.create_ledger_account("계좌", db_path=path)["account"]["id"]
+    parent = service.register_account_valuation(
+        account,
+        "2026-06-30",
+        100,
+        source_ref="statement-1",
+        verification_status="verified",
+        db_path=path,
+    )["valuation"]
+
+    first = service.correct_account_valuation(
+        parent["id"],
+        110,
+        "statement correction",
+        db_path=path,
+    )
+    replay = service.correct_account_valuation(
+        parent["id"],
+        110,
+        "statement correction",
+        db_path=path,
+    )
+    changed_amount = service.correct_account_valuation(
+        parent["id"],
+        111,
+        "statement correction",
+        db_path=path,
+    )
+    changed_reason = service.correct_account_valuation(
+        parent["id"],
+        110,
+        "different correction",
+        db_path=path,
+    )
+    changed_source = service.correct_account_valuation(
+        parent["id"],
+        110,
+        "statement correction",
+        source_ref="statement-2",
+        db_path=path,
+    )
+
+    assert first["success"] is True
+    assert replay["success"] is True
+    assert replay["reused"] is True
+    assert replay["valuation"]["id"] == first["valuation"]["id"]
+    for changed in (changed_amount, changed_reason, changed_source):
+        assert changed["success"] is False
+        assert changed["error_code"] == "correction_conflict"
+    assert service.list_account_valuations(account, db_path=path)["count"] == 2