feat: deliver schema 15 monthly settlement lifecycle

tests/test_monthly_settlement_overview.py

@@ -0,0 +1,58 @@
+from pathlib import Path
+import sqlite3
+
+from jarca_ledger_mcp.db import init_db
+from jarca_ledger_mcp.application.monthly_settlement_service import list_monthly_settlement_overview
+
+
+def test_monthly_overview_excludes_transaction_only_months(tmp_path: Path):
+    db = tmp_path / "fixture.sqlite3"
+    init_db(str(db))
+    with sqlite3.connect(db) as conn:
+        conn.execute(
+            "INSERT INTO transactions(id,transaction_date,type,amount,created_at,updated_at) VALUES (?,?,?,?,?,?)",
+            ("tx-1", "2026-09-03", "income", 100, "2026-09-03T00:00:00Z", "2026-09-03T00:00:00Z"),
+        )
+        conn.commit()
+    result = list_monthly_settlement_overview(db_path=str(db))
+    assert result["success"]
+    assert result["months"] == []
+
+
+def test_monthly_overview_keeps_existing_parent_and_joins_live_transaction_totals(tmp_path: Path):
+    db = tmp_path / "fixture.sqlite3"
+    init_db(str(db))
+    with sqlite3.connect(db) as conn:
+        conn.execute(
+            "INSERT INTO monthly_settlement(id,month,basis_date,status,version,created_by,created_at,updated_by,updated_at) VALUES (?,?,?,?,?,?,?,?,?)",
+            ("settlement-1", "2026-09", "2026-09-30", "draft", 1, "test", "now", "test", "now"),
+        )
+        conn.execute(
+            "INSERT INTO transactions(id,transaction_date,type,amount,created_at,updated_at) VALUES (?,?,?,?,?,?)",
+            ("tx-1", "2026-09-03", "income", 100, "2026-09-03T00:00:00Z", "2026-09-03T00:00:00Z"),
+        )
+        conn.commit()
+    result = list_monthly_settlement_overview(db_path=str(db))
+    assert result["success"]
+    assert len(result["months"]) == 1
+    row = result["months"][0]
+    assert row["month"] == "2026-09"
+    assert row["settlement_id"] == "settlement-1"
+    assert row["income"] == 100
+    assert row["net_cashflow_display"] is None
+    assert row["net_worth_display"] is None
+
+
+def test_monthly_overview_keeps_parent_without_transactions(tmp_path: Path):
+    db = tmp_path / "fixture.sqlite3"
+    init_db(str(db))
+    with sqlite3.connect(db) as conn:
+        conn.execute(
+            "INSERT INTO monthly_settlement(id,month,basis_date,status,version,created_by,created_at,updated_by,updated_at) VALUES (?,?,?,?,?,?,?,?,?)",
+            ("settlement-1", "2026-09", "2026-09-30", "draft", 1, "test", "now", "test", "now"),
+        )
+        conn.commit()
+    row = list_monthly_settlement_overview(db_path=str(db))["months"][0]
+    assert row["settlement_id"] == "settlement-1"
+    assert row["income"] == 0
+    assert row["expense"] == 0