diff --git a/lotto/app/backtest.py b/lotto/app/backtest.py
index 377c6f4..ed44d77 100644
--- a/lotto/app/backtest.py
+++ b/lotto/app/backtest.py
@@ -113,10 +113,12 @@ def _db():
     return _db_mod
 
 
-def calibrate_winner(draw_no: int, sample_m: int = 2000) -> Dict[str, Any]:
-    """DB 진입점: 회차 1개 캘리브레이션 후 저장 (멱등)."""
+def calibrate_winner(draw_no: int, sample_m: int = 2000, draws=None) -> Dict[str, Any]:
+    """DB 진입점: 회차 1개 캘리브레이션 후 저장 (멱등).
+    draws를 외부에서 전달하면 N+1 조회를 방지한다."""
     db = _db()
-    draws = db.get_all_draw_numbers()
+    if draws is None:
+        draws = db.get_all_draw_numbers()
     row = db.get_draw(draw_no)
     if row is None:
         return {"ok": False, "reason": "no_draw"}
@@ -142,7 +144,7 @@ def backfill_calibration(batch: int = 50, sample_m: int = 2000) -> Dict[str, Any
     todo.sort()
     n = 0
     for draw_no in todo[:batch]:
-        r = calibrate_winner(draw_no, sample_m=sample_m)
+        r = calibrate_winner(draw_no, sample_m=sample_m, draws=draws)
         if r.get("ok"):
             n += 1
     return {"calibrated": n, "remaining": max(0, len(todo) - batch)}
@@ -177,16 +179,18 @@ def run_forward_purchase(draw_no: int, k: int = 5000, pool_n: int = 20000,
             hist=graded, best_match=graded["best_match"], avg_meta_score=avg_meta,
         )
 
-    # 1) engine_w — 그 주 trials(있으면) 아니면 current_base
+    # 1) engine_w — 그 주 trials(있으면) 아니면 uniform fallback (leak-free)
+    from datetime import date as _date
     from . import weight_evolver as we
-    week_start = we.get_week_start()
-    trials = db.get_weekly_trials(week_start) if hasattr(db, "get_weekly_trials") else []
+    draw_date = _date.fromisoformat(row["drw_date"])
+    week_start = we.get_week_start(draw_date)
+    trials = db.get_weekly_trials(week_start)
     if trials:
         for t in trials:
             bought = purchase_tickets(pool, cache, t["weight"], k)
             _store("engine_w", f"w{t['day_of_week']}", t["weight"], t["id"], bought)
     else:
-        base = db.get_current_base() or [0.2] * 5
+        base = [0.2] * 5
         bought = purchase_tickets(pool, cache, base, k)
         _store("engine_w", "base", base, None, bought)
 
diff --git a/lotto/tests/test_backtest_db.py b/lotto/tests/test_backtest_db.py
index d68aeb2..6159124 100644
--- a/lotto/tests/test_backtest_db.py
+++ b/lotto/tests/test_backtest_db.py
@@ -106,6 +106,60 @@ def test_run_forward_purchase_persists_all_strategies(monkeypatch):
         assert r["n_tickets"] == 20
 
 
+def test_calibrate_winner_no_draw(monkeypatch):
+    """DB에 없는 회차 번호 → ok=False, reason='no_draw'."""
+    db = _fresh_db(monkeypatch)
+    _seed_draws(db, 40)
+    from app import backtest as bt
+    r = bt.calibrate_winner(99999)
+    assert r["ok"] is False
+    assert r["reason"] == "no_draw"
+
+
+def test_calibrate_winner_insufficient_history(monkeypatch):
+    """point-in-time 이력이 MIN_HISTORY(30) 미만인 회차 → reason='insufficient_history'.
+    draw_no=20이면 PIT 이력이 19개(draws 1~19)로 30 미만."""
+    db = _fresh_db(monkeypatch)
+    _seed_draws(db, 40)
+    from app import backtest as bt
+    r = bt.calibrate_winner(20)
+    assert r["ok"] is False
+    assert r["reason"] == "insufficient_history"
+
+
+def test_run_forward_purchase_with_trials(monkeypatch):
+    """그 주 weight_trials가 존재하면 engine_w 행의 weight_label이 'w0'..'w5' 형식이어야 한다."""
+    db = _fresh_db(monkeypatch)
+    _seed_draws(db, 40)
+    # draw 40: drw_date='2020-01-13' → week_start='2020-01-13'
+    from datetime import date, timedelta
+    draw_date = date.fromisoformat("2020-01-13")
+    ws = (draw_date - timedelta(days=draw_date.weekday())).isoformat()
+    # 해당 주에 trial 2개 심기 (day_of_week 0, 1)
+    db.save_weight_trial(ws, 0, [0.1, 0.3, 0.2, 0.2, 0.2], "perturb")
+    db.save_weight_trial(ws, 1, [0.25, 0.25, 0.25, 0.15, 0.1], "perturb")
+    from app import backtest as bt
+    res = bt.run_forward_purchase(draw_no=40, k=20, pool_n=500, sample_seed=5)
+    assert res["ok"] is True
+    rows = db.get_backtest_runs(draw_no=40)
+    engine_w_labels = {r["weight_label"] for r in rows if r["strategy"] == "engine_w"}
+    # trials가 있으므로 'base'가 아닌 'w0', 'w1' 형식이어야 한다
+    assert "base" not in engine_w_labels
+    assert any(lbl.startswith("w") for lbl in engine_w_labels)
+
+
+def test_run_forward_purchase_idempotent(monkeypatch):
+    """run_forward_purchase 두 번 호출 시 upsert — 행 수 변화 없음."""
+    db = _fresh_db(monkeypatch)
+    _seed_draws(db, 40)
+    from app import backtest as bt
+    bt.run_forward_purchase(draw_no=40, k=20, pool_n=500, sample_seed=5)
+    count_after_first = len(db.get_backtest_runs(draw_no=40))
+    bt.run_forward_purchase(draw_no=40, k=20, pool_n=500, sample_seed=5)
+    count_after_second = len(db.get_backtest_runs(draw_no=40))
+    assert count_after_second == count_after_first
+
+
 def test_get_calibrated_draw_nos(monkeypatch):
     """저장된 draw_no 집합이 get_calibrated_draw_nos에 포함되어야 한다."""
     db = _fresh_db(monkeypatch)