diff --git a/scripts/surfer/crypto_funding_paper.py b/scripts/surfer/crypto_funding_paper.py
index b20f18977..87412200a 100644
--- a/scripts/surfer/crypto_funding_paper.py
+++ b/scripts/surfer/crypto_funding_paper.py
@@ -115,6 +115,10 @@ def cmd_snapshot():
 
 def cmd_run():
     st = load_state()
+    today = datetime.datetime.now(datetime.timezone.utc).date().isoformat()
+    if st.get("last_run_date") == today:           # idempotent: one booking per UTC day
+        print(f"already booked {today} (day {st['days']}); skipping")
+        return
     prev = st["positions"]
     liq, tf30, last24 = scan(prev)
     realized = sum(w * last24.get(c, 0.0) for c, w in prev.items())
@@ -123,7 +127,7 @@ def cmd_run():
     newpos = {c: 1.0 / n for c in q} if n else {}
     turnover = sum(abs(newpos.get(c, 0) - prev.get(c, 0)) for c in set(newpos) | set(prev))
     net = realized - turnover * (COST_RT / 2)
-    st.update(positions=newpos, days=st["days"] + 1)
+    st.update(positions=newpos, days=st["days"] + 1, last_run_date=today)
     st["cum_gross"] += realized
     st["cum_net"] += net
     os.makedirs(os.path.dirname(STATE), exist_ok=True)