Tie the withdrawal minimum to the bet amount instead of a separate field

RoundConfig.min_amount_sats was an independently-configurable floor that
could drift out of sync with bet_amount_sats for no real reason (deposits
never had a server-side minimum anyway). Drop the field and enforce
amount_sats >= config.bet_amount_sats directly in request_withdrawal.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/routes/admin.py

@@ -27,7 +27,6 @@ _CONFIG_FIELDS = (
     "bet_amount_sats",
     "round_duration_seconds",
     "round_cooldown_seconds",
-    "min_amount_sats",
     "fee_rate_sat_vb",
     "rbf_timeout_seconds",
     "draw_animation_seconds",
@@ -40,7 +39,6 @@ class RoundConfigResponse(BaseModel):
     bet_amount_sats: int
     round_duration_seconds: int
     round_cooldown_seconds: int
-    min_amount_sats: int
     fee_rate_sat_vb: int
     rbf_timeout_seconds: int
     draw_animation_seconds: int
@@ -52,7 +50,6 @@ class RoundConfigUpdate(BaseModel):
     bet_amount_sats: int | None = None
     round_duration_seconds: int | None = None
     round_cooldown_seconds: int | None = None
-    min_amount_sats: int | None = None
     fee_rate_sat_vb: int | None = None
     rbf_timeout_seconds: int | None = None
     draw_animation_seconds: int | None = None

app/db/models.py

@@ -75,7 +75,7 @@ class RoundConfig(Base):
     """Single-row operational config, DB-backed so it's editable without a redeploy.
 
     Everything business/round-related lives here (round timing, bet amount, fee
-    rate, RBF timeout, minimum amount) so an operator can tune it live. Secrets
+    rate, RBF timeout) so an operator can tune it live. Secrets
     and infra wiring (master key, JWT secret, Electrum host, admin token,
     database URL) deliberately stay env-var-driven — those require a restart
     anyway and aren't safe to hot-swap."""
@@ -92,7 +92,6 @@ class RoundConfig(Base):
     # NOT gate the actual draw, which still waits for a real confirmed block for
     # its entropy (rounds/scheduler.py) — that can take longer than this value.
     draw_animation_seconds: Mapped[int] = mapped_column(default=20)
-    min_amount_sats: Mapped[int] = mapped_column(BigInteger, default=100_000_000)
     fee_rate_sat_vb: Mapped[int] = mapped_column(default=1)
     rbf_timeout_seconds: Mapped[int] = mapped_column(default=900)
     # Maintenance switch: when true, the round currently in progress still runs to

app/static/admin.html

@@ -250,8 +250,6 @@
             <input id="admin-fee-address" class="mono" placeholder="plm1q...">
             <label for="admin-bet-amount">Bet amount (PLM)</label>
             <input id="admin-bet-amount" inputmode="decimal" placeholder="es. 10">
-            <label for="admin-min-amount">Importo minimo deposito/prelievo (PLM)</label>
-            <input id="admin-min-amount" inputmode="decimal" placeholder="es. 1">
           </div>
           <div>
             <label for="admin-round-duration">Durata round (secondi)</label>
@@ -479,7 +477,6 @@ async function adminLoadConfig() {
     document.getElementById('admin-round-duration').value = data.round_duration_seconds;
     document.getElementById('admin-round-cooldown').value = data.round_cooldown_seconds;
     document.getElementById('admin-draw-animation').value = data.draw_animation_seconds;
-    document.getElementById('admin-min-amount').value = data.min_amount_sats / SATS_PER_PLM;
     document.getElementById('admin-fee-rate').value = data.fee_rate_sat_vb;
     document.getElementById('admin-rbf-timeout').value = data.rbf_timeout_seconds;
     renderMaintenanceState(data.paused);
@@ -533,14 +530,12 @@ async function adminSave() {
   const btn = document.getElementById('save-btn');
   const feeAddress = document.getElementById('admin-fee-address').value;
   const betAmountPlm = parseFloat(document.getElementById('admin-bet-amount').value);
-  const minAmountPlm = parseFloat(document.getElementById('admin-min-amount').value);
   const body = {
     fee_address: feeAddress,
     bet_amount_sats: Math.round(betAmountPlm * SATS_PER_PLM),
     round_duration_seconds: parseInt(document.getElementById('admin-round-duration').value, 10),
     round_cooldown_seconds: parseInt(document.getElementById('admin-round-cooldown').value, 10),
     draw_animation_seconds: parseInt(document.getElementById('admin-draw-animation').value, 10),
-    min_amount_sats: Math.round(minAmountPlm * SATS_PER_PLM),
     fee_rate_sat_vb: parseInt(document.getElementById('admin-fee-rate').value, 10),
     rbf_timeout_seconds: parseInt(document.getElementById('admin-rbf-timeout').value, 10),
   };

app/withdrawals/service.py

@@ -19,8 +19,8 @@ async def request_withdrawal(
     session: AsyncSession, client: ElectrumClient, user: User, external_address: str, amount_sats: int
 ) -> Withdrawal:
     config = await get_round_config(session)
-    if amount_sats < config.min_amount_sats:
-        raise WithdrawalError(f"amount below the minimum of {config.min_amount_sats} sats")
+    if amount_sats < config.bet_amount_sats:
+        raise WithdrawalError(f"amount below the minimum of {config.bet_amount_sats} sats")
 
     unspent = (
         await session.scalars(