feat(state-machine): split fee into per-flow commission rates

Add cashInFeePercent (3.33%) and cashOutFeePercent (7.77%) to context.
Set feePercent from the per-flow value on SELECT_CASH_IN/SELECT_CASH_OUT
transitions. Preserve both rates across resetContext.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/state-machine/src/machine.ts

@@ -158,6 +158,8 @@ export function createATMMachine(
         ...initialContext,
         currency: context.currency,
         inventory: context.inventory,
+        cashInFeePercent: context.cashInFeePercent,
+        cashOutFeePercent: context.cashOutFeePercent,
         cashInSessionId: null,
       })),
       setStartTime: assign({
@@ -165,6 +167,12 @@ export function createATMMachine(
         txid: () => generateTxId(),
         cashInSessionId: () => generateSessionId(),
       }),
+      setCashInFee: assign({
+        feePercent: ({ context }) => context.cashInFeePercent,
+      }),
+      setCashOutFee: assign({
+        feePercent: ({ context }) => context.cashOutFeePercent,
+      }),
       addBill: assign({
         billsInserted: ({ context, event }) => {
           if (event.type !== 'BILL_INSERTED') return context.billsInserted
@@ -383,11 +391,11 @@ export function createATMMachine(
         on: {
           SELECT_CASH_IN: {
             target: 'cashIn',
-            actions: 'setStartTime',
+            actions: ['setStartTime', 'setCashInFee'],
           },
           SELECT_CASH_OUT: {
             target: 'cashOut',
-            actions: 'setStartTime',
+            actions: ['setStartTime', 'setCashOutFee'],
           },
         },
       },

packages/state-machine/src/types.ts

@@ -31,8 +31,12 @@ export interface ATMContext {
   currency: string
   /** Exchange rate (sats per fiat unit) */
   exchangeRate: number
-  /** Fee percentage (0.02 = 2%) */
+  /** Fee percentage (0.02 = 2%) — used at runtime for the active flow */
   feePercent: number
+  /** Cash-in commission (0.02 = 2%) */
+  cashInFeePercent: number
+  /** Cash-out commission (0.02 = 2%) */
+  cashOutFeePercent: number
   /** ATM's available balance in sats (for limiting cash-in transactions) */
   availableBalance: number
 
@@ -129,7 +133,9 @@ export const initialContext: ATMContext = {
   satsAmount: 0,
   currency: 'USD',
   exchangeRate: 0,
-  feePercent: 0.02,
+  feePercent: 0.0333,
+  cashInFeePercent: 0.0333,
+  cashOutFeePercent: 0.0777,
   availableBalance: 0,
   invoice: null,
   clinkOffer: null,