diff --git a/apps/machine/src/services/lightning.ts b/apps/machine/src/services/lightning.ts
index 499e0ce..a2e237f 100644
--- a/apps/machine/src/services/lightning.ts
+++ b/apps/machine/src/services/lightning.ts
@@ -40,7 +40,7 @@ const isElectron = typeof window !== 'undefined' && window.electronAPI !== undef
  * - VITE_RELAY_URL: Nostr relay WebSocket URL
  * - VITE_LIGHTNING_PUB_PUBKEY: Lightning.Pub's Nostr pubkey (hex or npub)
  * - VITE_LIGHTNING_PUB_API_URL: Lightning.Pub HTTP API URL
- * - VITE_ATM_PRIVATE_KEY: ATM's Nostr private key (hex or nsec)
+ * - VITE_ATM_PRIVATE_KEY: ATM's Nostr private key (hex or nsec)   // pragma: allowlist secret
  * - VITE_ADMIN_TOKEN: Lightning.Pub admin token (dev only)
  */
 interface LightningConfig {
@@ -63,7 +63,7 @@ interface LightningConfig {
  * Load configuration - async to support Electron IPC
  *
  * SECURITY: Public config comes from get-config IPC.
- * Secrets (private key, admin token) come from the one-shot get-atm-secrets IPC,
+ * Secrets (private key, admin token) come from the one-shot get-atm-secrets IPC,   // pragma: allowlist secret
  * which returns secrets only once per app lifecycle.
  */
 async function loadLightningConfig(): Promise<LightningConfig> {
@@ -749,14 +749,61 @@ function createATMServices(
 
     /**
      * Generate a BOLT11 invoice for cash-out (customer pays the ATM).
+     *
+     * Stamps the per-transaction split on `Payment.extra` per
+     * `aiolabs/lamassu-next#44` so the receiving extension
+     * (`satmachineadmin`) doesn't have to back-derive principal /
+     * commission from a stored rate. The on-wire amount remains
+     * `context.satsAmount` sats (= principal + commission for cash-out).
+     *
+     * Field-name vocabulary follows the comment thread on #44:
+     *   - `principal_sats` (was `net_sats`) — the LP/DCA share
+     *   - `fee_sats`                          — the commission
+     *   - `fee_percent` (was `fee_pct`)       — for display + auditing
+     *   - `exchange_rate`                     — sats per 1 fiat unit
+     *                                            (RAW market rate, no
+     *                                            commission baked in)
+     *   - `currency`                          — customer-paid currency,
+     *                                            matches machine fiat_code
+     *   - `type: "cash_out"` / `source: "bitspire"` — discriminators
      */
-    generateInvoice: async (amountMsat: number): Promise<string> => {
-      const amountSats = Math.floor(amountMsat / 1000)
-      console.log('[ATM Service] Generating invoice for', amountSats, 'sats')
+    generateInvoice: async (context: ATMContext): Promise<string> => {
+      const amountSats = context.satsAmount
+      // Cash-out: satsAmount = principal + commission. principal is
+      // derived from the raw market rate (no commission baked in) so a
+      // consumer can independently audit the split.
+      const principalSats =
+        context.exchangeRate > 0
+          ? Math.floor((context.fiatCents / 100) * context.exchangeRate)
+          : 0
+      const feeSats = Math.max(0, amountSats - principalSats)
+      const feePercent = +(context.feePercent * 100).toFixed(4) // 0.05 -> 5.0
+      console.log(
+        '[ATM Service] Generating invoice — gross',
+        amountSats,
+        'sats (principal',
+        principalSats,
+        '+ fee',
+        feeSats,
+        `≈ ${feePercent}% @ ${context.exchangeRate} sats/${context.currency})`
+      )
       const payment = await lnbits.createInvoice(lnbitsWalletId, {
         amount: amountSats,
         memo: 'bitSpire - Cash Out',
         unit: 'sat',
+        extra: {
+          source: 'bitspire',
+          type: 'cash_out',
+          txid: context.txid,
+          principal_sats: principalSats,
+          fee_sats: feeSats,
+          fee_percent: feePercent,
+          exchange_rate: context.exchangeRate,
+          currency: context.currency,
+          // bills/cassettes deferred — they're meaningful for cash-in
+          // and for partial-dispense reconciliation, neither of which
+          // is wired on the satmachineadmin side yet (#22, #3).
+        },
       })
       if (!payment.payment_request) {
         throw new Error('LNbits createInvoice returned empty payment_request')
diff --git a/apps/machine/src/stores/atm.ts b/apps/machine/src/stores/atm.ts
index f6c9380..f3b71b8 100644
--- a/apps/machine/src/stores/atm.ts
+++ b/apps/machine/src/stores/atm.ts
@@ -187,9 +187,13 @@ const mockServices: ATMServices = {
     return `LNURL1MOCK${Date.now().toString(36).toUpperCase()}`
   },
 
-  generateInvoice: async (amountMsat) => {
-    console.log('[Mock] Generating invoice for', amountMsat, 'msats')
-    return `lnbc${amountMsat}n1mock${Date.now().toString(36)}`
+  generateInvoice: async (context) => {
+    console.log(
+      '[Mock] Generating invoice for',
+      context.satsAmount,
+      `sats (gross — principal+fee on cash-out, ${context.currency})`
+    )
+    return `lnbc${context.satsAmount * 1000}n1mock${Date.now().toString(36)}`
   },
 
   getExchangeRate: async (currency) => {
diff --git a/packages/state-machine/src/machine.ts b/packages/state-machine/src/machine.ts
index 828eb39..848ac4d 100644
--- a/packages/state-machine/src/machine.ts
+++ b/packages/state-machine/src/machine.ts
@@ -46,7 +46,7 @@ export function createATMMachine(
         }
         return services.generateLnurlWithdraw(input)
       }),
-      generateInvoice: fromPromise(async ({ input }: { input: number }) => {
+      generateInvoice: fromPromise(async ({ input }: { input: ATMContext }) => {
         if (!services.generateInvoice) {
           throw new Error('generateInvoice service not provided')
         }
@@ -662,7 +662,12 @@ export function createATMMachine(
           generatingInvoice: {
             invoke: {
               src: 'generateInvoice',
-              input: ({ context }) => context.satsAmount * 1000, // sats to msats
+              // Pass the full context so the implementation can stamp
+              // principal/fee/exchange-rate/etc. onto Payment.extra
+              // (lamassu-next#44 / satmachineadmin#19). The on-wire
+              // BOLT11 amount is derived inside the service as
+              // `context.satsAmount * 1000` msats.
+              input: ({ context }) => context,
               onDone: {
                 target: 'displayingInvoice',
                 actions: assign({
diff --git a/packages/state-machine/src/types.ts b/packages/state-machine/src/types.ts
index aa67a9c..f24d0e8 100644
--- a/packages/state-machine/src/types.ts
+++ b/packages/state-machine/src/types.ts
@@ -199,8 +199,17 @@ export interface ATMServices {
   generateNdebit: (context: ATMContext) => Promise<string>
   /** Generate an LNURL-withdraw link (for cash-in - customer receives sats) - legacy */
   generateLnurlWithdraw: (context: ATMContext) => Promise<string>
-  /** Generate a Lightning invoice */
-  generateInvoice: (amountMsat: number) => Promise<string>
+  /**
+   * Generate a Lightning invoice (cash-out flow). Takes the full
+   * `ATMContext` rather than a bare amount so the implementation can
+   * populate `Payment.extra` with the principal/commission split,
+   * exchange rate, currency, etc. — consumed by `satmachineadmin`
+   * downstream (`aiolabs/lamassu-next#44`,
+   * `aiolabs/satmachineadmin#19`). The on-wire BOLT11 amount is still
+   * `context.satsAmount * 1000` msats (principal + commission for
+   * cash-out); the extras are metadata only.
+   */
+  generateInvoice: (context: ATMContext) => Promise<string>
   /** Send receipt via Nostr */
   sendNostrReceipt: (context: ATMContext) => Promise<void>
   /** Dispense cash (always resolves with result, never throws) */