diff --git a/apps/machine/src/stores/atm.ts b/apps/machine/src/stores/atm.ts
index a65f900..f1764e0 100644
--- a/apps/machine/src/stores/atm.ts
+++ b/apps/machine/src/stores/atm.ts
@@ -1639,6 +1639,15 @@ export const useAtmStore = defineStore('atm', () => {
     send({ type: 'DEV_UNLOCK' })
   }
 
+  /**
+   * End the current tap-in session on demand and re-lock immediately (drops the
+   * loaded Bolt Card via `locked`'s entry), instead of waiting out the idle
+   * timeout. No-op unless the gate is active and we're on the idle menu.
+   */
+  function endSession() {
+    send({ type: 'END_SESSION' })
+  }
+
   // Convenience methods for common events
   function selectCashIn() {
     send({ type: 'SELECT_CASH_IN' })
@@ -1799,6 +1808,7 @@ export const useAtmStore = defineStore('atm', () => {
     grantAccess,
     denyAccess,
     devUnlock,
+    endSession,
 
     // Actions
     initialize,
diff --git a/apps/machine/src/views/IdleView.vue b/apps/machine/src/views/IdleView.vue
index 3465cc1..a538ff2 100644
--- a/apps/machine/src/views/IdleView.vue
+++ b/apps/machine/src/views/IdleView.vue
@@ -183,6 +183,21 @@ function handleCashOut() {
       ?
     </Button>
 
+    <!-- End-session button (top-right) — only while the access gate is engaged.
+         A tap-in loads the holder's Bolt Card for the whole session, so give
+         them an explicit way to re-lock the moment they're done instead of
+         relying on the idle timeout (which would leave the card usable by the
+         next person in the meantime). -->
+    <Button
+      v-if="atmStore.accessControl.enabled"
+      variant="outline"
+      size="kiosk"
+      class="absolute top-4 right-4 lg:top-8 lg:right-8 h-14 min-h-0 gap-2 rounded-full border-2 border-destructive/50 px-4 text-sm font-bold text-destructive lg:h-20 lg:px-8 lg:text-2xl"
+      @click="atmStore.endSession()"
+    >
+      🔒 End Session
+    </Button>
+
     <!-- Debug toggle (only visible when debug bar is hidden, never in production) -->
     <Button
       v-if="!atmStore.debugMode && atmStore.allowMockFallback"
diff --git a/packages/state-machine/src/__tests__/access-control.test.ts b/packages/state-machine/src/__tests__/access-control.test.ts
index 1302f81..e023b4c 100644
--- a/packages/state-machine/src/__tests__/access-control.test.ts
+++ b/packages/state-machine/src/__tests__/access-control.test.ts
@@ -90,6 +90,25 @@ describe('ATM access control (ADR-003)', () => {
     })
   })
 
+  describe('user-initiated end of session', () => {
+    it('END_SESSION re-locks immediately when the gate is active', () => {
+      const actor = createActor(createATMMachine({}, { accessControlEnabled: true }))
+      actor.start()
+      actor.send({ type: 'ACCESS_GRANTED', role: 'user', credentialIdHash: 'abc' })
+      expect(actor.getSnapshot().value).toBe('idle')
+      actor.send({ type: 'END_SESSION' })
+      expect(actor.getSnapshot().value).toBe('locked')
+    })
+
+    it('END_SESSION is a no-op when the gate is disabled (stays at idle)', () => {
+      const actor = createActor(createATMMachine()) // gate off → rests at idle
+      actor.start()
+      expect(actor.getSnapshot().value).toBe('idle')
+      actor.send({ type: 'END_SESSION' })
+      expect(actor.getSnapshot().value).toBe('idle')
+    })
+  })
+
   describe('build/dev bypass', () => {
     it('accessBypassFlag opens the gate even when enabled', () => {
       const actor = createActor(
diff --git a/packages/state-machine/src/machine.ts b/packages/state-machine/src/machine.ts
index 9943fc6..94353ee 100644
--- a/packages/state-machine/src/machine.ts
+++ b/packages/state-machine/src/machine.ts
@@ -549,6 +549,11 @@ export function createATMMachine(
             target: 'cashOut',
             actions: ['setStartTime', 'setCashOutFee'],
           },
+          // User taps "End session": re-lock now rather than waiting out
+          // IDLE_LOCK_TIMEOUT. Guarded to the active gate so a gate-disabled
+          // machine (which rests at idle) never leaves it via this event.
+          // `locked`'s entry clears the access session + loaded card.
+          END_SESSION: { guard: 'accessGateActive', target: 'locked' },
         },
       },
 
diff --git a/packages/state-machine/src/types.ts b/packages/state-machine/src/types.ts
index 9556004..fc8d4a7 100644
--- a/packages/state-machine/src/types.ts
+++ b/packages/state-machine/src/types.ts
@@ -179,6 +179,10 @@ export type ATMEvent =
   | { type: 'ACCESS_GRANTED'; role: AccessRole; credentialIdHash: string }
   | { type: 'ACCESS_DENIED'; reason: string }
   | { type: 'DEV_UNLOCK' }
+  // User-initiated end of a tap-in session: re-lock immediately instead of
+  // waiting out IDLE_LOCK_TIMEOUT, so a loaded Bolt Card can't be reused by
+  // the next person the moment its holder steps away.
+  | { type: 'END_SESSION' }
   | { type: 'SELECT_AMOUNT'; amount: number }
   | { type: 'FINISH_INSERTING' }
   | { type: 'USER_SCANNED_NPUB'; npub: string }