feat(tempo): support machine-token sessions without refunds

Author: parvahuja

.changeset/machine-sessions-route.md

@@ -0,0 +1,5 @@
+---
+'mppx': patch
+---
+
+Added opt-in machine-token settlement for Tempo sessions while preserving the merchant's configured payout currency. Machine-token channels can close after the full deposit is spent; partial close remains disabled until the reserve supports returning restricted escrow.

src/server/Methods.test-d.ts

@@ -5,7 +5,9 @@ import type { StripeClient } from '../stripe/internal/types.js'
 
 test('accepts the machine-token option on Tempo charges and the global constructor', () => {
   expectTypeOf(tempo.charge({ machineTokenEnabled: true })).toHaveProperty('verify')
+  expectTypeOf(tempo.session({ machineTokenEnabled: true })).toHaveProperty('verify')
   expectTypeOf(tempo({ machineTokenEnabled: true })[0]).toHaveProperty('verify')
+  expectTypeOf(tempo({ machineTokenEnabled: true })[1]).toHaveProperty('verify')
 })
 
 test('all server method constructors expose typed canOffer hooks', () => {

src/server/Methods.test.ts

@@ -6,13 +6,13 @@ import { accounts } from '~test/tempo/viem.js'
 const recipient = '0x0000000000000000000000000000000000000001'
 
 describe('Tempo machine token', () => {
-  test('preserves the option on direct and global charge methods', () => {
+  test('preserves the option on charge and session methods', () => {
     const direct = tempo.charge({ machineTokenEnabled: true })
     const [global, session] = tempo({ machineTokenEnabled: true })
 
     expect((direct.defaults as { machineTokenEnabled?: boolean }).machineTokenEnabled).toBe(true)
     expect((global.defaults as { machineTokenEnabled?: boolean }).machineTokenEnabled).toBe(true)
-    expect(session.defaults).not.toHaveProperty('machineTokenEnabled')
+    expect((session.defaults as { machineTokenEnabled?: boolean }).machineTokenEnabled).toBe(true)
   })
 })
 

src/tempo/Methods.test.ts

@@ -263,6 +263,41 @@ describe('session', () => {
     expect(request.methodDetails?.minVoucherDelta).toBe('100000')
   })
 
+  test('schema: binds machine-token capability without changing logical payment fields', () => {
+    const currency = '0x20c0000000000000000000000000000000000001'
+    const recipient = '0x1234567890abcdef1234567890abcdef12345678'
+    const request = Methods.session.schema.request.parse({
+      amount: '1',
+      currency,
+      decimals: 6,
+      machineTokenEnabled: true,
+      recipient,
+      unitType: 'token',
+    })
+
+    expect(request).toMatchObject({
+      currency,
+      methodDetails: { machineTokenEnabled: true },
+      recipient,
+    })
+  })
+
+  test('schema: omits refund-only machine-token credential fields', () => {
+    const authorizationSignature = `0x${'44'.repeat(65)}`
+    const refundSignature = `0x${'22'.repeat(65)}`
+    const credential = Methods.session.schema.credential.payload.parse({
+      action: 'close',
+      authorizationSignature,
+      channelId: `0x${'11'.repeat(32)}`,
+      cumulativeAmount: '100000',
+      refundSignature,
+      signature: `0x${'33'.repeat(65)}`,
+    })
+
+    expect(credential).not.toHaveProperty('authorizationSignature')
+    expect(credential).not.toHaveProperty('refundSignature')
+  })
+
   test('schema: preserves precompile session snapshots in method details', () => {
     const sessionSnapshot = {
       acceptedCumulative: '2',

src/tempo/Methods.ts

@@ -256,6 +256,7 @@ export const session = Method.from({
               z.transform((v): boolean => (typeof v === 'object' ? true : v)),
             ),
           ),
+          machineTokenEnabled: z.optional(z.boolean()),
           minVoucherDelta: z.optional(z.amount()),
           operator: z.optional(z.address()),
           recipient: z.optional(z.string()),
@@ -280,6 +281,7 @@ export const session = Method.from({
           decimals,
           escrowContract,
           feePayer,
+          machineTokenEnabled,
           minVoucherDelta,
           operator,
           sessionProtocol,
@@ -302,6 +304,7 @@ export const session = Method.from({
             }),
             ...(chainId !== undefined && { chainId }),
             ...(feePayer !== undefined && { feePayer }),
+            ...(machineTokenEnabled !== undefined && { machineTokenEnabled }),
             ...(operator !== undefined && { operator }),
             ...(sessionProtocol !== undefined && {
               [Constants.MethodDetailKeys.sessionProtocol]: sessionProtocol,

src/tempo/internal/defaults.ts

@@ -27,10 +27,17 @@ export const machineToken = {
     token: '0x20C0000000000000000000003793c39601711f19',
   },
   [chainId.testnet]: {
-    swap: '0x07f1FE0467Ae01DE340024aa4b7DD9729b1c169b',
-    token: '0x20c000000000000000000000f85bbCa724044De0',
+    feeToken: tokens.pathUsd,
+    session: true,
+    swap: '0x0EdC4d63Daf0FdeA89C95357eC85D6Fc2eD41cB8',
+    token: '0x20c00000000000000000000004645c8f96629cE6',
   },
-} as const satisfies Partial<Record<ChainId, { swap: `0x${string}`; token: `0x${string}` }>>
+} as const satisfies Partial<
+  Record<
+    ChainId,
+    { feeToken?: `0x${string}`; session?: true; swap: `0x${string}`; token: `0x${string}` }
+  >
+>
 
 /**
  * Default token decimals for TIP-20 stablecoins (e.g. pathUSD, USDC).

src/tempo/internal/machine-token.test.ts

@@ -10,6 +10,7 @@ const deployment = defaults.machineToken[chainId]
 const targetToken = '0x20c0000000000000000000000000000000000001'
 const recipient = '0x2222222222222222222222222222222222222222'
 const payer = '0x1111111111111111111111111111111111111111'
+const sessionPayee = '0x44d7c1edfdfdfdfdfdfdfdfd0000000000000001'
 const memo = `0x${'ab'.repeat(32)}` as const
 const client = createClient({
   transport: custom({ request: async () => undefined as never }),
@@ -176,4 +177,145 @@ describe('Tempo machine token', () => {
       }),
     ).toBeUndefined()
   })
+
+  test('resolves active session routes without exposing them to merchant configuration', async () => {
+    vi.resetModules()
+    vi.doMock('viem/actions', () => ({
+      call: vi.fn(),
+      readContract: vi.fn(async (_client, parameters: { functionName: string }) => {
+        if (parameters.functionName === 'sessionRouteFor') return sessionPayee
+        if (parameters.functionName === 'sessionRoutes') return [recipient, targetToken]
+        throw new Error(`unexpected function ${parameters.functionName}`)
+      }),
+    }))
+
+    try {
+      const MachineToken = await import('./machine-token.js')
+      await expect(
+        MachineToken.findSessionRoute(client, {
+          chainId,
+          merchant: recipient,
+          targetToken,
+        }),
+      ).resolves.toEqual({
+        merchant: recipient,
+        operator: deployment.swap,
+        payee: sessionPayee,
+        targetToken,
+        token: deployment.token,
+      })
+      await expect(
+        MachineToken.getSessionRoute(client, { chainId, payee: sessionPayee }),
+      ).resolves.toEqual({
+        merchant: recipient,
+        operator: deployment.swap,
+        payee: sessionPayee,
+        targetToken,
+        token: deployment.token,
+      })
+      await expect(
+        MachineToken.findVerifiedSessionRoute(client, {
+          chainId,
+          merchant: recipient,
+          targetToken,
+        }),
+      ).resolves.toEqual(expect.objectContaining({ merchant: recipient, payee: sessionPayee }))
+      await expect(
+        MachineToken.resolveSessionRoute(client, { chainId, payee: sessionPayee }),
+      ).resolves.toEqual({
+        merchant: recipient,
+        operator: deployment.swap,
+        payee: sessionPayee,
+        targetToken,
+        token: deployment.token,
+      })
+      await expect(
+        MachineToken.matchSessionRoute(client, {
+          chainId,
+          descriptor: {
+            operator: deployment.swap,
+            payee: sessionPayee,
+            token: deployment.token,
+          },
+          merchant: recipient,
+          targetToken,
+        }),
+      ).resolves.toEqual(expect.objectContaining({ merchant: recipient, targetToken }))
+      await expect(
+        MachineToken.matchSessionRoute(client, {
+          chainId,
+          descriptor: {
+            operator: deployment.swap,
+            payee: sessionPayee,
+            token: deployment.token,
+          },
+          merchant: payer,
+          targetToken,
+        }),
+      ).resolves.toBeUndefined()
+      expect(MachineToken.isSessionSupported(chainId)).toBe(true)
+      expect(MachineToken.isSessionSupported(defaults.chainId.mainnet)).toBe(false)
+      expect(MachineToken.getSessionFeeToken(chainId)).toBe(defaults.tokens.pathUsd)
+      expect(MachineToken.getSessionFeeToken(defaults.chainId.mainnet)).toBeUndefined()
+    } finally {
+      vi.doUnmock('viem/actions')
+      vi.resetModules()
+    }
+  })
+
+  test('separates the challenge capability flag from the trusted descriptor pair', async () => {
+    const MachineToken = await import('./machine-token.js')
+    expect(
+      MachineToken.isSessionEnabledChallenge({
+        request: { methodDetails: { chainId, machineTokenEnabled: true } },
+      }),
+    ).toBe(true)
+    expect(
+      MachineToken.isSessionEnabledChallenge({
+        request: { methodDetails: { chainId, machineTokenEnabled: false } },
+      }),
+    ).toBe(false)
+    expect(
+      MachineToken.matchSessionDescriptor({
+        chainId,
+        descriptor: { operator: deployment.swap, token: deployment.token },
+      }),
+    ).toEqual(deployment)
+    expect(
+      MachineToken.matchSessionDescriptor({
+        chainId,
+        descriptor: { operator: recipient, token: deployment.token },
+      }),
+    ).toBeUndefined()
+  })
+
+  test('rejects virtual payees that are no longer the active merchant route', async () => {
+    vi.resetModules()
+    vi.doMock('viem/actions', () => ({
+      call: vi.fn(),
+      readContract: vi.fn(async (_client, parameters: { functionName: string }) => {
+        if (parameters.functionName === 'sessionRoutes') return [recipient, targetToken]
+        if (parameters.functionName === 'sessionRouteFor')
+          return '0x0000000000000000000000000000000000000000'
+        throw new Error(`unexpected function ${parameters.functionName}`)
+      }),
+    }))
+
+    try {
+      const MachineToken = await import('./machine-token.js')
+      await expect(
+        MachineToken.resolveSessionRoute(client, { chainId, payee: sessionPayee }),
+      ).resolves.toBeUndefined()
+      await expect(
+        MachineToken.resolveSessionRoute(client, {
+          active: false,
+          chainId,
+          payee: sessionPayee,
+        }),
+      ).resolves.toEqual(expect.objectContaining({ merchant: recipient, targetToken }))
+    } finally {
+      vi.doUnmock('viem/actions')
+      vi.resetModules()
+    }
+  })
 })