Accept Delegated Payments

Let agents delegate channel budget to sub-agents.

Delegation lets an agent assign a portion of its channel budget to another keypair. The delegate can consume services against the channel up to a specified limit — no separate capital required.

How it works

1. Agent A opens a channel with $10
2. Agent A delegates $3 to Agent B's pubkey
3. Agent B makes requests using Agent A's channel, signing with its own key
4. The server verifies Agent B's signature against the channel's delegate field

Setting a delegate

import { Keypair } from "@solana/web3.js"
 
// Agent A's channel is already open
const subAgentKeypair = Keypair.generate()
 
await program.methods
  .setDelegate(subAgentKeypair.publicKey, new BN(3_000_000)) // $3 limit
  .accounts({
    funder: agentA.publicKey,
    channelState: channelPDA,
  })
  .signers([agentA])
  .rpc()

Sub-agent consumption

The sub-agent signs requests with its own keypair. The server checks the delegate field of the on-chain ChannelState:

// Sub-agent signs seq numbers with its own key
const seqBuf = Buffer.alloc(8)
seqBuf.writeBigUInt64LE(BigInt(seq))
const sig = nacl.sign.detached(seqBuf, subAgentKeypair.secretKey)
 
// Send request with the same channel PDA
fetch("https://api.example.com/v1/data", {
  headers: {
    "AMP-Channel": channelPDA.toBase58(),
    "AMP-Seq": seq.toString(),
    "AMP-Sig": bs58.encode(sig),
  },
})

Server-side validation

The server middleware automatically checks both the funder and delegate pubkeys when verifying signatures. No additional server configuration is needed.

On-chain state

The ChannelState PDA stores:

Next steps

• Channel chaining →
• Delegation protocol details →