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Channel Chaining

Create agent supply chains where services pay sub-services from the same budget.

Channel chaining enables value flow through a chain of services. When Service B needs to call Service C to fulfill a request, Service B can create a downstream channel funded from the upstream channel — no separate capital required.

The problem

Agent A ──$10──→ Service B (inference API)
                    ├── needs Service C (GPU) — costs $3
                    └── needs Service D (data) — costs $1
 
Without chaining: Service B needs its own $4 to pay C and D
With chaining: Service B forwards from Agent A's channel

How it works

  1. Agent A opens a channel with Service B ($10 deposit)
  2. Service B creates a downstream channel to Service C ($3 from upstream)
  3. Service B creates another downstream channel to Service D ($1 from upstream)
  4. Agent A's channel now has $6 available for Service B, $3 allocated to C, $1 to D
  5. When downstream channels close, remaining funds return to Service B's balance

Creating a downstream channel

await program.methods
  .chainChannel(
    new BN(3_000_000),  // $3 from upstream
    new BN(3_000_000),  // rate limit
    new BN(60),          // settle interval
    new BN(Date.now())   // nonce
  )
  .accounts({
    upstreamRecipient: serviceB.publicKey,
    upstreamChannel: upstreamPDA,
    upstreamVault: upstreamVaultPDA,
    downstreamRecipient: serviceC.publicKey,
    mint,
    downstreamChannel: downstreamPDA,
    downstreamVault: downstreamVaultPDA,
    systemProgram: SystemProgram.programId,
    tokenProgram: TOKEN_PROGRAM_ID,
  })
  .signers([serviceB])
  .rpc()

Chain depth limits

Chains have a maximum depth (default: 3) to prevent infinite chains:

  • Depth 0: Agent → Service (root channel)
  • Depth 1: Service → Sub-service
  • Depth 2: Sub-service → Sub-sub-service

The root channel funder sets max_chain_depth at channel open.

Closing chained channels

Closing works bottom-up:

  1. Leaf channels (no children) must close first
  2. Remaining balance from a downstream channel returns to the upstream vault
  3. Once all children are closed, the parent can close

Next steps