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A commitment is the signed off-chain message that moves a payment channel forward. It is the unilateral hot-path primitive in Agon V4 and the building block underneath every settlement mode.

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What a commitment represents

A commitment does not say “charge 25 more.” It says: “this channel is now authorized up to cumulative amount X.” Concretely, an agon-cmt-v5 message carries:
  • the deployment-scoped message_domain
  • the payer_id and payee_id
  • the token_id
  • a new committed_amount (cumulative, not incremental)
  • an optional authorized_settler
  • an Ed25519 signature by the channel’s current authorized_signer
When a payee settles the commitment on-chain, the program computes the delta against the channel’s current settled_cumulative and moves only that difference. Everything about the commitment that is not the delta is bookkeeping. For the exact byte layout, see Message formats.

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Why cumulative

Cumulative commitments have two practical consequences:
  1. The payee only needs the newest valid message. Intermediate commitments are superseded automatically. A payee can throw away older commitments as soon as a newer one arrives.
  2. Replay is monotonic and trivial to check. The program rejects any commitment whose committed_amount is less than or equal to the current settled_cumulative.
This is what lets one settlement transaction discharge many underlying payments.

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How commitments are issued

const channel = await program.account.channelState.fetch(channelPda);

const delta = new anchor.BN(250_000);
const committedAmount = channel.settledCumulative.add(delta);

const message = createCommitmentMessage({
  payerId: channel.payerId,
  payeeId: channel.payeeId,
  tokenId,
  committedAmount,
  messageDomain,
});

const signature = ed25519Sign(message, channel.authorizedSigner);
The signer above must match the channel’s current authorized_signer. The signature is verified by Solana’s Ed25519 program as a prefix instruction on the settlement transaction. See Your first payment for working code that builds and settles a commitment end-to-end.

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Off-chain lifecycle

Commitments live off-chain until settlement. Most integrations keep:
  1. the latest signed agon-cmt-v5 per channel
  2. local usage or metering state
  3. policy for when to sign the next commitment
Older commitments can be discarded. Only the newest valid one needs to reach the chain.

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What commitments do not encode

Commitments are deliberately minimal. They do not encode:
  • per-call pricing or metadata
  • fees to operators or coordinators
  • dispute or escape conditions
  • payee-side policy
Those concerns live in the application layer, in operator software, or in a separate channel. For operator compensation specifically, see Operator payment is separate.

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Commitments inside cooperative rounds

In a cooperative round, each channel’s cumulative target is still expressed the same way, but the target is carried inside a shared agon-round-v4 message signed by the participant roster instead of a standalone agon-cmt-v5. The channel semantics are identical: the program advances settled_cumulative to the signed target and applies the resulting balance changes. The difference is that cooperative rounds let many channels advance together and net against each other before participant balances are touched. See Clearing rounds for the full cooperative flow.

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See also