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SDM is not yet live. Stock public op-reth supports the SDM consensus and verification mechanism, but it does not implement a refund-producing policy. Enabling its operator gate does not cause it to issue refunds or append post-exec transactions.
This guide covers the operator control surface for Sequencer Defined Metering (SDM): turning it on, confirming it, and turning it off. For what SDM does and what changes on your chain when it activates, see the SDM explainer.

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Before you start

Run versions of op-reth, and of op-node or kona-node, that implement the Lagoon hardfork. Verifier operators do not opt in to anything and have no SDM configuration. If you run verifier nodes only, running up-to-date software is all you need to do, and the rest of this page does not apply to you.

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Chain operator opt-in

A sequencer appends a post-exec transaction only if Lagoon is active at the block’s timestamp and the operator has opted in on that node. If either is false, the node builds blocks under legacy gas accounting and appends nothing. The opt-in can be set before or after Lagoon, and does nothing until Lagoon activates. You do not have to time it, and nothing needs changing at the activation itself. It can be set three ways: The RPC only changes the value in memory. A restart loses it, and a standby sequencer that takes over starts from its own configuration. Set the CLI flag or environment variable for the value you want to stick, and use the RPC when you need to change it without restarting.

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Confirming which gate is holding

admin_sdmStatus reports both gates. It takes an optional query timestamp and defaults to the current time. On a sequencer that has opted in while Lagoon is still unscheduled:
admin_sdmStatus
effective is the AND of the two gates, and is the field that tells you whether the node is producing rebates. activationTime is the Lagoon activation timestamp once one is scheduled, and null before that. To inspect a receipt produced by an SDM-enabled sequencer:
Inspect a receipt
You can also fetch the containing block and check whether its last transaction has type 0x7D. A block without rebates has no post-exec transaction, so absence alone does not tell you whether the protocol is active. Check admin_sdmStatus instead.

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Disabling SDM

To stop a sequencer issuing rebates:
  1. Call admin_setOperatorSdmOptIn(false) on it. This applies from the next payload and needs no restart.
  2. Check admin_sdmStatus to confirm effective is now false.
  3. Set OP_RETH_OPERATOR_SDM_OPT_IN=false (or the CLI flag) in the deployment, or a restart will turn it back on.
This only affects blocks the sequencer builds from then on. Post-exec transactions already in the chain stay valid and verifiers keep validating them, so there is nothing to coordinate with verifier operators and no config or hardfork change to make.

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Stock op-reth production behavior

Released public op-reth uses a null refund policy. It never creates a non-empty refund payload and never appends a post-exec transaction, even when Lagoon is active and admin_setOperatorSdmOptIn(true) has been called. The admin surface remains available for protocol compatibility and downstream sequencer integrations; it is not a policy-selection interface in stock op-reth.

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Refund policies and OP Enterprise

Refund policies are tuned to a chain’s needs, and are a premium feature for OP Enterprise customers. The policy is what decides which transactions get rebated and by how much, so it varies from sequencer to sequencer. If you are interested in becoming an OP Enterprise customer, contact the OP Enterprise team.

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Debug replay

debug_replaySDMBlock is an operator and research diagnostic. It re-executes a historical block’s non-post-exec transactions under standard gas accounting to recover each transaction’s raw (pre-rebate) gas, reports that alongside the block’s claimed refunds, and flags any claim that breaks the spec’s validity rules. It does not recompute what the refunds should have been: that requires the sequencer’s policy, which stock op-reth does not implement. The endpoint requires historical state and should not be exposed on public RPC interfaces.

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Next steps