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Normative spec: This upgrade is normatively defined in the Lagoon specification. This page records activation data and operational pointers; it does not restate the spec. The Lagoon spec is not yet finalized.
Lagoon is the upcoming hardfork that activates Superchain interop. No superchain-wide activation defaults are set in the superchain-registry yet; the first activations are being prepared per chain — see the interop activation prep notice for OP Mainnet and Unichain, with OP Sepolia and Unichain Sepolia first.

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What’s included

Per the spec overview (subject to change while the spec is in development):
  • Interop: dependency set, cross-chain messaging, derivation, sequencer and verifier behavior, super roots, interop fault proofs, and the interop bridging contracts.
  • Execution layer: post-execution transactions and sequencer defined metering.