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Supersim fork mode to simulate and interact with the state of the chain without needing to re-deploy or modify the contracts. This is possible if you’re relying on contracts already deployed on testnet / mainnet chains. 
supersim fork

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How it works

The supersim fork command simplifies the process of forking multiple chains in the Superchain ecosystem simultaneously. It determines the appropriate block heights for each chain and launches both the L1 and L2 chains based on these values. This allows you to locally fork any chain in a superchain network of the superchain registry, default mainnet versions.

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Example startup logs

Available Accounts
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(0): 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266
--- truncated for brevity ---

Private Keys
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(0): 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80
--- truncated for brevity ---

Orchestrator Config:
L1:
  Name: mainnet    Chain ID: 1    RPC: http://127.0.0.1:8545    LogPath: /var/folders/0w/ethers-phoenix/T/anvil-chain-1-1521250718
L2:
  Name: op    Chain ID: 10    RPC: http://127.0.0.1:9545    LogPath: /var/folders/0w/ethers-phoenix/T/anvil-chain-10
  Name: base    Chain ID: 8453    RPC: http://127.0.0.1:9546    LogPath: /var/folders/0w/ethers-phoenix/T/anvil-chain-8453
  Name: zora    Chain ID: 7777777    RPC: http://127.0.0.1:9547    LogPath: /var/folders/0w/ethers-phoenix/T/anvil-chain-7777777

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Configuration

NAME:
   supersim fork - Locally fork a network in the superchain registry

USAGE:
   supersim fork [command options]

OPTIONS:

          --l1.fork.height value              (default: 0)                       ($SUPERSIM_L1_FORK_HEIGHT)
                L1 height to fork the superchain (bounds L2 time). `0` for latest

          --chains value                                                         ($SUPERSIM_CHAINS)
                chains to fork in the superchain, mainnet options: [arena-z, automata, base,
                bob, cyber, ethernity, funki, hashkeychain, ink, lisk, lyra, metal, mint, mode,
                op, orderly, polynomial, race, redstone, shape, soneium, sseed, swan, swell, tbn,
                unichain, worldchain, xterio-eth, zora]. In order to replace the public rpc endpoint
                for a chain, specify the ($SUPERSIM_RPC_URL_<CHAIN>) env variable. i.e
                SUPERSIM_RPC_URL_OP=http://optimism-mainnet.infura.io/v3/<API-KEY>

          --network value                     (default: "mainnet")               ($SUPERSIM_NETWORK)
                superchain network. options: mainnet, sepolia, sepolia-dev-0. In order to
                replace the public rpc endpoint for the network, specify the
                ($SUPERSIM_RPC_URL_<NETWORK>) env variable. i.e
                SUPERSIM_RPC_URL_MAINNET=http://mainnet.infura.io/v3/<API-KEY>

          --interop.enabled                   (default: true)                    ($SUPERSIM_INTEROP_ENABLED)
                enable interop predeploy and functionality

          --admin.port value                  (default: 8420)                    ($SUPERSIM_ADMIN_PORT)
                Listening port for the admin server

          --interop.l2tol2cdm.override value                                     ($SUPERSIM_INTEROP_L2TO2CDM_OVERRIDE)
                Path to the L2ToL2CrossDomainMessenger build artifact that overrides
                the default implementation

          --l1.port value                     (default: 8545)                    ($SUPERSIM_L1_PORT)
                Listening port for the L1 instance. `0` binds to any available port

          --l2.count value                    (default: 2)                       ($SUPERSIM_L2_COUNT)
                Number of L2s. Max of 5

          --l2.starting.port value            (default: 9545)                    ($SUPERSIM_L2_STARTING_PORT)
                Starting port to increment from for L2 chains. `0` binds each chain to any
                available port

          --interop.autorelay                 (default: false)                   ($SUPERSIM_INTEROP_AUTORELAY)
                Automatically relay messages sent to the L2ToL2CrossDomainMessenger using
                account 0xa0Ee7A142d267C1f36714E4a8F75612F20a79720

          --interop.delay value               (default: 0)                       ($SUPERSIM_INTEROP_DELAY)
                Delay before relaying messages sent to the L2ToL2CrossDomainMessenger

          --logs.directory value                                                 ($SUPERSIM_LOGS_DIRECTORY)
                Directory to store logs

          --l1.host value                     (default: "127.0.0.1")             ($SUPERSIM_L1_HOST)
                Host address for the L1 instance

          --l2.host value                     (default: "127.0.0.1")             ($SUPERSIM_L2_HOST)
                Host address for L2 instances

          --odyssey.enabled                   (default: false)                   ($SUPERSIM_ODYSSEY_ENABLED)
                Enable odyssey experimental features

          --dependency.set value                                                 ($SUPERSIM_DEPENDENCY_SET)
                Override local chain IDs in the dependency set.(format: '[901,902]' or '[]')

          --log.level value                   (default: INFO)                    ($SUPERSIM_LOG_LEVEL)
                The lowest log level that will be output

          --log.format value                  (default: text)                    ($SUPERSIM_LOG_FORMAT)
                Format the log output. Supported formats: 'text', 'terminal', 'logfmt', 'json',
                'json-pretty',

          --log.color                         (default: false)                   ($SUPERSIM_LOG_COLOR)
                Color the log output if in terminal mode

          --log.pid                           (default: false)                   ($SUPERSIM_LOG_PID)
                Show pid in the log

          --help, -h                          (default: false)
                show help

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Notes

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Fork height

The fork height is determined by L1 block height (default latest). This is then used to derive the corresponding L2 block to start from.

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Interoperability contracts

By default, interop contracts are not deployed on forked networks. To include them, run supersim with the --interop.enabled flag. 
supersim fork --chains=op,base,zora --interop.enabled

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Next steps

  • Explore the Supersim included contracts being used to help replicate the Superchain environment.
  • Learn how to deposit transactions with Supersim, using a much simpler approach that bypasses the derivation pipeline.
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