Fix eth_simulateV1 after Jovian fork

[kustrun]

After the Jovian fork, all eth_simulateV1 calls fail with the error: "error calculating DA footprint: missing deposit transaction".

The root cause is in CalcDAFootprint(), which assumes that a deposit transaction exists at txs[0] and that it contains the daFootprintGasScalar data. This value is required to calculate the rollup gas costs.

The proposed solution modifies ONLY eth_simulateV1 by injecting a synthetic Jovian deposit transaction before the user-provided simulation transactions. This allows CalcDAFootprint() to succeed while keeping the core block-processing logic unchanged, ensuring that simulations work without affecting normal execution.

[geoknee]

Could you comment about your use case here? In what context are you running these simulations?

[RealJohnnyTime]

+1
This is critical for accurately simulating transactions in backrunning strategies on OP Stack–based EVM chains. Many existing backrunners are currently broken because of this.

[kustrun]

@geoknee apologies for the delayed reply, was AFK. As @RealJohnnyTime mentioned, any transaction simulation currently fails (my specific use case is tx bundle simulation). Below is an example payload that reproduces the issue, in case it helps with diagnosing and resolving it.

For now, I'm using a quick workaround with an artificial Jovian transaction until we settle on a proper solution.

  curl -X POST \
    -H "Content-Type: application/json" \
    --data '{
      "jsonrpc": "2.0",
      "id": 1,
      "method": "eth_simulateV1",
      "params": [
        {
          "blockStateCalls": [
            {
              "stateOverrides": {
                "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045": {
                  "balance": "0x21e19e0c9bab2400000"
                }
              },
              "calls": [
                {
                  "from": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
                  "to": "0x4200000000000000000000000000000000000015",
                  "value": "0x0"
                }
              ]
            }
          ],
          "validation": false
        },
        "latest"
      ]
    }' \
    <YOUR_OP_STACK_RPC_URL>

[geoknee]

Thanks for the context @kustrun. I'll take another quick look and may push some commits to your branch.

[geoknee]

/ci authorize f2b3a69

[geoknee]

Adding an acceptance test to the monorepo here ethereum-optimism/optimism#18724.

[kustrun]

Tested the fix on the live node, and it’s resolving the bug. I really like the clean, minimal solution we arrived at!