"mev_simBundle" rpc method for enhanced transaction simulation

[zently]

Describe the feature

mev_simBundle is a rpc endpoint spec used for simulating a bundle in the virtual environment.
First introduced by the flashbot, it is widely recognized as THE BEST way to simulate a bundle (possibly multiple tx)

Currently eth_callBundle works well for similar purpose but mev_simBundle is better in that,
it returns transaction logs of the simulated transaction.

Having transaction logs is critical in multiple occasions such as,

• Pre-validating transaction before sending real transaction (for protection, test)
• Test / debugging contract
• Searchers checking whether specific pending transaction yields specific action (e.g. token transfer, swap)

Currently, within "mev.rs" struct for the mev_simBundle is already defined fully,
while its implementation is missing in the "bundle.rs".

Additional context

Flashbots document

[mattsse]

not opposed to this because I see this being useful and only does simulation
I think the reference impl is

https://github.com/flashbots/builder/blob/df9c765067d57ab4b2d0ad39dbb156cbe4965778/internal/ethapi/sbundle_api.go#L205

https://github.com/flashbots/builder/blob/df9c765067d57ab4b2d0ad39dbb156cbe4965778/core/sbundle_sim.go#L58

TODO

• add new mev namespace
• port simBundle function

[kien6034]

hello, can i work on this issue?

[mattsse]

yes please,

for ref ptal at the call_bundle impl:

reth/crates/rpc/rpc/src/eth/bundle.rs

Line 51 in df9cb81

pub async fn call_bundle(&self, bundle: EthCallBundle) -> EthResult<EthCallBundleResponse> {

[kien6034]

@mattsse
thank you sir

[jekkos]

Any progress on this? It would be nice to have the tx logs in the callbundle result. This used to be possible in a patched version of mev-geth as well.

[SkandaBhat]

@mattsse if there have been no updates on this, I would like to pick this up. Could you please assign this to me?

[mattsse]

cool @SkandaBhat this should be similar to ethcallBundle impl, so please follow that impl and we can also do this in incremental steps, like first add the type and a basic impl, then port the existing go impl 1:1

[SkandaBhat]

Working on the impl, will share a draft soon!

[SkandaBhat]

@mattsse We need to implement Bundle inside BundleItem in https://github.com/alloy-rs/alloy/blob/8d99c28da17232a26afe7af0251fde2cd00a89fe/crates/rpc-types-mev/src/mev_calls.rs#L83. I can implement and raise a PR over there

Issue created: alloy-rs/alloy#1416