feat: Base Foundry by lukasrosario · Pull Request #16224 · foundry-rs/foundry

lukasrosario · 2026-08-17T23:27:23Z

Motivation

Add support for Base precompiles + EVM following the precedent set by Monad support (#15343), building on shared native-network abstractions that landed with it.

Solution

Adds a non-default base feature providing BaseEvmNetwork and BaseEvmFactory on top of Base's own base-common-evm and BasePrecompiles, so execution semantics come from Base rather than a reimplementation in Foundry, and routes Base through Forge, Cast, Script, Chisel, Verify, and Anvil without any Ethereum or generic OP fallback.

Highlights:

Upgrade-gated precompiles. Azul excludes Beryl's set; Beryl installs the activation registry, B-20 factory, and policy registry with a chain-resolved activation admin; Cobalt adds the EIP-8130 nonce manager and transaction context. Tests assert the upgrades are behaviorally distinguishable rather than merely configured.
Anvil. Base-native execution with the complete post-Cobalt EIP-8130 surface: RPC, receipts carrying payer, metadata, and phaseStatuses, txpool lane replacement, expiry, payer reservations and replay protection, tracing, and lifecycle operations.
Deterministic replay. Fixtures captured once from Base mainnet across Jovian, Azul, and Beryl re-execute locally and compare status, gas, logs, L1 fee accounting, and touched-account deltas against node-reported values. No RPC at test time.
Trace decoding. The five fixed precompiles register labels and ABIs per address, gated on the upgrade that installs each. The B-20 token surface is registered globally by selector, as Tempo does for TIP20, since tokens live at factory-derived addresses. It deliberately omits the ERC-20, EIP-2612, and AccessControl members: the global map is not network-scoped, so competing candidates for transfer or balanceOf could change how ordinary token traces decode on other networks. A test pins that exclusion.
Code sentinel on state-holding precompiles. Solidity guards high-level calls to functions returning no data with an extcodesize check, which a code-less precompile fails in the caller. Base's 0xEF EIP-3541 sentinel is planted on the installed precompiles in both Anvil genesis and the executor, matching what Base's own tests expect a harness to do.
CI. A reusable base.yml mirroring monad.yml, wired into ci.yml as a required check, plus a Base+Optimism build and an explicit base_replay run because --lib skips that target.

Changes beyond the `base` feature

Four parts of this PR affect builds that don't enable base:

--hardfork on EvmArgs (crates/cli/src/opts/evm.rs) is a new shared flag for forge, cast, chisel, and script. It surfaces the existing Config::hardfork key, which previously could only be set in foundry.toml. Namespaced values such as base:Beryl or monad:MonadNine go through the existing FoundryHardfork parser.
Network inference in cast tx and cast block --raw. Both now resolve the network family rather than requiring an explicit --network, so Base deposit and EIP-8130 transactions decode by default. When neither --network nor a configured chain identifies the network, this costs one eth_chainId request; previously both defaulted to Ethereum with no round trip. Resolution now also reports a family that isn't compiled into the binary as an error, so these commands agree with cast call.
Monad in Cast's network dispatch. Making that dispatch exhaustive removed the _ catch-all Monad relied on, so both sites carry explicit NetworkVariant::Monad arms that use the Ethereum-typed provider. Behavior for Monad is unchanged.
Release binaries build with the base feature (.github/workflows/release.yml), matching how monad and optimism ship.

PR Checklist

Added Tests
Added Documentation
Breaking changes

github-actions · 2026-08-17T23:27:33Z

✅ Changelog found

The deterministic check will validate the changed entry.

mablr

Hi @lukasrosario 👋

It already looks pretty good overall.

We are currently doing some post Monad clean-ups to fix several design footguns, ideally by the end of the week, only after we will able to start deep reviewing process.

The 2 main requirements we want to strongly enforce for external chains:

complete/robust feature gating, no logic, structure, or anything else should leak
FoundryEvmNetwork/FoundryEvmFactory/NestedEvm surface must stay as pre-#15343, no chain-specific methods or types will be accepted except if very very well justified/documented and contained. Specific custom evm logic must go behind FoundryContextExt.

Some merge conflicts may appear due to clean-ups, I'll notice you when stabilized. In the meantime please check the 2 requirements above are properly enforced.

lukasrosario · 2026-08-19T21:09:15Z

thanks @mablr ! did another pass & pushed up a few changes, should be abiding by both requirements now. lmk when cleanup is done & will rebase

mablr · 2026-08-20T17:24:45Z

Nice!

After internal discussion, we will certainly ship this integration in several steps by cherry-pick from current PR. This will reduce round-trips.

lukasrosario · 2026-08-27T14:09:09Z

@mablr sounds good let me know if you need me to assist with anything. will leave the PR as is for now

figtracer · 2026-08-28T11:07:15Z

@mablr sounds good let me know if you need me to assist with anything. will leave the PR as is for now

we'll come back to this next week

stevencartavia · 2026-08-31T14:46:46Z

@lukasrosario, several shared changes that this implementation can build on have now landed: #16406, #16407, #16415, #16417, #16419, #16420, #16438, #16443, #16448, #16449, #16450, and #16458.

lukasrosario · 2026-08-31T18:32:41Z

@stevencartavia thank you, i'll rebase now

lukasrosario · 2026-09-01T17:31:53Z

@stevencartavia @figtracer @mablr just rebased, should be good now. lmk anything else

lukasrosario · 2026-09-02T22:08:16Z

looks like some new conflicts, rebasing again now

lukasrosario · 2026-09-10T14:21:08Z

on it

Skip network discovery in curl mode and allow RPC commands without a compiled local EVM. Honor configured networks during DA estimation and reject unsupported Base blob options before transaction construction. Add regression coverage for curl output, network precedence, feature combinations, blob rejection, and transaction encoding. Repair the Base-disabled call test to use the current network API.

lukasrosario · 2026-09-10T21:12:46Z

@mablr looks like reth doesn't yet have a release on 43, i think we'd need to wait for that on the base/base side

Pin Base dependencies to the Foundry fork at 2aa8bc46e6b4272ef3bf0905e1a5660ee2525e72 and allow its source in deny.toml. Remove the obsolete revm 42 dependency graph while preserving unrelated lockfile resolutions. AI-assisted dependency update.

mablr · 2026-09-11T08:20:14Z

Moved to our own fork https://github.com/foundry-rs/base/tree/mablr/revm-43

Accept serializable receipt logs to preserve Base timestamp fields. Move EIP-8130 transaction and RPC gates to Zenith while retaining Cobalt precompile activation, and map Denim and Zenith to Osaka. Update regression coverage and the Base changelog entry. AI-assisted.

Import Base types directly where names are unambiguous and replace qualified Base references with feature-gated imports. Retain aliases for name collisions.

Expose the selected network type through the provider dispatch macro so raw header encoding can select the consensus header inline. AI-assisted.

Inline activation-admin resolution and sentinel planting, and accept BaseUpgrade directly in the shared sentinel selector. Focus adapter tests on constructor behavior and halt conversion. AI-assisted.

Adopt the shared transaction network resolver from foundry-rs#16790 for Base dispatch. Report Base hardfork metadata through the concrete execution spec and resolve active trace labels using foundry-rs#16789's shared path. Preserve Base-only feature gates and extend focused regression coverage. AI-assisted

lukasrosario · 2026-09-11T13:15:28Z

@mablr what's the plan for this going forward? will you all continue to maintain that fork and bump deps accordingly before we pull them into base/base?

Disambiguate Base and Tempo request fields while preserving existing routing for ambiguous untyped requests. Project EIP-8130 transactions into simulation requests, reuse supplied encoded bytes, and preserve phase statuses through RPC receipt conversions and JSON roundtrips. Share deposit helpers between Base and Optimism and rationalize regression coverage across feature configurations.

mablr · 2026-09-11T14:01:08Z

@lukasrosario Not so far, I'd like to extract a minimal shippable scope from here (1 or 2 smaller PRs) today (current PR stays the working branch).

Basically if we leave anvil behind for next week, it's 90% ready. Pushing hard on the review, I'll tag you once minimal scope PR(s) are open.

mablr · 2026-09-11T14:03:09Z

It's fine for us to maintain a lean fork https://github.com/foundry-rs/base until your reth is fully bumped (it's even better for our supply chain sec tbh).

Ofc it would help us a lot if u maintain base/base frequently (revm/alloy bumps right after releases)

Retain Base EIP-8130 admission checks alongside upstream Tempo pool validation. Use genesis configuration for the Zenith nonce-manager transition, since ChainUpgrades excludes Zenith, and mark ambiguous Base simulation fixtures with their explicit transaction type.

lukasrosario · 2026-09-11T15:50:39Z

makes sense, thanks

mablr · 2026-09-11T17:00:55Z

@lukasrosario I've just opened #16809, which lands all what I reviewed/approved (basically everything except Anvil). Once merged, I'll rebase current PR and rescope it to land Anvil.

lukasrosario · 2026-09-11T17:22:50Z

cool sgtm, thanks!

github-project-automation Bot added this to Foundry Aug 17, 2026

lukasrosario marked this pull request as ready for review August 18, 2026 19:35

lukasrosario requested review from 0xrusowsky, DaniPopes, figtracer, grandizzy, mablr, mattsse and stevencartavia as code owners August 18, 2026 19:35

mablr reviewed Aug 19, 2026

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lukasrosario force-pushed the lukas/base-foundry branch 2 times, most recently from fa31e05 to 99381b7 Compare September 1, 2026 13:58

lukasrosario force-pushed the lukas/base-foundry branch from c8e73ac to 399ef8d Compare September 1, 2026 19:56

stevencartavia reviewed Sep 1, 2026

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Comment thread crates/common/fmt/src/ui.rs Outdated

stevencartavia reviewed Sep 1, 2026

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Comment thread crates/anvil/src/eth/backend/mem/mod.rs Outdated

lukasrosario force-pushed the lukas/base-foundry branch 3 times, most recently from cd8fffe to c988b70 Compare September 3, 2026 15:21

lukasrosario requested a review from stevencartavia September 3, 2026 16:41

lukasrosario added 2 commits September 3, 2026 20:34

rebase

4204d09

fix

ab8daeb

mablr added 2 commits September 10, 2026 15:07

chore: update Cargo.lock

c81a56f

style: organize Rust imports

d9e8b44

fix: use Base fork with revm 43

48b672e

Pin Base dependencies to the Foundry fork at 2aa8bc46e6b4272ef3bf0905e1a5660ee2525e72 and allow its source in deny.toml. Remove the obsolete revm 42 dependency graph while preserving unrelated lockfile resolutions. AI-assisted dependency update.

mablr added 6 commits September 11, 2026 10:29

Merge branch 'master' into lukas/base-foundry

62c5ba4

refactor(base): unify imports

e9df862

Import Base types directly where names are unambiguous and replace qualified Base references with feature-gated imports. Retain aliases for name collisions.

refactor(cast): inline block header encoding

2cc71bc

Expose the selected network type through the provider dispatch macro so raw header encoding can select the consensus header inline. AI-assisted.

refactor(base): simplify EVM adapter setup

8f13e0d

Inline activation-admin resolution and sentinel planting, and accept BaseUpgrade directly in the shared sentinel selector. Focus adapter tests on constructor behavior and halt conversion. AI-assisted.

mablr self-assigned this Sep 11, 2026

mablr added 4 commits September 11, 2026 16:28

fix(traces): scope B20 ABI fallbacks to Base

3d303cf

fix(traces): harden Base ABI decoding

5d43c0a

fix(evm): preserve OP hardfork discovery

3c42733

mablr added 2 commits September 11, 2026 17:58

fix: preserve fee and blob rules

688fb0a

Merge branch 'master' into lukas/base-foundry

9c212c8

mablr mentioned this pull request Sep 11, 2026

feat: add Base support MVP #16809

Open

mablr marked this pull request as draft September 11, 2026 16:56

Merge branch 'master' into lukas/base-foundry

e012a80

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Motivation

Solution

Changes beyond the base feature

PR Checklist

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github-actions Bot commented Aug 17, 2026

✅ Changelog found

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lukasrosario commented Aug 17, 2026 •

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Changes beyond the `base` feature

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