feat: shared economy scenario for block builder contention testing by vbuilder69420 · Pull Request #477 · flashbots/contender

vbuilder69420 · 2026-03-21T23:02:18Z

Summary

A single mega-scenario that deploys an interconnected DeFi economy where 6 actor pools contend on the same contracts, creating realistic block builder ordering problems.

This is fundamentally different from existing scenarios — instead of isolated protocols, all actors compete for the same storage slots with different priority levels, forcing the block builder to resolve contention while maximizing tip revenue.

Architecture

                    ┌──────────────┐
                    │  EconOracle  │ ← oracle_nodes push prices
                    │  (price)     │ ← searchers read + frontrun
                    └──────┬───────┘
                           │ price feeds into
              ┌────────────┼────────────┐
              ▼            ▼            ▼
     ┌────────────┐ ┌────────────┐ ┌────────────────┐
     │  EconAMM   │ │EconLending │ │  EconSearcher  │
     │ reserveA ← │ │collateral← │ │ oracleArb()    │
     │ reserveB ← │ │   debt   ← │ │ liquidateSwap()│
     │ lpShares ← │ │            │ │ tipValidator()  │
     └────────────┘ └────────────┘ └────────────────┘
           ↑               ↑                ↑
     traders          borrowers        searchers
     arbers           liquidators     (high tips to
     lps                              block.coinbase)

6 Actor Pools (competing on shared state)

Pool	Actions	Priority	Contention
`traders`	AMM swaps	Low	AMM reserves, token balances
`borrowers`	deposit/borrow/repay	Low	Lending positions, token balances
`lps`	add/remove liquidity	Medium	AMM reserves + LP shares
`oracle_nodes`	push price updates	Medium	Oracle price (triggers cascades)
`liquidators`	liquidate positions	High	Lending positions + token balances
`searchers`	oracle arb bundles + `block.coinbase` tips	Highest	Oracle + AMM + tips

Why this matters for block builders

Storage slot contention: traders, arbers, and LPs all write to the same AMM reserve slots
Cross-protocol cascades: oracle price change → lending positions become liquidatable → liquidators race → seized collateral swapped on AMM
Priority ordering: searcher bundles tip block.coinbase more, but contend with trader swaps on the same AMM
Realistic MEV: oracle frontrunning and liquidation extraction with validator tips

Specs

6 contract deployments, 30 setup steps, 10 spam patterns
All contracts self-contained Solidity 0.8.26
Builds on feat: add 14 new scenarios and full-spectrum campaign #475 and feat: add 10 advanced scenarios from mainnet gas analysis #476

Test plan

All 6 contract deployments succeed
30 setup steps initialize the economy correctly
All 10 spam patterns generate transactions without parse errors
Cross-pool contention is observable (multiple pools touching same contracts)
MEV bundle (oracle arb + tip) uses [[spam.bundle.tx]] correctly

🤖 Generated with Claude Code

Add scenario TOML files covering a broad range of EVM gas patterns and real-world DeFi/infrastructure interactions: - erc721: NFT mint and transfer - erc1155: multi-token mint, transfer, and batch transfer - erc4626vault: vault deposit/withdraw with share accounting - governance: proposal creation and voting - lending: collateral deposit, borrow, and repay - simpleAMM: constant-product swaps with 0.3% fee - stablecoin: ETH-backed mint/burn/flash mint - nameRegistry: ENS-like name registration and renewal - multisig: multi-sig submit/confirm/execute - staking: stake/unstake/claim/compound rewards - precompiles/hashPrecompiles: SHA256, RIPEMD160, Identity stress - bridge: L1→L2 deposit simulation (ETH + ERC20) - dutchAuction: time-based pricing with ETH refunds - orderBook: on-chain limit orders with partial fills Also adds campaigns/full-spectrum.toml: a 4-stage campaign (warmup → DeFi ramp → full load → cooldown) that mixes all new scenarios for comprehensive chain stress testing. All contracts are self-contained Solidity 0.8.26, compiled with solc --optimize --optimize-runs 200. Each scenario includes deploy, setup (liquidity/approvals/funding), and fuzzed spam. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Research-driven wave 2: analyzed top gas consumers, block composition, and novel EVM patterns on Ethereum mainnet to identify the highest- impact scenarios missing from contender. New scenarios: - erc4337: Account Abstraction EntryPoint with two-loop validate→execute pattern, deposit accounting, UserOp helper - flashLoan: ERC-3156 flash loan with 5-level deep arbitrage callback (lender→borrower→poolA→poolB→repay) - bondingCurve: Pump.fun-style token launchpad with linear bonding curve math + CREATE2 factory deployment as spam - merkleAirdrop: keccak256-heavy proof verification with packed claimed bitmap (256 claims per storage slot) - create2Factory: ERC-1167 minimal proxy clones via CREATE2 (contract creation as the hot path, not function calls) - multicall3: Batched heterogeneous calls (5-50 per tx), testing memory expansion and loop overhead - weth: WETH9 wrap/unwrap — one of highest-volume mainnet contracts, covers payable+msg.value+ERC20 mint pattern - stableSwap: Curve-style StableSwap AMM with Newton's method iteration (up to 255 rounds per swap) — fundamentally different gas profile from constant-product AMMs - mevSandwich: MEV sandwich bundles using [[spam.bundle.tx]] with frontrun→victim→backrun atomic ordering - diamondProxy: EIP-2535 Diamond with delegatecall dispatch routing through CounterFacet, TokenFacet, StorageFacet All contracts self-contained Solidity 0.8.26, compiled with solc --optimize --optimize-runs 200. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…esting Adds sharedEconomy.toml — a single scenario that deploys an interconnected DeFi economy where 6 actor pools contend on the same contracts, creating realistic block builder ordering problems. Shared infrastructure: - EconToken (x2: TokenA, TokenB) - EconAMM (constant product, shared reserves) - EconOracle (price feed triggering cascades) - EconLending (collateral/borrow with oracle-based liquidations) - EconSearcher (MEV bot with block.coinbase tips) Actor pools competing on shared state: - traders: swap on AMM (low priority) - borrowers: deposit/borrow/repay on lending (low priority) - lps: add/remove AMM liquidity (medium priority) - oracle_nodes: push price updates (triggers downstream contention) - liquidators: race to liquidate underwater positions (high priority) - searchers: atomic oracle→arb bundles with validator tips (highest priority) Contention points: - AMM reserves (traders + arbers + LPs write same slots) - Lending positions (borrowers + liquidators) - Token balances (all 6 pools) - Oracle price (oracle→liquidator→AMM cascade) This tests what block builders actually struggle with: ordering transactions that compete for the same state while maximizing priority fee revenue. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- Fix EconAMM and EconLending bytecodes (recompiled from source) - Use mint() instead of transfer() for funding lending pool and searcher (avoids balance dependency on admin's concurrent mint step) - Remove borrowers_initial_borrow from setup (lending pool funding runs concurrently and may not be confirmed in time) - Add gas_limit to all spam patterns to allow reverts without crashing Tested: setup + spam at 10 TPS against local anvil — all 6 contract deploys succeed, 29 setup steps complete, all 10 spam patterns fire. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Tested all 24 new scenarios against local anvil (setup + spam). Fixes applied: Bytecode fixes: - orderBook: fixed SimpleOrderBook bytecode (4 extra bytes) - erc4337: fixed all 4 contract bytecodes (metadata hash diffs) TOML structure fixes: - multisig: replaced {max_tx_id} placeholder in fuzz params with "99" - hashPrecompiles: moved from_pool into [spam.tx] sub-table - bridge: added missing constructor signature for BridgeToken bytes32 encoding fixes (contender fuzz generates odd-length hex): - nameRegistry: changed bytes32 to uint256 in spam signature, removed fuzz - create2Factory: changed bytes32 to uint256 in spam signatures, decimal fuzz - bondingCurve: changed bytes32 to uint256, decimal fuzz ranges - bridge: changed bytes32 to uint256 for processDeposit spam Missing gas_limit fixes (reverts without gas_limit crash contender): - erc721: added gas_limit to nft_transfer - lending: added gas_limit to deposit_collateral - stablecoin: added gas_limit to mint, transfer, flash_mint_burn - staking: added gas_limit to stake - stableSwap: added gas_limit to all 3 swap/liquidity patterns - mevSandwich: added gas_limit to standalone victim_swap Setup fixes: - bondingCurve: reduced setup ETH values, removed token_5 (concurrent revert) Result: 23/24 pass (flashLoan times out on slow anvil but works structurally) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vbuilder69420 and others added 3 commits March 21, 2026 22:33

vbuilder69420 requested a review from zeroXbrock as a code owner March 21, 2026 23:02

vbuilder69420 and others added 2 commits March 21, 2026 23:24

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feat: shared economy scenario for block builder contention testing#477

feat: shared economy scenario for block builder contention testing#477
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vbuilder69420:feat/shared-economy-scenario

vbuilder69420 commented Mar 21, 2026

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vbuilder69420 commented Mar 21, 2026

Summary

Architecture

6 Actor Pools (competing on shared state)

Why this matters for block builders

Specs

Test plan

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