Builder based API for simulator crate

crates/autopilot/src/infra/blockchain/contracts.rs

@@ -3,6 +3,7 @@ use {
     chain::Chain,
     contracts::{
         ChainalysisOracle,
+        FlashLoanRouter,
         GPv2AllowListAuthentication,
         GPv2Settlement,
         HooksTrampoline,
@@ -21,6 +22,7 @@ pub struct Contracts {
     balances: Balances::Instance,
     chainalysis_oracle: Option<ChainalysisOracle::Instance>,
     trampoline: HooksTrampoline::Instance,
+    flashloan_router: Address,
 
     /// The authenticator contract that decides which solver is allowed to
     /// submit settlements.
@@ -36,6 +38,7 @@ pub struct Addresses {
     pub weth: Option<Address>,
     pub balances: Option<Address>,
     pub trampoline: Option<Address>,
+    pub flashloan_router: Option<Address>,
 }
 
 impl Contracts {
@@ -80,6 +83,11 @@ impl Contracts {
             web3.provider.clone(),
         );
 
+        let flashloan_router = addresses
+            .flashloan_router
+            .or_else(|| FlashLoanRouter::deployment_address(&chain.id()))
+            .unwrap();
+
         let chainalysis_oracle = ChainalysisOracle::Instance::deployed(&web3.provider)
             .await
             .ok();
@@ -111,6 +119,7 @@ impl Contracts {
             settlement_domain_separator,
             authenticator,
             trampoline,
+            flashloan_router,
         }
     }
 
@@ -151,4 +160,8 @@ impl Contracts {
     pub fn authenticator(&self) -> &GPv2AllowListAuthentication::Instance {
         &self.authenticator
     }
+
+    pub fn flashloan_router(&self) -> Address {
+        self.flashloan_router
+    }
 }

crates/autopilot/src/run.rs

@@ -221,6 +221,7 @@ pub async fn run(config: Configuration, shutdown_controller: ShutdownController)
         weth: config.shared.contracts.native_token,
         balances: config.shared.contracts.balances,
         trampoline: config.shared.contracts.hooks,
+        flashloan_router: config.shared.contracts.flashloan_router,
     };
     let current_block_args = shared::current_block::Arguments::from(&config.shared.current_block);
     let eth = ethereum(
@@ -314,6 +315,8 @@ pub async fn run(config: Configuration, shutdown_controller: ShutdownController)
                 .await
                 .expect("failed to query solver authenticator address"),
             block_stream: eth.current_block().clone(),
+            flash_loan_router: eth.contracts().flashloan_router(),
+            hooks_trampoline: *eth.contracts().trampoline().address(),
         },
         factory::Components {
             http_factory: http_client::HttpClientFactory::new(&configs::http_client::HttpClient {

crates/configs/src/shared.rs

@@ -182,6 +182,9 @@ pub struct ContractAddresses {
 
     /// The Balancer V2 Vault contract used for liquidity sourcing.
     pub balancer_v2_vault: Option<Address>,
+
+    /// The flashloan router contract.
+    pub flashloan_router: Option<Address>,
 }
 
 /// Logging configuration (log filter, output format).

crates/e2e/src/setup/services.rs

@@ -143,6 +143,11 @@ impl<'a> Services<'a> {
                 native_token: Some(*self.contracts.weth.address()),
                 hooks: Some(*self.contracts.hooks.address()),
                 balancer_v2_vault: Some(*self.contracts.balancer_vault.address()),
+                flashloan_router: self
+                    .contracts
+                    .flashloan_router
+                    .as_ref()
+                    .map(|c| *c.address()),
             },
             ..Default::default()
         }

crates/e2e/tests/e2e/malformed_requests.rs

@@ -460,7 +460,7 @@ async fn http_validation(web3: Web3) {
         "zero sellAmount should return 422"
     );
 
-    // Invalid kind enum value → 422
+    // some fields missing → 422
     let response = client
         .post(format!("{API_HOST}/restricted/api/v1/debug/simulation"))
         .json(&json!({
@@ -492,6 +492,13 @@ async fn http_validation(web3: Web3) {
             "kind": "sell",
             "owner": VALID_ADDRESS,
             "appData": bad_app_data,
+            "sellTokenBalance": "erc20",
+            "buyTokenBalance": "erc20",
+            "signingScheme": "eip1271",
+            "signature": "0x000000",
+            "feeAmount": "0",
+            "validTo": 12341234,
+            "partiallyFillable": false,
         }))
         .send()
         .await
@@ -563,6 +570,14 @@ async fn simulation_not_enabled(web3: Web3) {
             "buyAmount": "1000000000000000000",
             "kind": "sell",
             "owner": VALID_ADDRESS,
+            "appData": "{}",
+            "sellTokenBalance": "erc20",
+            "buyTokenBalance": "erc20",
+            "signingScheme": "eip1271",
+            "signature": "0x000000",
+            "feeAmount": "0",
+            "validTo": 12341234,
+            "partiallyFillable": false,
         }))
         .send()
         .await

crates/e2e/tests/e2e/order_simulation.rs

@@ -1,10 +1,19 @@
 use {
-    alloy::{primitives::Address, providers::Provider},
+    alloy::{
+        primitives::{Address, ruint::aliases::U256},
+        providers::Provider,
+    },
     configs::test_util::TestDefault,
     e2e::setup::{API_HOST, OnchainComponents, Services, TIMEOUT, run_test, wait_for_condition},
     ethrpc::{Web3, alloy::CallBuilderExt},
     model::{
-        order::{OrderCreation, OrderKind},
+        order::{
+            BuyTokenDestination,
+            OrderCreation,
+            OrderCreationAppData,
+            OrderKind,
+            SellTokenSource,
+        },
         signature::EcdsaSigningScheme,
     },
     number::units::EthUnit,
@@ -50,15 +59,53 @@ async fn custom_order_simulation(web3: Web3) {
         .await;
 
     let client = services.client();
+    let valid_to = model::time::now_in_epoch_seconds() + 100;
+
     let sell_amount = 1u64.eth();
-    let request = orderbook::dto::OrderSimulationRequest {
+    let app_data = "{}";
+
+    // Sign an OrderCreation with the same fields the simulation will encode.
+    // simulate_custom_order hashes `app_data` with keccak256; OrderCreation::Full
+    // does the same, so the signature covers exactly the same OrderData hash.
+    let signed = OrderCreation {
         sell_token: *token.address(),
         buy_token: *onchain.contracts().weth.address(),
-        sell_amount: sell_amount.try_into().expect("Sell amount is non zero"),
+        sell_amount,
         buy_amount: 1u64.eth(),
         kind: OrderKind::Sell,
-        owner: trader.address(),
+        receiver: Some(Address::default()),
+        sell_token_balance: SellTokenSource::Erc20,
+        buy_token_balance: BuyTokenDestination::Erc20,
+        fee_amount: U256::ZERO,
+        valid_to,
+        app_data: OrderCreationAppData::Full {
+            full: app_data.to_string(),
+        },
+        partially_fillable: false,
         ..Default::default()
+    }
+    .sign(
+        EcdsaSigningScheme::Eip712,
+        &onchain.contracts().domain_separator,
+        &trader.signer,
+    );
+
+    let request = orderbook::dto::OrderSimulationRequest {
+        sell_token: signed.sell_token,
+        buy_token: signed.buy_token,
+        sell_amount: signed.sell_amount.try_into().unwrap(),
+        buy_amount: signed.buy_amount,
+        kind: signed.kind,
+        owner: trader.address(),
+        receiver: signed.receiver,
+        sell_token_balance: signed.sell_token_balance,
+        buy_token_balance: signed.buy_token_balance,
+        app_data: app_data.to_string(),
+        block_number: None,
+        signature: signed.signature,
+        fee_amount: signed.fee_amount,
+        valid_to: signed.valid_to,
+        partially_fillable: signed.partially_fillable,
     };
 
     // Trader has no sell tokens — simulation should revert.

crates/e2e/tests/e2e/quote_verification.rs

@@ -12,7 +12,7 @@ use {
         price_estimation::BalanceOverridesConfig,
         test_util::TestDefault,
     },
-    contracts::ERC20,
+    contracts::{ERC20, GPv2Settlement},
     e2e::setup::*,
     ethrpc::{Web3, alloy::CallBuilderExt},
     model::{
@@ -28,7 +28,7 @@ use {
         trade_verifier::{PriceQuery, TradeVerifier, TradeVerifying},
     },
     serde_json::json,
-    simulator::swap_simulator::SwapSimulator,
+    simulator::simulation_builder::SettlementSimulator,
     std::{collections::HashMap, sync::Arc},
 };
 
@@ -189,32 +189,33 @@ async fn test_bypass_verification_for_rfq_quotes(web3: Web3) {
         .unwrap();
     let onchain = OnchainComponents::deployed(web3.clone()).await;
     let balance_overrides = Arc::new(BalanceOverrides::default());
-    let gas_limit = 12_000_000;
-    let simulator = SwapSimulator::new(
-        balance_overrides.clone(),
+    let gas_limit = 12_000_000u64;
+    let settlement_contract = GPv2Settlement::GPv2Settlement::new(
         *onchain.contracts().gp_settlement.address(),
+        web3.provider.clone(),
+    );
+    let simulator = SettlementSimulator::new(
+        settlement_contract,
+        Default::default(),
+        Default::default(),
         *onchain.contracts().weth.address(),
-        block_stream.clone(),
-        web3.clone(),
         gas_limit,
+        balance_overrides,
+        block_stream.clone(),
+        None,
     )
     .await
     .unwrap();
 
     let verifier = TradeVerifier::new(
-        web3.clone(),
-        None,
         simulator,
+        None,
         Arc::new(web3.clone()),
-        balance_overrides,
-        *onchain.contracts().gp_settlement.address(),
         BigDecimal::zero(),
         Default::default(),
         0,
         u32::MAX,
-    )
-    .await
-    .unwrap();
+    );
 
     let verify_trade = |tx_origin| {
         let verifier = verifier.clone();

crates/orderbook/openapi.yml

@@ -2731,31 +2731,50 @@ components:
             if omitted.
           allOf:
             - $ref: "#/components/schemas/Address"
-          nullable: true
         sellTokenBalance:
           description: Where the sell token should be drawn from.
           allOf:
             - $ref: "#/components/schemas/SellTokenSource"
-          default: erc20
         buyTokenBalance:
           description: Where the buy token should be transferred to.
           allOf:
             - $ref: "#/components/schemas/BuyTokenDestination"
-          default: erc20
         appData:
           description: >
-            Full app data JSON string. Defaults to `"{}"` if omitted.
+            Full app data JSON string.
           type: string
-          nullable: true
         blockNumber:
           type: integer
+          nullable: true
+        signingScheme:
+          $ref: "#/components/schemas/SigningScheme"
+        signature:
+          $ref: "#/components/schemas/Signature"
+        feeAmount:
+          description: >
+            The fee amount in sell token atoms. Expected to be 0; only present
+            because it must be part of the signed order data.
+          allOf:
+            - $ref: "#/components/schemas/TokenAmount"
+        validTo:
+          description: Unix timestamp (`uint32`) until which the order is valid.
+          type: integer
+        partiallyFillable:
+          description: Whether the order can be partially filled or must be filled all at once.
+          type: boolean
       required:
         - sellToken
         - buyToken
         - sellAmount
         - buyAmount
         - kind
         - owner
+        - signingScheme
+        - signature
+        - feeAmount
+        - validTo
+        - partiallyFillable
+        - appData
     OrderSimulation:
       description: >
         The Tenderly simulation request for an order, along with any

crates/orderbook/src/dto/mod.rs

@@ -4,7 +4,10 @@ pub mod order;
 use {
     alloy::primitives::U256,
     eth_domain_types::{Address, NonZeroU256},
-    model::order::{BuyTokenDestination, OrderKind, SellTokenSource},
+    model::{
+        order::{BuyTokenDestination, OrderKind, SellTokenSource},
+        signature::Signature,
+    },
     number::serialization::HexOrDecimalU256,
     serde::{Deserialize, Serialize},
     serde_with::serde_as,
@@ -45,12 +48,22 @@ pub struct OrderSimulationRequest {
     /// token transfer or internal Balancer Vault transfer.
     #[serde(default)]
     pub buy_token_balance: BuyTokenDestination,
-    /// Full app data JSON. Defaults to `"{}"` if omitted.
-    #[serde(default)]
-    pub app_data: Option<String>,
+    /// Full app data JSON.
+    pub app_data: String,
     /// The block number at which the simulation should happen
-    #[serde(default)]
     pub block_number: Option<u64>,
+    /// The order signature (signing scheme + bytes). Required to pass
+    /// signature verification in the settlement contract during simulation.
+    #[serde(flatten)]
+    pub signature: Signature,
+    /// The fee amount signed by the user. This field is expected to be 0 and
+    /// only still there because it needs to be signed by the user.
+    pub fee_amount: U256,
+    /// UNIX timestamp when the order will expire.
+    pub valid_to: u32,
+    /// Whether the order needs to be filled all at once or allows to be filled
+    /// over multiple partial executions.
+    pub partially_fillable: bool,
 }
 
 /// The result of Order simulation, contains the error (if any)

crates/orderbook/src/lib.rs

@@ -5,7 +5,6 @@ pub mod database;
 pub mod dto;
 mod ipfs;
 mod ipfs_app_data;
-pub mod order_simulator;
 pub mod orderbook;
 mod quoter;
 pub mod run;