Add v1/orders POST endpoint to get orders in batches

[m-sz]

Description

Aave wants to track specific orders in bulk, knowing their ids.

Changes

Adds POST handler for v1/orders/lookup endpoint that requires a list of order uids and responds with a vector of their data. Has a hardcoded limit of 5000 orders per request.

How to test

Test on staging, query multiple orders using this API.

[gemini-code-assist]

Code Review

This pull request introduces a new endpoint v1/get_orders to retrieve orders in batches using a POST request with a limit of 5000 orders per request. The code adds a new module get_orders_by_uid.rs, modifies api.rs to include the new route, and updates database/orders.rs and orderbook.rs to support fetching multiple orders. I found a missing test case for the MAX_ORDERS_LIMIT validation.

[m-sz]

Tested on sepolia staging:

curl -d "[\"0x4f30bff027049ef2d2f8c8ba17be5e2e452c8fc9ad48273ef44d48c0e210bbc16406ce57254d45d503c7cb3e729aab9ddbbb3ec269738a51\", \"0x4f30bff027049ef2d2f8c8ba17be5e2e452c8fc9ad48273ef44d48c0e210bbc16406ce57254d45d503c7cb3e729aab9ddbbb3ec269738a51\"]" "https://barn.api.cow.fi/sepolia/api/v1/orders/lookup" -H "Content-Type: application/json"

(queries twice for the same order)

response

[
    {
        "creationDate": "2026-01-23T14:18:53.912159Z",
        "owner": "0x6406ce57254d45d503c7cb3e729aab9ddbbb3ec2",
        "uid": "0x4f30bff027049ef2d2f8c8ba17be5e2e452c8fc9ad48273ef44d48c0e210bbc16406ce57254d45d503c7cb3e729aab9ddbbb3ec269738a51",
        "availableBalance": null,
        "executedBuyAmount": "3931710370705679403",
        "executedSellAmount": "4000000000000000000",
        "executedSellAmountBeforeFees": "4000000000000000000",
        "executedFeeAmount": "0",
        "executedFee": "68289629294320597",
        "executedFeeToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "invalidated": false,
        "status": "fulfilled",
        "class": "limit",
        "settlementContract": "0x9008d19f58aabd9ed0d60971565aa8510560ab41",
        "isLiquidityOrder": false,
        "fullAppData": "{\"appCode\":\"CoW Swap\",\"environment\":\"barn\",\"metadata\":{\"orderClass\":{\"orderClass\":\"market\"},\"quote\":{\"slippageBips\":101,\"smartSlippage\":true}},\"version\":\"1.12.0\"}",
        "quote": {
            "gasAmount": "98318.00000000000",
            "gasPrice": "3575917434.000000",
            "sellTokenPrice": "0.008587696541803472",
            "sellAmount": "4000000000000000000",
            "buyAmount": "4000000000000000000",
            "feeAmount": "40939622000450720",
            "solver": "0x99b4136666ca1d13020830350ca8d01a0e5e466b",
            "verified": true,
            "metadata": {
                "interactions": [],
                "jitOrders": [],
                "preInteractions": [],
                "version": "1.0"
            }
        },
        "sellToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "buyToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "receiver": "0x6406ce57254d45d503c7cb3e729aab9ddbbb3ec2",
        "sellAmount": "4000000000000000000",
        "buyAmount": "3919073868181753833",
        "validTo": 1769179729,
        "appData": "0x8a8e8bdd353e10a8fb1aabb9594537fba2f1cce8fc655fdeaaa568286b3b53af",
        "feeAmount": "0",
        "kind": "sell",
        "partiallyFillable": false,
        "sellTokenBalance": "erc20",
        "buyTokenBalance": "erc20",
        "signingScheme": "eip712",
        "signature": "0x6cc9e9e2e8826cffb092a8531b103bbc3e70472e6455185af20245d1be14748e13a440f8e19e88db1a47320cff5d7b4a5ac32f07c76f708f94531616f597e8411b",
        "interactions": {
            "pre": [],
            "post": []
        }
    },
    {
        "creationDate": "2026-01-23T14:18:53.912159Z",
        "owner": "0x6406ce57254d45d503c7cb3e729aab9ddbbb3ec2",
        "uid": "0x4f30bff027049ef2d2f8c8ba17be5e2e452c8fc9ad48273ef44d48c0e210bbc16406ce57254d45d503c7cb3e729aab9ddbbb3ec269738a51",
        "availableBalance": null,
        "executedBuyAmount": "3931710370705679403",
        "executedSellAmount": "4000000000000000000",
        "executedSellAmountBeforeFees": "4000000000000000000",
        "executedFeeAmount": "0",
        "executedFee": "68289629294320597",
        "executedFeeToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "invalidated": false,
        "status": "fulfilled",
        "class": "limit",
        "settlementContract": "0x9008d19f58aabd9ed0d60971565aa8510560ab41",
        "isLiquidityOrder": false,
        "fullAppData": "{\"appCode\":\"CoW Swap\",\"environment\":\"barn\",\"metadata\":{\"orderClass\":{\"orderClass\":\"market\"},\"quote\":{\"slippageBips\":101,\"smartSlippage\":true}},\"version\":\"1.12.0\"}",
        "quote": {
            "gasAmount": "98318.00000000000",
            "gasPrice": "3575917434.000000",
            "sellTokenPrice": "0.008587696541803472",
            "sellAmount": "4000000000000000000",
            "buyAmount": "4000000000000000000",
            "feeAmount": "40939622000450720",
            "solver": "0x99b4136666ca1d13020830350ca8d01a0e5e466b",
            "verified": true,
            "metadata": {
                "interactions": [],
                "jitOrders": [],
                "preInteractions": [],
                "version": "1.0"
            }
        },
        "sellToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "buyToken": "0xbe72e441bf55620febc26715db68d3494213d8cb",
        "receiver": "0x6406ce57254d45d503c7cb3e729aab9ddbbb3ec2",
        "sellAmount": "4000000000000000000",
        "buyAmount": "3919073868181753833",
        "validTo": 1769179729,
        "appData": "0x8a8e8bdd353e10a8fb1aabb9594537fba2f1cce8fc655fdeaaa568286b3b53af",
        "feeAmount": "0",
        "kind": "sell",
        "partiallyFillable": false,
        "sellTokenBalance": "erc20",
        "buyTokenBalance": "erc20",
        "signingScheme": "eip712",
        "signature": "0x6cc9e9e2e8826cffb092a8531b103bbc3e70472e6455185af20245d1be14748e13a440f8e19e88db1a47320cff5d7b4a5ac32f07c76f708f94531616f597e8411b",
        "interactions": {
            "pre": [],
            "post": []
        }
    }
]

[m-sz]

By the way, we can have a discussion on what the endpoint itself should be.
This has to be a POST request since we need to provide JSON array of order ids and /v1/orders obviously creates an order so there has to be a different name

I got a couple suggestions from Claude

1. Nested under a "batch" or "bulk" path
   POST /v1/batch/orders
   POST /v1/bulk/orders
   Groups batch operations separately from the main resource routes.
2. Different verb-like suffix
   POST /v1/orders/fetch
   POST /v1/orders/get
   POST /v1/orders/list
   Less common but unambiguous.
3. Underscore-prefixed action
   POST /v1/orders/_search
   POST /v1/orders/_mget
   Elasticsearch uses this convention. The underscore signals "this is a special action, not a resource."
4. Hyphenated compound resource
   POST /v1/order-lookups
   POST /v1/order-queries
   Treats the bulk lookup as its own resource type.
5. RPC-style separate namespace
   POST /v1/rpc/get-orders
   POST /v1/actions/get-orders

based on the above suggestions I have opted for a custom not-order-id-like name /v1/orders/lookup - to lookup many orders, but I am open for discussion and don't have a strong opinion.