feat: add support for ERC-4337 accounts

docs/architecture.md

@@ -163,6 +163,11 @@ participant Site as Snap Companion Dapp
 
 User ->>+ Dapp: Create new sign request
 Dapp ->>+ MetaMask: ethereum.request(request)
+alt Is EIP-4337 account?
+  MetaMask ->>+ Snap: keyring_prepareRequest(request)
+  Snap ->> Snap: Custom logic to prepare request
+  Snap -->>- MetaMask: { request }
+end
 MetaMask ->> MetaMask: Display request to user
 User ->> MetaMask: Approve request
 
@@ -208,6 +213,11 @@ participant Snap
 
 User ->>+ Dapp: Create new sign request
 Dapp ->>+ MetaMask: ethereum.request(request)
+alt Is EIP-4337 account?
+  MetaMask ->>+ Snap: keyring_prepareRequest(request)
+  Snap ->> Snap: Custom logic to prepare request
+  Snap -->>- MetaMask: { request }
+end
 MetaMask ->> MetaMask: Display request to user
 User ->> MetaMask: Approve request
 

docs/diagrams/user_operation_signing.puml

@@ -0,0 +1,115 @@
+@startuml "ERC-4337 Account Support"
+autonumber
+skinparam fontname Arial
+
+title "ERC-4337 UserOperation Signing"
+
+participant Dapp
+participant MetaMask
+participant Snap
+
+Dapp -> MetaMask ++: ""{""\n\
+""  chainId, // Ignored by MetaMask""\n\
+""  from,""\n\
+""  to,""\n\
+""  value,""\n\
+""  data,""\n\
+}
+
+note over MetaMask
+    Currently, only one transaction
+    per UserOp will be supported
+end note
+
+MetaMask -> Snap ++: ""prepareUserOperation({""\n\
+""  account: account.id,""\n\
+""  scope: `eip155:${chainId}`,""\n\
+""  transactions: [ // List of transactions""\n\
+""    {""\n\
+""      to,""\n\
+""      value,""\n\
+""      data,""\n\
+""    },""\n\
+""  ]""\n\
+})
+
+Snap --> MetaMask --: ""{""\n\
+""  callData,""\n\
+""  initCode?,""\n\
+""  nonce,""\n\
+""  gasLimits?: {""\n\
+""    callGasLimit,""\n\
+""    verificationGasLimit,""\n\
+""    preVerificationGas,""\n\
+""  },""\n\
+""  dummySignature?,""\n\
+""  dummyPaymasterAndData?,""\n\
+""  bundler?,""\n\
+""}""
+
+MetaMask -> MetaMask: Check if the account is already deployed
+
+alt The account is already deployed
+  MetaMask -> MetaMask: Remove the ""initCode"" if set
+else The account is not deployed and the ""initCode"" isn't present
+  MetaMask -> Dapp: Throw an error (without the exact reason)
+end
+
+alt The ""gas"" isn't set
+  MetaMask -> MetaMask: Estimate and set gas values
+end
+
+MetaMask -> MetaMask: Estimate and set gas fees
+
+MetaMask -> Snap ++: ""patchUserOperation({""\n\
+""  sender,""\n\
+""  nonce,""\n\
+""  initCode,""\n\
+""  callData,""\n\
+""  callGasLimit,""\n\
+""  verificationGasLimit,""\n\
+""  preVerificationGas,""\n\
+""  maxFeePerGas,""\n\
+""  maxPriorityFeePerGas,""\n\
+""  paymasterAndData, // Dummy value or empty""\n\
+""  signature, // Dummy value or empty""\n\
+""})""
+
+Snap --> MetaMask --: ""{""\n\
+""  paymasterAndData?,""\n\
+""}""
+
+MetaMask -> MetaMask: Update ""paymasterAndData"" and\n\
+remove the dummy signature
+
+MetaMask -> MetaMask: Display approval UI
+
+MetaMask -> Snap ++: ""signUserOperation([""\n\
+""  {""\n\
+""    sender,""\n\
+""    nonce,""\n\
+""    initCode,""\n\
+""    callData,""\n\
+""    callGasLimit,""\n\
+""    verificationGasLimit,""\n\
+""    preVerificationGas,""\n\
+""    maxFeePerGas,""\n\
+""    maxPriorityFeePerGas,""\n\
+""    paymasterAndData,""\n\
+""    signature, // Empty""\n\
+""  },""\n\
+""  entrypoint, // Entrypoint deployed by""\n\
+""              // the Ethereum Foundation""\n\
+""])""
+
+Snap --> MetaMask --: ""{""\n\
+""  signature,""\n\
+""}""
+
+MetaMask -> MetaMask: Update UserOp's ""signature""
+
+MetaMask -> MetaMask: Submit UserOp to bundler and\n\
+wait for transaction hash
+
+MetaMask --> Dapp --: ""txHash""
+@enduml

docs/evm-methods.md

@@ -105,7 +105,7 @@ Adds support to [`eth_sendTransaction`][eth-send-transaction].
        - Pattern: `^0x[0-9a-fA-F]{1,2}$`
      - `nonce`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `to`
        - One-of:
          - Contract creation
@@ -118,22 +118,22 @@ Adds support to [`eth_sendTransaction`][eth-send-transaction].
        - Pattern: `^0x[0-9a-fA-F]{40}$`
      - `value`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `data`
        - Type: `string`
        - Pattern: `^0x[0-9a-f]*$`
      - `gasLimit`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `gasPrice`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `maxPriorityFeePerGas`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `maxFeePerGas`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
      - `accessList`:
        - Description: EIP-2930 access list
        - Type: `array`
@@ -150,7 +150,7 @@ Adds support to [`eth_sendTransaction`][eth-send-transaction].
                - Pattern: `^0x[0-9a-f]{64}$`
      - `chainId`
        - Type: `string`
-       - Pattern: `^0x([1-9a-f]+[0-9a-f]*|0)$`
+       - Pattern: `^0x([1-9a-f][0-9a-f]*|0)$`
 
 ### Returns