Core Contracts

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Syscalls.sol

Low-level Solidity wrappers for the supported Neo N3 syscall surface. This is the lowest-level devpack surface — every other contract and library ultimately delegates to Syscalls.

Category	Syscalls	Examples
Storage	GetContext, Get, Put, Delete, Find, AsReadOnly, Local.*	storageGet(), storagePut(), storageFind()
Runtime	CheckWitness, GetTime, GasLeft, Notify, Log, BurnGas	checkWitness(), gasLeft(), notify()
Contract	Call, GetCallFlags, CreateStandardAccount, CreateMultisigAccount	contractCall(), getCallFlags()
Crypto	CheckSig, CheckMultisig (via System.Crypto.*)	checkSig(), checkMultisig()
CryptoLib	SHA256, RIPEMD160, Keccak256, VerifyWithECDsa, Ed25519, BLS12-381, Murmur32	sha256(), verifyWithECDsa(), bls12381Pairing()
StdLib	serialize, deserialize, JSON, base64/58, hex, string ops, itoa/atoi	jsonSerialize(), base64Encode(), stringSplit()
Iterator	Next, Value	iteratorNext(), iteratorValue()
Advanced	GetRandom, GetNetwork, GetAddressVersion, GetInvocationCounter	getCurrentRandom(), getNetwork()

Syscalls.sol also defines the core data structures used throughout the devpack:

Struct	Description
Block	Trimmed block: hash, version, previousHash, merkleRoot, timestamp, nonce, index, primaryIndex, nextConsensus, txCount
Transaction	Base transaction: hash, version, nonce, sender, systemFee, networkFee, validUntilBlock, script
Witness	invocationScript + verificationScript
Signer	account, scopes, allowedContracts, allowedGroups, rules
WitnessRule	action (deny/allow) + condition bytes
StorageContext	Contract storage context (id + isReadOnly)
Iterator	NeoVM iterator handle (id, hasNext, currentKey, currentValue)
Notification	scriptHash, eventName, state array
ContractStateNative	id, updateCounter, hash, nef, manifest

TIP

Prefer NativeCalls wrappers over raw Syscalls.contractCall() — they generate specific manifest permissions instead of wildcards.

NativeCalls.sol

Direct wrappers for all Neo N3 native contracts. Each function calls through Syscalls.contractCall() with a deterministic contract hash constant, enabling the compiler to infer exact manifest permissions.

Native Contract	Hash Constant	Key Functions
NEO Token	NEO_CONTRACT	neoBalanceOf(), neoTransfer(), vote(), getCandidates(), getAccountState(), unclaimedGas()
GAS Token	GAS_CONTRACT	gasBalanceOf(), gasTransfer(), gasTotalSupply()
ContractManagement	CONTRACT_MANAGEMENT	deployContract(), updateContract(), destroyContract(), getContract(), hasMethod()
Policy	POLICY_CONTRACT	getFeePerByte(), getExecFeeFactor(), getStoragePrice(), blockAccount(), isBlocked()
Oracle	ORACLE_CONTRACT	requestOracleData(), getOraclePrice(), setOraclePrice()
RoleManagement	ROLE_MANAGEMENT	designateAsRole(), getDesignatedByRole()
Notary	NOTARY_CONTRACT	notaryVerify(), notaryBalanceOf(), notaryLockDepositUntil(), notaryWithdraw()
Treasury	TREASURY_CONTRACT	treasuryVerify(), treasuryOnNEP17Payment(), treasuryOnNEP11Payment()
Ledger	LEDGER_CONTRACT	currentIndex(), currentHash(), getBlock(), getTransaction()

Reference constants for CryptoLib (CRYPTO_LIB) and StdLib (STD_LIB) are also defined, but their methods are exposed through Syscalls.sol directly (e.g., Syscalls.sha256(), Syscalls.base64Encode()).

// Transfer GAS — generates permission: {"contract":"0xd2a4...","methods":["transfer"]}
bool ok = NativeCalls.gasTransfer(from, to, amount, "");

// Query NEO governance
NativeCalls.NeoCandidate[] memory candidates = NativeCalls.getCandidates();
uint256 unclaimed = NativeCalls.unclaimedGas(account, NativeCalls.currentIndex());

FrameworkBase.sol

Base contract providing common infrastructure for Neo N3 Solidity contracts:

• Ownership — transferOwnership(), renounceOwnership(), onlyOwner modifier
• Initialization — whenInitialized modifier, version tracking
• Witness-based access control — withWitness modifier (calls Runtime.checkWitness)
• Gas limit guards — withGasLimit(minGas) modifier (calls Runtime.gasLeft)
• Contract lifecycle — upgradeContract() with NEF + manifest update
• Events — FrameworkInitialized, OwnershipTransferred, ContractUpgraded, EmergencyStop

contract MyToken is FrameworkBase {
    function adminAction() public onlyOwner withWitness withGasLimit(20000000) {
        // Only owner, witness-verified, with at least 0.2 GAS remaining
    }
}

Framework.sol

Extended framework that inherits FrameworkBase. Previously exposed a fully dynamic callContract(address, string, bytes) surface, but this forced wildcard permissions in the manifest ({"contract":"*","methods":"*"}).

Strict-Manifest Mode

Framework.callContract() is intentionally disabled — it reverts at runtime. Use explicit NativeCalls.* or Syscalls.contractCall(KNOWN_HASH, ...) wrappers instead. If truly dynamic dispatch is unavoidable, compile with --manifest-permissions to supply explicit overrides.

OracleService.sol

Convenience wrapper around the Neo N3 Oracle native contract:

• request(url, filter, userData, gasForResponse) — issue an oracle data request, returns a requestId
• oracleCallback(url, userData, code, result) — receives the native Oracle callback (restricted to onlyOracleNative)
• Forwards responses to the original requester via IOracleServiceReceiver.onOracleResponse()
• Uses a fixed callback method name to avoid wildcard manifest permissions
• Tracks request metadata (requester, URL, filter, timestamps, completion status)

contract MyOracle is IOracleServiceReceiver {
    OracleService private _oracle;

    function fetchPrice(string calldata url) external {
        _oracle.request(url, "$.price", "", 100000000);
    }

    function onOracleResponse(
        uint256 requestId, uint256 code, bytes calldata result, bytes calldata userData
    ) external override {
        // Handle oracle response
    }
}

NEP17Rescue.sol

Optional extension for NEP-17 tokens that enables emergency recovery of accidentally sent native tokens (NEO and GAS only). In strict-manifest mode, rescuing arbitrary NEP-17 tokens is not supported because it would require wildcard contract permissions.

contract MyToken is NEP17Rescue {
    // Inherits emergencyTokenRecovery(token, to, amount, data)
    // Restricted to NEO_CONTRACT and GAS_CONTRACT targets
}