Unlike the other entries in this section, the Solidity package is not a client SDK for the Misar.Dev REST API. It is a set of smart contracts (@misar/dev-contracts) that record Misar.Dev API usage on-chain for verifiable billing.

To call the Misar.Dev API (projects, templates, chat, usage, etc.), use a client SDK such as TypeScript, Swift, Dart, or C#. The Solidity contracts are for on-chain usage attestation only.

Installation

The contracts are developed and tested with Hardhat:

npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox

The contract imports OpenZeppelin cryptography utilities:

npm install @openzeppelin/contracts

Compile and test:

npx hardhat compile
npx hardhat test

`MisarDevUsageOracle`

A contract that stores signed, replay-protected API usage records on-chain (Solidity ^0.8.24). Usage events are signed off-chain by a trusted oracleSigner and submitted on-chain, where the signature is verified before the record is accepted.

Constructor

constructor(address _oracleSigner)

Sets owner = msg.sender and the trusted oracleSigner. Reverts with ZeroAddress if the signer is the zero address.

Functions

Function	Access	Description
`recordUsage(bytes32 projectHash, bytes32 requestId, uint256 tokens, uint256 costMicroUsd, uint256 timestamp, bytes signature)`	public	Records a usage entry. Verifies the ECDSA signature against `oracleSigner`; reverts `ReplayDetected` if `requestId` was already recorded, or `InvalidSignature` on mismatch. Emits `UsageRecorded` and updates `cumulativeTokens` / `cumulativeCostMicroUsd` for the project.
`verifyUsage(bytes32 requestId) → bool`	view	Returns whether a usage record exists for the given request ID.
`setOracleSigner(address newSigner)`	`onlyOwner`	Rotates the trusted signer. Emits `OracleSignerUpdated`.
`transferOwnership(address newOwner)`	`onlyOwner`	Transfers contract ownership. Emits `OwnershipTransferred`.

Public state

Member	Type	Description
`owner`	`address`	Contract owner.
`oracleSigner`	`address`	Address whose signature authorizes usage records.
`usageRecords(bytes32)`	`UsageRecord`	Per-request usage record (`projectHash`, `tokens`, `costMicroUsd`, `timestamp`, `exists`).
`cumulativeTokens(bytes32)`	`uint256`	Running token total per `projectHash`.
`cumulativeCostMicroUsd(bytes32)`	`uint256`	Running cost total (micro-USD) per `projectHash`.

Events

UsageRecorded(bytes32 indexed projectHash, bytes32 indexed requestId, uint256 tokens, uint256 costMicroUsd, uint256 timestamp), OracleSignerUpdated(address indexed previous, address indexed next), OwnershipTransferred(address indexed previous, address indexed next).

Error handling

The contract uses custom errors (gas-efficient reverts): Unauthorized, InvalidSignature, ReplayDetected, and ZeroAddress.

Solidity Contracts