Snapshot_CheckSnapExists

Snapshot_CheckSnapExists is an async mandate that uses Chainlink Functions to verify the existence and state of a Snapshot proposal. It confirms that a proposal exists, is currently pending, and includes a specific voting choice.

Overview

This mandate acts as an oracle for off-chain governance state on Snapshot. It:

1. Queries the Snapshot GraphQL API using Chainlink Functions.
2. Verifies that a proposal with the given ID exists.
3. Checks that the proposal status is “pending”.
4. Ensures that the proposal includes the specified voting choice.
5. If verified, it triggers a fulfillment on the Powers contract (currently without executing any downstream actions).

Configuration

When adopting a Snapshot_CheckSnapExists instance, the following parameters are required:

1. spaceId (string): The Snapshot Space ID (e.g., “yam.eth”).
2. subscriptionId (uint64): The Chainlink Functions subscription ID.
3. gasLimit (uint32): The gas limit for the Chainlink Functions callback.
4. donID (bytes32): The Chainlink DON (Decentralized Oracle Network) ID.

Usage

Proposing an Action

When calling the mandate, the following parameters must be provided:

1. proposalId (string): The ID of the Snapshot proposal to verify.
2. choice (string): The voting choice to check for (e.g., “Yes”).
3. targets (address[]): (Unused) Intended for future execution logic.
4. values (uint256[]): (Unused) Intended for future execution logic.
5. calldatas (bytes[]): (Unused) Intended for future execution logic.
6. govDescription (string): A description of the governance action.

Execution Flow

1. Request Initiation (handleRequest)

   • Prepares arguments for the Chainlink Function: proposalId and choice.
   • Initiates the request to the Chainlink Oracle.

2. Oracle Call (_externalCall)

   • Sends the request to Chainlink.
   • The off-chain script queries https://hub.snapshot.org/graphql to fetch proposal details.

3. Verification & Fulfillment (fulfillRequest)

   • Off-Chain Checks:
     • Does the proposal exist?
     • Is the state “pending”?
     • Does the choices array include the requested choice?
   • On-Chain Verification:
     • Receives the result (“true” or error message).
     • If “true”, calls powers.fulfill.
   • Note: The current implementation executes fulfill with empty action arrays, meaning no state changes occur on the Powers contract other than marking the async action as complete.

Technical Specifications

Chainlink Source

The mandate uses a hardcoded JavaScript source to query the Snapshot API:

const proposalId = args[0];
const choice = args[1];
// ... queries https://hub.snapshot.org/graphql/ ...

Functions

initializeMandate

function initializeMandate(
    uint16 index,
    string memory nameDescription,
    bytes memory inputParams,
    bytes memory config
) public override

• Initializes Chainlink configuration.
• Sets input parameters.

handleRequest

function handleRequest(...) public view virtual override returns (...)

• Prepares Chainlink request arguments.

fulfillRequest

function fulfillRequest(bytes32 requestId, bytes memory response, bytes memory err) internal override

• Callback from Chainlink.
• Verifies response is “true”.
• Calls powers.fulfill.

Error Conditions

1. Chainlink Errors

   • “Proposal not recognised.”
   • “Proposal not pending.”
   • “Choice not present.”
   • “Request failed” (API error).

2. Validation Errors

   • “No response from the API”
   • “Request not found”

Current Deployments

Chain ID	Chain Name	Address