BatchToken.sol (ERC-1155)

The central token of the AsiliChain protocol. Each BatchToken ID represents one weighed, graded coffee batch. Minted at DELIVERED stage. Burns at SETTLED stage. The primary collateral unit for LendingVault.

Why ERC-1155

ERC-1155 is chosen over ERC-721 because:

• Semi-fungible: Batches of the same grade, cooperative, and season are interchangeable for collateral purposes
• Batch operations: A single transaction can mint multiple BatchTokens for multiple farmers in a cooperative delivery
• Gas efficiency: 30–40% cheaper than equivalent ERC-721 operations at scale

Key Data Structure

struct BatchData {
    string  batchId;              // e.g. "BATCH-2026-004821"
    string  farmerId;             // MAAIF farmer ID
    string  cooperativeId;        // e.g. "COOP-MBALE-001"
    uint256 weightKg;             // Scaled ×10 (e.g. 675 = 67.5 kg)
    string  grade;                // "screen18", "screen15", "FAQ"
    uint256 moisturePct;          // Scaled ×10 (e.g. 112 = 11.2%)
    bytes32 collectionPointHash;  // GPS hash of collection point
    bytes32 weightSlipIpfsCid;    // IPFS CID of weight slip photo
    uint256 mintTimestamp;
    TraceStage currentStage;      // DELIVERED through SETTLED
    bool    hasActiveLoan;        // Prevents double-collateralisation
}

mapping(uint256 => BatchData) public batchData;
uint256 public nextTokenId;

Interface

// Mint a new BatchToken (AGENT_ROLE required, farmer must be registered)
function mintBatch(
    address cooperativeWallet,
    string calldata farmerId,
    uint256 weightKg,
    string calldata grade,
    uint256 moisturePct,
    bytes32 collectionPointHash,
    bytes32 weightSlipIpfsCid
) external onlyRole(AGENT_ROLE) returns (uint256 tokenId);

// Get batch data (read by LendingVault for collateral valuation)
function getBatchData(uint256 tokenId) external view returns (BatchData memory);

// Check if batch has active loan (prevents double-collateralisation)
function hasActiveLoan(uint256 tokenId) external view returns (bool);

// Lock batch as collateral (called by LendingVault on loan origination)
function lockAsCollateral(uint256 tokenId) external onlyRole(VAULT_ROLE);

// Unlock collateral (called by LendingVault on repayment or liquidation)
function unlockCollateral(uint256 tokenId) external onlyRole(VAULT_ROLE);

// Burn on SETTLED (loan repaid and export settled)
function burnSettled(uint256 tokenId) external onlyRole(VAULT_ROLE);

Collateral Locking

When LendingVault originates a loan against a BatchToken:

1. LendingVault.originate(tokenId) is called
2. LendingVault calls BatchToken.lockAsCollateral(tokenId)
3. hasActiveLoan[tokenId] = true — prevents cooperative from transferring or using as collateral elsewhere
4. On EXPORTED + SETTLED: unlockCollateral then burnSettled execute atomically

This prevents double-collateralisation without requiring token transfer to the vault.

Valuation Formula

BatchToken value (USDC) = weightKg × coffeePriceUsd (Chainlink feed)
                                    × gradeMultiplier
                                    × stageMultiplier

Grade multipliers:
  screen18:  1.15
  screen15:  1.00
  FAQ:       0.85

Stage multipliers:
  DELIVERED:   0.60  (LTV 60%)
  GRADED:      0.65  (LTV 65%)
  WAREHOUSED:  0.70  (LTV 70%)
  COMMITTED:   0.80  (LTV 80%)

Events

event BatchMinted(
    uint256 indexed tokenId,
    string batchId,
    string farmerId,
    string cooperativeId,
    uint256 weightKg,
    string grade,
    uint256 timestamp
);

event CollateralLocked(uint256 indexed tokenId, address indexed vault);
event CollateralUnlocked(uint256 indexed tokenId);
event BatchSettled(uint256 indexed tokenId, uint256 timestamp);