Animal-backed lending/borrowing with ERC-1155 collateral, deployed via usecannon + Foundry. This doc explains how to build, why the Cannonfile looks the way it does, and the gotchas we hit (and solved) around oracles, dependency resolution, and schema quirks.

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TL;DR (what works)

• forge build && cannon build deploys:

  • MockUSDC (test stablecoin)

  • SpeciesToken (ERC-1155 animals)

  • SpeciesOracle (simple price oracle)

  • SpeciesLending (lending core)

• Seeds USDC + species balances, configures risk, and posts three price observations per species so the oracle’s median is valid.

• Accepts price for species id=1 only. (Ids 2 & 3 skip accept() due to the contract’s first-accept math edge-case; details below.)

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Stack

1. Solidity/Foundry for contracts & artifacts.

2. usecannon for deterministic deployments & post-deploy calls.

3. Local Anvil chain spawned by Cannon during build.

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Repo layout

We intentionally use artifact = "src/File.sol:Contract" to match Cannon’s legacy schema.

/src
  MockUSDC.sol
  SpeciesToken.sol
  SpeciesOracle.sol
  SpeciesLending.sol

cannonfile.toml

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Safety checklist (before mainnet)

• Migrate admin to a multisig.
• Remove all dev_* invokes.
• Verify contracts and publish sources.
• Add pause/guardian tests & runbooks.
• Add price-feed diversity (not just 1 reporter).
• Simulate stress events (oracle outage, price gaps, collateral cascades).

Financially it’s a lending market that mints/borrows stable liquidity (USDC) against tokenized livestock. You deposit cow-tokens, get credit, repay, or get liquidated if price drops below risk thresholds.

It’s basically Fungible Collateral → Borrow Fiat.

Technical risks: — Oracle assumptions: 3 price posts needed to form a median. If the reporter feeds garbage or is censored, risk parameters break. — Smart contract logic: underflow/overflow edge cases on first “accept” baseline. — Liquidations require precise price freshness or the bad actor can mint → borrow → dump within a stale heartbeat.