TUSDT Contracts Workspace

Ink! contracts for a collateralized TUSDT system with vault borrowing, interest accrual, and liquidation auctions.

Prerequisites

• Rust stable toolchain
• wasm32-unknown-unknown target
• cargo-contract
• Node.js + Yarn (for the isolated contract tooling under tools/)
• A Contracts-enabled Substrate node (local or remote)

rustup target add wasm32-unknown-unknown
cargo install --locked cargo-contract

Build

Build all crates:

cargo check

Build contract artifacts (.contract, .wasm, metadata):

cargo contract build --manifest-path contracts/tusdt-erc20/Cargo.toml
cargo contract build --manifest-path contracts/tusdt-auction/Cargo.toml
cargo contract build --manifest-path contracts/tusdt-oracle/Cargo.toml
cargo contract build --manifest-path contracts/tusdt-vault/Cargo.toml

Artifacts are produced in target/ink/.

Contract Tooling (tools/)

Shared deployment scripts and on-chain tests live in an isolated TypeScript subproject under tools/. The current iteration exposes upload support for erc20, auction, oracle, and vault, plus a single vault deployment entrypoint that instantiates the whole runtime flow.

Setup:

cd tools
yarn install
cp .env.example .env

Default .env values target a local dev node:

• WS_URL=ws://127.0.0.1:9944

Scripts and tests use the standard local dev accounts (//Alice, //Bob, //Charlie, //Dave, //Eve, //Ferdie) from the shared dev-account helper. When needed, you can override the selected account via SURI environment variables such as CONTRACT_UPLOADER=//Alice, CONTRACT_DEPLOYER=//Alice.

Useful commands:

cd tools
yarn build:erc20-artifacts
yarn build:auction-artifacts
yarn build:oracle-artifacts
yarn build:vault-artifacts
yarn erc20:upload
yarn auction:upload
yarn oracle:upload
yarn vault:upload
yarn vault:deploy --token-code-hash <TOKEN_CODE_HASH> --auction-code-hash <AUCTION_CODE_HASH> --oracle-code-hash <ORACLE_CODE_HASH>
yarn test:oracle

Deployment (Recommended Order)

tusdt-vault constructor requires the code hash of the token, auction, and oracle contracts, then instantiates all three internally.

1. Upload ERC20 code (tusdt-erc20) and capture code hash.
2. Upload Auction code (tusdt-auction) and capture code hash.
3. Upload Oracle code (tusdt-oracle) and capture code hash.
4. Instantiate Vault (tusdt-vault::new) with:
   • token_code_hash
   • auction_code_hash
   • oracle_code_hash

The deployed vault owner becomes the oracle owner during instantiation.

Example CLI (adjust URL/account):

cargo contract upload \
  --manifest-path contracts/tusdt-erc20/Cargo.toml \
  --suri //Alice --url ws://127.0.0.1:9944

cargo contract upload \
  --manifest-path contracts/tusdt-auction/Cargo.toml \
  --suri //Alice --url ws://127.0.0.1:9944

cargo contract upload \
  --manifest-path contracts/tusdt-oracle/Cargo.toml \
  --suri //Alice --url ws://127.0.0.1:9944

cargo contract instantiate \
  --manifest-path contracts/tusdt-vault/Cargo.toml \
  --constructor new \
  --args <ERC20_CODE_HASH> <AUCTION_CODE_HASH> <ORACLE_CODE_HASH> \
  --suri //Alice --url ws://127.0.0.1:9944

Prefer the tools/ workflow above instead of using cargo contract for upload/deploy operations where a TS script already exists. The current e2e test suite is intentionally oracle-only, and the only deployment script entrypoint is vault:deploy.

Working Flow

1) Vault lifecycle

1. User creates vault with native collateral: create_vault (payable).
2. User adds collateral: add_collateral (payable).
3. User borrows token: borrow_token.
4. User repays token: repay_token.
5. User releases collateral (only when debt is zero): release_collateral.

2) Interest model

• Accrual is day-based.
• Growth model is compound interest equivalent to: borrowed * e^(interest_rate * borrowed_days / 365).
• Implementation computes daily growth and compounds by elapsed full days.

3) Liquidation flow

1. Anyone can call trigger_liquidation_auction(owner, vault_id) when vault exceeds liquidation threshold.
2. Auction contract creates an auction tied to that vault.
3. Bidders approve token allowance to auction contract, then call place_bid.
4. After end time, call finalize_auction on auction contract.
5. Vault settlement: settle_liquidation_auction(owner, vault_id).

4) Admin flow

• Contract owner updates risk params (in percentages) with set_contract_params:
  • collateral_ratio
  • liquidation_ratio
  • interest_rate
  • liquidation_fee
  • auction_duration_ms
  • max_oracle_age_ms
• Oracle owner manages reporter access with set_reporter
• Oracle owner commits the active round with commit_round, optionally using a manual override price

Default params:

• Collateral ratio: 150%
• Liquidation ratio: 120%
• Interest rate: 5%
• Liquidation fee: 1%
• Auction duration: 3_600_000 milliseconds
• Max oracle age: 3_600_000 milliseconds

Useful Read Methods

• Vault: get_vault, get_contract_params, get_oracle_address, get_vaults, get_all_vaults
• Oracle: get_latest_price, get_current_round_summary, is_reporter
• Auction: get_auction, get_active_vault_auction, get_bid, get_all_auctions, get_active_auctions
• Token: balance_of, allowance, total_supply

Notes

• tusdt-vault owns the token and auction instances it creates.
• tusdt-vault reads collateral pricing from the external oracle contract.
• Borrowing mints TUSDT to borrower.
• Repayment and settlement burn TUSDT.