Creditra Contracts

Core smart contracts for the Creditra protocol, managing credit lines, draw operations, repayments, and risk parameters.

This repo contains the credit contract: it maintains credit lines, tracks utilization, enforces limits, and exposes methods for opening lines, drawing, repaying, and updating risk parameters. Draw logic includes a liquidity reserve check and token transfer flow.

Contract data model:

• CreditStatus: Active, Suspended, Defaulted, Closed, Restricted
• CreditLineData: borrower, credit_limit, utilized_amount, interest_rate_bps, risk_score, status, last_rate_update_ts, accrued_interest, last_accrual_ts

Behavior notes:

• after suspend_credit_line, draw_credit for that borrower reverts
• after default_credit_line, draw_credit reverts and repay_credit remains allowed
• repay_credit remains allowed while suspended or defaulted

Methods: init, set_liquidity_token, set_liquidity_source, open_credit_line, draw_credit, repay_credit, update_risk_parameters, suspend_credit_line, close_credit_line, default_credit_line, reinstate_credit_line, get_credit_line.

Liquidity reserve enforcement

• draw_credit now checks configured liquidity token balance at the configured liquidity source before transfer.
• If reserve balance is less than requested draw amount, the transaction reverts with: Insufficient liquidity reserve for requested draw amount.
• init defaults liquidity source to the contract address.
• repay_credit (when a liquidity token is configured) uses transfer_from to move tokens from the borrower to the configured liquidity source; borrowers must approve an allowance for the credit contract.
• Admin can configure:
  • set_liquidity_token — token contract used for reserve and draw transfers.
  • set_liquidity_source — reserve address to fund draws (contract or external source).

Suspend credit line behavior

• suspend_credit_line is admin only and requires the credit line to exist.
• Only lines in Active status can be suspended.
• draw_credit rejects any draw when the line is not Active (including Suspended).
• Repayments are intended to remain allowed while suspended.

Interest accrual design

• The contract already reserves accrued_interest and last_accrual_ts in storage for lazy interest accounting.
• The design note for implementing accrual is documented in docs/interest-accrual.md.
• Current code does not yet apply periodic accrual to balances; the new document defines the intended behavior before implementation.

Tech Stack

• Rust (edition 2021)
• soroban-sdk (Stellar Soroban)
• Build target: wasm32 for Soroban

Prerequisites

• Rust 1.75+ (recommend latest stable)

• wasm32 target:

  rustup target add wasm32-unknown-unknown

• Stellar Soroban CLI for deploy and invoke (optional for local build).

Setup and build

Build

cargo build

WASM build (release profile, size-optimized)

The workspace uses a release profile tuned for contract size (opt-level "z", LTO, strip symbols). To build the contract for Soroban:

rustup target add wasm32-unknown-unknown
cargo build --release --target wasm32-unknown-unknown -p creditra-credit

WASM output is at target/wasm32-unknown-unknown/release/creditra_credit.wasm. Size is kept small by:

• opt-level = "z" (optimize for size)
• lto = true (link-time optimization)
• strip = "symbols" (no debug symbols in release)
• codegen-units = 1 (better optimization)

CI enforces a size budget of 50 KB (51200 bytes) for this artifact to ensure deployability and fast runtime.

Avoid large dependencies; prefer minimal use of the Soroban SDK surface to stay within practical Soroban deployment limits.

Run tests

cargo test -p creditra-credit

Coverage

cargo llvm-cov --workspace --all-targets --fail-under-lines 95

Current result:

• Regions: 99.51%
• Lines: 98.94%

This satisfies the 95% minimum coverage target.

Security Documentation

• Threat model and trust assumptions: docs/threat-model.md

Deploy (with Soroban CLI)

Once the Soroban CLI and a network are configured:

soroban contract deploy --wasm target/wasm32-unknown-unknown/release/creditra_credit.wasm --source <identity> --network <network>

See Stellar Soroban docs for details.

Project layout

• Cargo.toml — workspace and release profile (opt for contract size)
• contracts/credit/ — credit line contract
  • Cargo.toml — crate config, soroban-sdk dependency
  • src/lib.rs — contract types and impl (stubs)

Merging to remote

This repo is a standalone git repository. After adding your remote:

git remote add origin <your-creditra-contracts-repo-url>
git push -u origin main