streampay-contracts

Soroban smart contracts for StreamPay — continuous payment streaming on the Stellar network.

Overview

This repo contains the on-chain logic for creating, starting, stopping, and settling payment streams. Contracts are written in Rust using the Soroban SDK.

Contract interface

• create_stream(payer, recipient, rate_per_second, initial_balance, recipient_can_stop) — Create a new stream (payer must auth). Set recipient_can_stop = true to allow the recipient to also stop the stream; defaults to false (payer-only).
• start_stream(stream_id) — Start an existing stream.
• stop_stream(stream_id, stopper) — Stop an active stream. stopper must be the payer (always allowed) or the recipient (only when recipient_can_stop was set at creation). stopper must authorise the call.
• settle_stream(stream_id) — Compute and deduct streamed amount since last settlement; returns amount.
• batch_settle(stream_ids) — Settle multiple streams in a single call; returns one settled amount per input id.
• archive_stream(stream_id) — Remove a fully-settled, inactive stream from storage (payer must auth).
• get_stream_info(stream_id) — Read stream metadata (payer, recipient, rate, balance, timestamps, active, recipient_can_stop).
• version() — Returns the contract version as a u32 (no auth required).

Batch settlement semantics

• batch_settle is all-or-nothing. If any stream id is missing or any item panics, the entire invocation reverts and no settlement updates are committed.
• Inactive streams settle to 0, matching settle_stream.
• The contract caps each batch at 25 stream ids to keep Soroban resource usage predictable. Off-chain indexers and payroll processors should chunk larger workloads into multiple transactions.

Storage Model

Streams are stored in Soroban persistent storage with per-stream TTL management. Each stream is an independent ledger entry that can expire independently. The contract instance storage holds only the next_id counter. The counter is 1-based; once it rolls over, the contract stores 0 as an exhausted sentinel and rejects further stream creation with stream id overflow.

See docs/factory-pattern.md for the full design rationale and future factory pattern graduation path.

Version encoding

The on-chain version uses a packed u32 scheme: major * 1_000_000 + minor * 1_000 + patch.

Semver	u32
0.1.0	1 000
1.0.0	1 000 000
1.2.3	1 002 003

When releasing, update both Cargo.toml version and the VERSION const in src/lib.rs.

Prerequisites

• Rust (stable, with rustfmt)
• Optional: Stellar CLI for deployment

Note: this crate uses soroban-sdk version 22.0 (see Cargo.toml).

Building, testing and deploying (copy-paste)

1. Build optimized WASM (recommended via Docker builder included):

# Build with local toolchain (WASM output in target/)
cargo build --release --target wasm32-unknown-unknown

# OR use deterministic Docker builder (produces streampay_contracts.wasm)
docker build -f docker/Dockerfile.build -t streampay-wasm .
docker run --rm -v "$(pwd)":/work streampay-wasm

2. Run unit tests locally:

cargo test

3. Deploy to Futurenet/Testnet using soroban CLI (example):

# install soroban CLI if not installed
curl -sSf https://soroban.stellar.org/install.sh | bash

# set the network (futurenet/testnet)
soroban config set network futurenet

# upload contract and get contract id (example paths)
soroban contract publish --wasm target/wasm32-unknown-unknown/release/streampay_contracts.wasm

# note the contract id printed by the publish command

4. Example invocation (replace <CONTRACT_ID> and addresses):

# create_stream(payer, recipient, rate_per_second, initial_balance)
soroban contract invoke --wasm target/wasm32-unknown-unknown/release/streampay_contracts.wasm \
   --id <CONTRACT_ID> --fn create_stream --args <PAYER_ADDRESS> <RECIPIENT_ADDRESS> 100 10000

# start_stream(stream_id)
soroban contract invoke --id <CONTRACT_ID> --fn start_stream --args 1

Notes

• The exact soroban CLI flags depend on the CLI version; consult soroban --help.
• For deterministic WASM builds in CI, use the provided docker/Dockerfile.build which pins the Rust toolchain.
• Ensure the soroban-sdk version in Cargo.toml is compatible with your soroban CLI and network.

Setup for contributors

1. Clone and enter the repo

   git clone <repo-url>
   cd streampay-contracts

2. Install Rust

   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   rustup component add rustfmt

3. Verify setup

   cargo fmt --all -- --check
   cargo build
   cargo test

Scripts

Command	Description
cargo build	Build the contract
cargo test	Run unit tests
cargo fmt	Format code
cargo fmt --all -- --check	Check formatting (CI)
./scripts/check-wasm-size.sh	Check optimized WASM size

CI/CD

On every push/PR to main, GitHub Actions runs:

• Format check: cargo fmt --all -- --check
• Build: cargo build
• Tests: cargo test
• WASM size check: Reports optimized contract size and warns if approaching limits

Ensure all checks pass before merging. See docs/resource-limits.md for details on Soroban resource constraints.

Releases

Tagged releases follow semver. Each release includes an optimized WASM artifact and SHA-256 checksum.

See docs/RELEASE.md for the full release process, including how to verify WASM builds.

Project structure

streampay-contracts/
├── src/
│   └── lib.rs                        # Contract and tests
├── docker/
│   └── Dockerfile.build              # Deterministic WASM builder
├── .github/workflows/
│   ├── ci.yml                        # Format, build, test
│   └── release.yml                   # Tagged release workflow
├── docs/
│   └── RELEASE.md                    # Release process guide
├── cliff.toml                        # Changelog generator config
├── rust-toolchain.toml               # Pinned Rust version
├── Cargo.toml
├── CHANGELOG.md
└── README.md

License

MIT

Documentation

Doc	Description
docs/timestamp-accrual.md	Ledger timestamp assumptions: validator behavior, coarse granularity, accrual edge cases, off-chain UX rounding
SECURITY.md	Security policy and responsible disclosure
CONTRIBUTING.md	Contribution guidelines
CHANGELOG.md	Release history