@sablier/flow/README.md

Flow smart contracts of the Sablier token distribution protocol

# Sablier Flow [![Github Actions][gha-badge]][gha] [![Coverage][codecov-badge]][codecov] [![Foundry][foundry-badge]][foundry] [![Discord][discord-badge]][discord]

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[foundry]: https://getfoundry.sh
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This repository contains the smart contracts for Sablier Flow protocol. Flow is a debt tracking protocol that tracks
tokens owed between two parties, enabling indefinite token streaming. A Flow stream is characterized by its rate per
second (rps). The relationship between the amount owed and time elapsed is linear and can be defined as:

```math
\text{amount owed} = rps \cdot \text{elapsed time}
```

Flow protocol can be used in several areas of everyday finance, such as payroll, distributing grants, insurance
premiums, loans interest, token ESOPs etc. If you are looking for vesting and airdrops, please refer to our
[Lockup](https://github.com/sablier-labs/v2-core/) protocol.

## Features

1. **Flexible deposit:** A stream can be funded with any amount, at any time, by anyone, in full or in parts.
2. **Flexible duration:** A stream can be created with no specific start or end time. It can run indefinitely.
3. **Pause:** A stream can be paused by the sender and can later be restarted without losing track of previously accrued
   debt.
4. **Refund:** Unstreamed amount can be refunded back to the sender at any time.
5. **Void:** Voiding a stream implies it cannot be restarted anymore. Voiding an insolvent stream forfeits the uncovered
   debt. Either party can void a stream at any time.
6. **Withdraw:** it is publicly callable as long as `to` is set to the recipient. However, a stream’s recipient is
   allowed to withdraw funds to any address.

## Install

### Node.js

This is the recommended approach.

Install Flow using your favorite package manager, e.g. with Bun:

```shell
bun add @sablier/flow
```

Then, if you are using Foundry, you need to add these to your `remappings.txt` file:

```text
@sablier/flow/=node_modules/@sablier/flow/
@openzeppelin/contracts/=node_modules/@openzeppelin/contracts/
@prb/math/=node_modules/@prb/math/
```

### Git Submodules

This installation method is not recommended, but it is available for those who prefer it.

Install the submodule using Forge:

```shell
forge install --no-commit sablier-labs/flow
```

Then, install the project's dependencies:

```shell
forge install --no-commit OpenZeppelin/openzeppelin-contracts@v5.0.2 PaulRBerg/prb-math#95f00b2
```

Finally, add these to your `remappings.txt` file:

```text
@sablier/flow/=lib/flow/
@openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
@prb/math/=lib/prb-math/
```

## Usage

This is just a glimpse of Sablier Flow. For more guides and examples, see the [documentation](https://docs.sablier.com)
and the [technical file](./TECHNICAL-DOC.md).

```solidity
import { ISablierFlow } from "@sablier/flow/src/interfaces/ISablierFlow.sol";

contract MyContract {
  ISablierFlow immutable flow;

  function doSomethingWithFlow(uint256 streamId) external {
    uint128 totalDebt = flow.totalDebtOf(streamId);
    // ...
  }
}
```

## Contributing

Feel free to dive in! [Open](https://github.com/sablier-labs/flow/issues/new) an issue,
[start](https://github.com/sablier-labs/flow/discussions/new) a discussion or submit
[a PR](https://github.com/sablier-labs/flow/compare). For any concerns or feedback, please join our
[Discord server](https://discord.gg/bSwRCwWRsT).

Refer to [CONTRIBUTING](./CONTRIBUTING.md) guidelines if you wish to create a PR.

## License

The primary license for Sablier Flow is the Business Source License 1.1 (`BUSL-1.1`), see [`LICENSE.md`](./LICENSE.md).
However, there are exceptions:

- All files in `src/` with the exception of `SablierFlow.sol` are licensed under `GPL-3.0-or-later`. Refer to
  [`LICENSE-GPL.md`](./LICENSE-GPL.md) for preamble.
- All files in `script/` are licensed under `GPL-3.0-or-later`.
- All files in `tests/` are unlicensed (as indicated in their SPDX headers).