# hydra-engine-wds
[](https://crates.io/crates/hydra-engine-wds)
[](https://github.com/neeraip/hydra/blob/main/LICENSE)
[](https://github.com/neeraip/hydra/actions/workflows/cargo-ci.yml)
Core simulation engine for [Hydra](https://github.com/neeraip/hydra) — water distribution network data model, EPANET INP/OUT/RPT I/O, Global Gradient Algorithm hydraulic solver, Lagrangian water quality engine, simulation session API, and post-simulation analytics.
> **Most users should depend on [`hydra-sdk`](https://crates.io/crates/hydra-sdk) instead.** `hydra-sdk` re-exports the complete public API of this crate as a single stable umbrella dependency.
## Scope
This crate owns:
| `model` | Network data model, state types, validation |
| `io` | Unit conversion; INP parser; binary `.out` reader/writer; `.rpt` writer |
| `hydraulics` | GGA Newton-Raphson solver |
| `quality` | Lagrangian transport, mixing, reactions, source tracing |
| `simulation` | Session API, controls, timestep orchestration, accounting |
| `analysis` | Post-simulation analytics |
This crate does **not** own interface logic (CLI, GUI) or filesystem/network I/O — callers supply bytes.
## License
[AGPL v3](https://github.com/neeraip/hydra/blob/main/LICENSE) — see [COMMERCIAL_LICENSE.md](https://github.com/neeraip/hydra/blob/main/.github/COMMERCIAL_LICENSE.md) for commercial licensing options.