# Prerequisites

Before building quicprochat you need a Rust toolchain. No other system tools are required — Protobuf compilation is handled automatically at build time by the `protobuf-src` crate, which vendors the `protoc` compiler. Docker is optional and useful for reproducible builds and deployment.

---

## Rust toolchain

**Minimum supported Rust version: 1.77+ (stable)**

quicprochat uses the 2021 edition and workspace resolver v2. Any stable Rust release from 1.77 onward should work. Install or update via [rustup](https://rustup.rs/):

```bash
# Install rustup (if not already present)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# Ensure you are on a recent stable release
rustup update stable
rustup default stable

# Verify
rustc --version   # should print 1.77.0 or later
cargo --version
```

The workspace depends on several crates that use procedural macros (`serde_derive`, `clap_derive`, `tls_codec_derive`, `thiserror`, `prost-derive`). These compile during the build step and require no additional system libraries beyond what `rustc` ships.

---

## No external compiler dependencies

In v2, all wire-format serialisation uses [Protobuf](https://protobuf.dev/) via the `prost` crate. The `quicprochat-proto` crate's `build.rs` script drives code generation through `prost-build`, which in turn uses the `protobuf-src` crate to compile and use a vendored copy of `protoc`. **You do not need to install `protoc` or any other system compiler.**

The legacy Cap'n Proto schemas (`schemas/`) are still present for reference, but the v2 runtime and RPC framework use Protobuf exclusively.

---

## Optional: Docker and Docker Compose

If you prefer to build and run quicprochat in containers, you will need:

- **Docker Engine** 20.10+ (or Docker Desktop)
- **Docker Compose** v2+ (the `docker compose` plugin, not the legacy `docker-compose` binary)

```bash
docker --version          # 20.10+
docker compose version    # v2+
```

The `docker/Dockerfile` is a multi-stage build that does not install any extra system packages in the builder stage — `protobuf-src` takes care of the Protobuf compiler at compile time.

See [Docker Deployment](docker.md) for full instructions.

---

## Summary checklist

| Dependency | Required? | How to check |
|---|---|---|
| Rust stable 1.77+ | Yes | `rustc --version` |
| `protoc` CLI | No (vendored automatically) | n/a |
| Docker + Compose | No (container builds only) | `docker --version` / `docker compose version` |

Once all prerequisites are satisfied, proceed to [Building from Source](building.md).
