The sidecar half of the Runic Gateway bridge for Rust. It terminates the loopback link from a Rust server's Oxide bridge plugin and exposes the WebSocket + REST surface the website consumes.

It is the mirror of RunicGateway/link, which does the same job for Ultima Online, and it keeps that bridge's central invariant unchanged:

The game server is never reachable from the website. The plugin dials out to this process; this process owns the listener. Only the sidecar is exposed, and only the website's backend talks to it.

Rust server + Oxide  (RunicGateway/Rust-Plugins, C#)
   │  loopback TCP 127.0.0.1:7799, newline-delimited JSON, bidirectional
   │  the PLUGIN dials out (the game opens no listening port for us)
   ▼
rust-link sidecar  (this repo, Rust)   ← the only network-facing bridge component
   │  WebSocket (live feed) + REST (point-in-time reads), bearer-token auth
   ▼
website backend + module-rust  (RunicGateway/Module-Rust, Node)

One server, one sidecar

This binary serves exactly one Rust game server. A community running six servers runs six pairs, each with its own port, database and token; module-rust holds six clients and the website core never learns there is more than one. Nothing here is multiplexed, and nothing here should become multiplexed.

Build and run

cd sidecar
cargo build --release          # → target/release/rust-link-sidecar
cargo run                      # info logging; writes sidecar.toml (with a generated token) on first run
RUST_LOG=debug cargo run       # verbose, including heartbeats

Everything is configured from sidecar.toml — nothing is compiled into the binary. Auth is always on: a blank token is generated and written back on first start, so there is no state in which this process listens without one. --print-config resolves the configuration and prints it as JSON, which is how an installer reads the token back without scraping a log.

See sidecar/README.md for the configuration reference and the endpoint list.

The protocol is a contract

The loopback JSON protocol (plugin ↔ sidecar) and this sidecar's HTTP/WS API (sidecar ↔ website) are versioned compatibility contracts, not build dependencies. PROTOCOL_VERSION lives in sidecar/src/main.rs; every response carries X-RustLink-Version, and a client that declares a different one is refused 409 rather than served something it will mis-parse.

A version is declared in three places and they must agree:

Where	Repo
`PROTOCOL_VERSION`	this repo
`overlay.toml`	`RunicGateway/Rust-Plugins`
`module.json`	`RunicGateway/Module-Rust`

The canonical spec is docs/rust-link/. If you add or change an event or a command, update all three repos and the spec in the same change.

Licence

GPL-3.0-or-later. See LICENSE.md.