# ADR 0001 — Static Backend Configuration

**Status**: Draft  
**Date**: 2026-07-23

## Context

The gateway needs to know which upstream inference servers to route requests to. During initial development, the set of backends is known at deploy time.

## Decision

Backends are configured via a static TOML config file. The binary reads `config.toml` from the working directory by default, or accepts another path through `--config <PATH>`.

```toml
[[backend]]
name = "gpu-01"
address = "http://10.0.1.10:8000"

[[backend]]
name = "gpu-02"
address = "http://10.0.1.11:8000"

[cache]
block_size = 512
expiry_seconds = 300
```

`name` is a human-readable identifier for logging/metrics. `address` is the backend base URL. Cache block size and cache-location idle expiry are global startup settings.

## Consequences

- Simple, no external dependencies.
- Adding/removing backends requires a config change and restart.
- Dynamic registration can be added later.

## Alternatives Considered

- CLI flags per backend, environment variables, dynamic API.