# Architecture

`rem-essentials` is intentionally feature-first. Every migrated behavior should
live in its own module and be registered as a named feature in `src/main.cpp`.

## Feature registration

Each feature has:

- a stable config key
- an init function
- an optional cleanup function
- a runtime side: `Client`, `Server`, or `Always`
- a code default

The INI file can override each default. Missing INI entries keep the compiled
default.

## Current feature keys

The full key list lives in `rem-essentials.ini`. Feature switches live in
`[rem-essentials]`; typed parameters used by the graphics, saves, and
screenshots behavior live in the `[flplusplus]` section.

## Design rules

- Prefer one feature flag per behavior, even when multiple behaviors share one
  option.
- Keep client and server hooks in separate files.
- Resolve optional Freelancer imports at runtime when practical.
- Keep adapted third-party code isolated under `third_party/` and wrap it with
  thin REM adapters instead of adding a second plugin entry point.

## Proton-sensitive fixes

Mouse features stay split because Wine/Proton can handle cursor APIs
differently from native Windows. The current conservative defaults are:

- `cursor_visibility_fix = true`
- `cursor_border_flicker_fix = false`
- `mouse_warp_fix = false`

These can be enabled per player in `rem-essentials.ini` after testing.