# FPS ability backend (fps.abilities)

## What it is for

Connects the combat.abilities kit to the offline first-person match, so abilities deal damage, heal, check line of sight, pay their costs and play synchronized cues through the match rules.

It needs `game.engine`, `fps.match`, `combat.abilities`; installing it brings them in.

## Turn it on

Install the kit in a project, then change a setting (the values shown are its defaults):

```text
gripforge_gamekit_install   { project_id: "gkp_…", id: "fps.abilities" }
gripforge_gamekit_configure { project_id: "gkp_…", id: "fps.abilities",
                              config: { "maxVolumes": 16, "healCap": 100 } }
```

## First example

<!-- test: kits/fps_abilities/tests/fps_abilities.rs::it_connects_itself_as_the_port_of_combat_abilities -->
This is the body of the passing test `it_connects_itself_as_the_port_of_combat_abilities`; the helper functions it calls are defined at the top of the same test file.

```rust
#[test]
fn it_connects_itself_as_the_port_of_combat_abilities() {
    let mut s = plain();
    assert_eq!(ok(&mut s, KIT, "available", json!([])), json!(true));
    assert_eq!(volumes(&mut s).len(), 0);
    assert!(call(&mut s, KIT, "dance", json!([]))
        .unwrap_err()
        .contains("fps.abilities.dance"));
    // Without a combat.abilities to connect to, it says so.
    let lonely = world_with(
        &[("fps.tactical", tactical()), (KIT, json!({}))],
        json!({"tactical_maps": [map()]}),
    );
    assert!(
        lonely
            .host
            .logs
            .iter()
            .any(|(level, m)| level == "error" && m.contains("fps.abilities")),
        "{:?}",
        lonely.host.logs
    );
}
```

## Settings and defaults

Descriptions come from the kit manifest and stay in English.

| Setting | Type | Default | Range or values | Meaning |
|---|---|---|---|---|
| `maxVolumes` | integer | `16` | 1–64 | Smoke and wall volumes alive at once. |
| `healCap` | number | `100` | 1–100000 | Health an ability heal never goes above (never revives). |

## Services, events, variables

- Service `fps.abilities`: 
- Events emitted:
  - `ability.cue` (`source`, `ability`, `cast`, `phase`, `target`, `presentation`) — The cues of combat.abilities for the FPS actors (windup, active, hit, recovery, ended, cancelled).

## Hooks and modding

- Hooks (a game or a mod can intercept them):
  - `fps.ability.heal` (fields a tap may change: `amount`, `cap`; cancellable) — A heal effect is about to land on a live FPS actor: amount of health, cap the health it never goes above (config healCap).
  - `fps.ability.deploy` (cancellable) — A spatial effect (smoke, wall or teleport) placed and checked is about to be deployed in the match, after the windup.
- Moddable settings: `maxVolumes`, `healCap`

## Engines

Declared targets: `web`, `rust`. `gripforge kit api fps.abilities` lists the exact settings and services of your version.

## Versions

Kit version 1.3.0.