> For the complete documentation index, see [llms.txt](https://developers.wiki.resourcefulbees.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.wiki.resourcefulbees.com/biome-modifiers/spawn-predicate.md).

# Spawn Predicate

Bee spawn biome modifiers may include an optional `spawnPredicate` using Minecraft's `LocationPredicate` codec.

All known top-level fields are optional.

| Field         | Type                 | Required | Default | Notes                                    |
| ------------- | -------------------- | -------- | ------- | ---------------------------------------- |
| `position`    | Position predicate   | No       | —       | Optional x/y/z bounds.                   |
| `biomes`      | Biome holder set     | No       | —       | Additional biome constraint.             |
| `structures`  | Structure holder set | No       | —       | Structure membership constraint.         |
| `dimension`   | dimension identifier | No       | —       | Example: `minecraft:overworld`.          |
| `smokey`      | boolean              | No       | —       | Matches smokey locations.                |
| `light`       | Light predicate      | No       | —       | Constrains light level.                  |
| `block`       | Block predicate      | No       | —       | Constrains block at the tested location. |
| `fluid`       | Fluid predicate      | No       | —       | Constrains fluid at the tested location. |
| `can_see_sky` | boolean              | No       | —       | Constrains sky visibility.               |

## Position predicate

`x`, `y`, and `z` each use `MinMaxBounds.Doubles` and are optional.

A bound can be an exact number:

```json
{
  "position": {
    "y": 64
  }
}
```

or an object:

```json
{
  "position": {
    "y": {
      "min": 60.0,
      "max": 128.0
    }
  }
}
```

The codec rejects `min > max`.

## Light predicate

`light.light` uses integer min/max bounds.

```json
{
  "light": {
    "light": {
      "min": 8,
      "max": 15
    }
  }
}
```

## Block predicate

Known fields include:

| Field    | Type                         | Required |
| -------- | ---------------------------- | -------- |
| `blocks` | Block holder set             | No       |
| `state`  | block-state predicate object | No       |
| `nbt`    | NBT predicate                | No       |

Minecraft data-component matcher fields are flattened into the same block predicate object. Those internals remain intentionally permissive in the schema because their complete codec definitions were not supplied.

## Fluid predicate

Known fields are:

| Field    | Type                         | Required |
| -------- | ---------------------------- | -------- |
| `fluids` | Fluid holder set             | No       |
| `state`  | fluid-state predicate object | No       |

## Full example

```json
{
  "position": {
    "y": {"min": 60.0, "max": 128.0}
  },
  "biomes": "#minecraft:is_overworld",
  "dimension": "minecraft:overworld",
  "smokey": false,
  "light": {
    "light": {"min": 8}
  },
  "block": {
    "blocks": ["minecraft:grass_block", "minecraft:dirt"]
  },
  "fluid": {
    "fluids": "minecraft:water"
  },
  "can_see_sky": true
}
```