# Client

## Domain Types

### Error

- `error: object { error }`

  Standard API error envelope. Every error response wraps a single `error` object with a machine-readable `code`, a human-readable `message`, and optional structured `details`.

  - `error: object { code, message, details }`

    Error payload

    - `code: string`

      Machine-readable error code (e.g. `invalid_request`, `not_found`, `rate_limited`, `query_error`, `daily_limit_exceeded`)

    - `message: string`

      Human-readable explanation of what went wrong

    - `details: optional map[unknown]`

      Structured details when available (e.g. field-level validation errors, rate limit metadata, billing info)

### Feature Collection

- `feature_collection: object { features, type }`

  GeoJSON FeatureCollection (RFC 7946). For paginated endpoints, metadata is returned in HTTP response headers rather than the body:

| Header          | Description                                      |
| --------------- | ------------------------------------------------ |
| `X-Limit`       | Requested result limit                           |
| `X-Has-More`    | `true` if more results exist                     |
| `X-Next-Cursor` | Opaque cursor for next page (cursor pagination)  |
| `X-Next-Offset` | Numeric offset for next page (offset pagination) |
| `Link`          | RFC 8288 `rel="next"` link to the next page      |

  Content-Type is `application/geo+json`.

  - `features: array of GeoJsonFeature`

    Array of GeoJSON Feature objects

    - `geometry: object { coordinates, type }`

      GeoJSON Geometry object per RFC 7946. Coordinates use [longitude, latitude] order. 3D coordinates [lng, lat, elevation] are used for elevation endpoints.

      - `coordinates: array of number or array of array of number or array of array of array of number or array of array of array of array of number`

        Coordinates array. Nesting depth varies by geometry type: Point = [lng, lat], LineString = [[lng, lat], ...], Polygon = [[[lng, lat], ...], ...], etc.

        - `Point: array of number`

          [longitude, latitude] or [longitude, latitude, elevation]

        - `LineString or MultiPoint: array of array of number`

          Array of [lng, lat] positions

        - `Polygon or MultiLineString: array of array of array of number`

          Array of linear rings / line strings

        - `MultiPolygon: array of array of array of array of number`

          Array of polygons

      - `type: "Point" or "LineString" or "Polygon" or 3 more`

        Geometry type

        - `"Point"`

        - `"LineString"`

        - `"Polygon"`

        - `"MultiPoint"`

        - `"MultiLineString"`

        - `"MultiPolygon"`

    - `properties: map[unknown]`

      OSM tags flattened as key-value pairs, plus `@type` (node/way/relation) and `@id` (OSM ID) metadata fields. May include `distance_m` for proximity queries.

    - `type: "Feature"`

      Always `Feature`

      - `"Feature"`

    - `id: optional string`

      Compound identifier in `type/osm_id` format

  - `type: "FeatureCollection"`

    Always `FeatureCollection`

    - `"FeatureCollection"`

### Geo Json Feature

- `geo_json_feature: object { geometry, properties, type, id }`

  GeoJSON Feature representing an OSM element. Tags from the original OSM element are flattened directly into `properties` (not nested under a `tags` key). Metadata fields `@type` and `@id` identify the OSM element type and ID within properties.

  - `geometry: object { coordinates, type }`

    GeoJSON Geometry object per RFC 7946. Coordinates use [longitude, latitude] order. 3D coordinates [lng, lat, elevation] are used for elevation endpoints.

    - `coordinates: array of number or array of array of number or array of array of array of number or array of array of array of array of number`

      Coordinates array. Nesting depth varies by geometry type: Point = [lng, lat], LineString = [[lng, lat], ...], Polygon = [[[lng, lat], ...], ...], etc.

      - `Point: array of number`

        [longitude, latitude] or [longitude, latitude, elevation]

      - `LineString or MultiPoint: array of array of number`

        Array of [lng, lat] positions

      - `Polygon or MultiLineString: array of array of array of number`

        Array of linear rings / line strings

      - `MultiPolygon: array of array of array of array of number`

        Array of polygons

    - `type: "Point" or "LineString" or "Polygon" or 3 more`

      Geometry type

      - `"Point"`

      - `"LineString"`

      - `"Polygon"`

      - `"MultiPoint"`

      - `"MultiLineString"`

      - `"MultiPolygon"`

  - `properties: map[unknown]`

    OSM tags flattened as key-value pairs, plus `@type` (node/way/relation) and `@id` (OSM ID) metadata fields. May include `distance_m` for proximity queries.

  - `type: "Feature"`

    Always `Feature`

    - `"Feature"`

  - `id: optional string`

    Compound identifier in `type/osm_id` format

### Geo Json Geometry

- `geo_json_geometry: object { coordinates, type }`

  GeoJSON Geometry object per RFC 7946. Coordinates use [longitude, latitude] order. 3D coordinates [lng, lat, elevation] are used for elevation endpoints.

  - `coordinates: array of number or array of array of number or array of array of array of number or array of array of array of array of number`

    Coordinates array. Nesting depth varies by geometry type: Point = [lng, lat], LineString = [[lng, lat], ...], Polygon = [[[lng, lat], ...], ...], etc.

    - `Point: array of number`

      [longitude, latitude] or [longitude, latitude, elevation]

    - `LineString or MultiPoint: array of array of number`

      Array of [lng, lat] positions

    - `Polygon or MultiLineString: array of array of array of number`

      Array of linear rings / line strings

    - `MultiPolygon: array of array of array of array of number`

      Array of polygons

  - `type: "Point" or "LineString" or "Polygon" or 3 more`

    Geometry type

    - `"Point"`

    - `"LineString"`

    - `"Polygon"`

    - `"MultiPoint"`

    - `"MultiLineString"`

    - `"MultiPolygon"`