# Client

## Domain Types

### Error

- `type Error struct{…}`

  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 ErrorError`

    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 map[string, unknown]`

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

### Feature Collection

- `type FeatureCollection struct{…}`

  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 []GeoJsonFeature`

    Array of GeoJSON Feature objects

    - `Geometry GeoJsonGeometry`

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

      - `Coordinates GeoJsonGeometryCoordinatesUnion`

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

        - `type GeoJsonGeometryCoordinatesPoint []float64`

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

        - `type GeoJsonGeometryCoordinatesLineStringOrMultiPoint [][]float64`

          Array of [lng, lat] positions

        - `type GeoJsonGeometryCoordinatesPolygonOrMultiLineString [][][]float64`

          Array of linear rings / line strings

        - `type GeoJsonGeometryCoordinatesMultiPolygon [][][][]float64`

          Array of polygons

      - `Type GeoJsonGeometryType`

        Geometry type

        - `const GeoJsonGeometryTypePoint GeoJsonGeometryType = "Point"`

        - `const GeoJsonGeometryTypeLineString GeoJsonGeometryType = "LineString"`

        - `const GeoJsonGeometryTypePolygon GeoJsonGeometryType = "Polygon"`

        - `const GeoJsonGeometryTypeMultiPoint GeoJsonGeometryType = "MultiPoint"`

        - `const GeoJsonGeometryTypeMultiLineString GeoJsonGeometryType = "MultiLineString"`

        - `const GeoJsonGeometryTypeMultiPolygon GeoJsonGeometryType = "MultiPolygon"`

    - `Properties map[string, 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 GeoJsonFeatureType`

      Always `Feature`

      - `const GeoJsonFeatureTypeFeature GeoJsonFeatureType = "Feature"`

    - `ID string`

      Compound identifier in `type/osm_id` format

  - `Type FeatureCollectionType`

    Always `FeatureCollection`

    - `const FeatureCollectionTypeFeatureCollection FeatureCollectionType = "FeatureCollection"`

### Geo Json Feature

- `type GeoJsonFeature struct{…}`

  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 GeoJsonGeometry`

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

    - `Coordinates GeoJsonGeometryCoordinatesUnion`

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

      - `type GeoJsonGeometryCoordinatesPoint []float64`

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

      - `type GeoJsonGeometryCoordinatesLineStringOrMultiPoint [][]float64`

        Array of [lng, lat] positions

      - `type GeoJsonGeometryCoordinatesPolygonOrMultiLineString [][][]float64`

        Array of linear rings / line strings

      - `type GeoJsonGeometryCoordinatesMultiPolygon [][][][]float64`

        Array of polygons

    - `Type GeoJsonGeometryType`

      Geometry type

      - `const GeoJsonGeometryTypePoint GeoJsonGeometryType = "Point"`

      - `const GeoJsonGeometryTypeLineString GeoJsonGeometryType = "LineString"`

      - `const GeoJsonGeometryTypePolygon GeoJsonGeometryType = "Polygon"`

      - `const GeoJsonGeometryTypeMultiPoint GeoJsonGeometryType = "MultiPoint"`

      - `const GeoJsonGeometryTypeMultiLineString GeoJsonGeometryType = "MultiLineString"`

      - `const GeoJsonGeometryTypeMultiPolygon GeoJsonGeometryType = "MultiPolygon"`

  - `Properties map[string, 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 GeoJsonFeatureType`

    Always `Feature`

    - `const GeoJsonFeatureTypeFeature GeoJsonFeatureType = "Feature"`

  - `ID string`

    Compound identifier in `type/osm_id` format

### Geo Json Geometry

- `type GeoJsonGeometry struct{…}`

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

  - `Coordinates GeoJsonGeometryCoordinatesUnion`

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

    - `type GeoJsonGeometryCoordinatesPoint []float64`

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

    - `type GeoJsonGeometryCoordinatesLineStringOrMultiPoint [][]float64`

      Array of [lng, lat] positions

    - `type GeoJsonGeometryCoordinatesPolygonOrMultiLineString [][][]float64`

      Array of linear rings / line strings

    - `type GeoJsonGeometryCoordinatesMultiPolygon [][][][]float64`

      Array of polygons

  - `Type GeoJsonGeometryType`

    Geometry type

    - `const GeoJsonGeometryTypePoint GeoJsonGeometryType = "Point"`

    - `const GeoJsonGeometryTypeLineString GeoJsonGeometryType = "LineString"`

    - `const GeoJsonGeometryTypePolygon GeoJsonGeometryType = "Polygon"`

    - `const GeoJsonGeometryTypeMultiPoint GeoJsonGeometryType = "MultiPoint"`

    - `const GeoJsonGeometryTypeMultiLineString GeoJsonGeometryType = "MultiLineString"`

    - `const GeoJsonGeometryTypeMultiPolygon GeoJsonGeometryType = "MultiPolygon"`