Function encode_single_tile 

pub fn encode_single_tile(
    features: &[ParsedFeature],
    z: u8,
    x: u32,
    y: u32,
    t: i64,
    config: &TileConfig,
    encoder: &EncoderConfig,
) -> Result<Option<Vec<u8>>>

Encode exactly one tile (z, x, y, t), discarding the placed-feature count. The convenience form of encode_single_tile_counted for callers that don’t apply a min_features_per_tile gate. Ok(None) means the tile is empty.