write
abstract suspend fun writeTile(z: Int, x: Int, y: Int, bytes: ByteArray, tileScale: Float, tileOffset: Float, etag: String? = null, lastModified: String? = null)
Persist the encoded tile bytes + ancillary metadata for (z, x, y), plus the network response's etag / lastModified validators so a later refresh can issue a conditional GET. Implementations should be idempotent — writing the same key twice replaces the prior row.