# readBlockSpentOutputs(at:) Reads the spent outputs (undo data) for a block from disk — the collection of UTXOs that this block consumed. ``` func readBlockSpentOutputs(at entry: BlockTreeEntry) -> BlockSpentOutputs? ``` ## Parameters `entry` The block tree entry pointing to the block. ## Return Value The block’s spent outputs, or `nil` on read failure. ## Discussion Spent-output data is what lets the kernel undo a block during a reorg. Returns `nil` for the genesis block (no inputs spent, no undo data written) and when the undo file is not present on disk.