Struct Checkpoint 

pub struct Checkpoint {
    pub epoch: u64,
    pub state_root: BytesImpl<32>,
    pub block_root: BytesImpl<32>,
    pub block_count: u32,
    pub tx_count: u64,
    pub total_fees: u64,
    pub prev_checkpoint: BytesImpl<32>,
    pub withdrawals_root: BytesImpl<32>,
    pub withdrawal_count: u32,
}

Epoch summary checkpoint: aggregate stats and Merkle roots for one L1-anchored epoch (SPEC §2.6, CKP-001).

Field semantics (informal)

• epoch: Monotonic epoch id this summary closes.
• state_root: Post-epoch L2 state commitment.
• block_root: Merkle root over block hashes in the epoch (CKP-006 will define construction).
• block_count / tx_count / total_fees: Scalar aggregates for light verification and scoring; block_count is the block factor in compute_score (CKP-004).
• prev_checkpoint: Hash / identity of the prior checkpoint header for chained verification (CKP-001 implementation notes).
• withdrawals_root / withdrawal_count: Merkle root and count over withdrawal records in the epoch.

Fields

epoch: u64

Epoch number this checkpoint summarizes.

state_root: BytesImpl<32>

L2 state root after applying all blocks in the epoch.

block_root: BytesImpl<32>

Merkle root over block hashes included in this epoch.

block_count: u32

Number of L2 blocks in the epoch.

tx_count: u64

Total transactions across blocks in the epoch.

total_fees: u64

Sum of fees collected in the epoch (same currency unit as receipt fees — see RCP-*).

prev_checkpoint: BytesImpl<32>

Link to the previous checkpoint (continuity for fraud/validity proofs).

withdrawals_root: BytesImpl<32>

Merkle root over withdrawal hashes in the epoch.

withdrawal_count: u32

Number of withdrawals in the epoch.

Implementations

impl Checkpoint

pub const HASH_PREIMAGE_LEN: usize = 160

Byte length of the SHA-256 preimage for Self::hash (SPEC §3.2: 8+32+32+4+8+8+32+32+4).

pub fn new() -> Checkpoint

Default empty checkpoint: epoch 0, zero counts, all roots Bytes32::default (CKP-001 constructor spec).

Usage: crate::builder::checkpoint_builder::CheckpointBuilder and tests start from this value then overwrite fields; production checkpoints should set non-zero roots before signing (CKP-005 / HSH-002).

pub fn compute_score(&self, stake_percentage: u64) -> u64

Competition score: stake_percentage * block_count (CKP-004, NORMATIVE § CKP-004).

Parameters

• stake_percentage: Integer stake share for the submitter, typically 0..=100 (CKP-004 implementation notes). The type is u64 so callers can scale fixed-point stake if needed without API churn.

Returns

Product in u64. Favors checkpoints with more blocks and higher backing stake. Overflow: Uses ordinary u64 multiplication (wraps on overflow; debug builds may panic on overflow — keep inputs within protocol bounds, e.g. epoch length ×100).

pub fn hash_preimage_bytes(&self) -> [u8; 160]

Fixed-order 160-byte preimage for HSH-002 / SPEC §3.2 (same bytes as fed to Self::hash).

Order: epoch, state_root, block_root, block_count, tx_count, total_fees, prev_checkpoint, withdrawals_root, withdrawal_count.

Note: HSH-002 spec pseudocode lists some counts as u64; the wire table in SPEC §3.2 and this struct use u32 LE for block_count and withdrawal_count (4 bytes each).

pub fn hash(&self) -> BytesImpl<32>

Canonical checkpoint identity: SHA-256 over Self::hash_preimage_bytes (SPEC §3.2).

Encoding: epoch, tx_count, total_fees as u64 LE; block_count, withdrawal_count as u32 LE (4 bytes each); four Bytes32 roots as raw 32-byte slices (HSH-002, NORMATIVE § HSH-002).

Primitive: Sha256 from chia-sha2 only (project crypto rules). CheckpointSubmission::hash delegates here (CKP-005).

pub fn to_bytes(&self) -> Vec<u8>

Serialize checkpoint summary to bincode bytes (SER-002, SPEC §8.2).

pub fn from_bytes(bytes: &[u8]) -> Result<Checkpoint, CheckpointError>

Deserialize a checkpoint from bincode bytes (SER-002).

Trait Implementations

impl Clone for Checkpoint

fn clone(&self) -> Checkpoint

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Checkpoint

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for Checkpoint

fn default() -> Checkpoint

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Checkpoint

fn deserialize<__D>( __deserializer: __D, ) -> Result<Checkpoint, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Checkpoint

fn eq(&self, other: &Checkpoint) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Checkpoint

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for Checkpoint

impl StructuralPartialEq for Checkpoint