starknet_api: define partial block hash

[ArielElp]

Note

Low Risk
Additive API change that reuses existing hashing logic with fixed constants; low risk aside from potential downstream assumptions about hash semantics/usage.

Overview
Adds a new PartialBlockHash wrapper type representing the hash of PartialBlockHashComponents only (excluding state root and parent hash).

PartialBlockHash::from_partial_block_hash_components reuses the existing calculate_block_hash formula by fixing state_root and parent_hash to zero constants, and introduces the needed StarkHash import/serialization traits for the new type.

^{Written by Cursor Bugbot for commit e529641. This will update automatically on new commits. Configure here.}

[reviewable-StarkWare]

This change is 

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Artifacts upload workflows:

• Started at 2026-02-10T11:42:06Z
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[ArielElp]

• apollo_batcher,apollo_consensus_orchestrator: consensus over partial block hash #12451
• starknet_api: define partial block hash #12450 👈 (View in Graphite)
• main-v0.14.2

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[nimrod-starkware]

@nimrod-starkware made 1 comment.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @ArielElp).

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 260 at r1 (raw file):

    )?;
    Ok(PartialBlockHash(block_hash.0))
}

consider this
IMO it's cleaner

Suggestion:

/// Hash of [`PartialBlockHashComponents`] only (no state root or parent hash).
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct PartialBlockHash(pub StarkHash);

impl PartialBlockHash {
    const GLOBAL_ROOT_FOR_PARTIAL_BLOCK_HASH = ..
    const PARENT_HASH_FOR_PARTIAL_BLOCK_HASH = ..
    
/// Hash of [`PartialBlockHashComponents`].
/// Uses the same formula as [`calculate_block_hash`] with the constants above for state root and
/// parent hash.
pub fn from_partial_components(
    partial_block_hash_components: &PartialBlockHashComponents,
) -> StarknetApiResult<Self> {
    let block_hash = calculate_block_hash(
        partial_block_hash_components,
        Self::GLOBAL_ROOT_FOR_PARTIAL_BLOCK_HASH,
        Self::PARENT_HASH_FOR_PARTIAL_BLOCK_HASH,
    )?;
    Ok(Self(block_hash.0))
}

[ArielElp]

@ArielElp made 1 comment.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on @nimrod-starkware).

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 260 at r1 (raw file):

Previously, nimrod-starkware wrote…

consider this
IMO it's cleaner

Done.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

[nimrod-starkware]

@nimrod-starkware made 3 comments and resolved 1 discussion.
Reviewable status: 0 of 1 files reviewed, 4 unresolved discussions (waiting on @ArielElp).

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 179 at r2 (raw file):

    /// Hash of [`PartialBlockHashComponents`].
    /// Uses the same formula as [`calculate_block_hash`] with the fixed constants above for the
    /// state root and parent hash..

Suggestion:

state root and parent hash.

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 180 at r2 (raw file):

    /// Uses the same formula as [`calculate_block_hash`] with the fixed constants above for the
    /// state root and parent hash..
    fn from_partial_block_hash_components(

Suggestion:

pub fn from_partial_block_hash_components(

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 188 at r2 (raw file):

            Self::PARENT_HASH_FOR_PARTIAL_BLOCK_HASH,
        )?;
        Ok(PartialBlockHash(block_hash.0))

Suggestion:

Self

[ArielElp]

@ArielElp made 3 comments.
Reviewable status: 0 of 1 files reviewed, 3 unresolved discussions (waiting on @nimrod-starkware).

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 179 at r2 (raw file):

    /// Hash of [`PartialBlockHashComponents`].
    /// Uses the same formula as [`calculate_block_hash`] with the fixed constants above for the
    /// state root and parent hash..

Done.

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 180 at r2 (raw file):

    /// Uses the same formula as [`calculate_block_hash`] with the fixed constants above for the
    /// state root and parent hash..
    fn from_partial_block_hash_components(

Done.

---

crates/starknet_api/src/block_hash/block_hash_calculator.rs line 188 at r2 (raw file):

            Self::PARENT_HASH_FOR_PARTIAL_BLOCK_HASH,
        )?;
        Ok(PartialBlockHash(block_hash.0))

Done.

[nimrod-starkware]

@nimrod-starkware reviewed 1 file and all commit messages, made 1 comment, and resolved 3 discussions.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ArielElp).