feat(bindings): align BeaconStateView with IBeaconStateView

[spiral-ladder]

This PR aligns the bindings to BeaconStateView and its native implementation with the requirements of the typescript interface found at IBeaconStateView.

Details

This should be ready for a look. This PR mostly aligns BeaconStateView to a 'good enough' state to be consumed by lodestar for state transition.

This PR mainly adds missing functions and fixes the function signatures of already implemented methods (which did not align with IBeaconStateView

Note that this does not include the following implementations, which are throw stubs for now:

• gloas related functions (we do pre-gloas STF for now)
• rewards API

Other related work that I broke into smaller PRs for reviewability:

#342, #348, #350, #366, #367, #368

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly expands the native BeaconStateView API to provide more comprehensive access to beacon state data and transition logic. It introduces new methods for querying shuffling, state roots, and validator information, while also refining existing serialization and execution-related functions to better align with the requirements of the Lodestar beacon node.

Highlights

• API Expansion: Added numerous new methods to BeaconStateView, including support for shuffling, state roots, and block roots at specific epochs or slots.
• Type and Serialization Updates: Updated ProposerRewards to use numbers instead of BigInts and improved serialization methods to support ByteViews.
• Execution Logic: Refined execution enabling logic and added support for checking merge transition blocks.
• Validator Management: Introduced bulk retrieval methods for validators and balances, along with filtering by status.

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[gemini-code-assist]

Code Review

This pull request expands the BeaconStateView N-API bindings to align with the IBeaconStateView interface, adding methods for shuffling data, validator/balance queries, and optimized execution-enabled checks. It also includes a fix for the argument order in isMergeTransitionBlock. The review feedback highlights critical risks of precision loss when converting u64 Gwei values to JS Number and recommends reverting these to BigInt. Furthermore, the reviewer suggests optimizing getValidatorsByStatus to avoid excessive N-API overhead and deduplicating the transition options parsing logic to improve maintainability.

[gemini-code-assist]

Changing the return type of getBalance from js.BigInt to js.Number introduces a risk of precision loss. Ethereum balances in Gwei are u64 values that can exceed Number.MAX_SAFE_INTEGER (2^53 - 1). For example, a total supply of 120M ETH is ~1.2e17 Gwei, which is significantly larger than 9e15. To ensure correctness and maintain compatibility with the existing IBeaconStateView interface, this should remain a BigInt.

pub fn getBalance(self: *const BeaconStateView, index_arg: js.Number) !js.BigInt {
    const cached_state = try self.requireState();
    const index_value: u64 = try index_arg.toU32();
    var balances = try cached_state.state.balances();
    const balance = try balances.get(index_value);
    return js.BigInt.from(balance);
}

[spiral-ladder]

We're using number in IBeaconStateView

[gemini-code-assist]

The current implementation of getValidatorsByStatus is highly inefficient. It performs multiple N-API calls (createStringUtf8, callFunction) inside a loop that iterates over the entire validator registry (which can contain over 1 million entries on mainnet). This will cause severe performance degradation. A better approach would be to pre-process the statuses_set into a Zig-native bitset or a small array of booleans corresponding to the ValidatorStatus enum values, and then perform the filtering entirely in Zig.

[gemini-code-assist]

Similar to the getBalance issue, converting u64 reward values to JS Number via createDouble can lead to precision loss if the values exceed 2^53 - 1. These fields should continue to use BigInt to safely represent the full range of u64 Gwei values.

    try obj.setNamedProperty("attestations", try env.createBigintUint64(rewards.attestations));
    try obj.setNamedProperty("syncAggregate", try env.createBigintUint64(rewards.sync_aggregate));
    try obj.setNamedProperty("slashing", try env.createBigintUint64(rewards.slashing));

[spiral-ladder]

we're using all numbers in RewardCache

[gemini-code-assist]

Reverting these fields to js.BigInt to avoid precision loss for u64 Gwei values, consistent with the feedback in BeaconStateView.zig.

    attestations: js.BigInt,
    syncAggregate: js.BigInt,
    slashing: js.BigInt,

[spiral-ladder]

We use number in IBeaconStateView instead of big ints

[gemini-code-assist]

Reverting to bigint to prevent precision loss for Gwei values and maintain consistency with the native implementation.

Suggested change

	attestations: number;
	syncAggregate: number;
	slashing: number;
	attestations: bigint;
	syncAggregate: bigint;
	slashing: bigint;

[spiral-ladder]

We use number in IBeaconStateView

[gemini-code-assist]

Reverting the return type to bigint to ensure safe representation of Gwei balances.

Suggested change

	getBalance(index: number): number;
	getBalance(index: number): bigint;

[spiral-ladder]

we use number in IBeaconStateView

[gemini-code-assist]

The logic for parsing transition options from a JS object is duplicated here. It would be better to share the parseOptions implementation from stateTransition.zig to ensure consistency and reduce maintenance overhead.