feat: model BeaconStateView #8773

twoeths · 2026-01-22T07:46:08Z

Motivation

see Decouple beacon-node and state-transition #8650

Description

implement IBeaconStateView interface
implement the ts BeaconStateView

blocked by #8728 to build successfully

gemini-code-assist · 2026-01-22T07:46:40Z

Summary of Changes

Hello @twoeths, 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 introduces a significant architectural improvement by implementing a BeaconStateView and its corresponding interface. This new abstraction layer encapsulates the complex BeaconState object, offering a simplified, read-only perspective that enhances code clarity and maintainability. By migrating existing state-accessing logic to this view, the PR aims to enforce better data encapsulation and prepare the codebase for future evolutions, particularly in areas like light client synchronization and state proof generation.

Highlights

Introduced BeaconStateView: A new class BeaconStateView and its interface IBeaconStateView have been added to provide a read-only, abstracted layer over the CachedBeaconStateAllForks. This promotes immutability and a cleaner API for state access.
Refactored State Access: Existing modules like processAttestationsAltair.ts, upgradeStateToAltair.ts, rootCache.ts, and shufflingDecisionRoot.ts have been updated to utilize the new IBeaconStateView interface, centralizing state interaction.
Light Client Proof Utilities: New files lightClient/proofs.ts and lightClient/types.ts were introduced to facilitate the generation of sync committee witnesses and proofs for various state components, crucial for light client functionality.
Type Enhancements: The capella/types.ts file now exports HistoricalSummaries, and validatorStatus.ts includes a new GeneralValidatorStatus type and a utility function mapToGeneralStatus for broader validator status categorization.

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Code Review

This pull request introduces the BeaconStateView interface and its implementation, providing a read-only facade over the CachedBeaconStateAllForks. This is a positive step towards encapsulating state access logic and improving maintainability. The changes also include refactoring RootCache and proposerShufflingDecisionRoot to utilize this new view, ensuring consistency. New types and utility functions for light client proofs and validator status mapping have also been added. Overall, the changes are well-structured and align with the goal of abstracting state access. There are a few areas identified for potential improvement regarding robustness and efficiency.

gemini-code-assist · 2026-01-22T07:48:14Z

packages/state-transition/src/lightClient/proofs.ts

+    const n2 = n1.left;
+    const n5 = n2.right;
+    const n10 = n5.left;
+    const n21 = n10.right;
+    const n43 = n21.right;


The direct access to n1.left, n2.right, etc., in getSyncCommitteesWitness relies heavily on the internal structure of the Tree and node properties. This makes the code brittle to future changes in the SSZ tree structure. If the SSZ structure is modified, these direct accesses could break silently or produce incorrect proofs, which is a critical correctness issue for light client proofs. It would be more robust to use explicit GINDEXes or a more abstract way to navigate the tree if available, or at least add comments explaining the gindex for each node access to make it easier to maintain.

gemini-code-assist · 2026-01-22T07:48:15Z

packages/state-transition/src/stateView/beaconStateView.ts

+  getValidatorsByStatus(statuses: Set<string>, currentEpoch: Epoch): phase0.Validator[] {
+    const validators: phase0.Validator[] = [];
+    const validatorsArr = this.cachedState.validators.getAllReadonlyValues();
+
+    for (const validator of validatorsArr) {
+      const validatorStatus = getValidatorStatus(validator, currentEpoch);
+      if (statuses.has(validatorStatus) || statuses.has(mapToGeneralStatus(validatorStatus))) {
+        validators.push(validator);
+      }
+    }


The getValidatorsByStatus method creates a new array validatorsArr by calling this.cachedState.validators.getAllReadonlyValues() on every invocation. If this method is called frequently and the validator list is large, this could lead to unnecessary memory allocations and performance overhead. Consider iterating directly over the cachedState.validators view or caching the getAllReadonlyValues() result if appropriate to improve efficiency.

gemini-code-assist · 2026-01-22T07:48:15Z

packages/state-transition/src/stateView/beaconStateView.ts

+// TODO: consider also populate index2pubkey?
+export function createBeaconStateView(config: BeaconConfig, stateBytes: Uint8Array): IBeaconStateView {
+  const state = getStateTypeFromBytes(config, stateBytes).deserializeToViewDU(stateBytes);
+  const pubkey2index = new PubkeyIndexMap();
+  // TODO: dedup?


The TODO comments on lines 536 and 540 indicate areas that might need further attention or are incomplete. While not a bug, they suggest potential future work or unresolved design decisions that could impact maintainability or correctness. It would be beneficial to address these or provide more context on their future resolution.

feat: model BeaconStateView

06c0b60

gemini-code-assist bot reviewed Jan 22, 2026

View reviewed changes

fix: load BeaconStateView using the same pubkey<->index cache

9bf8e0f

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twoeths commented Jan 22, 2026

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twoeths commented Jan 22, 2026

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