perf(fork-choice): precompute per-chain attestation scores (FCR)

packages/fork-choice/src/forkChoice/fastConfirmation/data.ts

@@ -12,8 +12,6 @@ export function createFastConfirmationCache(): FastConfirmationCache {
     blockByRoot: new Map(),
     ancestorRoots: new Map(),
     committeeBySlot: new Map(),
-    isDescendantByRootPair: new Map(),
-    voteWeightBySource: new Map(),
     checkpointStateByKey: new Map(),
   };
 }

packages/fork-choice/src/forkChoice/fastConfirmation/types.ts

@@ -7,6 +7,20 @@ import {CheckpointWithPayloadStatus} from "../store.ts";
 export type FastConfirmationBalanceSource = {
   state: IBeaconStateView | null;
   balances: EffectiveBalanceIncrements;
+  /**
+   * Per-validator effective balance, pre-zeroed for both inactive and slashed
+   * validators at the balance source epoch. Mirrors Lighthouse's `unslashed_balance`
+   * and is the single filter used by the per-validator hot loop in
+   * `precomputeChainAttestationScores` — removing all beacon-state access from
+   * that path.
+   *
+   * When `state` is available at construction, this is populated via
+   * `state.getEffectiveBalanceIncrementsZeroInactive()`, which zeros both
+   * inactive and slashed entries. When `state` is null, this equals `balances`
+   * (the fallback path's justified balances — inactive-zeroed but NOT
+   * slashed-zeroed).
+   */
+  unslashedActiveBalances: EffectiveBalanceIncrements;
 };
 
 export type ForkChoiceStateGetter = (
@@ -69,13 +83,21 @@ export type FastConfirmationCache = {
   blockByRoot: Map<RootHex, ProtoBlock | null>;
   ancestorRoots: Map<string, RootHex[] | null>;
   committeeBySlot: Map<Slot, Set<ValidatorIndex>>;
-  isDescendantByRootPair: Map<string, boolean>;
-  /** voteRoot -> totalWeight, keyed by sourceKey ("current" | "previous") */
-  voteWeightBySource: Map<string, Map<RootHex, number>>;
   headState?: IBeaconStateView;
   checkpointStateByKey: Map<string, IBeaconStateView | null>;
 };
 
+/**
+ * Minimal read-only view of a ProtoArray node, sufficient for parent-walking
+ * in `precomputeChainAttestationScores`. Narrowed from `ProtoNode` so mocks
+ * can satisfy this shape without constructing a real ProtoArray.
+ */
+export type ProtoNodeReadView = {
+  readonly parent?: number;
+  readonly slot: Slot;
+  readonly blockRoot: RootHex;
+};
+
 export type FastConfirmationContext = {
   config: {
     CONFIRMATION_BYZANTINE_THRESHOLD: number;
@@ -91,6 +113,33 @@ export type FastConfirmationContext = {
   getFinalizedCheckpoint(): CheckpointWithPayloadStatus;
   getEquivocatingIndices(): Set<ValidatorIndex>;
   getTrackedVotesCount(): number;
+
+  /**
+   * Returns all ProtoArray node indices for this root.
+   * - Pre-Gloas: `[fullIdx]`
+   * - Gloas, payload not yet observed: `[pendingIdx, emptyIdx]`
+   * - Gloas, payload observed: `[pendingIdx, emptyIdx, fullIdx]`
+   * - Unknown root: `[]`
+   *
+   * Used once per chain block by `precomputeChainAttestationScores` to build
+   * the `indexToPosition` map covering every variant of each chain block.
+   */
+  getNodeIndices(root: RootHex): readonly number[];
+
+  /**
+   * Read-only view of ProtoArray nodes for parent-walking in the precompute
+   * hot loop. Hoisted once at the top of `precomputeChainAttestationScores`
+   * so the inner walk does plain array access with no function-call overhead
+   * (walk runs up to O(V × depth) times per precompute invocation).
+   */
+  getProtoNodeView(): {readonly nodes: ReadonlyArray<ProtoNodeReadView>};
+
+  /**
+   * Read-only handle on `voteNextIndices`. Hoisted once at the top of
+   * `precomputeChainAttestationScores` for direct indexed access in the
+   * per-validator loop. `NULL_VOTE_INDEX` sentinel is preserved.
+   */
+  getVoteNextIndices(): readonly number[];
 };
 
 export interface IFastConfirmationRule {