worldmonitor/todos/014-pending-p2-simulation-package-perf-set-intersectany.md

status, priority, issue_id, tags

status	priority	issue_id	tags
pending	p2	014	code-review deep-forecast simulation-package performance

Two performance issues in simulation package builders: new Set in filter predicate + intersectAny O(n²)

Problem Statement

Two patterns in the new simulation package code introduce unnecessary allocations and O(n×m) comparisons that will grow with the actor registry size.

Findings

CRITICAL-1: intersectAny uses Array.includes — O(n×m) in the actor registry loop

buildSimulationPackageEntities builds allForecastIds as a flat array via flatMap, then passes it to intersectAny which calls right.includes(item) for each item in actor.forecastIds. With a 200-actor registry and 8 forecast IDs each, this is ~38,400 comparisons per call.

const allForecastIds = candidates.flatMap((c) => c.sourceSituationIds || []);
for (const actor of (actorRegistry || [])) {
  if (!intersectAny(actor.forecastIds || [], allForecastIds)) continue;

Fix: convert allForecastIds to a Set once before the loop.

CRITICAL-2: new Set(candidate.marketBucketIds || []) inside filter predicate

isMaritimeChokeEnergyCandidate constructs a new Set from marketBucketIds (typically 2-3 elements) on every candidate, then calls .has() twice. At 50 candidates this is 50 Set allocations for a 2-element array check. Array.includes is faster for arrays of this size.

const buckets = new Set(candidate.marketBucketIds || []);
return buckets.has('energy') || buckets.has('freight') || ...

Proposed Solutions

Fix both (Recommended)

// Fix 1: Set-based forecast ID lookup
const allForecastIdSet = new Set(candidates.flatMap((c) => c.sourceSituationIds || []));
for (const actor of (actorRegistry || [])) {
  if (!(actor.forecastIds || []).some((id) => allForecastIdSet.has(id))) continue;

// Fix 2: Array.includes instead of Set for small arrays
const bucketArr = candidate.marketBucketIds || [];
return bucketArr.includes('energy') || bucketArr.includes('freight') || topBucket === 'energy' || topBucket === 'freight'
  || SIMULATION_ENERGY_COMMODITY_KEYS.has(candidate.commodityKey || '');

Effort: Tiny | Risk: Low

Acceptance Criteria

• allForecastIds is a Set before the actor registry loop in buildSimulationPackageEntities
• isMaritimeChokeEnergyCandidate uses Array.includes or Array.some instead of new Set for marketBucketIds check
• All existing simulation package tests still pass

Technical Details

• File: scripts/seed-forecasts.mjs — isMaritimeChokeEnergyCandidate, buildSimulationPackageEntities

Work Log

• 2026-03-24: Found by compound-engineering:review:performance-oracle in PR #2204 review