perf(ai): optimize entity lookups in system prompt and right panel

src/components/studio/right-panel.tsx

@@ -3,6 +3,7 @@
 import { useStudioStore, useFilteredEntities } from '@/lib/studio/store'
 import { ENTITY_TYPE_META } from '@/lib/studio/types'
 import { search, type SearchResult } from '@/lib/search/retrieval'
+import { buildEntityIndex } from '@/lib/studio/graph-index'
 import { Search, X, Sparkles, FileText, Quote, ArrowRight } from 'lucide-react'
 import { useMemo, useRef, useState } from 'react'
 import { cn } from '@/lib/utils'
@@ -39,6 +40,7 @@ function SearchPanel({ onCreateEntity }: { onCreateEntity?: (name: string) => vo
   const startEdit = useStudioStore((s) => s.startEdit)
   const [mode, setMode] = useState<'keyword' | 'ranked'>('keyword')
   const filtered = useFilteredEntities()
+  const entityIndex = useMemo(() => buildEntityIndex(entities), [entities])
   const rankedResults = useMemo(
     () => (mode === 'ranked' ? search(entities, claims, searchQuery) : []),
     [mode, entities, claims, searchQuery],
@@ -112,7 +114,7 @@ function SearchPanel({ onCreateEntity }: { onCreateEntity?: (name: string) => vo
           <ul className="space-y-1.5" role="list" aria-label="Ranked search results">
             {rankedResults.map((r: SearchResult) => {
               const targetId = r.type === 'entity' ? r.id : r.entityId
-              const resolvedEntity = targetId ? entities.find((e) => e.id === targetId) : undefined
+              const resolvedEntity = targetId ? entityIndex.get(targetId) : undefined
               const meta = resolvedEntity ? ENTITY_TYPE_META[resolvedEntity.type] : undefined
               return (
                 <li key={r.id}>
@@ -187,7 +189,8 @@ function InspectorPanel() {
   const deleteEntity = useStudioStore((s) => s.deleteEntity)
   const selectEntity = useStudioStore((s) => s.selectEntity)
   const [showDeleteConfirm, setShowDeleteConfirm] = useState(false)
-  const entity = entities.find((e) => e.id === selectedEntityId) || entities[0]
+  const entityIndex = useMemo(() => buildEntityIndex(entities), [entities])
+  const entity = (selectedEntityId ? entityIndex.get(selectedEntityId) : undefined) || entities[0]
   const deleteCancelRef = useRef<HTMLButtonElement>(null)
 
   if (!entity) {
@@ -249,7 +252,7 @@ function InspectorPanel() {
             </h4>
             <ul className="space-y-1">
               {entity.links.map((l, i) => {
-                const target = entities.find((e) => e.id === l.targetId)
+                const target = entityIndex.get(l.targetId)
                 if (!target) return null
                 return (
                   <li key={i}>

src/lib/ai/context.test.ts

@@ -2,21 +2,19 @@ import { describe, it, expect } from 'vitest'
 import { buildSystemPrompt } from './context'
 import type { Entity, Claim } from '@/lib/studio/types'
 
-function makeEntity(overrides: Partial<Entity> = {}): Entity {
-  return {
-    id: '1',
-    name: 'Test Entity',
-    type: 'concept',
-    description: 'A test entity for unit testing',
-    content: '',
-    tags: ['test'],
-    claims: [],
-    links: [],
-    createdAt: '2026-01-01T00:00:00Z',
-    updatedAt: '2026-01-01T00:00:00Z',
-    ...overrides,
-  }
-}
+const makeEntity = (overrides: Partial<Entity> = {}): Entity => ({
+  id: '1',
+  name: 'Test Entity',
+  type: 'concept',
+  description: 'A test entity for unit testing',
+  content: '',
+  tags: ['test'],
+  claims: [],
+  links: [],
+  createdAt: '2026-01-01T00:00:00Z',
+  updatedAt: '2026-01-01T00:00:00Z',
+  ...overrides,
+})
 
 const NO_CLAIMS: Claim[] = []
 
@@ -41,4 +39,28 @@ describe('buildSystemPrompt', () => {
     const prompt = buildSystemPrompt('TypeScript', entities, NO_CLAIMS, true)
     expect(prompt).toContain('Relevant entities from your library')
   })
+
+  it('includes entity tags in prompt for matched entity results', () => {
+    const entities = [
+      makeEntity({ id: 'entity-ts', name: 'TypeScript Language', description: 'Strongly typed programming language', tags: ['javascript', 'compiler'] }),
+    ]
+    const prompt = buildSystemPrompt('TypeScript', entities, NO_CLAIMS, true)
+    expect(prompt).toContain('[javascript, compiler]')
+  })
+
+  it('performs indexed entity lookup rapidly for large entity corpora', () => {
+    const largeCorpus = Array.from({ length: 500 }, (_, i) =>
+      makeEntity({
+        id: `entity-${i}`,
+        name: `Knowledge Topic ${i}`,
+        description: `Detailed description for knowledge topic item number ${i} with searchable terms.`,
+        tags: [`tag-${i % 10}`],
+      }),
+    )
+    const start = performance.now()
+    const prompt = buildSystemPrompt('Topic 250', largeCorpus, NO_CLAIMS, true)
+    const elapsed = performance.now() - start
+    expect(prompt).toContain('Topic 250')
+    expect(elapsed).toBeLessThan(50)
+  })
 })

src/lib/ai/context.ts

@@ -1,6 +1,7 @@
 import type { Entity, Claim } from '@/lib/studio/types'
 import type { ChatMessage } from './types'
 import { search } from '@/lib/search/retrieval'
+import { buildEntityIndex } from '@/lib/studio/graph-index'
 import type { ResearchResult } from './research'
 import { buildResearchContext } from './research'
 
@@ -21,10 +22,11 @@ export function buildSystemPrompt(
   if (augmentWithLocal && entities.length > 0) {
     const results = search(entities, claims, query, 5)
     if (results.length > 0) {
+      const entityIndex = buildEntityIndex(entities)
       const contextParts = results.map((r) => {
-        const tags: string[] = []
-        const entity = entities.find((e) => e.id === r.entityId)
-        if (entity && entity.tags.length > 0) tags.push(...entity.tags)
+        const targetId = r.entityId ?? r.id
+        const entity = entityIndex.get(targetId)
+        const tags = entity?.tags ?? []
         const tagStr = tags.length > 0 ? ` [${tags.join(', ')}]` : ''
         const desc = r.snippet ? `: ${r.snippet.slice(0, 200)}` : ''
         return `- ${r.name}${tagStr}${desc}`