fix(find): near() searches around the anchor's own vector, and refuses by name without one

The proximity search fetched its anchor through get(), which omits vectors
by default, then handed a zero-length vector to the index — every
find({ near }) refused with a dimension mismatch, for every caller. Found
by the Rust planner's first-contact pins comparing outcomes with and
without the planner on a refused shape. The anchor is now fetched with its
vector, and an anchor that has none refuses by name — a proximity search
around an unvectored row has no meaning and must not fail inside the index.
Pinned in tests/integration/find-near.test.ts.

src/brainy.ts

@@ -15892,8 +15892,18 @@ export class Brainy<T = any> implements BrainyInterface<T> {
       )
     }
 
-    const nearEntity = await this.get(params.near.id)
+    // The anchor's VECTOR is the query; get() omits vectors by default, which
+    // fed a zero-length vector to the index and refused every near() with a
+    // dimension mismatch. Ask for it, and refuse by name when the anchor has
+    // none — a proximity search around an unvectored row has no meaning.
+    const nearEntity = await this.get(params.near.id, { includeVectors: true })
     if (!nearEntity) return []
+    if (!nearEntity.vector || nearEntity.vector.length === 0) {
+      throw new Error(
+        `find({ near }): entity '${params.near.id}' has no vector to search around — ` +
+          `it was never embedded (or was unvectored). Embed it, or search with a query instead.`
+      )
+    }
 
     const nearResults: [string, number][] = await this.index.search(nearEntity.vector, params.limit || 10)
 

tests/integration/find-near.test.ts

@@ -0,0 +1,48 @@
+/**
+ * @module tests/integration/find-near
+ * @description find({ near }) searches around the anchor's OWN vector (10.4.10).
+ *
+ * The proximity search fetched its anchor without vectors and fed a
+ * zero-length vector to the index — every near() refused with a dimension
+ * mismatch, for every caller. Found by the Rust planner's first-contact pins
+ * (the planner declines `near`; the pin compared outcomes with and without
+ * it). Now the anchor is fetched with its vector, and an anchor without one
+ * refuses by name instead of failing inside the index.
+ */
+import { describe, it, expect, beforeAll } from 'vitest'
+import { Brainy } from '../../src/brainy'
+import { NounType } from '../../src/types/graphTypes'
+import { v5 } from '../../src/universal/uuid'
+import { generateTestVector } from '../helpers/test-factory'
+
+describe('find({ near }) uses the anchor vector', () => {
+  let brain: Brainy<any>
+  const anchorVector = generateTestVector()
+
+  beforeAll(async () => {
+    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
+    await brain.init()
+    await brain.add({ id: 'anchor', data: 'anchor row', type: NounType.Thing, vector: anchorVector })
+    // A twin with the identical vector and a far row.
+    await brain.add({ id: 'twin', data: 'twin row', type: NounType.Thing, vector: [...anchorVector] })
+    await brain.add({ id: 'far', data: 'far row', type: NounType.Thing, vector: generateTestVector() })
+  })
+
+  it('returns the anchor\'s neighbours by its own vector', async () => {
+    const results = await brain.find({ near: { id: 'anchor' }, limit: 3 })
+    expect(results.length).toBeGreaterThan(0)
+    const ids = results.map((r) => r.entity.id)
+    expect(ids).toContain(v5('twin'))
+  })
+
+  it('refuses by name when the anchor has no vector', async () => {
+    await brain.add({
+      id: 'unvectored',
+      data: 'no vector here',
+      type: NounType.Thing,
+      deferEmbedding: true
+    })
+    ;(brain as any).kickEmbedWorker = () => {}
+    await expect(brain.find({ near: { id: 'unvectored' }, limit: 3 })).rejects.toThrow(/has no vector to search around/)
+  })
+})