From 0f172c2890ce5b9eab1cd4c15a0a5049c77f74fe Mon Sep 17 00:00:00 2001
From: Kartik <kartik.labhshetwar@mem0.ai>
Date: Fri, 14 Aug 2026 16:56:03 +0530
Subject: [PATCH] fix(ts-oss): stop prototype keys from short-circuiting
 embedding lookup (#6903)

---
 mem0-ts/src/oss/src/memory/index.ts           |  20 ++-
 .../memory.prototype-key-embedding.test.ts    | 125 ++++++++++++++++++
 2 files changed, 139 insertions(+), 6 deletions(-)
 create mode 100644 mem0-ts/src/oss/tests/memory.prototype-key-embedding.test.ts

diff --git a/mem0-ts/src/oss/src/memory/index.ts b/mem0-ts/src/oss/src/memory/index.ts
index 5cef1c256..58634cb55 100644
--- a/mem0-ts/src/oss/src/memory/index.ts
+++ b/mem0-ts/src/oss/src/memory/index.ts
@@ -1000,7 +1000,8 @@ export class Memory {
 
     for (const mem of extractedMemories) {
       const text = mem.text;
-      if (!text || !(text in embedMap)) continue;
+      if (!text || !Object.prototype.hasOwnProperty.call(embedMap, text))
+        continue;
 
       const memHash = createHash("md5").update(text).digest("hex");
       if (existingHashes.has(memHash) || seenHashes.has(memHash)) {
@@ -1943,8 +1944,12 @@ export class Memory {
     metadata: Record<string, any>,
   ): Promise<string> {
     const memoryId = uuidv4();
-    const embedding =
-      existingEmbeddings[data] || (await this.embedder.embed(data, "add"));
+    const embedding = Object.prototype.hasOwnProperty.call(
+      existingEmbeddings,
+      data,
+    )
+      ? existingEmbeddings[data]
+      : await this.embedder.embed(data, "add");
 
     const memoryMetadata = {
       ...metadata,
@@ -1987,9 +1992,12 @@ export class Memory {
     }
     const textChanged = newData !== prevValue;
 
-    const embedding =
-      existingEmbeddings[newData] ||
-      (await this.embedder.embed(newData, "update"));
+    const embedding = Object.prototype.hasOwnProperty.call(
+      existingEmbeddings,
+      newData,
+    )
+      ? existingEmbeddings[newData]
+      : await this.embedder.embed(newData, "update");
 
     const sanitizedMetadata = stripIdentityKeys(metadata);
 
diff --git a/mem0-ts/src/oss/tests/memory.prototype-key-embedding.test.ts b/mem0-ts/src/oss/tests/memory.prototype-key-embedding.test.ts
new file mode 100644
index 000000000..b96588f51
--- /dev/null
+++ b/mem0-ts/src/oss/tests/memory.prototype-key-embedding.test.ts
@@ -0,0 +1,125 @@
+/// <reference types="jest" />
+/** add() with infer=false must embed Object.prototype-colliding text instead of resolving it off the prototype chain. */
+import { Memory } from "../src/memory";
+import { MemoryVectorStore } from "../src/vector_stores/memory";
+import type { SearchResult } from "../src/types";
+
+const mockEmbedding = new Array(1536).fill(0.1);
+const mockEmbed = jest.fn().mockResolvedValue(mockEmbedding);
+
+jest.mock("../src/embeddings/openai", () => ({
+  OpenAIEmbedder: jest.fn().mockImplementation(() => ({
+    embed: mockEmbed,
+    embedBatch: jest.fn(),
+    embeddingDims: 1536,
+  })),
+}));
+
+function createMemory(): Memory {
+  return new Memory({
+    version: "v1.1",
+    embedder: {
+      provider: "openai",
+      config: { apiKey: "test-key", model: "text-embedding-3-small" },
+    },
+    vectorStore: {
+      provider: "memory",
+      config: {
+        collectionName: `test-proto-${Date.now()}-${Math.random()}`,
+        dimension: 1536,
+        dbPath: ":memory:",
+      },
+    },
+    llm: {
+      provider: "openai",
+      config: { apiKey: "test-key", model: "gpt-5-mini" },
+    },
+    historyDbPath: ":memory:",
+  });
+}
+
+describe("add() with infer=false and Object.prototype-colliding text", () => {
+  let memory: Memory;
+  let insertSpy: jest.SpyInstance;
+
+  beforeEach(() => {
+    memory = createMemory();
+    mockEmbed.mockClear();
+    insertSpy = jest.spyOn(MemoryVectorStore.prototype, "insert");
+  });
+
+  afterEach(async () => {
+    insertSpy.mockRestore();
+    await memory.reset();
+  });
+
+  test.each([
+    "constructor",
+    "toString",
+    "valueOf",
+    "hasOwnProperty",
+    "__proto__",
+  ])(
+    'embeds "%s" instead of resolving it off Object.prototype',
+    async (text) => {
+      const result: SearchResult = await memory.add(text, {
+        userId: "u1",
+        infer: false,
+      });
+
+      expect(mockEmbed).toHaveBeenCalledWith(text, "add");
+
+      const [storedVectors] =
+        insertSpy.mock.calls[insertSpy.mock.calls.length - 1];
+      expect(Array.isArray(storedVectors[0])).toBe(true);
+      expect(storedVectors[0]).toEqual(mockEmbedding);
+      expect(
+        storedVectors[0].every((n: unknown) => typeof n === "number"),
+      ).toBe(true);
+
+      expect(result.results[0].memory).toBe(text);
+    },
+  );
+});
+
+describe("update() metadata-only on Object.prototype-colliding text (#6323)", () => {
+  let memory: Memory;
+  let updateSpy: jest.SpyInstance;
+
+  beforeEach(() => {
+    memory = createMemory();
+    updateSpy = jest.spyOn(MemoryVectorStore.prototype, "update");
+  });
+
+  afterEach(async () => {
+    updateSpy.mockRestore();
+    await memory.reset();
+  });
+
+  test.each([
+    "constructor",
+    "toString",
+    "valueOf",
+    "hasOwnProperty",
+    "__proto__",
+  ])(
+    're-embeds "%s" on a metadata-only update instead of resolving it off Object.prototype',
+    async (text) => {
+      const added: SearchResult = await memory.add(text, {
+        userId: "u1",
+        infer: false,
+      });
+      const memoryId = added.results[0].id!;
+      mockEmbed.mockClear();
+
+      await memory.update(memoryId, { metadata: { pinned: true } });
+
+      expect(mockEmbed).toHaveBeenCalledWith(text, "update");
+
+      const [, storedVector] =
+        updateSpy.mock.calls[updateSpy.mock.calls.length - 1];
+      expect(Array.isArray(storedVector)).toBe(true);
+      expect(storedVector).toEqual(mockEmbedding);
+    },
+  );
+});