fix(ts-oss): forward responseFormat to Gemini in generateResponse (#6468)

mem0-ts/src/oss/src/llms/google.ts

@@ -59,6 +59,15 @@ export class GoogleLLM implements LLM {
       ];
     }
 
+    // Honor a requested JSON response format (parity with the Python SDK's
+    // mem0/llms/gemini.py). Gemini's structured output is opt-in via
+    // responseMimeType — without it the model is never told to emit JSON, so
+    // callers passing json_object silently get free-form text and depend on a
+    // fragile markdown-fence strip downstream.
+    if (responseFormat?.type === "json_object") {
+      config.responseMimeType = "application/json";
+    }
+
     const completion = await this.google.models.generateContent({
       contents,
       model: this.model,

mem0-ts/src/oss/tests/google-llm.test.ts

@@ -185,6 +185,37 @@ describe("GoogleLLM (unit)", () => {
     expect(response.toolCalls[1].name).toBe("add_graph_memory");
   });
 
+  // Regression: generateResponse accepted a responseFormat argument but never
+  // forwarded it, so Gemini was never told to emit JSON (parity with the Python
+  // SDK's mem0/llms/gemini.py, which sets response_mime_type/response_schema).
+  it("forwards json_object responseFormat as responseMimeType", async () => {
+    mockGenerateContent.mockResolvedValueOnce({
+      text: '{"facts": ["fact1"]}',
+      functionCalls: null,
+    });
+
+    const llm = new GoogleLLM({ apiKey: "test-key" });
+    await llm.generateResponse([{ role: "user", content: "Extract facts" }], {
+      type: "json_object",
+    });
+
+    const callArgs = mockGenerateContent.mock.calls[0][0];
+    expect(callArgs.config.responseMimeType).toBe("application/json");
+  });
+
+  it("does not set responseMimeType when no responseFormat is given", async () => {
+    mockGenerateContent.mockResolvedValueOnce({
+      text: "plain text",
+      functionCalls: null,
+    });
+
+    const llm = new GoogleLLM({ apiKey: "test-key" });
+    await llm.generateResponse([{ role: "user", content: "Hello" }]);
+
+    const callArgs = mockGenerateContent.mock.calls[0][0];
+    expect(callArgs.config.responseMimeType).toBeUndefined();
+  });
+
   it("formats generateChat messages and joins Gemini response parts", async () => {
     mockGenerateContent.mockResolvedValueOnce({
       candidates: [