feat(experiments): support freeform provider responses

tests/llm/provider.test.js

@@ -225,6 +225,139 @@ describe("OllamaLlmProvider chat capability detection", () => {
   });
 });
 
+describe("Ollama freeform semantics", () => {
+  it("omits format constraint when outputSchema is explicitly null (chat path)", async () => {
+    const originalBaseUrl = process.env.OLLAMA_BASE_URL;
+    const fetchSpy = vi.fn()
+      .mockResolvedValueOnce({ ok: true, text: async () => "" })
+      .mockResolvedValueOnce({
+        ok: true,
+        json: async () => ({ message: { content: '{"freeform":"output"}' } }),
+      });
+    vi.stubGlobal("fetch", fetchSpy);
+    process.env.OLLAMA_BASE_URL = "http://ollama.test";
+
+    try {
+      __resetChatSupportForTests();
+      const provider = getProvider();
+      const result = await provider.generateReconstruction("prompt", "model", null, { signal: undefined });
+
+      expect(result.response).toBe("{\"freeform\":\"output\"}");
+      expect(result.providerApiPath).toBe("/api/chat");
+
+      // No format key in request body when schema is explicitly null
+      const requestBody = JSON.parse(fetchSpy.mock.calls[1][1].body);
+      expect(requestBody).not.toHaveProperty("format");
+    } finally {
+      vi.unstubAllGlobals();
+      if (originalBaseUrl === undefined) delete process.env.OLLAMA_BASE_URL;
+      else process.env.OLLAMA_BASE_URL = originalBaseUrl;
+    }
+  });
+
+  it("omits format constraint when outputSchema is explicitly null (generate fallback)", async () => {
+    const originalBaseUrl = process.env.OLLAMA_BASE_URL;
+    const fetchSpy = vi.fn()
+      .mockResolvedValueOnce({ ok: false, status: 501, text: async () => "" })
+      .mockResolvedValueOnce({
+        ok: true,
+        json: async () => ({ response: "freeform text from /api/generate" }),
+      });
+    vi.stubGlobal("fetch", fetchSpy);
+    process.env.OLLAMA_BASE_URL = "http://ollama.test";
+
+    try {
+      __resetChatSupportForTests();
+      const provider = getProvider();
+      const result = await provider.generateReconstruction("prompt", "model", null, { signal: undefined });
+
+      expect(result.response).toBe("freeform text from /api/generate");
+      expect(result.providerApiPath).toBe("/api/generate");
+
+      // No format key in request body when schema is explicitly null
+      const requestBody = JSON.parse(fetchSpy.mock.calls[1][1].body);
+      expect(requestBody).not.toHaveProperty("format");
+    } finally {
+      vi.unstubAllGlobals();
+      if (originalBaseUrl === undefined) delete process.env.OLLAMA_BASE_URL;
+      else process.env.OLLAMA_BASE_URL = originalBaseUrl;
+    }
+  });
+
+  it("still applies default schema when outputSchema is undefined", async () => {
+    const originalBaseUrl = process.env.OLLAMA_BASE_URL;
+    const fetchSpy = vi.fn()
+      .mockResolvedValueOnce({ ok: true, text: async () => "" })
+      .mockResolvedValueOnce({
+        ok: true,
+        json: async () => ({ message: { content: "{}" } }),
+      });
+    vi.stubGlobal("fetch", fetchSpy);
+    process.env.OLLAMA_BASE_URL = "http://ollama.test";
+
+    try {
+      __resetChatSupportForTests();
+      await getProvider().generateReconstruction("prompt", "model", undefined, { signal: undefined });
+
+      const requestBody = JSON.parse(fetchSpy.mock.calls[1][1].body);
+      // undefined → fallback to reconstructionJsonSchema (format IS present)
+      expect(requestBody.format).toBeDefined();
+    } finally {
+      vi.unstubAllGlobals();
+      if (originalBaseUrl === undefined) delete process.env.OLLAMA_BASE_URL;
+      else process.env.OLLAMA_BASE_URL = originalBaseUrl;
+    }
+  });
+});
+
+describe("OpenAI freeform semantics", () => {
+  it("uses text format when outputSchema is explicitly null", async () => {
+    const provider = createOpenAIReconstructionProvider({
+      apiKey: "test-key",
+      fetchImpl: vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ output_text: "freeform text response" }),
+      }),
+    });
+
+    await provider.generateReconstruction("prompt", "model", null);
+
+    const request = JSON.parse(
+      provider.fetchImpl.mock.calls[0][1].body,
+    );
+    expect(request.text.format.type).toBe("text");
+  });
+
+  it("returns raw text without JSON recovery when outputSchema is explicitly null", async () => {
+    const provider = createOpenAIReconstructionProvider({
+      apiKey: "test-key",
+      fetchImpl: vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ output_text: "not-json-at-all {broken" }),
+      }),
+    });
+
+    const result = await provider.generateReconstruction("prompt", "model", null);
+    expect(result.response).toBe("not-json-at-all {broken");
+    expect(result.providerApiPath).toBe("/v1/responses");
+  });
+
+  it("still applies json_schema format when outputSchema is undefined", async () => {
+    const provider = createOpenAIReconstructionProvider({
+      apiKey: "test-key",
+      fetchImpl: vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ output_text: "{}" }),
+      }),
+    });
+
+    await provider.generateReconstruction("prompt");
+
+    const request = JSON.parse(provider.fetchImpl.mock.calls[0][1].body);
+    expect(request.text.format.type).toBe("json_schema");
+  });
+});
+
 describe("OpenAI reconstruction provider experiment seam", () => {
   function assertStrictObjectInvariant(schema, root = schema, visited = new Set()) {
     if (!schema || typeof schema !== "object" || visited.has(schema)) return;