🎭 feat: Override Custom Endpoint Schema with Specified Params Endpoint (#11788)

* 🔧 refactor: Simplify payload parsing and enhance getSaveOptions logic

- Removed unused bedrockInputSchema from payloadParser, streamlining the function.
- Updated payloadParser to handle optional chaining for model parameters.
- Enhanced getSaveOptions to ensure runOptions defaults to an empty object if parsing fails, improving robustness.
- Adjusted the assignment of maxContextTokens to use the instance variable for consistency.

* 🔧 fix: Update maxContextTokens assignment logic in initializeAgent function

- Enhanced the maxContextTokens assignment to allow for user-defined values, ensuring it defaults to a calculated value only when not provided or invalid. This change improves flexibility in agent initialization.

* 🧪 test: Add unit tests for initializeAgent function

- Introduced comprehensive unit tests for the initializeAgent function, focusing on maxContextTokens behavior.
- Tests cover scenarios for user-defined values, fallback calculations, and edge cases such as zero and negative values, enhancing overall test coverage and reliability of agent initialization logic.

* refactor: default params Endpoint Configuration Handling

- Integrated `getEndpointsConfig` to fetch endpoint configurations, allowing for dynamic handling of `defaultParamsEndpoint`.
- Updated `buildEndpointOption` to pass `defaultParamsEndpoint` to `parseCompactConvo`, ensuring correct parameter handling based on endpoint type.
- Added comprehensive unit tests for `buildDefaultConvo` and `cleanupPreset` to validate behavior with `defaultParamsEndpoint`, covering various scenarios and edge cases.
- Refactored related hooks and utility functions to support the new configuration structure, improving overall flexibility and maintainability.

* refactor: Centralize defaultParamsEndpoint retrieval

- Introduced `getDefaultParamsEndpoint` function to streamline the retrieval of `defaultParamsEndpoint` across various hooks and middleware.
- Updated multiple files to utilize the new function, enhancing code consistency and maintainability.
- Removed redundant logic for fetching `defaultParamsEndpoint`, simplifying the codebase.

api/server/middleware/buildEndpointOption.js

@@ -5,9 +5,11 @@ const {
   EModelEndpoint,
   isAgentsEndpoint,
   parseCompactConvo,
+  getDefaultParamsEndpoint,
 } = require('librechat-data-provider');
 const azureAssistants = require('~/server/services/Endpoints/azureAssistants');
 const assistants = require('~/server/services/Endpoints/assistants');
+const { getEndpointsConfig } = require('~/server/services/Config');
 const agents = require('~/server/services/Endpoints/agents');
 const { updateFilesUsage } = require('~/models');
 
@@ -19,9 +21,24 @@ const buildFunction = {
 
 async function buildEndpointOption(req, res, next) {
   const { endpoint, endpointType } = req.body;
+
+  let endpointsConfig;
+  try {
+    endpointsConfig = await getEndpointsConfig(req);
+  } catch (error) {
+    logger.error('Error fetching endpoints config in buildEndpointOption', error);
+  }
+
+  const defaultParamsEndpoint = getDefaultParamsEndpoint(endpointsConfig, endpoint);
+
   let parsedBody;
   try {
-    parsedBody = parseCompactConvo({ endpoint, endpointType, conversation: req.body });
+    parsedBody = parseCompactConvo({
+      endpoint,
+      endpointType,
+      conversation: req.body,
+      defaultParamsEndpoint,
+    });
   } catch (error) {
     logger.error(`Error parsing compact conversation for endpoint ${endpoint}`, error);
     logger.debug({
@@ -55,6 +72,7 @@ async function buildEndpointOption(req, res, next) {
         endpoint,
         endpointType,
         conversation: currentModelSpec.preset,
+        defaultParamsEndpoint,
       });
       if (currentModelSpec.iconURL != null && currentModelSpec.iconURL !== '') {
         parsedBody.iconURL = currentModelSpec.iconURL;

api/server/middleware/buildEndpointOption.spec.js

@@ -0,0 +1,237 @@
+/**
+ * Wrap parseCompactConvo: the REAL function runs, but jest can observe
+ * calls and return values. Must be declared before require('./buildEndpointOption')
+ * so the destructured reference in the middleware captures the wrapper.
+ */
+jest.mock('librechat-data-provider', () => {
+  const actual = jest.requireActual('librechat-data-provider');
+  return {
+    ...actual,
+    parseCompactConvo: jest.fn((...args) => actual.parseCompactConvo(...args)),
+  };
+});
+
+const { EModelEndpoint, parseCompactConvo } = require('librechat-data-provider');
+
+const mockBuildOptions = jest.fn((_endpoint, parsedBody) => ({
+  ...parsedBody,
+  endpoint: _endpoint,
+}));
+
+jest.mock('~/server/services/Endpoints/azureAssistants', () => ({
+  buildOptions: mockBuildOptions,
+}));
+jest.mock('~/server/services/Endpoints/assistants', () => ({
+  buildOptions: mockBuildOptions,
+}));
+jest.mock('~/server/services/Endpoints/agents', () => ({
+  buildOptions: mockBuildOptions,
+}));
+
+jest.mock('~/models', () => ({
+  updateFilesUsage: jest.fn(),
+}));
+
+const mockGetEndpointsConfig = jest.fn();
+jest.mock('~/server/services/Config', () => ({
+  getEndpointsConfig: (...args) => mockGetEndpointsConfig(...args),
+}));
+
+jest.mock('@librechat/api', () => ({
+  handleError: jest.fn(),
+}));
+
+const buildEndpointOption = require('./buildEndpointOption');
+
+const createReq = (body, config = {}) => ({
+  body,
+  config,
+  baseUrl: '/api/chat',
+});
+
+const createRes = () => ({
+  status: jest.fn().mockReturnThis(),
+  json: jest.fn().mockReturnThis(),
+});
+
+describe('buildEndpointOption - defaultParamsEndpoint parsing', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should pass defaultParamsEndpoint to parseCompactConvo and preserve maxOutputTokens', async () => {
+    mockGetEndpointsConfig.mockResolvedValue({
+      AnthropicClaude: {
+        type: EModelEndpoint.custom,
+        customParams: {
+          defaultParamsEndpoint: EModelEndpoint.anthropic,
+        },
+      },
+    });
+
+    const req = createReq(
+      {
+        endpoint: 'AnthropicClaude',
+        endpointType: EModelEndpoint.custom,
+        model: 'anthropic/claude-opus-4.5',
+        temperature: 0.7,
+        maxOutputTokens: 8192,
+        topP: 0.9,
+        maxContextTokens: 50000,
+      },
+      { modelSpecs: null },
+    );
+
+    await buildEndpointOption(req, createRes(), jest.fn());
+
+    expect(parseCompactConvo).toHaveBeenCalledWith(
+      expect.objectContaining({
+        defaultParamsEndpoint: EModelEndpoint.anthropic,
+      }),
+    );
+
+    const parsedResult = parseCompactConvo.mock.results[0].value;
+    expect(parsedResult.maxOutputTokens).toBe(8192);
+    expect(parsedResult.topP).toBe(0.9);
+    expect(parsedResult.temperature).toBe(0.7);
+    expect(parsedResult.maxContextTokens).toBe(50000);
+  });
+
+  it('should strip maxOutputTokens when no defaultParamsEndpoint is configured', async () => {
+    mockGetEndpointsConfig.mockResolvedValue({
+      MyOpenRouter: {
+        type: EModelEndpoint.custom,
+      },
+    });
+
+    const req = createReq(
+      {
+        endpoint: 'MyOpenRouter',
+        endpointType: EModelEndpoint.custom,
+        model: 'gpt-4o',
+        temperature: 0.7,
+        maxOutputTokens: 8192,
+        max_tokens: 4096,
+      },
+      { modelSpecs: null },
+    );
+
+    await buildEndpointOption(req, createRes(), jest.fn());
+
+    expect(parseCompactConvo).toHaveBeenCalledWith(
+      expect.objectContaining({
+        defaultParamsEndpoint: undefined,
+      }),
+    );
+
+    const parsedResult = parseCompactConvo.mock.results[0].value;
+    expect(parsedResult.maxOutputTokens).toBeUndefined();
+    expect(parsedResult.max_tokens).toBe(4096);
+    expect(parsedResult.temperature).toBe(0.7);
+  });
+
+  it('should strip bedrock region from custom endpoint without defaultParamsEndpoint', async () => {
+    mockGetEndpointsConfig.mockResolvedValue({
+      MyEndpoint: {
+        type: EModelEndpoint.custom,
+      },
+    });
+
+    const req = createReq(
+      {
+        endpoint: 'MyEndpoint',
+        endpointType: EModelEndpoint.custom,
+        model: 'gpt-4o',
+        temperature: 0.7,
+        region: 'us-east-1',
+      },
+      { modelSpecs: null },
+    );
+
+    await buildEndpointOption(req, createRes(), jest.fn());
+
+    const parsedResult = parseCompactConvo.mock.results[0].value;
+    expect(parsedResult.region).toBeUndefined();
+    expect(parsedResult.temperature).toBe(0.7);
+  });
+
+  it('should pass defaultParamsEndpoint when re-parsing enforced model spec', async () => {
+    mockGetEndpointsConfig.mockResolvedValue({
+      AnthropicClaude: {
+        type: EModelEndpoint.custom,
+        customParams: {
+          defaultParamsEndpoint: EModelEndpoint.anthropic,
+        },
+      },
+    });
+
+    const modelSpec = {
+      name: 'claude-opus-4.5',
+      preset: {
+        endpoint: 'AnthropicClaude',
+        endpointType: EModelEndpoint.custom,
+        model: 'anthropic/claude-opus-4.5',
+        temperature: 0.7,
+        maxOutputTokens: 8192,
+        maxContextTokens: 50000,
+      },
+    };
+
+    const req = createReq(
+      {
+        endpoint: 'AnthropicClaude',
+        endpointType: EModelEndpoint.custom,
+        spec: 'claude-opus-4.5',
+        model: 'anthropic/claude-opus-4.5',
+      },
+      {
+        modelSpecs: {
+          enforce: true,
+          list: [modelSpec],
+        },
+      },
+    );
+
+    await buildEndpointOption(req, createRes(), jest.fn());
+
+    const enforcedCall = parseCompactConvo.mock.calls[1];
+    expect(enforcedCall[0]).toEqual(
+      expect.objectContaining({
+        defaultParamsEndpoint: EModelEndpoint.anthropic,
+      }),
+    );
+
+    const enforcedResult = parseCompactConvo.mock.results[1].value;
+    expect(enforcedResult.maxOutputTokens).toBe(8192);
+    expect(enforcedResult.temperature).toBe(0.7);
+    expect(enforcedResult.maxContextTokens).toBe(50000);
+  });
+
+  it('should fall back to OpenAI schema when getEndpointsConfig fails', async () => {
+    mockGetEndpointsConfig.mockRejectedValue(new Error('Config unavailable'));
+
+    const req = createReq(
+      {
+        endpoint: 'AnthropicClaude',
+        endpointType: EModelEndpoint.custom,
+        model: 'anthropic/claude-opus-4.5',
+        temperature: 0.7,
+        maxOutputTokens: 8192,
+        max_tokens: 4096,
+      },
+      { modelSpecs: null },
+    );
+
+    await buildEndpointOption(req, createRes(), jest.fn());
+
+    expect(parseCompactConvo).toHaveBeenCalledWith(
+      expect.objectContaining({
+        defaultParamsEndpoint: undefined,
+      }),
+    );
+
+    const parsedResult = parseCompactConvo.mock.results[0].value;
+    expect(parsedResult.maxOutputTokens).toBeUndefined();
+    expect(parsedResult.max_tokens).toBe(4096);
+  });
+});