🔁 fix: Pass recursionLimit to OpenAI-Compatible Agents API Endpoint (#12510)

* fix: pass recursionLimit to processStream in OpenAI-compatible agents API

The OpenAI-compatible endpoint never passed recursionLimit to LangGraph's
processStream(), silently capping all API-based agent calls at the default
25 steps. Mirror the 3-step cascade already used by the UI path (client.js):
yaml config default → per-agent DB override → max cap.

* refactor: extract resolveRecursionLimit into shared utility

Extract the 3-step recursion limit cascade into a shared
resolveRecursionLimit() function in @librechat/api. Both openai.js and
client.js now call this single source of truth.

Also fixes falsy-guard edge cases where recursion_limit=0 or
maxRecursionLimit=0 would silently misbehave, by using explicit
typeof + positive checks.

Includes unit tests covering all cascade branches and edge cases.

* refactor: use resolveRecursionLimit in openai.js and client.js

Replace duplicated cascade logic in both controllers with the shared
resolveRecursionLimit() utility from @librechat/api.

In openai.js: hoist agentsEConfig to avoid double property walk,
remove displaced comment, add integration test assertions.

In client.js: remove inline cascade that was overriding config
after initial assignment.

* fix: hoist processStream mock for test accessibility

The processStream mock was created inline inside mockResolvedValue,
making it inaccessible via createRun.mock.results (which returns
the Promise, not the resolved value). Hoist it to a module-level
variable so tests can assert on it directly.

* test: improve test isolation and boundary coverage

Use mockReturnValueOnce instead of mockReturnValue to prevent mock
leaking across test boundaries. Add boundary tests for downward
agent override and exact-match maxRecursionLimit.

api/server/controllers/agents/__tests__/openai.spec.js

@@ -3,6 +3,7 @@
  * Tests that recordCollectedUsage is called correctly for token spending
  */
 
+const mockProcessStream = jest.fn().mockResolvedValue(undefined);
 const mockSpendTokens = jest.fn().mockResolvedValue({});
 const mockSpendStructuredTokens = jest.fn().mockResolvedValue({});
 const mockRecordCollectedUsage = jest
@@ -35,7 +36,7 @@ jest.mock('@librechat/agents', () => ({
 jest.mock('@librechat/api', () => ({
   writeSSE: jest.fn(),
   createRun: jest.fn().mockResolvedValue({
-    processStream: jest.fn().mockResolvedValue(undefined),
+    processStream: mockProcessStream,
   }),
   createChunk: jest.fn().mockReturnValue({}),
   buildToolSet: jest.fn().mockReturnValue(new Set()),
@@ -68,6 +69,7 @@ jest.mock('@librechat/api', () => ({
     toolCalls: new Map(),
     usage: { promptTokens: 100, completionTokens: 50, reasoningTokens: 0 },
   }),
+  resolveRecursionLimit: jest.fn().mockReturnValue(50),
   createToolExecuteHandler: jest.fn().mockReturnValue({ handle: jest.fn() }),
   isChatCompletionValidationFailure: jest.fn().mockReturnValue(false),
 }));
@@ -286,4 +288,36 @@ describe('OpenAIChatCompletionController', () => {
       );
     });
   });
+
+  describe('recursionLimit resolution', () => {
+    it('should pass resolveRecursionLimit result to processStream config', async () => {
+      const { resolveRecursionLimit } = require('@librechat/api');
+      resolveRecursionLimit.mockReturnValueOnce(75);
+
+      await OpenAIChatCompletionController(req, res);
+
+      expect(mockProcessStream).toHaveBeenCalledWith(
+        expect.anything(),
+        expect.objectContaining({ recursionLimit: 75 }),
+        expect.anything(),
+      );
+    });
+
+    it('should call resolveRecursionLimit with agentsEConfig and agent', async () => {
+      const { resolveRecursionLimit } = require('@librechat/api');
+      const { getAgent } = require('~/models');
+      const mockAgent = { id: 'agent-123', name: 'Test', recursion_limit: 200 };
+      getAgent.mockResolvedValueOnce(mockAgent);
+
+      req.config = {
+        endpoints: {
+          agents: { recursionLimit: 100, maxRecursionLimit: 150, allowedProviders: [] },
+        },
+      };
+
+      await OpenAIChatCompletionController(req, res);
+
+      expect(resolveRecursionLimit).toHaveBeenCalledWith(req.config.endpoints.agents, mockAgent);
+    });
+  });
 });