🖼️ refactor: Enhance Env Extraction & Agent Image Handling (#6131)

* refactor: use new image output format for agents using DALL-E tools

* refactor: Enhance image fetching with proxy support and adjust logging placement in DALL-E 3 integration

* refactor: Enhance StableDiffusionAPI to support agent-specific return values and display message for generated images

* refactor: Add unit test execution for librechat-mcp in backend review workflow

* refactor: Update environment variable extraction logic, export from serpate module to avoid circular refs, and remove deprecated tests

* refactor: Add unit tests for environment variable extraction and enhance StdioOptionsSchema to process env variables

packages/data-provider/specs/mcp.spec.ts

@@ -0,0 +1,52 @@
+import { StdioOptionsSchema } from '../src/mcp';
+
+describe('Environment Variable Extraction (MCP)', () => {
+  const originalEnv = process.env;
+
+  beforeEach(() => {
+    process.env = {
+      ...originalEnv,
+      TEST_API_KEY: 'test-api-key-value',
+      ANOTHER_SECRET: 'another-secret-value',
+    };
+  });
+
+  afterEach(() => {
+    process.env = originalEnv;
+  });
+
+  describe('StdioOptionsSchema', () => {
+    it('should transform environment variables in the env field', () => {
+      const options = {
+        command: 'node',
+        args: ['server.js'],
+        env: {
+          API_KEY: '${TEST_API_KEY}',
+          ANOTHER_KEY: '${ANOTHER_SECRET}',
+          PLAIN_VALUE: 'plain-value',
+          NON_EXISTENT: '${NON_EXISTENT_VAR}',
+        },
+      };
+
+      const result = StdioOptionsSchema.parse(options);
+
+      expect(result.env).toEqual({
+        API_KEY: 'test-api-key-value',
+        ANOTHER_KEY: 'another-secret-value',
+        PLAIN_VALUE: 'plain-value',
+        NON_EXISTENT: '${NON_EXISTENT_VAR}',
+      });
+    });
+
+    it('should handle undefined env field', () => {
+      const options = {
+        command: 'node',
+        args: ['server.js'],
+      };
+
+      const result = StdioOptionsSchema.parse(options);
+
+      expect(result.env).toBeUndefined();
+    });
+  });
+});