🛟 fix: Allow Empty modelSpecs.list to Unstick Admin-Panel Saves (#13036)

* 🛟 fix: Allow empty modelSpecs.list to unstick admin-panel saves

The unconditional `.min(1)` on `specsConfigSchema.list` rejected an empty
list even when `enforce: false`, leaving admin panels (which save fields
path-granularly) with no atomic way to clear the list once it had been
populated. Once an admin reached `list: [entry]` and deleted the only
entry, every subsequent save failed schema validation and the section
became stuck.

Relax the schema to `.default([])`. The `.min(1)` was added in #5218 as
part of bundled cleanup, not as a deliberate rule. Every consumer of
`modelSpecs.list` already handles the empty/undefined case (`?.list`,
`?? []`, length-checked), and `processModelSpecs` short-circuits to
`undefined` when the list is empty so the runtime treats it as "no
specs configured." No call site is load-bearing on length >= 1.

Tighten the `buildEndpointOption.js` enforce guard from
`?.list && ?.enforce` to `?.list?.length && ?.enforce`. Empty arrays
are truthy in JS, so the existing guard would have entered the enforce
branch on `list: []` and returned "No model spec selected" or "Invalid
model spec" had `processModelSpecs` ever been bypassed.

Add a runtime warn in `processModelSpecs` when `enforce: true` is
configured alongside an empty list, so operators see the resulting
"enforcement disabled" state in logs rather than silently getting a
permissive runtime.

Add coverage for the empty-list parse path in `config-schemas.spec.ts`
and for the empty-list-with-enforce branch in `buildEndpointOption.spec.js`.

* chore: update import order in config-schemas.spec.ts

api/server/middleware/buildEndpointOption.js

@@ -48,7 +48,7 @@ async function buildEndpointOption(req, res, next) {
   }
 
   const appConfig = req.config;
-  if (appConfig.modelSpecs?.list && appConfig.modelSpecs?.enforce) {
+  if (appConfig.modelSpecs?.list?.length && appConfig.modelSpecs?.enforce) {
     /** @type {{ list: TModelSpec[] }}*/
     const { list } = appConfig.modelSpecs;
     const { spec } = parsedBody;

api/server/middleware/buildEndpointOption.spec.js

@@ -234,4 +234,34 @@ describe('buildEndpointOption - defaultParamsEndpoint parsing', () => {
     expect(parsedResult.maxOutputTokens).toBeUndefined();
     expect(parsedResult.max_tokens).toBe(4096);
   });
+
+  it('should not enter the enforce branch when modelSpecs.list is empty', async () => {
+    mockGetEndpointsConfig.mockResolvedValue({});
+
+    const req = createReq(
+      {
+        endpoint: EModelEndpoint.openAI,
+        model: 'gpt-4',
+      },
+      {
+        modelSpecs: {
+          enforce: true,
+          list: [],
+        },
+      },
+    );
+    const res = createRes();
+    const { handleError } = require('@librechat/api');
+
+    await buildEndpointOption(req, res, jest.fn());
+
+    expect(handleError).not.toHaveBeenCalledWith(
+      res,
+      expect.objectContaining({ text: 'No model spec selected' }),
+    );
+    expect(handleError).not.toHaveBeenCalledWith(
+      res,
+      expect.objectContaining({ text: 'Invalid model spec' }),
+    );
+  });
 });