feat(cli): warn when workspace overrides global modelProviders (#3148)

* feat(cli): warn when workspace overrides user modelProviders

* fix(cli): align modelProviders warning with current merge behavior

---------

Co-authored-by: jinye.djy <jinye.djy@alibaba-inc.com>

packages/cli/src/config/settings.ts

@@ -20,6 +20,7 @@ import stripJsonComments from 'strip-json-comments';
 import { DefaultLight } from '../ui/themes/default-light.js';
 import { DefaultDark } from '../ui/themes/default.js';
 import { isWorkspaceTrusted } from './trustedFolders.js';
+import { hasOwnModelProviders } from './modelProvidersScope.js';
 import {
   type Settings,
   type MemoryImportFormat,
@@ -249,6 +250,57 @@ function getSettingsFileKeyWarnings(
   return warnings;
 }
 
+function isPlainObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function hasAnyProviderEntries(modelProviders: unknown): boolean {
+  if (!isPlainObject(modelProviders)) {
+    return false;
+  }
+
+  return Object.values(modelProviders).some(
+    (providerModels) => Array.isArray(providerModels) && providerModels.length > 0,
+  );
+}
+
+function getModelProvidersOverrideWarnings(
+  loadedSettings: LoadedSettings,
+): string[] {
+  // Untrusted workspaces are ignored in merge, so they cannot shadow user modelProviders.
+  if (!loadedSettings.isTrusted) {
+    return [];
+  }
+
+  const userOriginal =
+    loadedSettings.user.originalSettings as unknown as Record<string, unknown>;
+  const workspaceOriginal =
+    loadedSettings.workspace.originalSettings as unknown as Record<
+      string,
+      unknown
+    >;
+
+  if (!hasOwnModelProviders(userOriginal) || !hasOwnModelProviders(workspaceOriginal)) {
+    return [];
+  }
+
+  const userModelProviders = userOriginal['modelProviders'];
+  const workspaceModelProviders = workspaceOriginal['modelProviders'];
+  const workspaceIsEmptyModelProviders =
+    isPlainObject(workspaceModelProviders) &&
+    Object.keys(workspaceModelProviders).length === 0;
+
+  if (!workspaceIsEmptyModelProviders || !hasAnyProviderEntries(userModelProviders)) {
+    return [];
+  }
+
+  return [
+    `Warning: '${loadedSettings.workspace.path}' defines an empty 'modelProviders' object. ` +
+      `This has no effect with current merge behavior, but may indicate a configuration error. ` +
+      `If REPLACE semantics are introduced for 'modelProviders' in the future, this would override user-level model providers in '${loadedSettings.user.path}'.`,
+  ];
+}
+
 /**
  * Collects warnings for ignored legacy and unknown settings keys,
  * as well as migration warnings.
@@ -283,6 +335,10 @@ export function getSettingsWarnings(loadedSettings: LoadedSettings): string[] {
     }
   }
 
+  for (const warning of getModelProvidersOverrideWarnings(loadedSettings)) {
+    warningSet.add(warning);
+  }
+
   return [...warningSet];
 }