feat: support codex collaboration_modes

cli/src/codex/utils/appServerConfig.test.ts

@@ -48,6 +48,17 @@ describe('appServerConfig', () => {
         expect(params.model).toBe('o3');
     });
 
+    it('puts collaboration mode in turn params with model settings', () => {
+        const params = buildTurnStartParams({
+            threadId: 'thread-1',
+            message: 'hello',
+            mode: { permissionMode: 'default', model: 'o3', collaborationMode: 'plan' }
+        });
+
+        expect(params.collaborationMode).toEqual({ mode: 'plan', settings: { model: 'o3' } });
+        expect(params.model).toBeUndefined();
+    });
+
     it('applies CLI overrides for turns when permission mode is default', () => {
         const params = buildTurnStartParams({
             threadId: 'thread-1',

cli/src/codex/utils/appServerConfig.ts

@@ -136,8 +136,14 @@ export function buildTurnStartParams(args: {
         params.sandboxPolicy = sandboxPolicy;
     }
 
+    const collaborationMode = args.mode?.collaborationMode;
     const model = args.overrides?.model ?? args.mode?.model;
-    if (model) {
+    if (collaborationMode) {
+        const settings = model ? { model } : undefined;
+        params.collaborationMode = settings
+            ? { mode: collaborationMode, settings }
+            : { mode: collaborationMode };
+    } else if (model) {
         params.model = model;
     }