feat(codex): /personality slash + in-session app-server params (#1265)

* feat(codex): support /personality via in-session override

Intercept /personality in the Codex slash layer, keep the value in CLI
memory only, and forward it on thread/turn start when set. Unset means
omit the field so Codex config/thread defaults apply—no Hub DB or web UI.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(codex): refuse fake /personality clear (sticky thread setting)

turn/start.personality sticks for later turns; omitting the field does not
restore config.toml. Drop default|auto|clear success paths and require an
explicit friendly|pragmatic|none instead.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

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

@@ -241,6 +241,41 @@ describe('appServerConfig', () => {
         expect('serviceTier' in nullParams).toBe(false);
     });
 
+    it('forwards personality only when explicitly set on the mode', () => {
+        const omitted = buildTurnStartParams({
+            threadId: 'thread-1',
+            message: 'hello',
+            cwd: '/workspace/project',
+            mode: { permissionMode: 'default', model: 'gpt-5.5', collaborationMode: 'default' }
+        });
+        expect('personality' in omitted).toBe(false);
+
+        const set = buildTurnStartParams({
+            threadId: 'thread-1',
+            message: 'hello',
+            cwd: '/workspace/project',
+            mode: {
+                permissionMode: 'default',
+                model: 'gpt-5.5',
+                collaborationMode: 'default',
+                personality: 'pragmatic'
+            }
+        });
+        expect(set.personality).toBe('pragmatic');
+
+        const thread = buildThreadStartParams({
+            cwd: '/workspace/project',
+            mode: {
+                permissionMode: 'default',
+                model: 'gpt-5.5',
+                collaborationMode: 'default',
+                personality: 'friendly'
+            },
+            mcpServers
+        });
+        expect(thread.personality).toBe('friendly');
+    });
+
     it('builds turn params with mode defaults', () => {
         const params = buildTurnStartParams({
             threadId: 'thread-1',