Revert "Move skills watcher to app-server" (#21460)

Reverts openai/codex#21287

codex-rs/core/src/session/session.rs

@@ -364,6 +364,7 @@ impl Session {
         skills_manager: Arc<SkillsManager>,
         plugins_manager: Arc<PluginsManager>,
         mcp_manager: Arc<McpManager>,
+        skills_watcher: Arc<SkillsWatcher>,
         agent_control: AgentControl,
         environment_manager: Arc<EnvironmentManager>,
         analytics_events_client: Option<AnalyticsEventsClient>,
@@ -830,6 +831,7 @@ impl Session {
                 skills_manager,
                 plugins_manager: Arc::clone(&plugins_manager),
                 mcp_manager: Arc::clone(&mcp_manager),
+                skills_watcher,
                 agent_control,
                 network_proxy,
                 network_approval: Arc::clone(&network_approval),
@@ -916,6 +918,8 @@ impl Session {
                 sess.send_event_raw(event).await;
             }
 
+            // Start the watcher after SessionConfigured so it cannot emit earlier events.
+            sess.start_skills_watcher_listener();
             let mut required_mcp_servers: Vec<String> = mcp_servers
                 .iter()
                 .filter(|(_, server)| server.enabled && server.required)