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

Reverts openai/codex#21287

codex-rs/core/src/codex_thread.rs

@@ -1,5 +1,6 @@
 use crate::agent::AgentStatus;
 use crate::config::ConstraintResult;
+use crate::file_watcher::WatchRegistration;
 use crate::goals::ExternalGoalSet;
 use crate::goals::GoalRuntimeEvent;
 use crate::session::Codex;
@@ -30,7 +31,6 @@ use codex_protocol::protocol::Submission;
 use codex_protocol::protocol::ThreadMemoryMode;
 use codex_protocol::protocol::ThreadSource;
 use codex_protocol::protocol::TokenUsageInfo;
-use codex_protocol::protocol::TurnEnvironmentSelection;
 use codex_protocol::protocol::W3cTraceContext;
 use codex_protocol::user_input::UserInput;
 use codex_thread_store::StoredThread;
@@ -101,6 +101,7 @@ pub struct CodexThread {
     session_configured: SessionConfiguredEvent,
     rollout_path: Option<PathBuf>,
     out_of_band_elicitation_count: Mutex<u64>,
+    _watch_registration: WatchRegistration,
 }
 
 /// Conduit for the bidirectional stream of messages that compose a thread
@@ -111,6 +112,7 @@ impl CodexThread {
         session_configured: SessionConfiguredEvent,
         rollout_path: Option<PathBuf>,
         session_source: SessionSource,
+        watch_registration: WatchRegistration,
     ) -> Self {
         Self {
             codex,
@@ -118,6 +120,7 @@ impl CodexThread {
             session_configured,
             rollout_path,
             out_of_band_elicitation_count: Mutex::new(0),
+            _watch_registration: watch_registration,
         }
     }
 
@@ -461,10 +464,6 @@ impl CodexThread {
         self.codex.session.get_config().await
     }
 
-    pub async fn environment_selections(&self) -> Vec<TurnEnvironmentSelection> {
-        self.codex.thread_environment_selections().await
-    }
-
     pub async fn read_mcp_resource(
         &self,
         server: &str,