codex: Delete older versions after installing new one (#41191)

Release Notes:

- codex: Fixed an issue where downloading a new version would not delete
older versions

crates/agent_servers/src/codex.rs

@@ -79,8 +79,6 @@ impl AgentServer for Codex {
                         root_dir.as_deref(),
                         extra_env,
                         delegate.status_tx,
-                        // For now, report that there are no updates.
-                        // (A future PR will use the GitHub Releases API to fetch them.)
                         delegate.new_version_available,
                         &mut cx.to_async(),
                     ))

crates/project/src/agent_server_store.rs

@@ -1212,7 +1212,7 @@ impl ExternalAgentServer for LocalCodex {
         &mut self,
         root_dir: Option<&str>,
         extra_env: HashMap<String, String>,
-        _status_tx: Option<watch::Sender<SharedString>>,
+        status_tx: Option<watch::Sender<SharedString>>,
         _new_version_available_tx: Option<watch::Sender<Option<String>>>,
         cx: &mut AsyncApp,
     ) -> Task<Result<(AgentServerCommand, String, Option<task::SpawnInTerminal>)>> {
@@ -1261,6 +1261,10 @@ impl ExternalAgentServer for LocalCodex {
 
                 let version_dir = dir.join(&release.tag_name);
                 if !fs.is_dir(&version_dir).await {
+                    if let Some(mut status_tx) = status_tx {
+                        status_tx.send("Installing…".into()).ok();
+                    }
+
                     let tag = release.tag_name.clone();
                     let version_number = tag.trim_start_matches('v');
                     let asset_name = asset_name(version_number)
@@ -1287,6 +1291,9 @@ impl ExternalAgentServer for LocalCodex {
                         },
                     )
                     .await?;
+
+                    // remove older versions
+                    util::fs::remove_matching(&dir, |entry| entry != version_dir).await;
                 }
 
                 let bin_name = if cfg!(windows) {