fix(maestro): chain default-terminal into new-session instead of pre-set

CI e2e tests failed with "tmux exited with code 1: server exited
unexpectedly" because the startup `start-server \; set-option -g
default-terminal` call left an empty server that tmux's default
`exit-empty on` killed before the first `new-session` could attach.

Move the `set-option -g default-terminal tmux-256color` into the same
tmux command as `new-session` (chained with `;`) so a single tmux
invocation creates the server, sets the option, and spawns the pane.
The pane reads `default-terminal` at creation time, so chaining before
`new-session` still applies to the very first session.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/maestro-daemon/src/main.rs

@@ -121,12 +121,6 @@ async fn run(config_override: Option<PathBuf>) -> Result<(), Box<dyn Error>> {
     let sidecar = SidecarStore::new(config.sidecar_dir());
     let worktree_mgr = WorktreeManager::new(config.worktree_root.clone());
     let tmux = Tmux::new();
-    // The pane process's TERM comes from tmux's `default-terminal`, which on
-    // most distros is `screen` (8 colors). Promote it so attach clients see
-    // 256-color output. NAP-252.
-    if let Err(e) = tmux.set_option_global("default-terminal", "tmux-256color") {
-        tracing::warn!(error = ?e, "failed to set tmux default-terminal — sessions may lack color");
-    }
     let manager = SessionManager::new_with_replay(
         config.daemon_id.clone(),
         tmux,

crates/maestro-daemon/src/tmux.rs

@@ -77,13 +77,17 @@ impl Tmux {
         c
     }
 
-    /// `tmux new-session -d -e TERM=xterm-256color -e COLORTERM=truecolor -s maestro-<id> -c <cwd> <command>`.
+    /// `tmux set-option -g default-terminal tmux-256color \; new-session -d -e TERM=xterm-256color -e COLORTERM=truecolor -s maestro-<id> -c <cwd> <command>`.
     ///
     /// `command` is passed as a single shell-line argument to tmux, which
-    /// invokes it via `$SHELL -c`. The `-e TERM=…`/`COLORTERM=…` flags ensure
-    /// the spawned shell sees sensible color env vars even when `maestrod`
-    /// runs from a stripped systemd unit. Pair with [`Self::set_option_global`]
-    /// of `default-terminal` for true 256-color output in the pane.
+    /// invokes it via `$SHELL -c`. Two layers ensure attach clients see color:
+    /// the `-e TERM=…`/`COLORTERM=…` flags populate the spawned shell's env
+    /// even when `maestrod` runs from a stripped systemd unit, and the chained
+    /// `set-option -g default-terminal tmux-256color` overrides tmux's
+    /// distro-default `screen` (8-color) terminfo for the pane process. The
+    /// `set-option` is chained into the same tmux invocation because a
+    /// stand-alone server with no sessions exits immediately under tmux's
+    /// default `exit-empty on`.
     pub fn new_session(&self, id: Uuid, cwd: &Path, command: &str) -> Result<(), TmuxError> {
         let name = session_name(id);
         let out = self
@@ -93,19 +97,6 @@ impl Tmux {
         check(out)
     }
 
-    /// `tmux start-server \; set-option -g <name> <value>`. Used on daemon
-    /// startup to set `default-terminal` to `tmux-256color` so the pane's
-    /// `TERM` is a 256-color terminfo entry (the distro default `screen` caps
-    /// at 8). The chained `start-server` makes the call work before any
-    /// session exists.
-    pub fn set_option_global(&self, name: &str, value: &str) -> Result<(), TmuxError> {
-        let out = self
-            .cmd()
-            .args(["start-server", ";", "set-option", "-g", name, value])
-            .output()?;
-        check(out)
-    }
-
     /// `tmux kill-session -t maestro-<id>`.
     pub fn kill_session(&self, id: Uuid) -> Result<(), TmuxError> {
         let name = session_name(id);
@@ -224,6 +215,11 @@ pub fn session_name(id: Uuid) -> String {
 /// can be asserted without invoking tmux.
 fn new_session_args(name: &str, cwd: &Path, command: &str) -> Vec<OsString> {
     vec![
+        OsString::from("set-option"),
+        OsString::from("-g"),
+        OsString::from("default-terminal"),
+        OsString::from("tmux-256color"),
+        OsString::from(";"),
         OsString::from("new-session"),
         OsString::from("-d"),
         OsString::from("-e"),
@@ -254,12 +250,17 @@ mod tests {
     use super::*;
 
     #[test]
-    fn new_session_args_pass_256color_env() {
+    fn new_session_args_pass_256color_env_and_default_terminal() {
         let args = new_session_args("maestro-abc", Path::new("/tmp/proj"), "sleep 30");
         let strs: Vec<&str> = args.iter().map(|s| s.to_str().unwrap()).collect();
         assert_eq!(
             strs,
             vec![
+                "set-option",
+                "-g",
+                "default-terminal",
+                "tmux-256color",
+                ";",
                 "new-session",
                 "-d",
                 "-e",

crates/maestro-daemon/tests/tmux.rs

@@ -123,10 +123,6 @@ fn new_session_sets_256color_env_and_default_terminal() {
     let sink_path = sink.path().join("env.log");
     let id = Uuid::new_v4();
 
-    fx.tmux
-        .set_option_global("default-terminal", "tmux-256color")
-        .expect("set default-terminal");
-
     fx.tmux
         .new_session(id, cwd.path(), "bash --noprofile --norc")
         .expect("new_session");