config: allow spawning clients with tags

jay-config/src/_private/client.rs

@@ -348,7 +348,15 @@ impl ConfigClient {
             .drain()
             .map(|(a, b)| (a, b.into_raw_fd()))
             .collect();
-        if fds.is_empty() {
+        if command.tag.is_some() {
+            self.send(&ClientMessage::Run3 {
+                prog: &command.prog,
+                args: command.args.clone(),
+                env,
+                fds,
+                tag: command.tag.as_deref(),
+            });
+        } else if fds.is_empty() {
             self.send(&ClientMessage::Run {
                 prog: &command.prog,
                 args: command.args.clone(),

jay-config/src/_private/ipc.rs

@@ -834,6 +834,13 @@ pub enum ClientMessage<'a> {
     SetXWaylandEnabled {
         enabled: bool,
     },
+    Run3 {
+        prog: &'a str,
+        args: Vec<String>,
+        env: Vec<(String, String)>,
+        fds: Vec<(i32, i32)>,
+        tag: Option<&'a str>,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]

jay-config/src/exec.rs

@@ -22,6 +22,7 @@ pub struct Command {
     pub(crate) args: Vec<String>,
     pub(crate) env: HashMap<String, String>,
     pub(crate) fds: RefCell<HashMap<i32, OwnedFd>>,
+    pub(crate) tag: Option<String>,
 }
 
 impl Command {
@@ -37,6 +38,7 @@ impl Command {
             args: vec![],
             env: Default::default(),
             fds: Default::default(),
+            tag: Default::default(),
         }
     }
 
@@ -97,6 +99,12 @@ impl Command {
         self
     }
 
+    /// Adds a tag to Wayland connections created by the spawned command.
+    pub fn tag(&mut self, tag: &str) -> &mut Self {
+        self.tag = Some(tag.to_owned());
+        self
+    }
+
     /// Executes the command.
     ///
     /// This consumes all attached file descriptors.