pty/run's busy names the program holding the terminal

busy said only that something ran. Where the host can tell (Linux, the
tty's foreground group's /proc comm, a new fg_name host call), it says
busy: <program> is running; elsewhere, busy as before. The GUI's host
gains the one small callback (render agent's file: gui.zig, fgName).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/tty/tty.zig b/src/tty/tty.zig
index 754b4b96..e7eddec4 100644
--- a/src/tty/tty.zig
+++ b/src/tty/tty.zig
@@ -946,6 +946,7 @@ const Shell = struct {
         .pty_signal = ptySignal,
         .close_pty = closePty,
         .tty_taken = ttyTaken,
+        .fg_name = fgName,
         .kill_job = killJob,
         .write_file = writeFile,
         .write_dump = writeDump,
@@ -1295,6 +1296,12 @@ const Shell = struct {
         return host_io.ttyTaken(pt.pid, pt.file.handle);
     }
 
+    fn fgName(ctx: ?*anyopaque, pane: u8, buf: []u8) ?[]const u8 {
+        const s = of(ctx);
+        const pt = s.ptys[pane] orelse return null;
+        return host_io.foregroundName(pt.pid, pt.file.handle, buf);
+    }
+
     /// The command panes' exits, told once their output is in (host_io).
     fn takeExits(s: *@This()) void {
         host_io.takeExits(s.core, &s.ptys, s, closeWatched);