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, 8 insertions, 0 deletions

diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index 491373a8..de5da1e7 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -4045,6 +4045,7 @@ const Shell = struct {
         .pty_signal = ptySignal,
         .close_pty = closePaneShell,
         .tty_taken = ttyTaken,
+        .fg_name = fgName,
         .kill_job = killJob,
         .write_file = writeFile,
         .write_dump = writeDump,
@@ -4507,6 +4508,13 @@ fn ttyTaken(ctx: ?*anyopaque, pane: u8) bool {
     return host_io.ttyTaken(pt.pid, pt.fd);
 }
 
+fn fgName(ctx: ?*anyopaque, pane: u8, buf: []u8) ?[]const u8 {
+    const s = shellOf(ctx);
+    const pt = s.ptys[pane] orelse return null;
+    if (pt.fd < 0) return null;
+    return host_io.foregroundName(pt.pid, pt.fd, buf);
+}
+
 fn killJob(ctx: ?*anyopaque, pane: u8) bool {
     const s = shellOf(ctx);
     const pt = s.ptys[pane] orelse return false;