gbctl: 'hud' kills any existing HUD pane before spawning (no double-HUD)

gbctl hud now scans tmux for panes started with gbhud.py and kills them before
spawning, so there's never more than one HUD (fixes the double-spawn flicker).
Added 'gbctl hud --kill' to just tear the HUD down.

1 files changed, 26 insertions, 1 deletions

diff --git a/gbctl b/gbctl
index 4c3d4f9..287b16a 100755
--- a/gbctl
+++ b/gbctl
@@ -284,11 +284,35 @@ def cmd_screen(argv):
     r = subprocess.run(args, capture_output=True, text=True)
     sys.stdout.write(r.stdout)
 
+def _kill_hud_panes():
+    # kill any pane whose start command references the HUD, so there's never
+    # more than one HUD running (avoids the double-spawn tmux flicker).
+    n = 0
+    try:
+        r = subprocess.run(
+            ["tmux", "list-panes", "-a", "-F", "#{pane_id}\t#{pane_start_command}"],
+            capture_output=True, text=True)
+        for line in r.stdout.splitlines():
+            pid, _, startcmd = line.partition("\t")
+            if "gbhud.py" in startcmd:
+                subprocess.run(["tmux", "kill-pane", "-t", pid], capture_output=True)
+                n += 1
+    except Exception:
+        pass
+    return n
+
 def cmd_hud(argv):
     # spawn a tmux pane running the live debug HUD, bound to the resolved socket
+    killonly = "--kill" in argv
+    if killonly:
+        argv = [a for a in argv if a != "--kill"]
+        k = _kill_hud_panes()
+        print("killed %d hud pane(s)" % k)
+        return
     sock_path = _resolve_sock(argv)
     if "TMUX" not in os.environ:
         die("not inside tmux; gbctl hud needs a tmux session")
+    killed = _kill_hud_panes()          # never leave a second HUD around
     hud = os.path.join(HERE, "tools", "gbhud.py")
     split = "-h"
     if "--split" in argv:
@@ -298,7 +322,8 @@ def cmd_hud(argv):
                        capture_output=True, text=True)
     if r.returncode != 0:
         die("tmux spawn failed: %s" % r.stderr.strip())
-    print("hud pane=%s sock=%s" % (r.stdout.strip(), sock_path))
+    note = (" (replaced %d)" % killed) if killed else ""
+    print("hud pane=%s sock=%s%s" % (r.stdout.strip(), sock_path, note))
 
 def cmd_monitor(argv):
     secs = float(argv[0]) if argv and _isnum(argv[0]) else None