Monitor: add r hotkey for config reload

Generalizes the one-shot ask behind u into a shared helper; r sends
reload-env and reports the service's reply (unchanged / restarting with
the changed setting names / invalid config) in the note line. Footer now
lists q, u, r.

cmd/gpu-turnstile/monitor.go

@@ -22,13 +22,14 @@ const (
 )
 
 // hotkeysLine is the monitor's footer.
-const hotkeysLine = " " + cDim + "q quit · u update now" + cReset + "\x1b[K\n"
+const hotkeysLine = " " + cDim + "q quit · u update now · r reload config" + cReset + "\x1b[K\n"
 
 // monitorCommand renders a live status view of the running service,
 // refreshed every second from the control channel. When the service
 // reports a different version and the executable on disk changed (the
 // updater replaced it), the monitor restarts itself onto the new binary.
-// Hotkeys: q quits, u triggers an update check on the service.
+// Hotkeys: q quits, u triggers an update check on the service, r asks the
+// service to reload its config file.
 func monitorCommand() int {
 	if !stdoutIsTerminal() {
 		fmt.Fprintln(os.Stderr, "gpu-turnstile: --monitor needs an interactive terminal")
@@ -57,7 +58,27 @@ func monitorCommand() int {
 	var note string
 	var noteAt time.Time
 	noteCh := make(chan string, 1)
-	updatePending := false
+	askPending := false
+
+	// ask sends a one-shot command to the service and reports the reply in
+	// the note line. Only one ask runs at a time.
+	ask := func(cmd, busy, label string) {
+		if askPending {
+			return
+		}
+		askPending = true
+		note, noteAt = busy, time.Now()
+		go func() {
+			reply, err := control.Ask(cmd)
+			if err != nil {
+				noteCh <- label + ": no answer from the service"
+				return
+			}
+			msg := strings.TrimPrefix(reply, "OK ")
+			msg = strings.TrimPrefix(msg, "ERR ")
+			noteCh <- label + ": " + msg
+		}()
+	}
 
 	poll := func() string {
 		frame := renderWaiting()
@@ -104,23 +125,12 @@ func monitorCommand() int {
 			case 'q', 'Q', 3: // q or Ctrl+C (raw mode delivers it as a byte)
 				return 0
 			case 'u', 'U':
-				if !updatePending {
-					updatePending = true
-					note, noteAt = "checking for updates…", time.Now()
-					go func() {
-						reply, err := control.Ask(control.CmdUpdateNow)
-						if err != nil {
-							noteCh <- "update: no answer from the service"
-							return
-						}
-						msg := strings.TrimPrefix(reply, "OK ")
-						msg = strings.TrimPrefix(msg, "ERR ")
-						noteCh <- "update: " + msg
-					}()
-				}
+				ask(control.CmdUpdateNow, "checking for updates…", "update")
+			case 'r', 'R':
+				ask(control.CmdReloadEnv, "reloading config…", "reload")
 			}
 		case n := <-noteCh:
-			updatePending = false
+			askPending = false
 			note, noteAt = n, time.Now()
 		}
 	}