Monitor: hotkeys (q quit, u update now) with footer line; show GPU VRAM usage

internal/game/game.go

@@ -132,6 +132,29 @@ func queryComputeApps(ctx context.Context) ([]computeApp, error) {
 	return parseComputeApps(string(out))
 }
 
+// QueryVRAMMB returns used and total GPU VRAM in MiB via nvidia-smi.
+// Unlike the per-process list this works under WDDM too.
+func QueryVRAMMB(ctx context.Context) (used, total int, err error) {
+	out, err := exec.CommandContext(ctx, "nvidia-smi",
+		"--query-gpu=memory.used,memory.total", "--format=csv,noheader,nounits").Output()
+	if err != nil {
+		return 0, 0, err
+	}
+	usedStr, totalStr, ok := strings.Cut(strings.TrimSpace(string(out)), ",")
+	if !ok {
+		return 0, 0, fmt.Errorf("nvidia-smi: unexpected output %q", strings.TrimSpace(string(out)))
+	}
+	used, err = strconv.Atoi(strings.TrimSpace(usedStr))
+	if err != nil {
+		return 0, 0, fmt.Errorf("nvidia-smi: unexpected used memory in %q", strings.TrimSpace(string(out)))
+	}
+	total, err = strconv.Atoi(strings.TrimSpace(totalStr))
+	if err != nil {
+		return 0, 0, fmt.Errorf("nvidia-smi: unexpected total memory in %q", strings.TrimSpace(string(out)))
+	}
+	return used, total, nil
+}
+
 // parseComputeApps parses "pid, used_memory" CSV lines (no header, MiB
 // units). Unsupported rows ("N/A" on WDDM) are skipped.
 func parseComputeApps(out string) ([]computeApp, error) {