Pin compose example to v0.2.9

Fix control-pipe client race: retry CreateFile on ERROR_PIPE_BUSY
WaitNamedPipe can report an instance that a concurrent client (the monitor polls status every second) grabs before our CreateFile runs; the single-attempt Ask then failed with 'no answer from the service'. Retry the wait+open until a 5s overall deadline.
2026-09-22 11:23:17 +02:00 · 2026-09-22 11:22:27 +02:00 · 2026-09-22 10:53:29 +02:00 · 2026-09-22 09:24:27 +02:00 · 2026-09-22 09:10:14 +02:00 · 2026-09-22 09:10:14 +02:00
20 changed files with 1050 additions and 167 deletions
@@ -34,8 +34,8 @@ Each consumer is enabled by setting its URL (`OLLAMA_URL`, `COMFY_URL`) and
 disabled by leaving it empty — at least one is required. With only Ollama
 the proxy is a pass-through (no image jobs can arrive); with only ComfyUI
 the Ollama unload/warm steps are skipped. A third, URL-less consumer —
-detection of foreign GPU holders such as games — is enabled by `GAME_PROCS`
-and/or `GPU_FOREIGN_VRAM_MB` (see below).
+detection of foreign GPU holders such as games — is enabled by `GAME_PROCS`,
+`GPU_FOREIGN_VRAM_MB` and/or `GPU_FOREIGN_UTIL_PCT` (see below).

 ## Configuration

@@ -64,7 +64,8 @@ override file values. Invalid values fail at startup.
 | `COMFY_START_TIMEOUT` | `2m` | Max wait for the managed ComfyUI to come up |
 | `GAME_PROCS` | _(empty = disabled)_ | Process names (comma-separated); while any runs, the GPU counts as held: requests wait, Ollama unloads, managed ComfyUI stops |
 | `GPU_FOREIGN_VRAM_MB` | `0` (disabled) | Also treat the GPU as held when a non-ignored process uses more VRAM than this (needs nvidia-smi) |
-| `GPU_IGNORE_PROCS` | `ollama,ollama app,ollama_llama_server,python,pythonw` | Process names never counted as foreign GPU users |
+| `GPU_FOREIGN_UTIL_PCT` | `0` (disabled) | Also treat the GPU as held when a non-ignored process uses more than this percent of the GPU 3D engine (Windows PDH counters — what Task Manager shows; catches games without an exe list) |
+| `GPU_IGNORE_PROCS` | `ollama,ollama app,ollama_llama_server,python,pythonw,dwm` | Process names never counted as foreign GPU users |
 | `GAME_POLL_INTERVAL` | `15s` | How often game/VRAM detection runs (don't go below ~10s — nvidia-smi polls keep the GPU awake) |
 | `LOGLEVEL` | `warn` | `info` logs every request (colored arrows in text mode), `debug` adds lock transitions. `LOG_LEVEL` works as an alias |
 | `LOG_FORMAT` | `text` | `json` for structured JSON logs |
@@ -148,20 +149,25 @@ adds a `BindPaths=` to the systemd unit on Linux. Re-run it after changing
 Want to game on the same GPU without Ollama/ComfyUI squatting on the VRAM?
 gpu-turnstile can watch for foreign GPU holders and, while one is active,
 make LLM/image requests wait (or 503, per `LLM_BUSY_MODE`), unload Ollama's
-models and stop the managed ComfyUI so the game gets the memory. Two
+models and stop the managed ComfyUI so the game gets the memory. Three
 detection paths, each optional, polled every `GAME_POLL_INTERVAL` (15s):

 ```
-GAME_PROCS=cyberpunk2077.exe,bg3.exe     # the reliable way on Windows
+GPU_FOREIGN_UTIL_PCT=30                  # zero-config on Windows: any non-ignored
+                                         # process using >30% of the GPU 3D engine
+GAME_PROCS=cyberpunk2077.exe,bg3.exe     # explicit exe watch list
 GPU_FOREIGN_VRAM_MB=1024                 # catch-all via nvidia-smi
 ```

-`GAME_PROCS` matches running process names (case-insensitive, `.exe`
-optional). `GPU_FOREIGN_VRAM_MB` asks nvidia-smi which processes hold GPU
-memory and treats anything not in `GPU_IGNORE_PROCS` above the threshold as
-foreign — handy as a catch-all, but note that under Windows' WDDM driver
-graphics-only games may not show up in nvidia-smi's per-process list, so
-name your games in `GAME_PROCS` there; on Linux both paths work. When the
+`GPU_FOREIGN_UTIL_PCT` reads the same per-process GPU engine counters as
+Task Manager (PDH), which cover graphics work under Windows' WDDM driver —
+so games show up without naming them, and the offender is named in the log
+and monitor. Windows-only. `GAME_PROCS` matches running process names
+(case-insensitive, `.exe` optional). `GPU_FOREIGN_VRAM_MB` asks nvidia-smi
+which processes hold GPU memory and treats anything not in
+`GPU_IGNORE_PROCS` above the threshold as foreign — handy as a catch-all on
+Linux, but under WDDM graphics-only games may not show up in nvidia-smi's
+per-process list, so on Windows prefer `GPU_FOREIGN_UTIL_PCT`. When the
 game exits, requests resume automatically.

 ## Build and run
@@ -55,9 +55,9 @@ consumer gets no listener, no startup probe, and no lock participation:
 - **Only `COMFY_URL`**: image jobs are tracked and ComfyUI's VRAM is freed
  afterwards, but the Ollama unload and warm-reload steps are skipped.
 - **Game detection** is a third, optional consumer without a URL: enabled by
-  `GAME_PROCS` and/or `GPU_FOREIGN_VRAM_MB` it watches for foreign processes
-  holding the GPU (see below) and plugs into the same lock the same way —
-  excluded when both knobs are unset.
+  `GAME_PROCS`, `GPU_FOREIGN_VRAM_MB` and/or `GPU_FOREIGN_UTIL_PCT` it
+  watches for foreign processes holding the GPU (see below) and plugs into
+  the same lock the same way — excluded when all knobs are unset.

 ### Lock semantics

@@ -171,20 +171,26 @@ files are flagged in the startup log.
 ## Game detection (foreign GPU holders)

 Games and other foreign GPU users sit outside the URL-based consumer model —
-nothing proxies through gpu-turnstile for them. Two independent detection
-paths, polled every `GAME_POLL_INTERVAL` (default 15 s); either one being
+nothing proxies through gpu-turnstile for them. Three independent detection
+paths, polled every `GAME_POLL_INTERVAL` (default 15 s); any one being
 configured enables the feature:

 - **Process watch list** (`GAME_PROCS`, comma-separated, case-insensitive,
  `.exe` optional): while any listed process runs, the GPU counts as held.
-  This is the reliable path on Windows.
+- **Foreign 3D-engine utilization** (`GPU_FOREIGN_UTIL_PCT`, Windows only):
+  per-process GPU engine counters from PDH — the same data Task Manager
+  shows — cover graphics work under WDDM, so any process not in
+  `GPU_IGNORE_PROCS` using more than the threshold percent of the 3D engine
+  counts as a foreign holder, with no exe list needed. Values are summed per
+  process across engines; a missing/failing PDH counter disables the path
+  (logged once).
 - **Foreign VRAM threshold** (`GPU_FOREIGN_VRAM_MB`): `nvidia-smi
  --query-compute-apps` lists per-process GPU memory; any process not in
-  `GPU_IGNORE_PROCS` (default: Ollama and python — ComfyUI runs under python)
-  holding more than the threshold counts as a foreign holder. Needs
-  nvidia-smi on the PATH (absent: logged once, path disabled) and works best
-  on Linux — under Windows' WDDM driver, graphics-only games may not appear
-  in the per-process list.
+  `GPU_IGNORE_PROCS` (default: Ollama and python — ComfyUI runs under python
+  — plus dwm, the desktop compositor) holding more than the threshold counts
+  as a foreign holder. Needs nvidia-smi on the PATH (absent: logged once,
+  path disabled) and works best on Linux — under Windows' WDDM driver,
+  graphics-only games may not appear in the per-process list.

 While a holder is detected, gpu-turnstile:

@@ -230,7 +236,8 @@ override file values. A missing file is fine; a malformed one is fatal.
 | `COMFY_START_TIMEOUT` | `2m` | how long a request waits for the managed ComfyUI to come up |
 | `GAME_PROCS` | _(empty = disabled)_ | comma-separated process names (case-insensitive, `.exe` optional); while any runs, the GPU counts as held by it: requests wait, Ollama unloads, the managed ComfyUI stops |
 | `GPU_FOREIGN_VRAM_MB` | `0` (disabled) | also treat the GPU as held when a process not in `GPU_IGNORE_PROCS` uses more VRAM than this; needs nvidia-smi |
-| `GPU_IGNORE_PROCS` | `ollama,ollama app,ollama_llama_server,python,pythonw` | process names never counted as foreign GPU users |
+| `GPU_FOREIGN_UTIL_PCT` | `0` (disabled) | also treat the GPU as held when a process not in `GPU_IGNORE_PROCS` uses more than this percent of the GPU 3D engine (Windows PDH counters, as shown by Task Manager; catches games without an exe list) |
+| `GPU_IGNORE_PROCS` | `ollama,ollama app,ollama_llama_server,python,pythonw,dwm` | process names never counted as foreign GPU users |
 | `GAME_POLL_INTERVAL` | `15s` | how often game/VRAM detection runs (nvidia-smi polls keep the GPU awake; don't go below ~10s) |
 | `LOGLEVEL` | `warn` | `info` logs every request (colored arrows in text mode), `debug` adds lock transitions. `LOG_LEVEL` is accepted as an alias |
 | `LOG_FORMAT` | `text` | `json` for structured JSON logs |
@@ -16,6 +16,7 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
+	"reflect"
 	"runtime"
 	"strings"
 	"sync"
@@ -39,7 +40,8 @@ import (
 var version = "dev"

 // exitCodeUpdate tells the service recovery configuration to restart the
-// process: a signed update has been staged and the GPU lock is idle.
+// process: a signed update has been staged or a changed config reload was
+// requested, and the GPU lock is idle.
 const exitCodeUpdate = 3

 // exitCodeStaged is returned by an elevated --force-update child when it
@@ -59,7 +61,7 @@ func stdoutIsTerminal() bool {
 // --install-service / --remove-service switches, --no-copy, -h/--help,
 // -v/--version, --force-update and the hidden --elevated-child marker from
 // args.
-func parseFlags(args []string) (configPath string, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, monitor, elevatedChild bool, rest []string) {
+func parseFlags(args []string) (configPath string, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, reloadEnv, monitor, elevatedChild bool, rest []string) {
 	rest = args[:0]
 	for i := 0; i < len(args); i++ {
 		switch {
@@ -82,6 +84,8 @@ func parseFlags(args []string) (configPath string, install, remove, noCopy, help
 			forceUpdate = true
 		case args[i] == "--update-now" || args[i] == "-update-now":
 			updateNow = true
+		case args[i] == "--reload-env" || args[i] == "-reload-env":
+			reloadEnv = true
 		case args[i] == "--monitor" || args[i] == "-monitor" || args[i] == "-m":
 			monitor = true
 		case args[i] == "--elevated-child":
@@ -90,7 +94,7 @@ func parseFlags(args []string) (configPath string, install, remove, noCopy, help
 			rest = append(rest, args[i])
 		}
 	}
-	return configPath, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, monitor, elevatedChild, rest
+	return configPath, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, reloadEnv, monitor, elevatedChild, rest
 }

 // versionLine is printed at the top of every help and error screen.
@@ -109,6 +113,9 @@ Usage:
                                                              (no admin needed when the service runs)
  gpu-turnstile --update-now                                  like --force-update, but only
                                                              through the running service
+  gpu-turnstile --reload-env                                  make the service re-read and
+                                                              validate its config file, then
+                                                              restart onto it if it changed
  gpu-turnstile -m | --monitor                                live status view (downstreams,
                                                              GPU lock, queue); Ctrl+C quits
  gpu-turnstile -h | --help                                   this help
@@ -141,12 +148,12 @@ func fatalUsage(format string, args ...any) {
 }

 func main() {
-	configPath, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, monitor, elevatedChild, args := parseFlags(os.Args[1:])
+	configPath, install, remove, noCopy, help, showVersion, forceUpdate, updateNow, reloadEnv, monitor, elevatedChild, args := parseFlags(os.Args[1:])
 	if showVersion {
 		fmt.Println(version)
 		return
 	}
-	bare := configPath == "" && !install && !remove && !forceUpdate && !updateNow && !monitor && !elevatedChild && len(args) == 0
+	bare := configPath == "" && !install && !remove && !forceUpdate && !updateNow && !reloadEnv && !monitor && !elevatedChild && len(args) == 0
 	if help || (bare && stdoutIsTerminal()) {
 		// Bare invocation in a terminal (e.g. double-clicked on Windows)
 		// shows the help instead of starting a proxy window with no visible
@@ -171,7 +178,9 @@ func main() {
 		fatalUsage("error: --force-update cannot be combined with --install-service/--remove-service")
 	case updateNow && (install || remove || forceUpdate):
 		fatalUsage("error: --update-now cannot be combined with other commands")
-	case monitor && (install || remove || forceUpdate || updateNow):
+	case reloadEnv && (install || remove || forceUpdate || updateNow):
+		fatalUsage("error: --reload-env cannot be combined with other commands")
+	case monitor && (install || remove || forceUpdate || updateNow || reloadEnv):
 		fatalUsage("error: --monitor cannot be combined with other commands")
 	case install:
 		os.Exit(serviceCommand(configPath, true, noCopy, elevatedChild))
@@ -181,6 +190,8 @@ func main() {
 		os.Exit(forceUpdateCommand(configPath, elevatedChild))
 	case updateNow:
 		os.Exit(updateNowCommand())
+	case reloadEnv:
+		os.Exit(reloadEnvCommand())
 	case monitor:
 		os.Exit(monitorCommand())
 	}
@@ -202,7 +213,7 @@ func main() {
 	syncEnvFile(resolveConfigPath(configPath), cfg.LogFile, log)

 	if service.IsService() {
-		if err := service.Run(func(ctx context.Context) error { return run(ctx, cfg, log, logOut, true) }); err != nil {
+		if err := service.Run(func(ctx context.Context) error { return run(ctx, cfg, log, logOut, true, configPath) }); err != nil {
 			log.Error("service failed", "err", err)
 			os.Exit(1)
 		}
@@ -210,7 +221,7 @@ func main() {
 	}
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()
-	if err := run(ctx, cfg, log, logOut, false); err != nil {
+	if err := run(ctx, cfg, log, logOut, false, configPath); err != nil {
 		log.Error("listener failed", "err", err)
 		os.Exit(1)
 	}
@@ -362,6 +373,10 @@ func forceUpdateCommand(configPath string, elevatedChild bool) int {
 		fmt.Fprintf(os.Stderr, "gpu-turnstile: cannot locate executable: %v\n", err)
 		return 1
 	}
+	// One-shot CLI: the updater logs to stderr, never to the service's
+	// LOG_FILE — that file is ACL'd to the service account, and a CLI run
+	// has nothing worth persisting there.
+	cfg.LogFile = ""
 	log, _, logCloser := newLogger(cfg)
 	defer logCloser.Close()
 	if cfg.AppVersion == "dev" {
@@ -447,6 +462,18 @@ func updateNowCommand() int {
 	return printControlReply(reply)
 }

+// reloadEnvCommand asks the running service, over the control channel, to
+// re-read and validate its config file. The client sends no path — the
+// service only ever re-reads its own configured file.
+func reloadEnvCommand() int {
+	reply, err := control.Ask(control.CmdReloadEnv)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s\n\ngpu-turnstile: no running service to ask\n", versionLine())
+		return 1
+	}
+	return printControlReply(reply)
+}
+
 // reportElevatedUpdate prints the parent's summary of an elevated
 // --force-update child: exitCodeStaged means the child staged a new binary,
 // 0 means it found nothing to do. to is the tag the parent's own check
@@ -527,7 +554,7 @@ func managedComfyCommand(cfg config.Config) string {
 	return ""
 }

-func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Writer, isService bool) error {
+func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Writer, isService bool, configPath string) error {
 	// ComfyUI can run as a managed child — COMFY_CMD verbatim, or the
 	// standard venv layout derived from COMFY_DIR alone: started on demand
 	// by the proxy, stopped after COMFY_IDLE_TIMEOUT idle (and on shutdown)
@@ -565,6 +592,7 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 		"comfy_start_timeout", cfg.ComfyStartTimeout,
 		"game_procs", cfg.GameProcs,
 		"gpu_foreign_vram_mb", cfg.GPUForeignVRAMMB,
+		"gpu_foreign_util_pct", cfg.GPUForeignUtilPct,
 		"gpu_ignore_procs", cfg.GPUIgnoreProcs,
 		"game_poll_interval", cfg.GamePollInterval,
 		"auto_update", cfg.AutoUpdate,
@@ -699,11 +727,14 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 		go healthLoop(ctx, cfg.HealthInterval, cfg.ProbeTimeout, log, probes, health)
 	}

-	// Foreign GPU holders (games, other ML jobs) — enabled by GAME_PROCS
-	// and/or GPU_FOREIGN_VRAM_MB — hold the lock externally while they run.
-	if len(cfg.GameProcs) > 0 || cfg.GPUForeignVRAMMB > 0 {
-		det := game.New(cfg.GameProcs, cfg.GPUForeignVRAMMB, cfg.GPUIgnoreProcs, log)
-		go gameLoop(ctx, cfg, log, det, lk, ollamaClient, comfySup)
+	// Foreign GPU holders (games, other ML jobs) — enabled by GAME_PROCS,
+	// GPU_FOREIGN_VRAM_MB and/or GPU_FOREIGN_UTIL_PCT — hold the lock
+	// externally while they run. gw collects the VRAM reading and the last
+	// check result for the status channel.
+	gw := &gpuWatch{enabled: len(cfg.GameProcs) > 0 || cfg.GPUForeignVRAMMB > 0 || cfg.GPUForeignUtilPct > 0}
+	if gw.enabled {
+		det := game.New(cfg.GameProcs, cfg.GPUForeignVRAMMB, cfg.GPUForeignUtilPct, cfg.GPUIgnoreProcs, log)
+		go gameLoop(ctx, cfg, log, det, lk, ollamaClient, comfySup, gw)
 	}

 	// Bind the listeners up front so a port conflict fails fast and the
@@ -743,6 +774,22 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri

 	var u *update.Updater
 	var exePath string
+	// restartWhenIdle exits with exitCodeUpdate once the GPU lock is idle;
+	// the service recovery configuration brings the process back. Shared by
+	// staged updates and config reloads; the once guard makes repeated
+	// triggers idempotent.
+	var restartOnce sync.Once
+	restartWhenIdle := func(reason string) {
+		log.Warn("restarting once the GPU is idle", "reason", reason)
+		restartOnce.Do(func() {
+			go func() {
+				if waitForIdle(ctx, lk, 24*time.Hour) {
+					log.Warn("restarting now", "reason", reason)
+					os.Exit(exitCodeUpdate)
+				}
+			}()
+		})
+	}
 	applyStaged := func(to string) {}
 	if cfg.AutoUpdate {
 		if p, err := os.Executable(); err != nil {
@@ -750,34 +797,24 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 		} else {
 			exePath = p
 			u = &update.Updater{Repo: cfg.UpdateRepo, Asset: cfg.UpdateAsset, Version: version, Desired: cfg.AppVersion, Log: log}
-			// applyStaged is shared by the hourly loop and the control
-			// channel; the once guard keeps a second trigger from
-			// double-waiting on the GPU lock.
-			var once sync.Once
 			applyStaged = func(to string) {
 				if !isService {
 					log.Warn("auto-update: new binary staged; restart gpu-turnstile to apply", "version", to)
 					return
 				}
-				log.Warn("auto-update: staged; restarting once the GPU is idle", "version", to)
-				once.Do(func() {
-					go func() {
-						if waitForIdle(ctx, lk, 24*time.Hour) {
-							log.Warn("auto-update: restarting to apply update")
-							os.Exit(exitCodeUpdate)
-						}
-					}()
-				})
+				restartWhenIdle("update to " + to)
 			}
 			go updateLoop(ctx, cfg.UpdateInterval, log, u, exePath, applyStaged)
 		}
 	}

-	// The control channel (status for --monitor, update-now trigger) is
-	// served whenever running as a service, independent of AUTO_UPDATE.
+	// The control channel (status for --monitor, update-now and reload-env
+	// triggers) is served whenever running as a service, independent of
+	// AUTO_UPDATE.
 	if isService {
 		serveControl(ctx, log, u, exePath, applyStaged,
-			statusProvider(cfg, lk, comfySup, health, started))
+			statusProvider(cfg, lk, comfySup, health, started, gw),
+			reloadHandler(cfg, configPath, restartWhenIdle))
 	}

 	select {
@@ -801,12 +838,48 @@ func run(ctx context.Context, cfg config.Config, log *slog.Logger, logOut io.Wri
 // (idle); health checks skip it instead of logging an outage.
 var errManagedDown = errors.New("managed upstream intentionally stopped")

+// gpuWatch records the latest VRAM reading and game-detector finding from
+// the game detector's poll loop, for the status channel. Enabled is false
+// when game detection is not configured (no polling happens then); Known is
+// false until the first successful nvidia-smi reading.
+type gpuWatch struct {
+	mu      sync.Mutex
+	enabled bool
+	usedMB  int
+	total   int
+	known   bool
+	foreign string // last Check result: external holders, "" when none
+	at      time.Time
+}
+
+func (g *gpuWatch) setVRAM(used, total int) {
+	g.mu.Lock()
+	g.usedMB, g.total, g.known = used, total, true
+	g.mu.Unlock()
+}
+
+func (g *gpuWatch) setCheck(foreign string) {
+	g.mu.Lock()
+	g.foreign, g.at = foreign, time.Now()
+	g.mu.Unlock()
+}
+
+func (g *gpuWatch) get() (used, total int, known bool, foreign string, ageS int64) {
+	g.mu.Lock()
+	defer g.mu.Unlock()
+	ageS = -1
+	if !g.at.IsZero() {
+		ageS = int64(time.Since(g.at).Seconds())
+	}
+	return g.usedMB, g.total, g.known, g.foreign, ageS
+}
+
 // gameLoop polls for foreign GPU holders (a game, another ML job). While one
 // is detected it holds the lock externally so new LLM and image requests
 // wait (or are rejected per LLM_BUSY_MODE), and — once in-flight work has
 // drained — frees VRAM for it: the managed ComfyUI is stopped and Ollama's
 // resident models are unloaded.
-func gameLoop(ctx context.Context, cfg config.Config, log *slog.Logger, det *game.Detector, lk *lock.Lock, ollamaClient *ollama.Client, comfySup *supervise.Process) {
+func gameLoop(ctx context.Context, cfg config.Config, log *slog.Logger, det *game.Detector, lk *lock.Lock, ollamaClient *ollama.Client, comfySup *supervise.Process, gw *gpuWatch) {
 	ticker := time.NewTicker(cfg.GamePollInterval)
 	defer ticker.Stop()
 	held, freed := false, false
@@ -820,6 +893,10 @@ func gameLoop(ctx context.Context, cfg config.Config, log *slog.Logger, det *gam
 		if err != nil && ctx.Err() == nil {
 			log.Warn("game detection failed", "err", err)
 		}
+		gw.setCheck(summarizeHolders(holders))
+		if used, total, verr := game.QueryVRAMMB(ctx); verr == nil {
+			gw.setVRAM(used, total)
+		}
 		switch {
 		case len(holders) > 0 && !held:
 			held = true
@@ -945,17 +1022,29 @@ func updateLoop(ctx context.Context, interval time.Duration, log *slog.Logger, u

 // serveControl opens the local control channel (named pipe on Windows,
 // unix socket on Linux) so unprivileged local users can query status
-// (--monitor) and trigger an update check (--force-update/--update-now)
-// without admin rights. The update payload is signature-verified regardless
-// of who asks; triggers are rate-limited to one per minute so the channel
-// cannot be used to spam restarts. u is nil when AUTO_UPDATE=false.
-func serveControl(ctx context.Context, log *slog.Logger, u *update.Updater, exePath string, applyStaged func(to string), status func() string) {
+// (--monitor), trigger an update check (--force-update/--update-now) and
+// poke a config reload (--reload-env) without admin rights. The update
+// payload is signature-verified regardless of who asks; update triggers
+// are rate-limited to one per minute so the channel cannot be used to spam
+// restarts. u is nil when AUTO_UPDATE=false.
+func serveControl(ctx context.Context, log *slog.Logger, u *update.Updater, exePath string, applyStaged func(to string), status func() string, reload func() string) {
 	var mu sync.Mutex
-	var lastTrigger time.Time
+	var lastTrigger, lastReload time.Time
 	h := func(cmd string) string {
 		switch cmd {
 		case control.CmdStatus:
 			return "OK " + status()
+		case control.CmdReloadEnv:
+			// reload re-reads the config file from disk; a short limiter
+			// keeps a local flood from turning into disk churn.
+			mu.Lock()
+			if wait := 2*time.Second - time.Since(lastReload); wait > 0 {
+				mu.Unlock()
+				return fmt.Sprintf("ERR rate limited: retry in %ds", int(wait.Seconds())+1)
+			}
+			lastReload = time.Now()
+			mu.Unlock()
+			return reload()
 		case control.CmdUpdateNow:
 		default:
 			return "ERR unknown command: " + cmd
@@ -1034,15 +1123,79 @@ type statusSnapshot struct {
 	UptimeS     int64              `json:"uptime_s"`
 	Downstreams []statusDownstream `json:"downstreams"`
 	Lock        statusLock         `json:"lock"`
+	// GPU carries the latest VRAM reading and detector finding; Enabled is
+	// false when game detection (and with it nvidia-smi polling) is not
+	// configured.
+	GPU statusGPU `json:"gpu"`
+	// MonitorNote is set client-side (never over the wire) when the
+	// monitor's own binary differs from the service's version.
+	MonitorNote string `json:"-"`
+}
+
+type statusGPU struct {
+	// Enabled reports whether game detection is configured (and with it
+	// VRAM polling); when false the other fields carry no information.
+	Enabled bool `json:"enabled"`
+	UsedMB  int  `json:"used_mb"`
+	TotalMB int  `json:"total_mb"`
+	Known   bool `json:"known"`
+	// Foreign is the last detector finding (external GPU holders), empty
+	// when the last check found none.
+	Foreign string `json:"foreign,omitempty"`
+	// AgeS is how long ago the last check ran; -1 before the first check.
+	AgeS int64 `json:"age_s"`
+}
+
+// reloadHandler re-reads and validates the service's config file for
+// CmdReloadEnv. An invalid config is reported and the service keeps running
+// untouched; a valid, changed config triggers a GPU-idle-gated restart onto
+// it (same mechanism as staged updates); unchanged is a no-op.
+func reloadHandler(current config.Config, configPath string, restartWhenIdle func(reason string)) func() string {
+	return func() string {
+		ncfg, err := loadMergedConfig(configPath)
+		if err != nil {
+			return "ERR config invalid: " + err.Error()
+		}
+		changed := diffConfig(current, ncfg)
+		if len(changed) == 0 {
+			return "OK config unchanged"
+		}
+		restartWhenIdle("config reload (" + strings.Join(changed, ", ") + ")")
+		return "OK config valid; restarting once the GPU is idle (changed: " + strings.Join(changed, ", ") + ")"
+	}
+}
+
+// diffConfig lists the env names of settings whose values differ between
+// two configs (from each field's env tag, so users recognize them).
+func diffConfig(a, b config.Config) []string {
+	va, vb := reflect.ValueOf(a), reflect.ValueOf(b)
+	t := va.Type()
+	var out []string
+	for i := 0; i < t.NumField(); i++ {
+		if !reflect.DeepEqual(va.Field(i).Interface(), vb.Field(i).Interface()) {
+			name := t.Field(i).Tag.Get("env")
+			if name == "" {
+				name = t.Field(i).Name
+			}
+			out = append(out, name)
+		}
+	}
+	return out
 }

 // statusProvider assembles the one-line JSON snapshot for CmdStatus.
-func statusProvider(cfg config.Config, lk *lock.Lock, comfySup *supervise.Process, health *healthTracker, started time.Time) func() string {
+func statusProvider(cfg config.Config, lk *lock.Lock, comfySup *supervise.Process, health *healthTracker, started time.Time, gw *gpuWatch) func() string {
 	return func() string {
 		snap := statusSnapshot{
 			Version: version,
 			UptimeS: int64(time.Since(started).Seconds()),
 		}
+		used, total, known, foreign, ageS := gw.get()
+		snap.GPU = statusGPU{
+			Enabled: gw.enabled,
+			UsedMB:  used, TotalMB: total, Known: known,
+			Foreign: foreign, AgeS: ageS,
+		}
 		if cfg.OllamaURL != "" {
 			snap.Downstreams = append(snap.Downstreams, statusDownstream{
 				Name: "ollama", URL: cfg.OllamaURL, Up: health.get("ollama"),
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"os/exec"
 	"strings"
 	"time"

@@ -20,33 +21,147 @@ const (
 	cCyan   = "\x1b[36m"
 )

+// hotkeysLine is the monitor's footer.
+const hotkeysLine = " " + cDim + "q quit · u update now" + cReset + "\x1b[K\n"
+
 // monitorCommand renders a live status view of the running service,
-// refreshed every second from the control channel. Ctrl+C quits.
+// 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.
 func monitorCommand() int {
 	if !stdoutIsTerminal() {
 		fmt.Fprintln(os.Stderr, "gpu-turnstile: --monitor needs an interactive terminal")
 		return 1
 	}
 	enableVirtualTerminal()
+	restore := enableRawKeys()
+	defer func() {
+		if restore != nil {
+			restore()
+		}
+	}()
 	fmt.Print("\x1b[2J") // clear once; frames then redraw in place
 	defer fmt.Print(cReset + "\n")
-	for {
+	exe, _ := os.Executable()
+	var exeStamp time.Time
+	if st, err := os.Stat(exe); err == nil {
+		exeStamp = st.ModTime()
+	}
+
+	keys := make(chan byte, 8)
+	go readKeys(keys)
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+
+	var note string
+	var noteAt time.Time
+	noteCh := make(chan string, 1)
+	updatePending := false
+
+	poll := func() string {
 		frame := renderWaiting()
 		if reply, err := control.Ask(control.CmdStatus); err == nil {
 			if msg, ok := strings.CutPrefix(reply, "OK "); ok {
 				var snap statusSnapshot
 				if json.Unmarshal([]byte(msg), &snap) == nil {
+					if snap.Version != "" && snap.Version != version {
+						if exeChanged(exe, exeStamp) {
+							fmt.Print("\x1b[2J\x1b[H")
+							fmt.Printf("gpu-turnstile: service updated to %s — restarting the monitor\n", snap.Version)
+							restartSelf(exe, "--monitor")
+							return "" // re-execed; this process exits below
+						}
+						snap.MonitorNote = fmt.Sprintf("note: the service runs %s, this monitor is %s", snap.Version, version)
+					}
+					if note != "" {
+						snap.MonitorNote = note
+					}
 					frame = renderMonitor(snap, termWidth())
 				}
 			}
 		}
+		return frame
+	}
+
+	for {
+		frame := poll()
+		if frame == "" {
+			return 0 // restartSelf fired
+		}
 		fmt.Print("\x1b[H" + frame + "\x1b[J") // home, frame, clear below
-		time.Sleep(time.Second)
+		select {
+		case <-ticker.C:
+			if note != "" && time.Since(noteAt) > 15*time.Second {
+				note = ""
+			}
+		case k, ok := <-keys:
+			if !ok {
+				keys = nil
+				continue
+			}
+			switch k {
+			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
+					}()
+				}
+			}
+		case n := <-noteCh:
+			updatePending = false
+			note, noteAt = n, time.Now()
+		}
 	}
 }

+// readKeys reads single keypresses from stdin (raw mode was enabled by the
+// caller) and delivers them until stdin fails.
+func readKeys(keys chan<- byte) {
+	defer close(keys)
+	buf := make([]byte, 1)
+	for {
+		n, err := os.Stdin.Read(buf)
+		if n > 0 {
+			keys <- buf[0]
+		}
+		if err != nil {
+			return
+		}
+	}
+}
+
+// exeChanged reports whether the executable on disk was replaced since the
+// recorded stamp (the updater swaps it via rename, which changes ModTime).
+func exeChanged(exe string, stamp time.Time) bool {
+	if exe == "" || stamp.IsZero() {
+		return false
+	}
+	st, err := os.Stat(exe)
+	return err == nil && !st.ModTime().Equal(stamp)
+}
+
+// restartSelf starts a fresh copy of this executable with the given args on
+// the same console; the caller exits right after.
+func restartSelf(exe string, args ...string) {
+	cmd := exec.Command(exe, args...)
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
+	cmd.Start() //nolint:errcheck // best effort: on failure we just exit
+}
+
 func renderWaiting() string {
-	return cDim + " gpu-turnstile — waiting for a running service…" + cReset + "\x1b[K\n"
+	return cDim + " gpu-turnstile — waiting for a running service…" + cReset + "\x1b[K\n\x1b[K\n" + hotkeysLine
 }

 // renderMonitor draws one full frame. Each line ends with \x1b[K (clear to
@@ -81,9 +196,51 @@ func renderMonitor(snap statusSnapshot, width int) string {
 		b.WriteString(fmt.Sprintf(" Queue: %s%d image job(s) waiting%s\x1b[K\n",
 			cYellow, snap.Lock.ImageQueue, cReset))
 	}
+	if snap.GPU.Enabled {
+		b.WriteString(renderGPU(snap.GPU) + "\x1b[K\n")
+	}
+	if snap.MonitorNote != "" {
+		b.WriteString(" " + cYellow + snap.MonitorNote + cReset + "\x1b[K\n")
+	}
+	b.WriteString("\x1b[K\n")
+	b.WriteString(hotkeysLine)
 	return b.String()
 }

+// renderGPU renders the GPU line: VRAM usage (when nvidia-smi answered),
+// the game detector's last finding, and how long ago it ran.
+func renderGPU(g statusGPU) string {
+	s := " GPU: "
+	if g.Known {
+		s += renderVRAM(g.UsedMB, g.TotalMB)
+	} else {
+		s += cDim + "VRAM unknown (nvidia-smi not answering)" + cReset
+	}
+	if g.Foreign != "" {
+		s += " · external: " + cRed + g.Foreign + cReset
+	} else {
+		s += cDim + " · no external process" + cReset
+	}
+	if g.AgeS >= 0 {
+		s += cDim + fmt.Sprintf(" (checked %s ago)", fmtDur(g.AgeS)) + cReset
+	}
+	return s
+}
+
+// renderVRAM renders "4.2 / 16.0 GiB used" (or MiB below 1 GiB).
+func renderVRAM(used, total int) string {
+	format := func(mb int) string {
+		if mb >= 1024 {
+			return fmt.Sprintf("%.1f GiB", float64(mb)/1024)
+		}
+		return fmt.Sprintf("%d MiB", mb)
+	}
+	if total > 0 {
+		return format(used) + " / " + format(total) + " used"
+	}
+	return format(used) + " used"
+}
+
 // printableLen counts characters without ANSI escapes (ASCII-only content).
 func printableLen(s string) int { return len(s) }

@@ -1,6 +1,8 @@
 package main

 import (
+	"gpu-turnstile/internal/config"
+	"reflect"
 	"strings"
 	"testing"
 )
@@ -29,6 +31,22 @@ func TestRenderMonitor(t *testing.T) {
 			t.Errorf("frame missing %q:\n%s", want, frame)
 		}
 	}
+
+	snap.GPU = statusGPU{Enabled: true, Known: true, UsedMB: 4300, TotalMB: 16384, Foreign: "cyberpunk2077.exe (pid 1234)", AgeS: 12}
+	frame = renderMonitor(snap, 80)
+	for _, want := range []string{"GPU:", "4.2 GiB / 16.0 GiB used", "external:", "checked 12s ago"} {
+		if !strings.Contains(frame, want) {
+			t.Errorf("frame missing %q:\n%s", want, frame)
+		}
+	}
+
+	snap.GPU = statusGPU{Enabled: true, AgeS: 4}
+	frame = renderMonitor(snap, 80)
+	for _, want := range []string{"VRAM unknown", "no external process"} {
+		if !strings.Contains(frame, want) {
+			t.Errorf("frame missing %q:\n%s", want, frame)
+		}
+	}
 }

 func TestFmtDur(t *testing.T) {
@@ -39,3 +57,29 @@ func TestFmtDur(t *testing.T) {
 		}
 	}
 }
+
+func TestDiffConfig(t *testing.T) {
+	a := config.Defaults()
+	b := a
+	if got := diffConfig(a, b); len(got) != 0 {
+		t.Fatalf("identical configs: got %v", got)
+	}
+	b.LogLevel = -4
+	b.GameProcs = []string{"game.exe"}
+	got := diffConfig(a, b)
+	if len(got) != 2 || got[0] != "GAME_PROCS" || got[1] != "LOGLEVEL" {
+		t.Fatalf("got %v, want [GAME_PROCS LOGLEVEL]", got)
+	}
+}
+
+// Every Config field must carry an env tag so user-facing output (the
+// reload diff) can name the setting the user would actually change.
+func TestConfigFieldsHaveEnvTags(t *testing.T) {
+	typ := reflect.TypeOf(config.Config{})
+	for i := 0; i < typ.NumField(); i++ {
+		f := typ.Field(i)
+		if f.Tag.Get("env") == "" {
+			t.Errorf("config.Config.%s has no env tag", f.Name)
+		}
+	}
+}
@@ -19,3 +19,21 @@ func termWidth() int {
 	}
 	return int(ws.Col)
 }
+
+// enableRawKeys switches the terminal to per-keypress mode (ICANON and ECHO
+// off) and returns the restore function, nil when stdin is not a terminal.
+func enableRawKeys() func() {
+	fd := int(os.Stdin.Fd())
+	term, err := unix.IoctlGetTermios(fd, unix.TCGETS)
+	if err != nil {
+		return nil
+	}
+	raw := *term
+	raw.Lflag &^= unix.ICANON | unix.ECHO
+	raw.Cc[unix.VMIN] = 1
+	raw.Cc[unix.VTIME] = 0
+	if err := unix.IoctlSetTermios(fd, unix.TCSETS, &raw); err != nil {
+		return nil
+	}
+	return func() { unix.IoctlSetTermios(fd, unix.TCSETS, term) } //nolint:errcheck
+}
@@ -27,3 +27,23 @@ func termWidth() int {
 	}
 	return int(info.Window.Right-info.Window.Left) + 1
 }
+
+// enableRawKeys puts the console's stdin into per-keypress mode (no line
+// buffering, no echo) and returns the restore function. When stdin is not a
+// real console (mintty/Git Bash pipes) it returns nil: ptys already deliver
+// keystrokes immediately.
+func enableRawKeys() func() {
+	h := windows.Handle(os.Stdin.Fd())
+	var mode uint32
+	if err := windows.GetConsoleMode(h, &mode); err != nil {
+		return nil
+	}
+	const (
+		enableLineInput = 0x0002
+		enableEchoInput = 0x0004
+	)
+	if err := windows.SetConsoleMode(h, mode&^(enableLineInput|enableEchoInput)); err != nil {
+		return nil
+	}
+	return func() { windows.SetConsoleMode(h, mode) } //nolint:errcheck
+}
@@ -6,7 +6,7 @@
 # ComfyUI --listen 0.0.0.0 --port 8189).
 services:
  gpu-turnstile:
-    image: git.rambossek.at/public/gpu-turnstile:v0.2.5
+    image: git.rambossek.at/public/gpu-turnstile:v0.2.9
    restart: unless-stopped
    environment:
      # Each consumer is enabled by setting its URL; leave one unset to
@@ -13,43 +13,45 @@ import (
 	"time"
 )

-// Config holds every gpu-turnstile setting.
+// Config holds every gpu-turnstile setting. Each field's env tag names the
+// environment variable / config-file key that sets it; user-facing output
+// (e.g. the reload diff) uses those names, never the Go field names.
 type Config struct {
-	ListenOllama   string
-	ListenComfy    string
-	OllamaURL      string
-	ComfyURL       string
-	UnloadTimeout  time.Duration
-	JobTimeout     time.Duration
-	LLMWaitTimeout time.Duration
+	ListenOllama   string        `env:"LISTEN_OLLAMA"`
+	ListenComfy    string        `env:"LISTEN_COMFY"`
+	OllamaURL      string        `env:"OLLAMA_URL"`
+	ComfyURL       string        `env:"COMFY_URL"`
+	UnloadTimeout  time.Duration `env:"UNLOAD_TIMEOUT"`
+	JobTimeout     time.Duration `env:"JOB_TIMEOUT"`
+	LLMWaitTimeout time.Duration `env:"LLM_WAIT_TIMEOUT"`

-	UnloadPollInterval  time.Duration
-	HistoryPollInterval time.Duration
-	ProbeTimeout        time.Duration
-	HealthInterval      time.Duration
-	FreeTimeout         time.Duration
-	WarmTimeout         time.Duration
-	ShutdownTimeout     time.Duration
-	BackoffInitial      time.Duration
-	BackoffMax          time.Duration
-	PromptCaptureLimit  int64
+	UnloadPollInterval  time.Duration `env:"UNLOAD_POLL_INTERVAL"`
+	HistoryPollInterval time.Duration `env:"HISTORY_POLL_INTERVAL"`
+	ProbeTimeout        time.Duration `env:"PROBE_TIMEOUT"`
+	HealthInterval      time.Duration `env:"HEALTH_INTERVAL"`
+	FreeTimeout         time.Duration `env:"FREE_TIMEOUT"`
+	WarmTimeout         time.Duration `env:"WARM_TIMEOUT"`
+	ShutdownTimeout     time.Duration `env:"SHUTDOWN_TIMEOUT"`
+	BackoffInitial      time.Duration `env:"BACKOFF_INITIAL"`
+	BackoffMax          time.Duration `env:"BACKOFF_MAX"`
+	PromptCaptureLimit  int64         `env:"PROMPT_CAPTURE_LIMIT"`

-	AutoUpdate     bool
-	UpdateInterval time.Duration
-	UpdateRepo     string
-	UpdateAsset    string
+	AutoUpdate     bool          `env:"AUTO_UPDATE"`
+	UpdateInterval time.Duration `env:"UPDATE_INTERVAL"`
+	UpdateRepo     string        `env:"UPDATE_REPO"`
+	UpdateAsset    string        `env:"UPDATE_ASSET"`

 	// AppVersion is the version the user wants to run: "dev" disables
 	// updates, "stable" tracks the latest release, anything else is an
 	// exact vX.Y.Z release to pin. From APP_VER; defaults to "stable".
-	AppVersion string
+	AppVersion string `env:"APP_VER"`

 	// LLMBusyMode is "wait" (hold requests until the lock is free or
 	// LLMWaitTimeout expires) or "reject" (immediately answer with
 	// LLMBusyStatus + Retry-After when an image job is active or pending).
-	LLMBusyMode    string
-	LLMBusyStatus  int
-	BusyRetryAfter int
+	LLMBusyMode    string `env:"LLM_BUSY_MODE"`
+	LLMBusyStatus  int    `env:"LLM_BUSY_STATUS"`
+	BusyRetryAfter int    `env:"BUSY_RETRY_AFTER"`

 	// ComfyCmd spawns and supervises a ComfyUI server on demand. When
 	// ComfyCmd is empty but ComfyDir is set, management is enabled with the
@@ -59,26 +61,29 @@ type Config struct {
 	// set explicitly. The managed server is stopped after ComfyIdleTimeout
 	// without requests, freeing its VRAM; ComfyStartTimeout bounds how long
 	// a request waits for it to come up.
-	ComfyCmd          string
-	ComfyDir          string
-	ComfyIdleTimeout  time.Duration
-	ComfyStartTimeout time.Duration
+	ComfyCmd          string        `env:"COMFY_CMD"`
+	ComfyDir          string        `env:"COMFY_DIR"`
+	ComfyIdleTimeout  time.Duration `env:"COMFY_IDLE_TIMEOUT"`
+	ComfyStartTimeout time.Duration `env:"COMFY_START_TIMEOUT"`

 	// GameProcs (GAME_PROCS) is a watch list of process names; while any of
 	// them runs, the GPU is treated as held by a foreign process. The
 	// nvidia-smi path (GPUForeignVRAMMB, GPU_FOREIGN_VRAM_MB) does the same
 	// when a process not in GPUIgnoreProcs (GPU_IGNORE_PROCS) holds more than
-	// that many MiB of VRAM. GamePollInterval (GAME_POLL_INTERVAL) is how
-	// often both checks run.
-	GameProcs        []string
-	GPUForeignVRAMMB int
-	GPUIgnoreProcs   []string
-	GamePollInterval time.Duration
+	// that many MiB of VRAM, and the PDH path (GPUForeignUtilPct,
+	// GPU_FOREIGN_UTIL_PCT) when such a process uses more than that many
+	// percent of the GPU 3D engine (Windows only). GamePollInterval
+	// (GAME_POLL_INTERVAL) is how often all checks run.
+	GameProcs         []string      `env:"GAME_PROCS"`
+	GPUForeignVRAMMB  int           `env:"GPU_FOREIGN_VRAM_MB"`
+	GPUForeignUtilPct int           `env:"GPU_FOREIGN_UTIL_PCT"`
+	GPUIgnoreProcs    []string      `env:"GPU_IGNORE_PROCS"`
+	GamePollInterval  time.Duration `env:"GAME_POLL_INTERVAL"`

-	WarmModel string
-	LogLevel  slog.Level
-	LogJSON   bool
-	LogFile   string
+	WarmModel string     `env:"WARM_MODEL"`
+	LogLevel  slog.Level `env:"LOGLEVEL"`
+	LogJSON   bool       `env:"LOG_FORMAT"`
+	LogFile   string     `env:"LOG_FILE"`
 }

 // Defaults returns the configuration used when neither the environment nor
@@ -117,8 +122,9 @@ func Defaults() Config {
 		ComfyStartTimeout: 2 * time.Minute,

 		// ComfyUI runs under python; excluding it (and Ollama) by name keeps
-		// our own consumers from tripping the foreign-VRAM check.
-		GPUIgnoreProcs:   []string{"ollama", "ollama app", "ollama_llama_server", "python", "pythonw"},
+		// our own consumers from tripping the foreign-VRAM check. dwm is the
+		// desktop compositor — it always shows some 3D-engine usage.
+		GPUIgnoreProcs:   []string{"ollama", "ollama app", "ollama_llama_server", "python", "pythonw", "dwm"},
 		GamePollInterval: 15 * time.Second,

 		LogLevel: slog.LevelWarn,
@@ -241,6 +247,13 @@ func Load(getenv func(string) string) (Config, error) {
 		}
 		cfg.GPUForeignVRAMMB = n
 	}
+	if v := getenv("GPU_FOREIGN_UTIL_PCT"); v != "" {
+		n, err := strconv.Atoi(v)
+		if err != nil || n < 0 || n > 100 {
+			return cfg, fmt.Errorf("GPU_FOREIGN_UTIL_PCT: must be an integer in 0-100 (percent of the GPU 3D engine, 0 = disabled)")
+		}
+		cfg.GPUForeignUtilPct = n
+	}
 	if v := getenv("PROMPT_CAPTURE_LIMIT"); v != "" {
 		n, err := strconv.ParseInt(v, 10, 64)
 		if err != nil || n < 0 {
@@ -34,7 +34,8 @@ func sampleEntries(logFile string) []sampleEntry {
 		{"COMFY_START_TIMEOUT", "2m", "How long a request waits for the managed ComfyUI to come up", false},
 		{"GAME_PROCS", "cyberpunk2077.exe,hl2.exe", "While a listed process runs, the GPU counts as held by it: requests wait, Ollama unloads, managed ComfyUI stops (default: empty = disabled)", false},
 		{"GPU_FOREIGN_VRAM_MB", "1024", "Also treat the GPU as held when a process not in GPU_IGNORE_PROCS uses more VRAM than this (needs nvidia-smi; 0/empty = disabled)", false},
-		{"GPU_IGNORE_PROCS", "ollama,ollama app,ollama_llama_server,python,pythonw", "Process names never counted as foreign GPU users (ComfyUI runs under python)", false},
+		{"GPU_FOREIGN_UTIL_PCT", "30", "Also treat the GPU as held when a process not in GPU_IGNORE_PROCS uses more than this percent of the GPU 3D engine (Windows Task-Manager counters; catches games without an exe list; 0/empty = disabled)", false},
+		{"GPU_IGNORE_PROCS", "ollama,ollama app,ollama_llama_server,python,pythonw,dwm", "Process names never counted as foreign GPU users (ComfyUI runs under python; dwm is the desktop compositor)", false},
 		{"GAME_POLL_INTERVAL", "15s", "How often game/VRAM detection runs (nvidia-smi polls keep the GPU awake; don't go below ~10s)", false},
 		{"UNLOAD_TIMEOUT", "60s", "How long to wait for Ollama to unload a model", false},
 		{"JOB_TIMEOUT", "15m", "Maximum time to wait for a ComfyUI job", false},
@@ -7,6 +7,13 @@
 // triggers, so the worst a local user can cause is a cheap, throttled
 // check and a GPU-idle-gated restart onto a signed binary.
 //
+// Abuse hardening: the command read is capped (4 KiB), each connection is
+// force-closed after connTimeout so a stalled client cannot pin a goroutine
+// (or a Windows pipe instance) forever, and concurrently served connections
+// are capped at maxConns — beyond that, connections are closed on arrival.
+// On Windows the pipe's ACL additionally denies network logons, so the
+// channel cannot be reached from another machine.
+//
 // Protocol: the client writes one command line, the server answers with
 // one reply line ("OK ..." or "ERR ...") and hangs up.
 package control
@@ -17,6 +24,7 @@ import (
 	"fmt"
 	"io"
 	"strings"
+	"time"
 )

 // CmdUpdateNow asks the service to check for, stage and (once the GPU is
@@ -26,6 +34,10 @@ const CmdUpdateNow = "update-now"
 // CmdStatus asks for a one-line JSON status snapshot (monitor mode).
 const CmdStatus = "status"

+// CmdReloadEnv asks the service to re-read and validate its config file,
+// and to restart onto it (once the GPU is idle) when it changed.
+const CmdReloadEnv = "reload-env"
+
 // ErrUnavailable means no running service offers the control channel.
 var ErrUnavailable = errors.New("control channel unavailable")

@@ -33,9 +45,50 @@ var ErrUnavailable = errors.New("control channel unavailable")
 // line. It must start with "OK " or "ERR ".
 type Handler func(cmd string) string

+// connTimeout bounds one connection's lifetime: a client that stops
+// mid-command or never reads the reply would otherwise pin its goroutine
+// (and on Windows one of the pipe instances) indefinitely. A var so tests
+// can shrink it.
+var connTimeout = 10 * time.Second
+
+// maxConns caps concurrently served connections; beyond it, new
+// connections are closed on arrival. Bound on the goroutines a local
+// flood can pile up.
+const maxConns = 32
+
+var connSem = make(chan struct{}, maxConns)
+
+// serve dispatches connection handling under the concurrency cap. It
+// returns false when the cap is reached — the caller must then close the
+// connection itself.
+func serve(c io.ReadWriteCloser, h Handler) bool {
+	select {
+	case connSem <- struct{}{}:
+		go func() {
+			defer func() { <-connSem }()
+			serveConn(c, h)
+		}()
+		return true
+	default:
+		return false
+	}
+}
+
+// forceCloser is implemented by connections that can be torn down
+// abortively, unblocking pending reads and writes (Windows pipe:
+// DisconnectNamedPipe; unix socket: a deadline in the past). The
+// connection watchdog uses it; normal closes still flush the reply.
+type forceCloser interface {
+	ForceClose() error
+}
+
 // serveConn runs the line protocol on one accepted connection.
 func serveConn(c io.ReadWriteCloser, h Handler) {
 	defer c.Close()
+	if fc, ok := c.(forceCloser); ok {
+		timer := time.AfterFunc(connTimeout, func() { fc.ForceClose() })
+		defer timer.Stop()
+	}
 	line, err := bufio.NewReader(io.LimitReader(c, 4096)).ReadString('\n')
 	cmd := strings.TrimSpace(line)
 	if cmd == "" {
@@ -37,12 +37,24 @@ func Serve(ctx context.Context, h Handler, log *slog.Logger) error {
 			if err != nil {
 				return // shutting down
 			}
-			go serveConn(c, h)
+			uc := unixConn{c}
+			if !serve(uc, h) {
+				uc.ForceClose()
+			}
 		}
 	}()
 	return nil
 }

+// unixConn adds an abortive ForceClose to net.Conn: a deadline in the
+// past fails pending and future I/O immediately.
+type unixConn struct{ net.Conn }
+
+func (c unixConn) ForceClose() error {
+	c.SetDeadline(time.Now().Add(-time.Second)) //nolint:errcheck // best effort
+	return c.Conn.Close()
+}
+
 // Ask sends one command to the running service and returns its reply.
 func Ask(cmd string) (string, error) {
 	c, err := net.DialTimeout("unix", sockPath, 2*time.Second)
@@ -5,6 +5,7 @@ import (
 	"net"
 	"strings"
 	"testing"
+	"time"
 )

 func TestRoundTrip(t *testing.T) {
@@ -44,3 +45,59 @@ func TestEmptyReplyIsUnavailable(t *testing.T) {
 		t.Fatalf("err = %v, want ErrUnavailable", err)
 	}
 }
+
+func TestServeCap(t *testing.T) {
+	for i := 0; i < maxConns; i++ {
+		connSem <- struct{}{}
+	}
+	defer func() {
+		for i := 0; i < maxConns; i++ {
+			<-connSem
+		}
+	}()
+	server, client := net.Pipe()
+	defer server.Close()
+	defer client.Close()
+	if serve(server, func(string) string { return "OK" }) {
+		t.Fatal("serve accepted a connection beyond the cap")
+	}
+}
+
+// forcePipe records ForceClose calls for the watchdog test.
+type forcePipe struct {
+	net.Conn
+	forced chan struct{}
+}
+
+func (c forcePipe) ForceClose() error {
+	err := c.Conn.Close()
+	close(c.forced)
+	return err
+}
+
+func TestConnWatchdog(t *testing.T) {
+	old := connTimeout
+	connTimeout = 50 * time.Millisecond
+	defer func() { connTimeout = old }()
+
+	server, client := net.Pipe()
+	defer client.Close()
+	fc := forcePipe{Conn: server, forced: make(chan struct{})}
+	done := make(chan struct{})
+	go func() {
+		serveConn(fc, func(string) string { return "OK" })
+		close(done)
+	}()
+	// The client never sends anything; the watchdog must tear the
+	// connection down instead of blocking forever.
+	select {
+	case <-fc.forced:
+	case <-time.After(5 * time.Second):
+		t.Fatal("watchdog did not force-close the stalled connection")
+	}
+	select {
+	case <-done:
+	case <-time.After(5 * time.Second):
+		t.Fatal("serveConn still blocked after the force close")
+	}
+}
@@ -8,6 +8,7 @@ import (
 	"log/slog"
 	"os"
 	"syscall"
+	"time"
 	"unsafe"

 	"golang.org/x/sys/windows"
@@ -77,18 +78,19 @@ func Serve(ctx context.Context, h Handler, log *slog.Logger) error {
 				log.Warn("control channel stopped", "err", err)
 				return
 			}
-			go func() {
-				// Blocks until a client connects; on process exit the
-				// handle goes away with everything else. A client that
-				// raced us and connected between CreateNamedPipe and
-				// ConnectNamedPipe reports ERROR_PIPE_CONNECTED — that is
-				// a success, not a failure.
-				if err := windows.ConnectNamedPipe(pipe, nil); err != nil && err != errnoPipeConnected {
-					windows.CloseHandle(pipe)
-					return
-				}
-				serveConn(&pipeConn{f: os.NewFile(uintptr(pipe), pipePath), h: pipe}, h)
-			}()
+			// Blocks until a client connects — only then is the next
+			// instance created, so instances are not burned without
+			// clients. ERROR_PIPE_CONNECTED means the client raced us
+			// and connected before the call: that is a success. Process
+			// exit reaps the blocked call on shutdown.
+			if err := windows.ConnectNamedPipe(pipe, nil); err != nil && err != errnoPipeConnected {
+				windows.CloseHandle(pipe)
+				continue
+			}
+			conn := &pipeConn{f: os.NewFile(uintptr(pipe), pipePath), h: pipe}
+			if !serve(conn, h) {
+				conn.ForceClose()
+			}
 		}
 	}()
 	return nil
@@ -98,6 +100,11 @@ func Serve(ctx context.Context, h Handler, log *slog.Logger) error {
 // called" result, which means the connection is established.
 var errnoPipeConnected = syscall.Errno(535) // ERROR_PIPE_CONNECTED

+// errnoPipeBusy is CreateFile's "all pipe instances are busy" result. It
+// loses the race against another client that grabbed the instance
+// WaitNamedPipe just reported — the caller must wait and retry.
+var errnoPipeBusy = syscall.Errno(231) // ERROR_PIPE_BUSY
+
 // pipeConn adapts a pipe handle to io.ReadWriteCloser. Close flushes first
 // (FlushFileBuffers blocks until the client has read the reply) and then
 // disconnects — closing the bare handle right after writing can discard
@@ -116,22 +123,45 @@ func (c *pipeConn) Close() error {
 	return c.f.Close()
 }

+// ForceClose aborts the connection without flushing: disconnecting
+// unblocks pending reads and writes at the cost of possibly discarding an
+// unread reply. Used by the connection watchdog; normal closes flush.
+func (c *pipeConn) ForceClose() error {
+	windows.DisconnectNamedPipe(c.h) //nolint:errcheck // best effort
+	return c.f.Close()
+}
+
 // Ask sends one command to the running service and returns its reply.
+//
+// The server keeps exactly one listening instance per connection, so
+// concurrent clients race for it: WaitNamedPipe can report an instance
+// that another client grabs before our CreateFile runs (ERROR_PIPE_BUSY).
+// Retry on that — with the monitor polling status every second, a single
+// attempt loses that race regularly.
 func Ask(cmd string) (string, error) {
 	name, err := windows.UTF16PtrFromString(pipePath)
 	if err != nil {
 		return "", err
 	}
-	if err := waitNamedPipe(name, 2000); err != nil {
-		return "", ErrUnavailable
+	deadline := time.Now().Add(5 * time.Second)
+	for {
+		if err := waitNamedPipe(name, 2000); err != nil {
+			return "", ErrUnavailable
+		}
+		handle, err := windows.CreateFile(name,
+			windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil,
+			windows.OPEN_EXISTING, 0, 0)
+		if err == errnoPipeBusy {
+			if time.Now().After(deadline) {
+				return "", ErrUnavailable
+			}
+			continue
+		}
+		if err != nil {
+			return "", ErrUnavailable
+		}
+		f := os.NewFile(uintptr(handle), pipePath)
+		defer f.Close()
+		return readReply(f, cmd)
 	}
-	handle, err := windows.CreateFile(name,
-		windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil,
-		windows.OPEN_EXISTING, 0, 0)
-	if err != nil {
-		return "", ErrUnavailable
-	}
-	f := os.NewFile(uintptr(handle), pipePath)
-	defer f.Close()
-	return readReply(f, cmd)
 }
@@ -1,8 +1,10 @@
 // Package game detects processes outside gpu-turnstile's control that hold
 // the GPU — typically a game — so the proxy can block new GPU work and free
-// VRAM while they run. Two detection paths: an explicit process watch list
-// (GAME_PROCS) and a foreign-VRAM threshold via nvidia-smi
-// (GPU_FOREIGN_VRAM_MB) that catches anything not on the ignore list.
+// VRAM while they run. Three detection paths: an explicit process watch
+// list (GAME_PROCS), a foreign-VRAM threshold via nvidia-smi
+// (GPU_FOREIGN_VRAM_MB), and a per-process GPU 3D-engine utilization
+// threshold via Windows PDH counters (GPU_FOREIGN_UTIL_PCT). The latter two
+// catch anything not on the ignore list without naming individual games.
 package game

 import (
@@ -11,6 +13,7 @@ import (
 	"fmt"
 	"log/slog"
 	"os/exec"
+	"slices"
 	"strconv"
 	"strings"
 )
@@ -28,28 +31,33 @@ type computeApp struct {
 }

 // Detector checks whether a foreign process holds the GPU. The zero value
-// (no watch list, no threshold) never detects anything; main only starts the
-// poll loop when at least one path is configured.
+// (no watch list, no thresholds) never detects anything; main only starts
+// the poll loop when at least one path is configured.
 type Detector struct {
 	procs    map[string]bool // normalized names from GAME_PROCS
 	vramMB   int             // foreign VRAM threshold; 0 = disabled
+	utilPct  int             // foreign 3D-engine utilization threshold; 0 = disabled
 	ignore   map[string]bool // normalized names never counted as foreign
 	log      *slog.Logger
-	noNvidia bool // nvidia-smi was not found; VRAM path disabled for good
+	noNvidia bool              // nvidia-smi was not found; VRAM path disabled for good
+	sampler  *gpuEngineSampler // open PDH query, opened lazily on first Check
+	noPDH    bool              // engine counters unavailable; util path disabled for good
 }

 // New builds a Detector from the configured watch list, VRAM threshold in
-// MiB (0 disables the nvidia-smi path) and ignore list. Names are matched
-// case-insensitively, with or without a trailing ".exe".
-func New(procs []string, vramMB int, ignore []string, log *slog.Logger) *Detector {
+// MiB, 3D-engine utilization threshold in percent (both 0 = disabled) and
+// ignore list. Names are matched case-insensitively, with or without a
+// trailing ".exe".
+func New(procs []string, vramMB, utilPct int, ignore []string, log *slog.Logger) *Detector {
 	if log == nil {
 		log = slog.Default()
 	}
 	return &Detector{
-		procs:  nameSet(procs),
-		vramMB: vramMB,
-		ignore: nameSet(ignore),
-		log:    log,
+		procs:   nameSet(procs),
+		vramMB:  vramMB,
+		utilPct: utilPct,
+		ignore:  nameSet(ignore),
+		log:     log,
 	}
 }

@@ -73,34 +81,63 @@ func nameSet(names []string) map[string]bool {
 // description of each (empty when the GPU is free for gpu-turnstile's
 // consumers). A failing nvidia-smi call is returned as an error only when
 // the process list found nothing; a missing nvidia-smi binary disables the
-// VRAM path permanently (logged once).
+// VRAM path permanently (logged once), as do missing engine counters.
 func (d *Detector) Check(ctx context.Context) ([]string, error) {
 	ps, psErr := processes()
-	if d.vramMB <= 0 || d.noNvidia {
-		return d.detect(ps, nil), psErr
+	utils := d.engineUtil()
+	var apps []computeApp
+	if d.vramMB > 0 && !d.noNvidia {
+		var err error
+		apps, err = queryComputeApps(ctx)
+		if errors.Is(err, exec.ErrNotFound) {
+			d.noNvidia = true
+			d.log.Warn("GPU_FOREIGN_VRAM_MB is set but nvidia-smi was not found; VRAM detection disabled")
+		} else if err != nil {
+			return d.detect(ps, nil, utils), err
+		}
 	}
-	apps, err := queryComputeApps(ctx)
-	if errors.Is(err, exec.ErrNotFound) {
-		d.noNvidia = true
-		d.log.Warn("GPU_FOREIGN_VRAM_MB is set but nvidia-smi was not found; VRAM detection disabled")
-		return d.detect(ps, nil), nil
-	}
-	if err != nil {
-		return d.detect(ps, nil), err
-	}
-	return d.detect(ps, apps), nil
+	return d.detect(ps, apps, utils), psErr
 }

-// detect is the pure core of Check: given the process table and (optionally)
-// the nvidia-smi compute-apps list, it returns the foreign holders.
-func (d *Detector) detect(ps []Process, apps []computeApp) []string {
+// engineUtil samples per-process 3D-engine utilization via PDH. The first
+// call only primes the rate counters and returns nil. A failing open or
+// sample disables the path permanently (logged once).
+func (d *Detector) engineUtil() map[int]float64 {
+	if d.utilPct <= 0 || d.noPDH {
+		return nil
+	}
+	if d.sampler == nil {
+		s, err := openGPUEngineSampler()
+		if err != nil {
+			d.noPDH = true
+			d.log.Warn("GPU_FOREIGN_UTIL_PCT is set but per-process GPU counters are unavailable; engine detection disabled", "err", err)
+			return nil
+		}
+		d.sampler = s
+	}
+	utils, err := d.sampler.sample()
+	if err != nil {
+		if errors.Is(err, errNotPrimed) {
+			return nil
+		}
+		d.noPDH = true
+		d.log.Warn("per-process GPU counters failed; engine detection disabled", "err", err)
+		return nil
+	}
+	return utils
+}
+
+// detect is the pure core of Check: given the process table and
+// (optionally) the nvidia-smi compute-apps list and the PDH engine
+// utilization, it returns the foreign holders.
+func (d *Detector) detect(ps []Process, apps []computeApp, utils map[int]float64) []string {
 	var holders []string
 	for _, p := range ps {
 		if d.procs[normName(p.Name)] {
 			holders = append(holders, fmt.Sprintf("%s (pid %d)", p.Name, p.PID))
 		}
 	}
-	if d.vramMB > 0 && apps != nil {
+	if (d.vramMB > 0 && apps != nil) || (d.utilPct > 0 && utils != nil) {
 		names := make(map[int]string, len(ps))
 		for _, p := range ps {
 			names[p.PID] = p.Name
@@ -115,6 +152,23 @@ func (d *Detector) detect(ps []Process, apps []computeApp) []string {
 			}
 			holders = append(holders, fmt.Sprintf("%s (pid %d) using %d MiB VRAM", name, a.PID, a.UsedMB))
 		}
+		// Sorted for stable output (map iteration order is random).
+		pids := make([]int, 0, len(utils))
+		for pid := range utils {
+			pids = append(pids, pid)
+		}
+		slices.Sort(pids)
+		for _, pid := range pids {
+			util := utils[pid]
+			name := names[pid]
+			if d.ignore[normName(name)] || util < float64(d.utilPct) {
+				continue
+			}
+			if name == "" {
+				name = "unknown process"
+			}
+			holders = append(holders, fmt.Sprintf("%s (pid %d) using %.0f%% GPU", name, pid, util))
+		}
 	}
 	return holders
 }
@@ -132,6 +186,29 @@ 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) {
@@ -45,7 +45,7 @@ func TestParseComputeApps(t *testing.T) {
 }

 func TestDetect(t *testing.T) {
-	d := New([]string{"Cyberpunk2077.exe", "hl2"}, 1024,
+	d := New([]string{"Cyberpunk2077.exe", "hl2"}, 1024, 0,
 		[]string{"ollama", "python", "pythonw"}, nil)
 	ps := []Process{
 		{PID: 10, Name: "ollama.exe"},
@@ -58,7 +58,7 @@ func TestDetect(t *testing.T) {
 		{PID: 40, UsedMB: 2048}, // foreign, above threshold
 		{PID: 50, UsedMB: 100},  // foreign but below threshold
 	}
-	holders := d.detect(ps, apps)
+	holders := d.detect(ps, apps, nil)
 	if len(holders) != 2 {
 		t.Fatalf("got %v, want 2 holders", holders)
 	}
@@ -70,13 +70,52 @@ func TestDetect(t *testing.T) {
 	}
 }

+func TestDetectEngineUtil(t *testing.T) {
+	d := New(nil, 0, 30, []string{"dwm", "python"}, nil)
+	ps := []Process{
+		{PID: 10, Name: "dwm.exe"},
+		{PID: 20, Name: "game.exe"},
+		{PID: 40, Name: "browser.exe"},
+	}
+	utils := map[int]float64{
+		10: 45, // ignored: dwm
+		20: 61, // foreign, above threshold
+		30: 82, // foreign, unknown name
+		40: 5,  // below threshold
+	}
+	holders := d.detect(ps, nil, utils)
+	want := []string{
+		"game.exe (pid 20) using 61% GPU",
+		"unknown process (pid 30) using 82% GPU",
+	}
+	if !slices.Equal(holders, want) {
+		t.Errorf("got %v, want %v", holders, want)
+	}
+}
+
 func TestDetectNothingConfigured(t *testing.T) {
-	d := New(nil, 0, nil, nil)
-	if got := d.detect([]Process{{PID: 1, Name: "game.exe"}}, nil); len(got) != 0 {
+	d := New(nil, 0, 0, nil, nil)
+	if got := d.detect([]Process{{PID: 1, Name: "game.exe"}}, nil, nil); len(got) != 0 {
 		t.Errorf("got %v, want none", got)
 	}
 }

+func TestParseGPUEngineInstance(t *testing.T) {
+	pid, eng, ok := parseGPUEngineInstance("pid_1234_luid_0x00000000_0x00011A2B_phys_0_eng_0_engtype_3D")
+	if !ok || pid != 1234 || eng != "3D" {
+		t.Errorf("got %d, %q, %v", pid, eng, ok)
+	}
+	pid, eng, ok = parseGPUEngineInstance("pid_42_luid_0x0_0x0_phys_0_eng_1_engtype_Copy")
+	if !ok || pid != 42 || eng != "Copy" {
+		t.Errorf("got %d, %q, %v", pid, eng, ok)
+	}
+	for _, bad := range []string{"", "something", "pid_", "pid_x_luid", "pid_-1_luid_0"} {
+		if _, _, ok := parseGPUEngineInstance(bad); ok {
+			t.Errorf("%q parsed, want failure", bad)
+		}
+	}
+}
+
 func TestProcessesLive(t *testing.T) {
 	if runtime.GOOS != "windows" && runtime.GOOS != "linux" {
 		t.Skip("no process listing on this platform")
@@ -0,0 +1,36 @@
+package game
+
+import (
+	"errors"
+	"strconv"
+	"strings"
+)
+
+// errNotPrimed marks the first PDH sample after opening a query: rate-based
+// counters (like engine utilization) need two collections before they
+// return meaningful values.
+var errNotPrimed = errors.New("GPU engine counter needs a second sample")
+
+// parseGPUEngineInstance splits a PDH "GPU Engine" instance name —
+// "pid_1234_luid_0x00000000_0x00011A2B_phys_0_eng_0_engtype_3D" — into PID
+// and engine type ("3D", "Copy", "VideoDecode", ...). engType is empty when
+// the name carries no engtype marker.
+func parseGPUEngineInstance(name string) (pid int, engType string, ok bool) {
+	rest, found := strings.CutPrefix(name, "pid_")
+	if !found {
+		return 0, "", false
+	}
+	digits, rest, found := strings.Cut(rest, "_")
+	if !found {
+		return 0, "", false
+	}
+	pid, err := strconv.Atoi(digits)
+	if err != nil || pid < 0 {
+		return 0, "", false
+	}
+	const marker = "engtype_"
+	if i := strings.LastIndex(rest, marker); i >= 0 {
+		engType = rest[i+len(marker):]
+	}
+	return pid, engType, true
+}
@@ -0,0 +1,16 @@
+//go:build !windows
+
+package game
+
+import "errors"
+
+// errNoEngineCounters marks platforms without per-process GPU engine
+// counters (the PDH path is Windows-only).
+var errNoEngineCounters = errors.New("per-process GPU engine counters are only available on Windows")
+
+// gpuEngineSampler is a stub on non-Windows platforms.
+type gpuEngineSampler struct{}
+
+func openGPUEngineSampler() (*gpuEngineSampler, error) { return nil, errNoEngineCounters }
+
+func (s *gpuEngineSampler) sample() (map[int]float64, error) { return nil, errNoEngineCounters }
@@ -0,0 +1,111 @@
+//go:build windows
+
+package game
+
+import (
+	"fmt"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// Per-process GPU engine utilization via PDH — the same counters Task
+// Manager's "GPU engine" columns read. Unlike nvidia-smi's compute-apps
+// this covers graphics work under WDDM, so games show up. The counter is
+// added with PdhAddEnglishCounterW, which is independent of the Windows
+// display language.
+
+var (
+	pdhDLL                          = windows.NewLazySystemDLL("pdh.dll")
+	procPdhOpenQuery                = pdhDLL.NewProc("PdhOpenQueryW")
+	procPdhAddEnglishCounter        = pdhDLL.NewProc("PdhAddEnglishCounterW")
+	procPdhCollectQueryData         = pdhDLL.NewProc("PdhCollectQueryData")
+	procPdhGetFormattedCounterArray = pdhDLL.NewProc("PdhGetFormattedCounterArrayW")
+	procPdhCloseQuery               = pdhDLL.NewProc("PdhCloseQuery")
+)
+
+const (
+	pdhFmtDouble = 0x00000200 // PDH_FMT_DOUBLE
+	pdhMoreData  = 0x800007D2 // PDH_MORE_DATA
+)
+
+// pdhCountervalueItem mirrors PDH_FMT_COUNTERVALUE_ITEM (64-bit, double).
+type pdhCountervalueItem struct {
+	name    *uint16
+	cStatus uint32
+	_       uint32 // alignment padding
+	value   float64
+}
+
+// gpuEngineSampler holds an open PDH query on the wildcard GPU Engine
+// utilization counter. Keeping the query open across polls is what makes
+// the rate-based values meaningful; the sampler lives as long as the
+// process (PdhCloseQuery would only matter on unload).
+type gpuEngineSampler struct {
+	query   uintptr // PDH_HQUERY
+	counter uintptr // PDH_HCOUNTER
+	primed  bool
+}
+
+// openGPUEngineSampler opens a query on the per-process GPU engine
+// utilization counter (all instances).
+func openGPUEngineSampler() (*gpuEngineSampler, error) {
+	var q uintptr
+	if r, _, _ := procPdhOpenQuery.Call(0, 0, uintptr(unsafe.Pointer(&q))); r != 0 {
+		return nil, fmt.Errorf("PdhOpenQuery: status %#x", r)
+	}
+	path, err := windows.UTF16PtrFromString(`\GPU Engine(*)\Utilization Percentage`)
+	if err != nil {
+		procPdhCloseQuery.Call(q)
+		return nil, err
+	}
+	var c uintptr
+	if r, _, _ := procPdhAddEnglishCounter.Call(q, uintptr(unsafe.Pointer(path)), 0, uintptr(unsafe.Pointer(&c))); r != 0 {
+		procPdhCloseQuery.Call(q)
+		return nil, fmt.Errorf("PdhAddEnglishCounter: status %#x", r)
+	}
+	return &gpuEngineSampler{query: q, counter: c}, nil
+}
+
+// sample collects the counter once and returns per-PID 3D-engine
+// utilization in percent. The first call after open only primes the rate
+// calculation and returns errNotPrimed. Processes can drive several 3D
+// engines; their values are summed.
+func (s *gpuEngineSampler) sample() (map[int]float64, error) {
+	if r, _, _ := procPdhCollectQueryData.Call(s.query); r != 0 {
+		return nil, fmt.Errorf("PdhCollectQueryData: status %#x", r)
+	}
+	if !s.primed {
+		s.primed = true
+		return nil, errNotPrimed
+	}
+	var size, count uint32
+	r, _, _ := procPdhGetFormattedCounterArray.Call(s.counter, pdhFmtDouble,
+		uintptr(unsafe.Pointer(&size)), uintptr(unsafe.Pointer(&count)), 0)
+	if r == pdhMoreData && size == 0 {
+		return nil, nil // no GPU engine instances at all
+	}
+	if r != pdhMoreData {
+		return nil, fmt.Errorf("PdhGetFormattedCounterArray(size): status %#x", r)
+	}
+	buf := make([]byte, size)
+	r, _, _ = procPdhGetFormattedCounterArray.Call(s.counter, pdhFmtDouble,
+		uintptr(unsafe.Pointer(&size)), uintptr(unsafe.Pointer(&count)),
+		uintptr(unsafe.Pointer(&buf[0])))
+	if r != 0 {
+		return nil, fmt.Errorf("PdhGetFormattedCounterArray: status %#x", r)
+	}
+	items := unsafe.Slice((*pdhCountervalueItem)(unsafe.Pointer(&buf[0])), int(count))
+	out := make(map[int]float64)
+	for i := range items {
+		if items[i].cStatus != 0 || items[i].name == nil {
+			continue
+		}
+		pid, engType, ok := parseGPUEngineInstance(windows.UTF16PtrToString(items[i].name))
+		if !ok || engType != "3D" {
+			continue // only the 3D engine marks game-like work
+		}
+		out[pid] += items[i].value
+	}
+	return out, nil
+}
@@ -0,0 +1,33 @@
+//go:build windows
+
+package game
+
+import (
+	"errors"
+	"testing"
+	"time"
+)
+
+// TestGPUEngineSamplerLive opens the real PDH query and takes two samples;
+// the first only primes the rate counters. Skipped (not failed) when the
+// machine has no GPU counters.
+func TestGPUEngineSamplerLive(t *testing.T) {
+	s, err := openGPUEngineSampler()
+	if err != nil {
+		t.Skipf("no GPU engine counters: %v", err)
+	}
+	if _, err := s.sample(); !errors.Is(err, errNotPrimed) {
+		t.Fatalf("first sample: err = %v, want errNotPrimed", err)
+	}
+	time.Sleep(200 * time.Millisecond)
+	utils, err := s.sample()
+	if err != nil {
+		t.Fatalf("second sample: %v", err)
+	}
+	for pid, util := range utils {
+		if pid < 0 || util < 0 {
+			t.Errorf("pid %d: util %.2f", pid, util)
+		}
+	}
+	t.Logf("%d processes with 3D-engine usage", len(utils))
+}
Author	SHA1	Message	Date
mram	e98331bb9e	Pin compose example to v0.2.9 ci / test (push) Successful in 14s Details ci / docker (push) Successful in 1m8s Details ci / release (push) Successful in 16s Details	2026-09-22 11:23:17 +02:00
mram	54174787d5	Fix control-pipe client race: retry CreateFile on ERROR_PIPE_BUSY WaitNamedPipe can report an instance that a concurrent client (the monitor polls status every second) grabs before our CreateFile runs; the single-attempt Ask then failed with 'no answer from the service'. Retry the wait+open until a 5s overall deadline.	2026-09-22 11:22:27 +02:00
mram	d259b2e96c	Add GPU_FOREIGN_UTIL_PCT: game detection via per-process GPU 3D-engine usage Reads the same PDH counters as Task Manager (\GPU Engine(*)\Utilization Percentage, locale-independent via PdhAddEnglishCounterW), which cover graphics work under WDDM — games are caught without an exe list and the offender is named. Windows-only; a missing or failing counter disables the path with one log line. dwm (the desktop compositor) joins the default ignore list.	2026-09-22 10:53:29 +02:00
mram	8fccd333aa	Env names in reload diff; monitor shows last VRAM check result; harden control channel against floods - diffConfig reports the env var names (from new struct tags) instead of Go field names, so the reload-env reply names what the user can change - the monitor's GPU line now shows the game detector's last finding (external holders or none) and how long ago the check ran - control channel: 10s per-connection watchdog (abortive force-close), cap of 32 concurrent connections, reload-env rate-limited; command read was already capped at 4 KiB	2026-09-22 09:24:27 +02:00
mram	4bd5f34ce7	Pin compose example to v0.2.8 ci / test (push) Successful in 15s Details ci / docker (push) Successful in 1m6s Details ci / release (push) Successful in 15s Details	2026-09-22 09:10:14 +02:00
mram	b9d3f91403	Monitor: hotkeys (q quit, u update now) with footer line; show GPU VRAM usage	2026-09-22 09:10:14 +02:00
mram	98d2d714ca	Add --reload-env: service re-reads and validates its config, restarts when idle if it changed	2026-09-22 09:02:25 +02:00
mram	7a6409831c	Pin compose example to v0.2.7 ci / test (push) Successful in 14s Details ci / docker (push) Successful in 1m7s Details ci / release (push) Successful in 16s Details	2026-09-22 08:47:47 +02:00
mram	c7b8747d85	Fix control pipe accept loop: create instances only after a client connects; CLI force-update never touches the service log file	2026-09-22 08:43:58 +02:00
mram	09d4e81eab	Pin compose example to v0.2.6 ci / test (push) Successful in 15s Details ci / docker (push) Successful in 1m6s Details ci / release (push) Successful in 15s Details	2026-09-22 08:36:36 +02:00
mram	1264afe40e	Monitor restarts itself when the service updated its binary on disk	2026-09-22 08:34:47 +02:00