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

internal/config/config.go

@@ -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
@@ -59,10 +61,10 @@ 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
@@ -70,15 +72,15 @@ type Config struct {
 	// 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
+	GameProcs        []string      `env:"GAME_PROCS"`
+	GPUForeignVRAMMB int           `env:"GPU_FOREIGN_VRAM_MB"`
+	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