CFG_VER/APP_VER in the env file: invalid configs replaced, updates follow APP_VER (dev/stable/pin)

internal/config/config.go

@@ -38,6 +38,11 @@ type Config struct {
 	UpdateRepo     string
 	UpdateAsset    string
 
+	// 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
+
 	// 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).
@@ -76,6 +81,7 @@ func Defaults() Config {
 		UpdateInterval: 6 * time.Hour,
 		UpdateRepo:     "https://git.rambossek.at/PUBLIC/gpu-turnstile",
 		UpdateAsset:    "gpu-turnstile.exe",
+		AppVersion:     "stable",
 
 		LLMBusyMode:    "wait",
 		LLMBusyStatus:  503,
@@ -205,6 +211,17 @@ func Load(getenv func(string) string) (Config, error) {
 		}
 		cfg.BusyRetryAfter = n
 	}
+	if v := getenv("APP_VER"); v != "" {
+		switch {
+		case v == "dev" || v == "stable":
+			cfg.AppVersion = v
+		default:
+			if _, ok := parseVersion(v); !ok {
+				return cfg, fmt.Errorf("APP_VER: must be \"dev\", \"stable\" or a vX.Y.Z version")
+			}
+			cfg.AppVersion = "v" + strings.TrimPrefix(v, "v")
+		}
+	}
 	// LOGLEVEL is the canonical spelling; LOG_LEVEL is kept as an alias.
 	logLevelValue := getenv("LOGLEVEL")
 	if logLevelValue == "" {