add linux

client/internal/guard/guard_linux.go

@@ -0,0 +1,90 @@
+//go:build linux
+
+package guard
+
+import (
+	"sync"
+	"time"
+
+	"github.com/kbinani/screenshot"
+)
+
+var (
+	guardOnce               sync.Once
+	guardViolation          func(string)
+	guardStop               chan struct{}
+	suppressMu              sync.Mutex
+	suppressViolationsUntil time.Time
+)
+
+// SuppressFor temporarily suspends environment violation checks (e.g. when transition screen)
+func SuppressFor(d time.Duration) {
+	if d <= 0 {
+		return
+	}
+	suppressMu.Lock()
+	next := time.Now().Add(d)
+	if next.After(suppressViolationsUntil) {
+		suppressViolationsUntil = next
+	}
+	suppressMu.Unlock()
+}
+
+func violationsSuppressed() bool {
+	suppressMu.Lock()
+	defer suppressMu.Unlock()
+	return time.Now().Before(suppressViolationsUntil)
+}
+
+// Start monitors the Linux desktop environment (multi-display check)
+func Start(onViolation func(reason string)) {
+	guardOnce.Do(func() {
+		if onViolation == nil {
+			return
+		}
+		guardViolation = onViolation
+		guardStop = make(chan struct{})
+
+		if screenshot.NumActiveDisplays() > 1 {
+			onViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng chỉ dùng một màn hình khi chạy Simple Care.")
+			return
+		}
+
+		go pollLoop()
+	})
+}
+
+// Stop stops the environment guard
+func Stop() {
+	if guardStop != nil {
+		select {
+		case <-guardStop:
+			// already closed
+		default:
+			close(guardStop)
+		}
+	}
+}
+
+func pollLoop() {
+	ticker := time.NewTicker(3 * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-guardStop:
+			return
+		case <-ticker.C:
+			checkEnvironment()
+		}
+	}
+}
+
+func checkEnvironment() {
+	if guardViolation == nil || violationsSuppressed() {
+		return
+	}
+	if n := screenshot.NumActiveDisplays(); n > 1 {
+		guardViolation("Phát hiện nhiều hơn 1 màn hình. Vui lòng rút/bật tắt màn hình phụ.")
+		return
+	}
+}

client/internal/guard/guard_other.go

@@ -1,4 +1,4 @@
-//go:build !windows && !darwin
+//go:build !windows && !darwin && !linux
 
 package guard