feat(android): detect foreground package via adb dumpsys

internal/android/android.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"slices"
 	"strings"
 	"time"
@@ -236,6 +237,38 @@ func waitForBoot(ctx context.Context, timeout time.Duration) error {
 	}
 }
 
+// ForegroundPackage returns the package of the currently resumed activity on
+// the connected device, or "" when it cannot be determined.
+func ForegroundPackage(ctx context.Context) (string, error) {
+	adb, err := AdbBinary()
+	if err != nil {
+		return "", err
+	}
+	output, err := exec.CommandContext(ctx, adb, "shell", "dumpsys", "activity", "activities").Output()
+	if err != nil {
+		return "", err
+	}
+	return parseForegroundPackage(string(output)), nil
+}
+
+// resumedActivityPackage matches the "<package>/<activity>" component name that
+// dumpsys prints on ResumedActivity lines, capturing the package.
+var resumedActivityPackage = regexp.MustCompile(`([a-zA-Z][a-zA-Z0-9_.]*)/[a-zA-Z0-9_.$]+`)
+
+// parseForegroundPackage extracts the foreground package from `dumpsys activity
+// activities` output by reading the first ResumedActivity component name.
+func parseForegroundPackage(dumpsys string) string {
+	for line := range strings.SplitSeq(dumpsys, "\n") {
+		if !strings.Contains(line, "ResumedActivity") {
+			continue
+		}
+		if match := resumedActivityPackage.FindStringSubmatch(line); match != nil {
+			return match[1]
+		}
+	}
+	return ""
+}
+
 func bootCompleted(ctx context.Context) (bool, error) {
 	adb, err := AdbBinary()
 	if err != nil {