6 files changed, 149 insertions, 3 deletions
diff --git a/tests/e2e/arg_integrity_test.go b/tests/e2e/arg_integrity_test.go
new file mode 100644
index 0000000..7121c2b
--- /dev/null
+++ b/tests/e2e/arg_integrity_test.go
@@ -0,0 +1,45 @@
+package e2e
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+func TestArgumentIntegrity(t *testing.T) {
+	payloads := []string{
+		"$(whoami)",
+		"; rm -rf /",
+		"`id`",
+		"| wall 'hacked'",
+		"\"'\"'\"", // Complex quoting
+		"   spaced   argument   ",
+		"$\nnewline",
+	}
+
+	for _, payload := range payloads {
+		t.Run(fmt.Sprintf("Payload_%s", payload), func(t *testing.T) {
+			binaryPath := GetBinaryPath()
+			cmd := exec.Command(binaryPath, "test-args", payload)
+			out, err := cmd.CombinedOutput()
+			if err != nil {
+				t.Fatalf("wg-wrap test-args failed for payload %s: %v\nOutput: %s", payload, err, string(out))
+			}
+
+			lines := strings.Split(strings.TrimSpace(string(out)), "\n")
+			if len(lines) < 3 {
+				t.Fatalf("Unexpected output format for payload %s\nOutput: %s", payload, string(out))
+			}
+
+			parts := strings.Split(lines[len(lines)-1], ":")
+			if len(parts) < 2 {
+				t.Fatalf("Malformed hex line for payload %s: %s", payload, lines[len(lines)-1])
+			}
+
+			if parts[1] != fmt.Sprintf("%x", payload) {
+				t.Errorf("8-bit mismatch!\nSent Hex: %s\nRecv Hex: %s\nPayload: %q", fmt.Sprintf("%x", payload), parts[1], payload)
+			}
+		})
+	}
+}
diff --git a/tests/e2e/e2e_test.go b/tests/e2e/e2e_test.go
index 4339a8b..fb763b3 100644
--- a/tests/e2e/e2e_test.go
+++ b/tests/e2e/e2e_test.go
@@ -20,10 +20,10 @@ func TestNetworkIsolation(t *testing.T) {
 		t.Fatalf("Failed to get cwd: %v", err)
 	}
 	root := filepath.Join(cwd, "..", "..")
-	
+
 	// 2. Build the project to ensure we have a fresh binary
 	buildCmd := exec.Command("bash", "-c", fmt.Sprintf(
-		"cd %s && gcc -static -O2 internal/namespace/launcher_src/launcher.c -o internal/namespace/launcher.bin && export CGO_ENABLED=1 && go build -o wg-wrap cmd/wg-wrap/main.go", 
+		"cd %s && gcc -static -O2 internal/namespace/launcher_src/launcher.c -o internal/namespace/launcher.bin && export CGO_ENABLED=1 && go build -o wg-wrap cmd/wg-wrap/main.go",
 		root))
 	if err := buildCmd.Run(); err != nil {
 		t.Fatalf("Failed to build project for E2E test: %v", err)
@@ -43,7 +43,7 @@ func TestNetworkIsolation(t *testing.T) {
 	}
 
 	// Cleanup
-	os.Remove(binaryPath)
+	_ = os.Remove(binaryPath)
 }
 
 func TestDNSLeakage(t *testing.T) {
diff --git a/tests/e2e/fuzz_args_test.go b/tests/e2e/fuzz_args_test.go
new file mode 100644
index 0000000..0d4a45b
--- /dev/null
+++ b/tests/e2e/fuzz_args_test.go
@@ -0,0 +1,52 @@
+package e2e
+
+import (
+	"fmt"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+func FuzzArgumentIntegrity(f *testing.F) {
+	binaryPath := GetBinaryPath()
+
+	f.Add("; rm -rf /")
+	f.Add("$(whoami)")
+	f.Add("   spaced   ")
+	f.Add("\"'\"'\"")
+	f.Add("\x00null\x00")
+
+	f.Fuzz(func(t *testing.T, payload string) {
+		out, err := exec.Command(binaryPath, "test-args", payload).CombinedOutput()
+
+		if strings.Contains(payload, "\x00") {
+			if err != nil || strings.Contains(string(out), "contains null byte") {
+				return
+			}
+		}
+
+		if err != nil {
+			// If we hit a system limit (like disk quota in /tmp during heavy fuzzing),
+			// it's an environmental issue, not a bug in our binary.
+			if strings.Contains(string(out), "disk quota exceeded") ||
+				strings.Contains(string(out), "no space left on device") {
+				return
+			}
+			t.Fatalf("Binary crashed for payload %q: %v\nOutput: %s", payload, err, string(out))
+		}
+
+		lines := strings.Split(strings.TrimSpace(string(out)), "\n")
+		if len(lines) < 3 {
+			t.Fatalf("Unexpected output format for payload %q\nOutput: %s", payload, string(out))
+		}
+
+		parts := strings.Split(lines[len(lines)-1], ":")
+		if len(parts) < 2 {
+			t.Fatalf("Malformed hex line for payload %q: %s", payload, lines[len(lines)-1])
+		}
+
+		if parts[1] != fmt.Sprintf("%x", payload) {
+			t.Errorf("8-bit mismatch!\nSent Hex: %s\nRecv Hex: %s\nPayload: %q", fmt.Sprintf("%x", payload), parts[1], payload)
+		}
+	})
+}
diff --git a/tests/e2e/test_helpers.go b/tests/e2e/test_helpers.go
new file mode 100644
index 0000000..34aae3f
--- /dev/null
+++ b/tests/e2e/test_helpers.go
@@ -0,0 +1,45 @@
+package e2e
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+)
+
+// GetBinaryPath resolves the path to the wg-wrap binary.
+// It checks the current directory, then the project root, then the system PATH.
+func GetBinaryPath() string {
+	binaryName := "wg-wrap"
+	if runtime.GOOS == "windows" {
+		binaryName += ".exe"
+	}
+
+	// 1. Check current working directory
+	if _, err := os.Stat(binaryName); err == nil {
+		abs, _ := filepath.Abs(binaryName)
+		return abs
+	}
+
+	// 2. Check common project root relative paths
+	// Since go test can be run from root or package dir, we try both.
+	candidates := []string{
+		filepath.Join("..", "..", binaryName), // from tests/e2e
+		filepath.Join("..", binaryName),       // from tests/
+		binaryName,                           // from root
+	}
+	for _, c := range candidates {
+		if _, err := os.Stat(c); err == nil {
+			abs, _ := filepath.Abs(c)
+			return abs
+		}
+	}
+
+	// 3. Check system PATH
+	path, err := exec.LookPath(binaryName)
+	if err == nil {
+		return path
+	}
+
+	return binaryName 
+}
diff --git a/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/4316c263ab833860 b/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/4316c263ab833860
new file mode 100644
index 0000000..4a4e8b6
--- /dev/null
+++ b/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/4316c263ab833860
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("\xd7")
diff --git a/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/771e938e4458e983 b/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/771e938e4458e983
new file mode 100644
index 0000000..ee3f339
--- /dev/null
+++ b/tests/e2e/testdata/fuzz/FuzzArgumentIntegrity/771e938e4458e983
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("0")