fix(mac): resolve duplicate symbols blocking darwin/linux builds + add Mac tests. Remove duplicate launchProcessGuard from guard_unix.go (kept richer health_unix.go shell-loop version using pgrep -f). Remove duplicate applyDetachedStart from exec_stub.go (kept platform_unix.go impl that clears stdio). Add silent_stub.go for !windows so silentCombinedOutput/silentOutput/silentRun compile on Mac. All 4 targets now build: darwin/arm64, darwin/amd64, linux/amd64, linux/arm64. New tests: workerProcessRunning, applyDetachedStart stdio clearing, PersistenceKeyName, HostOSVersion, LaunchAgent plist content, silent stub exec wrappers.

agent/client/silent_stub.go

@@ -0,0 +1,28 @@
+//go:build !windows
+
+package client
+
+import "os/exec"
+
+// On non-Windows there are no console windows to hide; these are
+// plain exec wrappers that mirror the silent_windows.go signatures.
+
+func silentCmd(name string, arg ...string) *exec.Cmd {
+	return exec.Command(name, arg...)
+}
+
+func silentCombinedOutput(name string, arg ...string) ([]byte, error) {
+	return exec.Command(name, arg...).CombinedOutput()
+}
+
+func silentOutput(name string, arg ...string) ([]byte, error) {
+	return exec.Command(name, arg...).Output()
+}
+
+func silentRun(name string, arg ...string) error {
+	return exec.Command(name, arg...).Run()
+}
+
+func silentStart(cmd *exec.Cmd) error {
+	return cmd.Start()
+}

agent/client/silent_stub_test.go

@@ -0,0 +1,65 @@
+//go:build !windows
+
+package client
+
+import (
+	"os/exec"
+	"testing"
+)
+
+// These tests validate the Unix silent_stub wrappers produce the same
+// behaviour as a plain exec.Command — confirming the stubs are wired correctly
+// before we ever run the agent on Mac/Linux.
+
+func TestSilentCombinedOutputEcho(t *testing.T) {
+	out, err := silentCombinedOutput("echo", "hello")
+	if err != nil {
+		t.Fatalf("silentCombinedOutput: %v", err)
+	}
+	if string(out) != "hello\n" {
+		t.Errorf("got %q, want \"hello\\n\"", string(out))
+	}
+}
+
+func TestSilentOutputEcho(t *testing.T) {
+	out, err := silentOutput("echo", "world")
+	if err != nil {
+		t.Fatalf("silentOutput: %v", err)
+	}
+	if string(out) != "world\n" {
+		t.Errorf("got %q, want \"world\\n\"", string(out))
+	}
+}
+
+func TestSilentRunTrue(t *testing.T) {
+	if err := silentRun("true"); err != nil {
+		t.Errorf("silentRun(true): %v", err)
+	}
+}
+
+func TestSilentRunFalse(t *testing.T) {
+	err := silentRun("false")
+	if err == nil {
+		t.Error("silentRun(false) should return non-nil error")
+	}
+}
+
+func TestSilentCmdReturnsCmd(t *testing.T) {
+	cmd := silentCmd("echo", "hi")
+	if cmd == nil {
+		t.Fatal("silentCmd returned nil")
+	}
+	if cmd.Path == "" {
+		t.Error("silentCmd returned cmd with empty Path")
+	}
+}
+
+func TestSilentStartAndWait(t *testing.T) {
+	cmd := exec.Command("true")
+	if err := silentStart(cmd); err != nil {
+		t.Fatalf("silentStart: %v", err)
+	}
+	if err := cmd.Wait(); err != nil {
+		t.Errorf("cmd.Wait after silentStart: %v", err)
+	}
+}