diff --git a/tests/test_core.py b/tests/test_core.py
index aaf2faf..978ca27 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -638,3 +638,159 @@ def test_args_secret_warning_env_not_triggered():
 def test_args_secret_warning_empty():
     assert c.args_secret_warning({}) is None
     assert c.args_secret_warning({"args": []}) is None
+
+
+# --------------------------------------------------------------------------- #
+# restart_claude_desktop / profile_targets_claude_desktop (issue #9)
+# --------------------------------------------------------------------------- #
+def test_profile_targets_claude_desktop_true_for_desktop_config():
+    p = c.Profile(label="Claude", path="/x/Claude/claude_desktop_config.json", config_exists=True)
+    assert c.profile_targets_claude_desktop(p)
+
+
+def test_profile_targets_claude_desktop_false_for_claude_code():
+    p = c.Profile(label="Claude Code", path="/home/me/.claude.json", config_exists=True)
+    assert not c.profile_targets_claude_desktop(p)
+
+
+def test_profile_targets_claude_desktop_false_for_legacy_settings():
+    p = c.Profile(
+        label="Claude Code (legacy settings.json)",
+        path="/home/me/.claude/settings.json",
+        config_exists=True,
+    )
+    assert not c.profile_targets_claude_desktop(p)
+
+
+class _FakeCompletedProcess:
+    def __init__(self, returncode=0, stdout="", stderr=""):
+        self.returncode = returncode
+        self.stdout = stdout
+        self.stderr = stderr
+
+
+def test_restart_claude_desktop_macos_commands(monkeypatch):
+    """macOS: pkill -x "Claude" then open -a Claude, in that order."""
+    calls = []
+
+    def fake_run(cmd, **kwargs):
+        calls.append(cmd)
+        return _FakeCompletedProcess(returncode=0)
+
+    monkeypatch.setattr(c.sys, "platform", "darwin")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert result.success
+    assert calls[0] == ["pkill", "-x", "Claude"]
+    assert calls[1] == ["open", "-a", "Claude"]
+
+
+def test_restart_claude_desktop_macos_pkill_not_running_is_fine(monkeypatch):
+    """pkill exiting non-zero (nothing to kill) must NOT be treated as failure."""
+
+    def fake_run(cmd, **kwargs):
+        if cmd[0] == "pkill":
+            return _FakeCompletedProcess(returncode=1)  # no matching process
+        return _FakeCompletedProcess(returncode=0)
+
+    monkeypatch.setattr(c.sys, "platform", "darwin")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert result.success
+
+
+def test_restart_claude_desktop_macos_relaunch_failure_reported(monkeypatch):
+    def fake_run(cmd, **kwargs):
+        if cmd[0] == "open":
+            return _FakeCompletedProcess(returncode=1, stderr="Unable to find application")
+        return _FakeCompletedProcess(returncode=1)
+
+    monkeypatch.setattr(c.sys, "platform", "darwin")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert not result.success
+    assert "Unable to find application" in result.detail
+
+
+def test_restart_claude_desktop_macos_pkill_binary_missing_does_not_raise(monkeypatch):
+    """pkill raising OSError (binary missing) must be swallowed, not propagated --
+    relaunch is still attempted."""
+
+    def fake_run(cmd, **kwargs):
+        if cmd[0] == "pkill":
+            raise OSError("pkill not found")
+        return _FakeCompletedProcess(returncode=0)
+
+    monkeypatch.setattr(c.sys, "platform", "darwin")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert result.success
+
+
+def test_restart_claude_desktop_windows_commands(monkeypatch):
+    """Windows: taskkill the process, then relaunch via the Start-menu shortcut."""
+    calls = []
+
+    def fake_run(cmd, **kwargs):
+        calls.append(cmd)
+        return _FakeCompletedProcess(returncode=0)
+
+    monkeypatch.setattr(c.sys, "platform", "win32")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert result.success
+    assert calls[0] == ["taskkill", "/IM", "Claude.exe", "/F"]
+    assert calls[1][:3] == ["cmd", "/c", "start"]
+    assert calls[1][-1].endswith("Claude.lnk")
+
+
+def test_restart_claude_desktop_windows_relaunch_failure_reported(monkeypatch):
+    def fake_run(cmd, **kwargs):
+        if cmd[0] == "cmd":
+            return _FakeCompletedProcess(returncode=1, stderr="not found")
+        return _FakeCompletedProcess(returncode=0)
+
+    monkeypatch.setattr(c.sys, "platform", "win32")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    result = c.restart_claude_desktop()
+    assert not result.success
+    assert "not found" in result.detail
+
+
+def test_restart_claude_desktop_linux_commands(monkeypatch):
+    """Linux: pkill claude, then relaunch via a detached Popen (no waiting)."""
+    run_calls = []
+    popen_calls = []
+
+    def fake_run(cmd, **kwargs):
+        run_calls.append(cmd)
+        return _FakeCompletedProcess(returncode=0)
+
+    class _FakePopen:
+        def __init__(self, cmd, **kwargs):
+            popen_calls.append((cmd, kwargs))
+
+    monkeypatch.setattr(c.sys, "platform", "linux")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    monkeypatch.setattr(c.subprocess, "Popen", _FakePopen)
+    result = c.restart_claude_desktop()
+    assert result.success
+    assert run_calls == [["pkill", "claude"]]
+    cmd, kwargs = popen_calls[0]
+    assert cmd == ["claude"]
+    assert kwargs.get("start_new_session") is True
+
+
+def test_restart_claude_desktop_linux_popen_failure_reported(monkeypatch):
+    def fake_run(cmd, **kwargs):
+        return _FakeCompletedProcess(returncode=0)
+
+    def fake_popen(cmd, **kwargs):
+        raise OSError("no such file or directory")
+
+    monkeypatch.setattr(c.sys, "platform", "linux")
+    monkeypatch.setattr(c.subprocess, "run", fake_run)
+    monkeypatch.setattr(c.subprocess, "Popen", fake_popen)
+    result = c.restart_claude_desktop()
+    assert not result.success
+    assert "Claude Desktop" in result.detail