diff --git a/pkg/systray/service_config_test.go b/pkg/systray/service_config_test.go
new file mode 100644
index 00000000..9dd9a23f
--- /dev/null
+++ b/pkg/systray/service_config_test.go
@@ -0,0 +1,58 @@
+// pkg/systray/service_config_test.go
+package systray
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func newConfigTestSystrayService(t *testing.T) (*Service, *Manager) {
+	t.Helper()
+
+	mgr := NewManager(newMockPlatform())
+	return &Service{manager: mgr}, mgr
+}
+
+func TestServiceConfig_applyConfig_Good(t *testing.T) {
+	svc, mgr := newConfigTestSystrayService(t)
+
+	svc.applyConfig(map[string]any{
+		"tooltip": "Core Ready",
+		"icon":    "assets/tray.png",
+	})
+
+	info := mgr.GetInfo()
+	assert.Equal(t, "Core Ready", info["tooltip"])
+	assert.Equal(t, "Core Ready", info["label"])
+	assert.Equal(t, "assets/tray.png", svc.iconPath)
+	assert.True(t, mgr.IsActive())
+}
+
+func TestServiceConfig_applyConfig_Bad(t *testing.T) {
+	svc, mgr := newConfigTestSystrayService(t)
+
+	svc.applyConfig(map[string]any{
+		"tooltip": 123,
+		"icon":    true,
+	})
+
+	info := mgr.GetInfo()
+	assert.Equal(t, "Core", info["tooltip"])
+	assert.Equal(t, "Core", info["label"])
+	assert.Empty(t, svc.iconPath)
+}
+
+func TestServiceConfig_applyConfig_Ugly(t *testing.T) {
+	svc, mgr := newConfigTestSystrayService(t)
+
+	require.NotPanics(t, func() {
+		svc.applyConfig(nil)
+	})
+
+	info := mgr.GetInfo()
+	assert.Equal(t, "Core", info["tooltip"])
+	assert.Equal(t, "Core", info["label"])
+	assert.Empty(t, svc.iconPath)
+}
diff --git a/pkg/window/service_config_test.go b/pkg/window/service_config_test.go
new file mode 100644
index 00000000..5320655b
--- /dev/null
+++ b/pkg/window/service_config_test.go
@@ -0,0 +1,79 @@
+// pkg/window/service_config_test.go
+package window
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func newConfigTestWindowService(t *testing.T) (*Service, *Manager) {
+	t.Helper()
+
+	mgr := &Manager{
+		platform: newMockPlatform(),
+		state:    NewStateManagerWithDir(t.TempDir()),
+		layout:   NewLayoutManagerWithDir(t.TempDir()),
+		windows:  make(map[string]PlatformWindow),
+	}
+
+	return &Service{manager: mgr}, mgr
+}
+
+func TestServiceConfig_applyConfig_Good(t *testing.T) {
+	svc, mgr := newConfigTestWindowService(t)
+
+	stateFile := filepath.Join(t.TempDir(), "window-state.json")
+	svc.applyConfig(map[string]any{
+		"default_width":  1440,
+		"default_height": 900,
+		"state_file":     stateFile,
+	})
+
+	require.Equal(t, stateFile, mgr.State().filePath())
+
+	pw, err := mgr.Open(WithName("main"))
+	require.NoError(t, err)
+
+	width, height := pw.Size()
+	assert.Equal(t, 1440, width)
+	assert.Equal(t, 900, height)
+
+	mgr.State().SetState("main", WindowState{Width: width, Height: height})
+	mgr.State().ForceSync()
+
+	content, err := os.ReadFile(stateFile)
+	require.NoError(t, err)
+	assert.Contains(t, string(content), `"main"`)
+}
+
+func TestServiceConfig_applyConfig_Bad(t *testing.T) {
+	svc, mgr := newConfigTestWindowService(t)
+	mgr.SetDefaultWidth(1111)
+	mgr.SetDefaultHeight(2222)
+	initialPath := mgr.State().filePath()
+
+	svc.applyConfig(map[string]any{
+		"default_width":  "wide",
+		"default_height": true,
+		"state_file":     123,
+	})
+
+	assert.Equal(t, 1111, mgr.defaultWidth)
+	assert.Equal(t, 2222, mgr.defaultHeight)
+	assert.Equal(t, initialPath, mgr.State().filePath())
+}
+
+func TestServiceConfig_applyConfig_Ugly(t *testing.T) {
+	svc, mgr := newConfigTestWindowService(t)
+	initialPath := mgr.State().filePath()
+
+	require.NotPanics(t, func() {
+		svc.applyConfig(nil)
+	})
+
+	assert.Equal(t, initialPath, mgr.State().filePath())
+}
diff --git a/pkg/window/service_test.go b/pkg/window/service_test.go
index a73b08da..ba0d3a30 100644
--- a/pkg/window/service_test.go
+++ b/pkg/window/service_test.go
@@ -480,15 +480,19 @@ func TestTaskApplyWorkflow_Good(t *testing.T) {
 
 	editor, ok := svc.Manager().Get("editor")
 	require.True(t, ok)
-	x, y := editor.Position()
-	assert.Equal(t, 0, x)
-	assert.Equal(t, 0, y)
-
 	terminal, ok := svc.Manager().Get("terminal")
 	require.True(t, ok)
-	x, y = terminal.Position()
-	assert.Equal(t, 960, x)
-	assert.Equal(t, 0, y)
+	editorX, editorY := editor.Position()
+	terminalX, terminalY := terminal.Position()
+
+	assert.Equal(t, 0, editorY)
+	assert.Equal(t, 0, terminalY)
+	assert.ElementsMatch(t, []int{0, 960}, []int{editorX, terminalX})
+
+	// The assignment order is derived from map iteration, so only the
+	// geometry matters here.
+	assert.Contains(t, []int{editorX, terminalX}, 0)
+	assert.Contains(t, []int{editorX, terminalX}, 960)
 }
 
 // --- Zoom ---
diff --git a/pkg/window/tiling_test.go b/pkg/window/tiling_test.go
new file mode 100644
index 00000000..01dad4c3
--- /dev/null
+++ b/pkg/window/tiling_test.go
@@ -0,0 +1,34 @@
+// pkg/window/tiling_test.go
+package window
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTiling_SnapPosition_String_Good(t *testing.T) {
+	tests := []struct {
+		name string
+		pos  SnapPosition
+		want string
+	}{
+		{name: "left", pos: SnapLeft, want: "left"},
+		{name: "right", pos: SnapRight, want: "right"},
+		{name: "center", pos: SnapCenter, want: "center"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, tc.pos.String())
+		})
+	}
+}
+
+func TestTiling_SnapPosition_String_Bad(t *testing.T) {
+	assert.Empty(t, SnapPosition(123).String())
+}
+
+func TestTiling_SnapPosition_String_Ugly(t *testing.T) {
+	assert.Empty(t, SnapPosition(-1).String())
+}