perf(tui): cache Detect+Plan results in wizard renderPlan

internal/tui/wizard/wizard_test.go

@@ -31,14 +31,14 @@ func TestSyncSelected(t *testing.T) {
 func TestRenderPlanWithHello(t *testing.T) {
 	reg := module.NewRegistry()
 	_ = reg.Register(hello.Module{Path: t.TempDir() + "/marker"})
-	out := renderPlan(context.Background(), reg, []string{"hello"})
+	out := renderPlanCached(context.Background(), reg, []string{"hello"}, newPlanCache())
 	if !strings.Contains(out, "hello") {
 		t.Fatalf("output missing hello: %q", out)
 	}
 }
 
 func TestRenderPlanEmpty(t *testing.T) {
-	if got := renderPlan(context.Background(), module.NewRegistry(), nil); got != "No modules selected." {
+	if got := renderPlanCached(context.Background(), module.NewRegistry(), nil, newPlanCache()); got != "No modules selected." {
 		t.Fatalf("got %q", got)
 	}
 }
@@ -63,6 +63,65 @@ func TestParseIntClamp(t *testing.T) {
 	}
 }
 
+func TestRenderPlanCachesDetectAndPlan(t *testing.T) {
+	var detects, plans int
+	m := countingModule{
+		meta:     module.Meta{ID: "count", Name: "Count"},
+		onDetect: func() { detects++ },
+		onPlan:   func() { plans++ },
+	}
+	reg := module.NewRegistry()
+	if err := reg.Register(m); err != nil {
+		t.Fatal(err)
+	}
+	cache := newPlanCache()
+	_ = renderPlanCached(context.Background(), reg, []string{"count"}, cache)
+	_ = renderPlanCached(context.Background(), reg, []string{"count"}, cache)
+	_ = renderPlanCached(context.Background(), reg, []string{"count"}, cache)
+	if detects != 1 || plans != 1 {
+		t.Fatalf("want 1 detect and 1 plan, got detects=%d plans=%d", detects, plans)
+	}
+}
+
+func TestRenderPlanInvalidatesOnSelectionChange(t *testing.T) {
+	var detects int
+	m := countingModule{
+		meta:     module.Meta{ID: "count", Name: "Count"},
+		onDetect: func() { detects++ },
+	}
+	reg := module.NewRegistry()
+	_ = reg.Register(m)
+	cache := newPlanCache()
+	_ = renderPlanCached(context.Background(), reg, []string{"count"}, cache)
+	_ = renderPlanCached(context.Background(), reg, []string{}, cache)
+	_ = renderPlanCached(context.Background(), reg, []string{"count"}, cache)
+	if detects != 2 {
+		t.Fatalf("deselect+reselect should re-detect; detects=%d (want 2)", detects)
+	}
+}
+
+type countingModule struct {
+	meta     module.Meta
+	onDetect func()
+	onPlan   func()
+}
+
+func (c countingModule) Meta() module.Meta { return c.meta }
+func (c countingModule) Detect(context.Context) (module.State, error) {
+	if c.onDetect != nil {
+		c.onDetect()
+	}
+	return nil, nil
+}
+func (c countingModule) Plan(context.Context, module.State) (module.Plan, error) {
+	if c.onPlan != nil {
+		c.onPlan()
+	}
+	return module.Plan{}, nil
+}
+func (c countingModule) Apply(context.Context, module.Plan, module.Reporter) error { return nil }
+func (c countingModule) Verify(context.Context) error                              { return nil }
+
 func TestRunCancelledContextReturnsNoConfirmation(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()