Validate render identity and daypart fallbacks

internal/reporttemplate/reporttemplate_test.go

@@ -704,6 +704,26 @@ func TestRenderDaypartTemplatesUseRichHelperFields(t *testing.T) {
 	}
 }
 
+func TestRenderTodayUsesDaypartFallbackWhenRowsAreNotDisplayable(t *testing.T) {
+	rendered, err := Render("today", testTodayRenderContext{
+		Report:        testTodayReportContext{Title: "Today", ForecastDateLabel: "Monday, June 15, 2026"},
+		GeneratedText: testTomorrowGeneratedText{Summary: "Today summary."},
+		Modules: testTodayModules{Dayparts: []testTomorrowDaypart{
+			{Key: "morning", Summary: testDaypartSummary{DisplayName: "Morning"}},
+		}},
+	})
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	text := string(rendered)
+	if !strings.Contains(text, "## Daypart Forecast\n- No daypart forecast details are available.") {
+		t.Fatalf("rendered template missing daypart fallback:\n%s", text)
+	}
+	if strings.Contains(text, "- **Morning:**") {
+		t.Fatalf("rendered template included an unavailable daypart row:\n%s", text)
+	}
+}
+
 func TestRenderTomorrowOmitsPrecipitationTimingWithoutWindows(t *testing.T) {
 	rendered, err := Render("tomorrow", testTomorrowRenderContext{
 		Report: testTomorrowReportContext{
@@ -1013,6 +1033,15 @@ type testTodayModules struct {
 	TodayPlanning         *testTodayPlanning
 }
 
+func (modules testTodayModules) HasDaypartDetails() bool {
+	for _, daypart := range modules.Dayparts {
+		if daypart.Summary.DominantConditionDisplay != "" || daypart.Summary.DominantCondition != "" {
+			return true
+		}
+	}
+	return false
+}
+
 type testDailyModules struct {
 	Dayparts              []testDailyDaypart
 	PrecipTiming          *testPrecipTiming