Correct daypart identity and display handling

internal/generatedtext/render_context_test.go

@@ -244,6 +244,35 @@ func TestBuildTodayRenderContext(t *testing.T) {
 	}
 }
 
+func TestTodayRenderContextPreservesUnicodeDaypartDisplayNames(t *testing.T) {
+	metadata := testTodayMetadata()
+	snapshot := testTodaySnapshot(t)
+	for i := range snapshot.Outputs {
+		if snapshot.Outputs[i].ID != module.DerivedDaypartSummaries {
+			continue
+		}
+		dayparts := snapshot.Outputs[i].Value.(map[string]briefing.DerivedDaypartSummaryModule)
+		morning := dayparts["morning"]
+		morning.DisplayName = "Mañana"
+		dayparts["morning"] = morning
+	}
+
+	ctx, err := BuildTodayRenderContext(metadata, snapshot, Today{
+		Summary:            "Today summary.",
+		ForecastDiscussion: []string{"Morning conditions stay quiet."},
+	}, testCollected(), testTodayDerived())
+	if err != nil {
+		t.Fatalf("BuildTodayRenderContext() error = %v", err)
+	}
+	rendered, err := reporttemplate.Render("today", ctx)
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	if !strings.Contains(string(rendered), "Mañana") {
+		t.Fatalf("rendered report = %q, want Unicode daypart display name", rendered)
+	}
+}
+
 func TestBuildTodayRenderContextAllowsOmittedOptionalModules(t *testing.T) {
 	snapshot, err := module.NewSnapshot(nil)
 	if err != nil {