Add Tomorrow render context and template

2026-06-14 23:36:47 +00:00
parent 295f06915f
commit ddda42453f
5 changed files with 698 additions and 2 deletions
--- a/internal/generatedtext/render_context.go
+++ b/internal/generatedtext/render_context.go
@@ -2,10 +2,14 @@ package generatedtext

 import (
 	"fmt"
+	"sort"
+	"strings"
 	"time"
+	"unicode"

 	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/facts"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/forecast"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
 )
@@ -40,6 +44,46 @@ type HourlyTemplateModules struct {
 	WeatherStory            *briefing.WeatherStoryModule
 }

+type TomorrowRenderContext struct {
+	Report        TomorrowReportContext
+	GeneratedText Tomorrow
+	Modules       TomorrowTemplateModules
+	Collected     facts.CollectedFacts
+	Derived       facts.DerivedFacts
+}
+
+type TomorrowReportContext struct {
+	Title             string
+	ForecastDate      time.Time
+	ForecastDateLabel string
+	ForecastDayName   string
+	GeneratedAt       time.Time
+	GeneratedAtLabel  string
+	ValidPeriod       timeutil.Period
+	Timezone          string
+}
+
+type TomorrowTemplateModules struct {
+	Metadata                *briefing.MetadataModule
+	CurrentConditions       *briefing.CurrentConditionsModule
+	HourlyForecast          *briefing.HourlyForecastModule
+	DerivedDailySummary     *briefing.DerivedDailySummaryModule
+	DerivedDaypartSummaries *map[string]briefing.DerivedDaypartSummaryModule
+	Dayparts                []TomorrowDaypartContext
+	PrecipTiming            *briefing.PrecipTimingModule
+	AlertDigest             *briefing.AlertDigestModule
+	SPCConvectiveOutlooks   *briefing.SPCConvectiveOutlooksModule
+	AreaForecastDiscussion  *briefing.AreaForecastDiscussionModule
+	SPCConvectiveDiscussion *briefing.SPCConvectiveDiscussionModule
+	WeatherStory            *briefing.WeatherStoryModule
+	TomorrowPlanning        *briefing.TomorrowPlanningModule
+}
+
+type TomorrowDaypartContext struct {
+	Key     string
+	Summary briefing.DerivedDaypartSummaryModule
+}
+
 func BuildHourlyRenderContext(metadata briefing.Metadata, snapshot module.Snapshot, generated Hourly, collected facts.CollectedFacts, derived facts.DerivedFacts) (HourlyRenderContext, error) {
 	location, err := timeutil.LoadLocation(metadata.Timezone)
 	if err != nil {
@@ -72,6 +116,41 @@ func BuildHourlyRenderContext(metadata briefing.Metadata, snapshot module.Snapsh
 	}, nil
 }

+func BuildTomorrowRenderContext(metadata briefing.Metadata, snapshot module.Snapshot, generated Tomorrow, collected facts.CollectedFacts, derived facts.DerivedFacts) (TomorrowRenderContext, error) {
+	location, err := timeutil.LoadLocation(metadata.Timezone)
+	if err != nil {
+		return TomorrowRenderContext{}, fmt.Errorf("build tomorrow render context: %w", err)
+	}
+	if metadata.GeneratedAt.IsZero() {
+		return TomorrowRenderContext{}, fmt.Errorf("build tomorrow render context: generatedAt is required")
+	}
+	if !metadata.ValidPeriod.IsValid() {
+		return TomorrowRenderContext{}, fmt.Errorf("build tomorrow render context: valid period is required")
+	}
+	modules, err := tomorrowTemplateModules(snapshot, derived)
+	if err != nil {
+		return TomorrowRenderContext{}, err
+	}
+	forecastDate := metadata.ValidPeriod.Start.In(location)
+	forecastDayName := forecastDate.Format("Monday")
+	return TomorrowRenderContext{
+		Report: TomorrowReportContext{
+			Title:             forecastDayName + "'s Weather",
+			ForecastDate:      forecastDate,
+			ForecastDateLabel: forecastDate.Format("Monday, January 2, 2006"),
+			ForecastDayName:   forecastDayName,
+			GeneratedAt:       metadata.GeneratedAt,
+			GeneratedAtLabel:  generatedAtLabel(metadata.GeneratedAt, location),
+			ValidPeriod:       metadata.ValidPeriod,
+			Timezone:          metadata.Timezone,
+		},
+		GeneratedText: generated,
+		Modules:       modules,
+		Collected:     collected,
+		Derived:       derived,
+	}, nil
+}
+
 func hourlyTemplateModules(snapshot module.Snapshot) (HourlyTemplateModules, error) {
 	metadata, err := optionalStanza[briefing.MetadataModule](snapshot, string(module.Metadata))
 	if err != nil {
@@ -122,6 +201,72 @@ func hourlyTemplateModules(snapshot module.Snapshot) (HourlyTemplateModules, err
 	}, nil
 }

+func tomorrowTemplateModules(snapshot module.Snapshot, derived facts.DerivedFacts) (TomorrowTemplateModules, error) {
+	metadata, err := optionalStanza[briefing.MetadataModule](snapshot, string(module.Metadata))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	current, err := optionalStanza[briefing.CurrentConditionsModule](snapshot, string(module.CurrentConditions))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	hourly, err := optionalStanza[briefing.HourlyForecastModule](snapshot, string(module.HourlyForecast))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	daily, err := optionalStanza[briefing.DerivedDailySummaryModule](snapshot, string(module.DerivedDailySummary))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	dayparts, err := optionalStanza[map[string]briefing.DerivedDaypartSummaryModule](snapshot, string(module.DerivedDaypartSummaries))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	precip, err := optionalStanza[briefing.PrecipTimingModule](snapshot, string(module.PrecipTiming))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	alerts, err := optionalStanza[briefing.AlertDigestModule](snapshot, string(module.AlertDigest))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	outlooks, err := optionalStanza[briefing.SPCConvectiveOutlooksModule](snapshot, string(module.SPCConvectiveOutlooks))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	discussion, err := optionalStanza[briefing.AreaForecastDiscussionModule](snapshot, string(module.AreaForecastDiscussion))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	spcDiscussion, err := optionalStanza[briefing.SPCConvectiveDiscussionModule](snapshot, string(module.SPCConvectiveDiscussion))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	story, err := optionalStanza[briefing.WeatherStoryModule](snapshot, string(module.WeatherStory))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	planning, err := optionalStanza[briefing.TomorrowPlanningModule](snapshot, string(module.TomorrowPlanning))
+	if err != nil {
+		return TomorrowTemplateModules{}, err
+	}
+	return TomorrowTemplateModules{
+		Metadata:                metadata,
+		CurrentConditions:       current,
+		HourlyForecast:          hourly,
+		DerivedDailySummary:     daily,
+		DerivedDaypartSummaries: dayparts,
+		Dayparts:                orderedTomorrowDayparts(dayparts, derived.DaypartSummaries),
+		PrecipTiming:            precip,
+		AlertDigest:             alerts,
+		SPCConvectiveOutlooks:   outlooks,
+		AreaForecastDiscussion:  discussion,
+		SPCConvectiveDiscussion: spcDiscussion,
+		WeatherStory:            story,
+		TomorrowPlanning:        planning,
+	}, nil
+}
+
 func optionalStanza[T any](snapshot module.Snapshot, name string) (*T, error) {
 	output, ok := snapshot.LookupStanza(name)
 	if !ok || output.Value == nil {
@@ -129,11 +274,74 @@ func optionalStanza[T any](snapshot module.Snapshot, name string) (*T, error) {
 	}
 	value, _, err := module.StanzaValue[T](snapshot, name)
 	if err != nil {
-		return nil, fmt.Errorf("build hourly render context: %w", err)
+		return nil, fmt.Errorf("build render context: %w", err)
 	}
 	return &value, nil
 }

+func orderedTomorrowDayparts(dayparts *map[string]briefing.DerivedDaypartSummaryModule, ordered []forecast.DaypartSummary) []TomorrowDaypartContext {
+	if dayparts == nil || len(*dayparts) == 0 {
+		return nil
+	}
+	out := make([]TomorrowDaypartContext, 0, len(*dayparts))
+	seen := map[string]struct{}{}
+	for _, daypart := range ordered {
+		for _, key := range daypartModuleKeyCandidates(daypart) {
+			value, ok := (*dayparts)[key]
+			if !ok {
+				continue
+			}
+			if _, exists := seen[key]; exists {
+				continue
+			}
+			seen[key] = struct{}{}
+			out = append(out, TomorrowDaypartContext{Key: key, Summary: value})
+			break
+		}
+	}
+
+	var remaining []string
+	for key := range *dayparts {
+		if _, ok := seen[key]; !ok {
+			remaining = append(remaining, key)
+		}
+	}
+	sort.Strings(remaining)
+	for _, key := range remaining {
+		out = append(out, TomorrowDaypartContext{Key: key, Summary: (*dayparts)[key]})
+	}
+	return out
+}
+
+func daypartModuleKeyCandidates(daypart forecast.DaypartSummary) []string {
+	key := normalizedDaypartKey(daypart.Name)
+	if key == "" {
+		key = "unnamed"
+	}
+	if daypart.Period.Start.IsZero() {
+		return []string{key}
+	}
+	return []string{key, daypart.Period.Start.Format(timeutil.DateLayout) + "_" + key}
+}
+
+func normalizedDaypartKey(value string) string {
+	lower := strings.ToLower(strings.TrimSpace(value))
+	var out strings.Builder
+	lastUnderscore := false
+	for _, r := range lower {
+		if unicode.IsLetter(r) || unicode.IsDigit(r) {
+			out.WriteRune(r)
+			lastUnderscore = false
+			continue
+		}
+		if !lastUnderscore {
+			out.WriteByte('_')
+			lastUnderscore = true
+		}
+	}
+	return strings.Trim(out.String(), "_")
+}
+
 func locationName(metadata briefing.Metadata) string {
 	if metadata.Location != nil {
 		if metadata.Location.Name != "" && metadata.Location.Region != "" {
--- a/internal/generatedtext/render_context_test.go
+++ b/internal/generatedtext/render_context_test.go
@@ -114,6 +114,120 @@ func TestBuildHourlyRenderContextAllowsOmittedOptionalModules(t *testing.T) {
 	}
 }

+func TestBuildTomorrowRenderContext(t *testing.T) {
+	metadata := testTomorrowMetadata()
+	snapshot := testTomorrowSnapshot(t)
+	generated := Tomorrow{
+		Summary: "Tomorrow starts quiet, then showers become more likely later in the day.",
+		ForecastDiscussion: []string{
+			"Morning conditions should stay mostly dry.",
+			"Rain chances increase during the afternoon as deeper moisture arrives.",
+		},
+		PrecipitationTiming: "The most likely rain window is from midafternoon into early evening.",
+	}
+	collected := testCollected()
+	derived := testTomorrowDerived()
+
+	ctx, err := BuildTomorrowRenderContext(metadata, snapshot, generated, collected, derived)
+	if err != nil {
+		t.Fatalf("BuildTomorrowRenderContext() error = %v", err)
+	}
+	if ctx.Report.Title != "Monday's Weather" {
+		t.Fatalf("Report.Title = %q, want Monday's Weather", ctx.Report.Title)
+	}
+	if ctx.Report.ForecastDateLabel != "Monday, June 15, 2026" || ctx.Report.ForecastDayName != "Monday" {
+		t.Fatalf("forecast date labels = %q/%q, want Monday labels", ctx.Report.ForecastDateLabel, ctx.Report.ForecastDayName)
+	}
+	if ctx.Report.GeneratedAtLabel != "Sunday, June 14, 2026 at 9:14 AM" {
+		t.Fatalf("Report.GeneratedAtLabel = %q, want friendly generated-at label", ctx.Report.GeneratedAtLabel)
+	}
+	if ctx.Modules.Metadata == nil || ctx.Modules.Metadata.ReportID != report.Tomorrow {
+		t.Fatalf("Modules.Metadata = %#v, want tomorrow metadata", ctx.Modules.Metadata)
+	}
+	if ctx.Modules.CurrentConditions == nil || ctx.Modules.HourlyForecast == nil {
+		t.Fatalf("current/hourly modules = %#v/%#v, want available in render context", ctx.Modules.CurrentConditions, ctx.Modules.HourlyForecast)
+	}
+	if ctx.Modules.DerivedDailySummary == nil || ctx.Modules.DerivedDailySummary.HighTempF == nil || *ctx.Modules.DerivedDailySummary.HighTempF != 74 {
+		t.Fatalf("Modules.DerivedDailySummary = %#v, want daily summary", ctx.Modules.DerivedDailySummary)
+	}
+	if ctx.Modules.DerivedDaypartSummaries == nil || len(*ctx.Modules.DerivedDaypartSummaries) != 2 {
+		t.Fatalf("Modules.DerivedDaypartSummaries = %#v, want daypart map", ctx.Modules.DerivedDaypartSummaries)
+	}
+	if len(ctx.Modules.Dayparts) != 2 || ctx.Modules.Dayparts[0].Key != "morning" || ctx.Modules.Dayparts[1].Key != "afternoon" {
+		t.Fatalf("Modules.Dayparts = %#v, want configured order", ctx.Modules.Dayparts)
+	}
+	if ctx.Modules.PrecipTiming == nil || len(ctx.Modules.PrecipTiming.PrecipitationWindows) != 1 {
+		t.Fatalf("Modules.PrecipTiming = %#v, want precipitation window", ctx.Modules.PrecipTiming)
+	}
+	if ctx.Modules.AlertDigest == nil || ctx.Modules.SPCConvectiveOutlooks == nil || ctx.Modules.AreaForecastDiscussion == nil || ctx.Modules.SPCConvectiveDiscussion == nil || ctx.Modules.WeatherStory == nil || ctx.Modules.TomorrowPlanning == nil {
+		t.Fatalf("optional modules missing from render context: %#v", ctx.Modules)
+	}
+	if !ctx.Collected.FetchedAt.Equal(collected.FetchedAt) {
+		t.Fatalf("Collected.FetchedAt = %s, want %s", ctx.Collected.FetchedAt, collected.FetchedAt)
+	}
+	if len(ctx.Derived.DaypartSummaries) != 2 {
+		t.Fatalf("Derived.DaypartSummaries = %#v, want passthrough facts", ctx.Derived.DaypartSummaries)
+	}
+
+	rendered, err := reporttemplate.Render("tomorrow", ctx)
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	text := string(rendered)
+	for _, want := range []string{
+		"# Monday's Weather",
+		"**Forecast date:** Monday, June 15, 2026",
+		"Tomorrow starts quiet, then showers become more likely later in the day.",
+		"- **Morning:** low 60s and partly cloudy.",
+		"- **Afternoon:** mid 70s and showers. Precipitation chances peak at 70% at 3:00 PM.",
+		"## Precipitation Timing",
+		"- **3:00 PM** to **6:00 PM**: Precipitation is expected during this period. The peak precipitation chance is 70% at 3:00 PM.",
+		"The most likely rain window is from midafternoon into early evening.",
+		"Morning conditions should stay mostly dry.",
+		"Rain chances increase during the afternoon as deeper moisture arrives.",
+	} {
+		if !strings.Contains(text, want) {
+			t.Fatalf("rendered template missing %q:\n%s", want, text)
+		}
+	}
+	assertOrderedText(t, text, []string{
+		"# Monday's Weather",
+		"## Daypart Forecast",
+		"- **Morning:**",
+		"- **Afternoon:**",
+		"## Precipitation Timing",
+		"## Forecast Discussion",
+	})
+}
+
+func TestBuildTomorrowRenderContextAllowsOmittedOptionalModules(t *testing.T) {
+	snapshot, err := module.NewSnapshot(nil)
+	if err != nil {
+		t.Fatalf("NewSnapshot() error = %v", err)
+	}
+	ctx, err := BuildTomorrowRenderContext(testTomorrowMetadata(), snapshot, Tomorrow{
+		Summary:            "Dry weather is expected tomorrow.",
+		ForecastDiscussion: []string{"High pressure keeps conditions quiet."},
+	}, testCollected(), facts.DerivedFacts{})
+	if err != nil {
+		t.Fatalf("BuildTomorrowRenderContext() error = %v", err)
+	}
+	if ctx.Modules.PrecipTiming != nil || len(ctx.Modules.Dayparts) != 0 {
+		t.Fatalf("Modules = %#v, want omitted optional modules", ctx.Modules)
+	}
+	rendered, err := reporttemplate.Render("tomorrow", ctx)
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	text := string(rendered)
+	if strings.Contains(text, "## Precipitation Timing") {
+		t.Fatalf("rendered template included precipitation section without windows:\n%s", text)
+	}
+	if !strings.Contains(text, "- No daypart forecast details are available.") {
+		t.Fatalf("rendered template missing daypart fallback:\n%s", text)
+	}
+}
+
 func testMetadata() briefing.Metadata {
 	generatedAt := time.Date(2026, 5, 29, 13, 30, 0, 0, time.UTC)
 	return briefing.Metadata{
@@ -134,6 +248,26 @@ func testMetadata() briefing.Metadata {
 	}
 }

+func testTomorrowMetadata() briefing.Metadata {
+	generatedAt := time.Date(2026, 6, 14, 14, 14, 0, 0, time.UTC)
+	return briefing.Metadata{
+		RunID:       "run-tomorrow",
+		ReportID:    report.Tomorrow,
+		PromptID:    "weather.tomorrow_generated_text",
+		GeneratedAt: generatedAt,
+		Units:       "imperial",
+		Timezone:    "America/Chicago",
+		ValidPeriod: timeutil.Period{
+			Start: time.Date(2026, 6, 15, 5, 0, 0, 0, time.UTC),
+			End:   time.Date(2026, 6, 16, 5, 0, 0, 0, time.UTC),
+		},
+		Location: &briefing.LocationContext{
+			Name:   "Brentwood",
+			Region: "MO",
+		},
+	}
+}
+
 func testCollected() facts.CollectedFacts {
 	return facts.CollectedFacts{FetchedAt: time.Date(2026, 5, 29, 13, 31, 0, 0, time.UTC)}
 }
@@ -142,6 +276,29 @@ func testDerived() facts.DerivedFacts {
 	return facts.DerivedFacts{PrecipTiming: forecast.PrecipTiming{ThunderMentioned: true}}
 }

+func testTomorrowDerived() facts.DerivedFacts {
+	morningStart := time.Date(2026, 6, 15, 11, 0, 0, 0, time.UTC)
+	afternoonStart := time.Date(2026, 6, 15, 17, 0, 0, 0, time.UTC)
+	return facts.DerivedFacts{
+		DaypartSummaries: []forecast.DaypartSummary{
+			{
+				Name: "morning",
+				Period: timeutil.Period{
+					Start: morningStart,
+					End:   afternoonStart,
+				},
+			},
+			{
+				Name: "afternoon",
+				Period: timeutil.Period{
+					Start: afternoonStart,
+					End:   time.Date(2026, 6, 15, 23, 0, 0, 0, time.UTC),
+				},
+			},
+		},
+	}
+}
+
 func testSnapshot(t *testing.T) module.Snapshot {
 	t.Helper()
 	snapshot, err := module.NewSnapshot([]module.Output{
@@ -273,6 +430,129 @@ func testSnapshot(t *testing.T) module.Snapshot {
 	return snapshot
 }

+func testTomorrowSnapshot(t *testing.T) module.Snapshot {
+	t.Helper()
+	snapshot, err := module.NewSnapshot([]module.Output{
+		{
+			ID:         module.Metadata,
+			StanzaName: string(module.Metadata),
+			Value: briefing.MetadataModule{
+				RunID:       "run-tomorrow",
+				ReportID:    report.Tomorrow,
+				PromptID:    "weather.tomorrow_generated_text",
+				GeneratedAt: testTomorrowMetadata().GeneratedAt,
+				Units:       "imperial",
+				Timezone:    "America/Chicago",
+				ValidPeriod: testTomorrowMetadata().ValidPeriod,
+			},
+		},
+		{
+			ID:         module.CurrentConditions,
+			StanzaName: string(module.CurrentConditions),
+			Value: briefing.CurrentConditionsModule{
+				ConditionTextLower: "clear",
+				TemperatureF:       intPtr(58),
+			},
+		},
+		{
+			ID:         module.HourlyForecast,
+			StanzaName: string(module.HourlyForecast),
+			Value: briefing.HourlyForecastModule{
+				Periods: []briefing.HourlyForecastPeriod{
+					{HourLabel: "7:00 AM", TextDescriptionLower: "partly cloudy", TemperatureF: floatPtr(63)},
+				},
+			},
+		},
+		{
+			ID:         module.DerivedDailySummary,
+			StanzaName: string(module.DerivedDailySummary),
+			Value: briefing.DerivedDailySummaryModule{
+				Date:                          "Monday, June 15, 2026",
+				HighTempF:                     intPtr(74),
+				LowTempF:                      intPtr(61),
+				DailyPrecipitationProbability: intPtr(70),
+			},
+		},
+		{
+			ID:         module.DerivedDaypartSummaries,
+			StanzaName: string(module.DerivedDaypartSummaries),
+			Value: map[string]briefing.DerivedDaypartSummaryModule{
+				"afternoon": {
+					DisplayName:            "Afternoon",
+					TemperaturePhraseF:     "mid 70s",
+					DominantConditionLower: "showers",
+					MaxPopPercent:          intPtr(70),
+					MaxPopTimeLabel:        "3:00 PM",
+					MentionPrecipitation:   true,
+				},
+				"morning": {
+					DisplayName:            "Morning",
+					TemperaturePhraseF:     "low 60s",
+					DominantConditionLower: "partly cloudy",
+				},
+			},
+		},
+		{
+			ID:         module.PrecipTiming,
+			StanzaName: string(module.PrecipTiming),
+			Value: briefing.PrecipTimingModule{
+				MaxPopPercent: intPtr(70),
+				MaxPopTime:    "3 PM",
+				PrecipitationWindows: []briefing.PrecipitationWindowModule{
+					{PeriodBeginsHourLabel: "3:00 PM", PeriodEndsHourLabel: "6:00 PM", MaxPopPercent: intPtr(70), MaxPopHourLabel: "3:00 PM"},
+				},
+			},
+		},
+		{
+			ID:         module.AlertDigest,
+			StanzaName: string(module.AlertDigest),
+			Value: briefing.AlertDigestModule{
+				Checked: true,
+			},
+		},
+		{
+			ID:         module.SPCConvectiveOutlooks,
+			StanzaName: string(module.SPCConvectiveOutlooks),
+			Value: briefing.SPCConvectiveOutlooksModule{
+				Checked: true,
+			},
+		},
+		{
+			ID:         module.AreaForecastDiscussion,
+			StanzaName: string(module.AreaForecastDiscussion),
+			Value: briefing.AreaForecastDiscussionModule{
+				KeyMessages: []string{"Rain chances increase late."},
+			},
+		},
+		{
+			ID:         module.SPCConvectiveDiscussion,
+			StanzaName: string(module.SPCConvectiveDiscussion),
+			Value: briefing.SPCConvectiveDiscussionModule{
+				IncludedBecause: "convective outlook",
+			},
+		},
+		{
+			ID:         module.WeatherStory,
+			StanzaName: string(module.WeatherStory),
+			Value: briefing.WeatherStoryModule{
+				Available: true,
+				Title:     "Rain returns",
+			},
+		},
+		{
+			ID:         module.TomorrowPlanning,
+			StanzaName: string(module.TomorrowPlanning),
+			Value: briefing.TomorrowPlanningModule{
+				MorningReadiness: []string{"Take sunglasses early."},
+			},
+		},
+	})
+	if err != nil {
+		t.Fatalf("NewSnapshot() error = %v", err)
+	}
+	return snapshot
+}
+
 func floatPtr(value float64) *float64 {
 	return &value
 }
@@ -280,3 +560,18 @@ func floatPtr(value float64) *float64 {
 func intPtr(value int) *int {
 	return &value
 }
+
+func assertOrderedText(t *testing.T, text string, ordered []string) {
+	t.Helper()
+	previousIndex := -1
+	for _, want := range ordered {
+		index := strings.Index(text, want)
+		if index < 0 {
+			t.Fatalf("text missing %q:\n%s", want, text)
+		}
+		if index <= previousIndex {
+			t.Fatalf("%q appears out of order in:\n%s", want, text)
+		}
+		previousIndex = index
+	}
+}
--- a/internal/reporttemplate/reporttemplate.go
+++ b/internal/reporttemplate/reporttemplate.go
@@ -12,7 +12,8 @@ import (
 var assets embed.FS

 var templates = map[string]string{
-	"hourly": "templates/hourly.md.tmpl",
+	"hourly":   "templates/hourly.md.tmpl",
+	"tomorrow": "templates/tomorrow.md.tmpl",
 }

 var schemas = map[string]string{
--- a/internal/reporttemplate/reporttemplate_test.go
+++ b/internal/reporttemplate/reporttemplate_test.go
@@ -18,6 +18,18 @@ func TestTemplateLookup(t *testing.T) {
 	}
 }

+func TestTomorrowTemplateLookup(t *testing.T) {
+	source, err := Template("tomorrow")
+	if err != nil {
+		t.Fatalf("Template() error = %v", err)
+	}
+	for _, want := range []string{"# {{ .Report.Title }}", "**Forecast date:**", "## Daypart Forecast", "## Precipitation Timing", "## Forecast Discussion"} {
+		if !strings.Contains(source, want) {
+			t.Fatalf("template missing %q:\n%s", want, source)
+		}
+	}
+}
+
 func TestSchemaLookup(t *testing.T) {
 	data, err := Schema("hourly")
 	if err != nil {
@@ -191,6 +203,119 @@ func TestRenderHourly(t *testing.T) {
 	})
 }

+func TestRenderTomorrow(t *testing.T) {
+	rendered, err := Render("tomorrow", testTomorrowRenderContext{
+		Report: testTomorrowReportContext{
+			Title:             "Monday's Weather",
+			ForecastDateLabel: "Monday, June 15, 2026",
+			GeneratedAtLabel:  "Sunday, June 14, 2026 at 9:14 AM",
+		},
+		GeneratedText: testTomorrowGeneratedText{
+			Summary: "Tomorrow starts dry before showers return later in the day.",
+			ForecastDiscussion: []string{
+				"Clouds increase after sunrise.",
+				"Rain chances peak during the afternoon.",
+			},
+			PrecipitationTiming: "A few showers may linger into early evening.",
+		},
+		Modules: testTomorrowModules{
+			Dayparts: []testTomorrowDaypart{
+				{
+					Key: "morning",
+					Summary: testDaypartSummary{
+						DisplayName:            "Morning",
+						TemperaturePhraseF:     "low 60s",
+						DominantConditionLower: "partly cloudy",
+					},
+				},
+				{
+					Key: "afternoon",
+					Summary: testDaypartSummary{
+						DisplayName:            "Afternoon",
+						TemperaturePhraseF:     "mid 70s",
+						DominantConditionLower: "showers",
+						MaxPopPercent:          intPtr(70),
+						MaxPopTimeLabel:        "3:00 PM",
+						MentionPrecipitation:   true,
+					},
+				},
+			},
+			PrecipTiming: &testPrecipTiming{
+				PrecipitationWindows: []testPrecipWindow{
+					{PeriodBeginsHourLabel: "3:00 PM", PeriodEndsHourLabel: "6:00 PM", MaxPopPercent: intPtr(70), MaxPopHourLabel: "3:00 PM"},
+				},
+			},
+		},
+	})
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	text := string(rendered)
+	for _, want := range []string{
+		"# Monday's Weather",
+		"**Forecast date:** Monday, June 15, 2026",
+		"**Updated:** Sunday, June 14, 2026 at 9:14 AM",
+		"Tomorrow starts dry before showers return later in the day.",
+		"- **Morning:** low 60s and partly cloudy.",
+		"- **Afternoon:** mid 70s and showers. Precipitation chances peak at 70% at 3:00 PM.",
+		"- **3:00 PM** to **6:00 PM**: Precipitation is expected during this period. The peak precipitation chance is 70% at 3:00 PM.",
+		"A few showers may linger into early evening.",
+		"Clouds increase after sunrise.",
+		"Rain chances peak during the afternoon.",
+	} {
+		if !strings.Contains(text, want) {
+			t.Fatalf("rendered template missing %q:\n%s", want, text)
+		}
+	}
+	assertOrderedText(t, text, []string{
+		"# Monday's Weather",
+		"## Daypart Forecast",
+		"- **Morning:**",
+		"- **Afternoon:**",
+		"## Precipitation Timing",
+		"## Forecast Discussion",
+		"Clouds increase after sunrise.",
+		"Rain chances peak during the afternoon.",
+	})
+}
+
+func TestRenderTomorrowOmitsPrecipitationTimingWithoutWindows(t *testing.T) {
+	rendered, err := Render("tomorrow", testTomorrowRenderContext{
+		Report: testTomorrowReportContext{
+			Title:             "Monday's Weather",
+			ForecastDateLabel: "Monday, June 15, 2026",
+			GeneratedAtLabel:  "Sunday, June 14, 2026 at 9:14 AM",
+		},
+		GeneratedText: testTomorrowGeneratedText{
+			Summary:             "Dry weather is expected tomorrow.",
+			ForecastDiscussion:  []string{"High pressure keeps rain chances low."},
+			PrecipitationTiming: "Any stray shower chance is too low to highlight.",
+		},
+		Modules: testTomorrowModules{
+			Dayparts: []testTomorrowDaypart{
+				{
+					Key: "morning",
+					Summary: testDaypartSummary{
+						DisplayName:            "Morning",
+						TemperaturePhraseF:     "low 60s",
+						DominantConditionLower: "clear",
+					},
+				},
+			},
+			PrecipTiming: &testPrecipTiming{},
+		},
+	})
+	if err != nil {
+		t.Fatalf("Render() error = %v", err)
+	}
+	text := string(rendered)
+	for _, unwanted := range []string{"## Precipitation Timing", "Any stray shower chance is too low to highlight."} {
+		if strings.Contains(text, unwanted) {
+			t.Fatalf("dry render includes %q:\n%s", unwanted, text)
+		}
+	}
+}
+
 func TestRenderHourlyOmitsConditionalSectionsForClearWeather(t *testing.T) {
 	rendered, err := Render("hourly", testRenderContext{
 		Report: testReportContext{
@@ -256,6 +381,12 @@ type testRenderContext struct {
 	Modules       testModules
 }

+type testTomorrowRenderContext struct {
+	Report        testTomorrowReportContext
+	GeneratedText testTomorrowGeneratedText
+	Modules       testTomorrowModules
+}
+
 type testReportContext struct {
 	Title            string
 	LocationName     string
@@ -270,6 +401,19 @@ type testGeneratedText struct {
 	Confidence          string
 }

+type testTomorrowReportContext struct {
+	Title             string
+	ForecastDateLabel string
+	GeneratedAtLabel  string
+}
+
+type testTomorrowGeneratedText struct {
+	Summary             string
+	ForecastDiscussion  []string
+	PrecipitationTiming string
+	Confidence          string
+}
+
 type testModules struct {
 	CurrentConditions       *testCurrentConditions
 	HourlyForecast          *testHourlyForecast
@@ -281,6 +425,28 @@ type testModules struct {
 	WeatherStory            *testWeatherStory
 }

+type testTomorrowModules struct {
+	Dayparts     []testTomorrowDaypart
+	PrecipTiming *testPrecipTiming
+}
+
+type testTomorrowDaypart struct {
+	Key     string
+	Summary testDaypartSummary
+}
+
+type testDaypartSummary struct {
+	DisplayName            string
+	TempRangeF             string
+	TemperaturePhraseF     string
+	MaxPopPercent          *int
+	MaxPopTime             string
+	MaxPopTimeLabel        string
+	MentionPrecipitation   bool
+	DominantCondition      string
+	DominantConditionLower string
+}
+
 type testCurrentConditions struct {
 	ConditionText           string
 	ConditionTextLower      string
--- a/internal/reporttemplate/templates/tomorrow.md.tmpl
+++ b/internal/reporttemplate/templates/tomorrow.md.tmpl
@@ -0,0 +1,26 @@
+# {{ .Report.Title }}
+
+**Forecast date:** {{ .Report.ForecastDateLabel }}
+**Updated:** {{ .Report.GeneratedAtLabel }}
+
+{{ .GeneratedText.Summary }}
+
+## Daypart Forecast
+{{ with .Modules.Dayparts }}{{ range . }}{{ $daypart := . }}
+- **{{ if .Summary.DisplayName }}{{ .Summary.DisplayName }}{{ else }}{{ .Key }}{{ end }}:** {{ if .Summary.TemperaturePhraseF }}{{ .Summary.TemperaturePhraseF }}{{ with .Summary.DominantConditionLower }} and {{ . }}{{ end }}{{ else }}{{ with .Summary.DominantConditionLower }}{{ . }}{{ else }}Forecast details are limited{{ end }}{{ end }}.{{ if .Summary.MentionPrecipitation }}{{ with .Summary.MaxPopPercent }} Precipitation chances peak at {{ . }}%{{ with $daypart.Summary.MaxPopTimeLabel }} at {{ . }}{{ else }}{{ with $daypart.Summary.MaxPopTime }} at {{ . }}{{ end }}{{ end }}.{{ end }}{{ end }}
+{{ end }}{{ else }}
+- No daypart forecast details are available.
+{{ end }}
+
+{{ with .Modules.PrecipTiming }}{{ with .PrecipitationWindows }}
+## Precipitation Timing
+{{ range . }}{{ $window := . }}
+- **{{ if .PeriodBeginsHourLabel }}{{ .PeriodBeginsHourLabel }}{{ else }}{{ .PeriodBegins }}{{ end }}**{{ with .PeriodEndsHourLabel }} to **{{ . }}**{{ else }}{{ with .PeriodEnds }} to **{{ . }}**{{ end }}{{ end }}: Precipitation is expected during this period.{{ with .MaxPopPercent }} The peak precipitation chance is {{ . }}%{{ with $window.MaxPopHourLabel }} at {{ . }}{{ else }}{{ with $window.MaxPopTime }} at {{ . }}{{ end }}{{ end }}.{{ end }}
+{{ end }}{{ with $.GeneratedText.PrecipitationTiming }}
+{{ . }}
+{{ end }}
+{{ end }}{{ end }}
+## Forecast Discussion
+{{ range .GeneratedText.ForecastDiscussion }}
+{{ . }}
+{{ end }}