Add Daily briefing JSON generation

internal/app/app_test.go

@@ -65,6 +65,71 @@ func TestFetchAndSaveBundleRequiresOutputPath(t *testing.T) {
 	}
 }
 
+func TestGenerateDailyBriefingWritesArtifact(t *testing.T) {
+	server := dailyBundleServer(t)
+	cfg := config.Defaults()
+	cfg.WeatherAPI.BaseURL = server.URL + "/"
+	cfg.WeatherAPI.Timezone = "America/Chicago"
+	resolved, err := ResolveGenerate(GenerateRequest{
+		Config: cfg,
+		Report: ReportDaily,
+		Date:   mustParse("2026-05-29T12:00:00-05:00"),
+	}, mustParse("2026-05-29T05:00:00-05:00"))
+	if err != nil {
+		t.Fatalf("ResolveGenerate() error = %v", err)
+	}
+	path := filepath.Join(t.TempDir(), "daily.briefing.json")
+
+	result, err := GenerateDailyBriefing(context.Background(), DailyBriefingRequest{
+		Config:     cfg,
+		Resolved:   resolved,
+		OutputPath: path,
+	})
+	if err != nil {
+		t.Fatalf("GenerateDailyBriefing() error = %v", err)
+	}
+	if result.OutputPath != path {
+		t.Fatalf("OutputPath = %q, want %q", result.OutputPath, path)
+	}
+	if result.Package.Daily == nil {
+		t.Fatal("Daily = nil")
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read briefing artifact: %v", err)
+	}
+	if !strings.Contains(string(data), `"schemaVersion"`) || !strings.Contains(string(data), `"daily"`) {
+		t.Fatalf("briefing artifact missing expected fields:\n%s", string(data))
+	}
+}
+
+func TestGenerateDailyBriefingDefaultPath(t *testing.T) {
+	server := dailyBundleServer(t)
+	cfg := config.Defaults()
+	cfg.WeatherAPI.BaseURL = server.URL + "/"
+	cfg.WeatherAPI.Timezone = "America/Chicago"
+	cfg.Workspace.Root = t.TempDir()
+	resolved, err := ResolveGenerate(GenerateRequest{
+		Config: cfg,
+		Report: ReportDaily,
+		Date:   mustParse("2026-05-29T12:00:00-05:00"),
+	}, mustParse("2026-05-29T05:00:00-05:00"))
+	if err != nil {
+		t.Fatalf("ResolveGenerate() error = %v", err)
+	}
+
+	result, err := GenerateDailyBriefing(context.Background(), DailyBriefingRequest{
+		Config:   cfg,
+		Resolved: resolved,
+	})
+	if err != nil {
+		t.Fatalf("GenerateDailyBriefing() error = %v", err)
+	}
+	if !strings.HasSuffix(result.OutputPath, filepath.Join("snapshots", "daily", "2026-05-29", "2026-05-29.daily_today.briefing.json")) {
+		t.Fatalf("OutputPath = %q, want deterministic daily briefing path", result.OutputPath)
+	}
+}
+
 func TestResolveGenerateMapsCommandToReportDefinition(t *testing.T) {
 	cfg := config.Defaults()
 	cfg.WeatherAPI.Timezone = "America/Chicago"
@@ -88,6 +153,30 @@ func TestResolveGenerateMapsCommandToReportDefinition(t *testing.T) {
 	}
 }
 
+func dailyBundleServer(t *testing.T) *httptest.Server {
+	t.Helper()
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/observations":
+			_, _ = w.Write([]byte(`{"data":{"timestamp":"2026-05-29T14:00:00Z","conditionCode":3}}`))
+		case "/conditions/current":
+			_, _ = w.Write([]byte(`{"data":{"conditionText":"Clear"}}`))
+		case "/forecast/hourly":
+			_, _ = w.Write([]byte(`{"data":{"locationId":"test-grid","locationName":"Testville","issuedAt":"2026-05-29T10:30:00-05:00","product":"hourly","periods":[{"startTime":"2026-05-29T06:00:00-05:00","endTime":"2026-05-29T07:00:00-05:00","textDescription":"Showers and thunderstorms","temperatureF":66,"probabilityOfPrecipitationPercent":80,"windGustMph":32}]}}`))
+		case "/forecast/narrative":
+			_, _ = w.Write([]byte(`{"data":{"issuedAt":"2026-05-29T10:30:00-05:00","product":"narrative","periods":[{"startTime":"2026-05-29T06:00:00-05:00","endTime":"2026-05-29T18:00:00-05:00","textDescription":"Morning storms, then partly sunny."}]}}`))
+		case "/alerts/active":
+			_, _ = w.Write([]byte(`{"data":{"alerts":[{"event":"Flood Watch","effective":"2026-05-29T05:00:00-05:00","expires":"2026-05-29T09:00:00-05:00"}]}}`))
+		case "/discussion":
+			_, _ = w.Write([]byte(`{"data":{"product":"discussion","issuedAt":"2026-05-29T09:25:00-05:00","keyMessages":["Storms are most likely during the morning."]}}`))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	t.Cleanup(server.Close)
+	return server
+}
+
 func TestResolveGenerateStorm(t *testing.T) {
 	cfg := config.Defaults()
 	cfg.WeatherAPI.Timezone = "America/Chicago"