Validate Distributor endpoints before publication

internal/app/app.go

@@ -250,6 +250,9 @@ func GenerateDetailed(ctx context.Context, req GenerateRequest) (*ReportResult,
 		return nil, err
 	}
 	result := initialReportResult(req, resolved, PromptInspectionResult{})
+	if err := preflightDistributorNotification(req.Config); err != nil {
+		return result, err
+	}
 	outputPath, err := resolveReportOutputPath(req.WorkingDir, req.OutputPath, req.Config.Output.Directory, resolved)
 	if err != nil {
 		return result, err
@@ -302,6 +305,9 @@ func RunBatchDetailed(ctx context.Context, req BatchRequest) (*BatchResult, erro
 	if _, err := report.BatchForCommandName(string(req.Batch)); err != nil {
 		return nil, err
 	}
+	if err := preflightDistributorNotification(req.Config); err != nil {
+		return nil, err
+	}
 	outputDir, err := resolveOutputDirWithConfigured(req.WorkingDir, req.OutputDir, req.Config.Output.Directory)
 	if err != nil {
 		return nil, err
@@ -512,6 +518,16 @@ func reportNotifier(cfg config.Config, notifier Notifier) (Notifier, bool) {
 	}, true
 }
 
+func preflightDistributorNotification(cfg config.Config) error {
+	if !cfg.Notify.Distributor.Enabled {
+		return nil
+	}
+	if err := config.ValidateDistributorEndpoint(cfg.Notify.Distributor.Endpoint); err != nil {
+		return fmt.Errorf("validate notify.distributor.endpoint: %w", err)
+	}
+	return nil
+}
+
 func buildNotificationRequest(cfg config.Config, resolved report.Resolved, outputPath, runID string, generatedAt time.Time) (NotificationRequest, error) {
 	values, err := distributorTemplateValuesForReport(cfg, resolved, runID, filepath.Base(outputPath))
 	if err != nil {

internal/app/batch_generation_test.go

@@ -61,6 +61,29 @@ func TestRunBatchDetailedNotifiesOnlyAfterAllOutputsExist(t *testing.T) {
 	}
 }
 
+func TestRunBatchDetailedRejectsUnsupportedDistributorEndpointBeforeWork(t *testing.T) {
+	outputDir := t.TempDir()
+	cfg := generationDistributorConfig()
+	cfg.Notify.Distributor.Endpoint = "ftp://distributor.example.test"
+	bundle := generationBundle(t)
+	collector := &generationCollector{bundle: &bundle}
+	executor := &generationExecutor{}
+	notifier := &generationNotifier{}
+
+	result, err := RunBatchDetailed(context.Background(), BatchRequest{
+		Config: cfg, Batch: BatchMorning,
+		Now: generationTime("2026-05-29T08:30:00-05:00"), WorkingDir: t.TempDir(), OutputDir: outputDir,
+		Collector: collector, Executor: executor, Notifier: notifier,
+	})
+	if err == nil || result != nil || collector.called || executor.promptInspections != 0 || executor.called || notifier.calls != 0 || notifier.batchCalls != 0 {
+		t.Fatalf("RunBatchDetailed() result/error/collector/executor/notifier = %#v/%v/%t/%#v/%#v", result, err, collector.called, executor, notifier)
+	}
+	entries, readErr := os.ReadDir(outputDir)
+	if readErr != nil || len(entries) != 0 {
+		t.Fatalf("output directory entries/error = %v/%v", entries, readErr)
+	}
+}
+
 func TestRunBatchDetailedUsesDefaultAndConfiguredOutputDirectories(t *testing.T) {
 	tests := []struct {
 		name      string

internal/app/generation_test.go

@@ -311,6 +311,28 @@ func TestGenerateDetailedRejectsOverlongOutputBeforeWork(t *testing.T) {
 	}
 }
 
+func TestGenerateDetailedRejectsUnsupportedDistributorEndpointBeforeWork(t *testing.T) {
+	outputPath := filepath.Join(t.TempDir(), "daily.md")
+	cfg := generationDistributorConfig()
+	cfg.Notify.Distributor.Endpoint = "ftp://distributor.example.test"
+	bundle := generationBundle(t)
+	collector := &generationCollector{bundle: &bundle}
+	executor := &generationExecutor{}
+	notifier := &generationNotifier{}
+
+	result, err := GenerateDetailed(context.Background(), GenerateRequest{
+		Config: cfg, Report: ReportDaily,
+		Date: generationTime("2026-05-29T12:00:00-05:00"), Now: generationTime("2026-05-29T08:30:00-05:00"),
+		WorkingDir: t.TempDir(), OutputPath: outputPath, Collector: collector, Executor: executor, Notifier: notifier,
+	})
+	if err == nil || result == nil || collector.called || executor.promptInspections != 0 || executor.called || notifier.calls != 0 {
+		t.Fatalf("GenerateDetailed() result/error/collector/executor/notifier = %#v/%v/%t/%#v/%#v", result, err, collector.called, executor, notifier)
+	}
+	if _, statErr := os.Stat(outputPath); !os.IsNotExist(statErr) {
+		t.Fatalf("output exists after endpoint preflight failure: %v", statErr)
+	}
+}
+
 func TestGenerateDetailedReturnsResolvedResultWhenCollectionFails(t *testing.T) {
 	cfg := config.Defaults()
 	cfg.WeatherAPI.Timezone, cfg.Location.ID = "America/Chicago", "home"