Add comparison command request parsing

internal/app/comparison_test.go

@@ -13,6 +13,7 @@ import (
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/config"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/promptexec"
 	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
+	"gitea.maximumdirect.net/eric/weatherreporter/internal/weatherdata"
 )
 
 func TestCompareDetailedPublishesOneCoherentBundle(t *testing.T) {
@@ -102,6 +103,33 @@ func TestCompareDetailedPreflightsBeforePromptOrCollection(t *testing.T) {
 	}
 }
 
+func TestCompareDetailedLeavesDestinationWhenCollectionOrPreparationFails(t *testing.T) {
+	collectionErr := errors.New("weather collection failed")
+	for _, test := range []struct {
+		name      string
+		collector *generationCollector
+	}{
+		{name: "collection", collector: &generationCollector{err: collectionErr}},
+		{name: "preparation", collector: &generationCollector{bundle: &weatherdata.Bundle{}}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			workingDir := t.TempDir()
+			executor := &generationExecutor{}
+			result, err := CompareDetailed(context.Background(), ComparisonRequest{
+				Config: comparisonConfig(), Report: ReportDaily, ProfileIDs: []string{"weather-light", "weather-deep"},
+				WorkingDir: workingDir, Date: generationTime("2026-05-29T12:00:00-05:00"),
+				Clock: timeutil.FixedClock{Time: generationTime("2026-05-29T08:30:00-05:00")}, Collector: test.collector, Executor: executor,
+			})
+			if err == nil || result == nil || executor.executeCalls != 0 || result.ManifestPath != "" || result.DataPackagePath != "" {
+				t.Fatalf("CompareDetailed() result/error/executor = %#v/%v/%#v", result, err, executor)
+			}
+			if _, statErr := os.Stat(filepath.Join(workingDir, "comparison-daily-2026-05-29")); !os.IsNotExist(statErr) {
+				t.Fatalf("comparison destination stat error = %v", statErr)
+			}
+		})
+	}
+}
+
 func TestCompareDetailedPublishesManifestWhenEveryProfileFails(t *testing.T) {
 	bundle := generationBundle(t)
 	executor := &generationExecutor{executeErrors: map[string]error{