Harden report output publication

internal/app/generation_test.go

@@ -26,6 +26,20 @@ type generationCollector struct {
 	beforeRun func()
 }
 
+type publicationGateContext struct {
+	context.Context
+	err    error
+	checks int
+}
+
+func (c *publicationGateContext) Err() error {
+	c.checks++
+	if c.checks >= 2 {
+		return c.err
+	}
+	return nil
+}
+
 func (c *generationCollector) Run(context.Context, collect.Request) (*collect.Result, error) {
 	if c.beforeRun != nil {
 		c.beforeRun()
@@ -385,6 +399,41 @@ func TestGenerateDetailedPreservesDestinationWhenContextDeadlineExpiresBeforePub
 	}
 }
 
+func TestGenerateDetailedPreservesDestinationWhenContextChangesDuringPublication(t *testing.T) {
+	for _, tt := range []struct {
+		name     string
+		err      error
+		category promptexec.ErrorCategory
+	}{
+		{name: "canceled", err: context.Canceled, category: promptexec.Canceled},
+		{name: "deadline", err: context.DeadlineExceeded, category: promptexec.DeadlineExceeded},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			outputPath := filepath.Join(t.TempDir(), "daily.md")
+			const previousReport = "previous report"
+			if err := os.WriteFile(outputPath, []byte(previousReport), 0o600); err != nil {
+				t.Fatal(err)
+			}
+			ctx := &publicationGateContext{Context: context.Background(), err: tt.err}
+			cfg := generationConfig()
+			cfg.Notify.Distributor.Enabled = true
+			cfg.Notify.Distributor.PipelineIDTemplate = "weather"
+			bundle := generationBundle(t)
+			notifier := &generationNotifier{}
+			result, err := GenerateDetailed(ctx, 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: &generationCollector{bundle: &bundle}, Executor: &generationExecutor{}, Notifier: notifier,
+			})
+			data, readErr := os.ReadFile(outputPath)
+			matches, globErr := filepath.Glob(filepath.Join(filepath.Dir(outputPath), ".weatherreporter-*.tmp"))
+			if !errors.Is(err, tt.err) || promptexec.CategoryOf(err) != tt.category || result == nil || result.OutputPath != "" || notifier.calls != 0 || readErr != nil || string(data) != previousReport || globErr != nil || len(matches) != 0 {
+				t.Fatalf("GenerateDetailed() result/error/output/notification/temp = %#v/%v/%q/%#v/%v/%v", result, err, data, notifier, matches, globErr)
+			}
+		})
+	}
+}
+
 func TestGenerateDetailedRetainsPublishedOutputWhenNotificationFails(t *testing.T) {
 	cfg := generationConfig()
 	cfg.Notify.Distributor.Enabled = true
@@ -407,10 +456,35 @@ func TestGenerateDetailedDoesNotReplaceDirectoryOutput(t *testing.T) {
 	if err := os.Mkdir(outputPath, 0o700); err != nil {
 		t.Fatal(err)
 	}
-	result, err := GenerateDetailed(context.Background(), GenerateRequest{Config: generationConfig(), 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: &generationCollector{bundle: &bundle}, Executor: &generationExecutor{}})
+	collector := &generationCollector{bundle: &bundle}
+	executor := &generationExecutor{}
+	notifier := &generationNotifier{}
+	result, err := GenerateDetailed(context.Background(), GenerateRequest{Config: generationConfig(), 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})
 	info, statErr := os.Stat(outputPath)
-	if err == nil || result == nil || statErr != nil || !info.IsDir() {
-		t.Fatalf("GenerateDetailed() result/error/output-info = %#v/%v/%#v (%v)", result, err, info, statErr)
+	if err == nil || result == nil || statErr != nil || !info.IsDir() || collector.called || executor.promptInspections != 0 || executor.called || notifier.calls != 0 {
+		t.Fatalf("GenerateDetailed() result/error/output-info/collector/executor/notifier = %#v/%v/%#v (%v)/%t/%#v/%#v", result, err, info, statErr, collector.called, executor, notifier)
+	}
+}
+
+func TestGenerateDetailedDoesNotReplaceSymbolicLinkOutput(t *testing.T) {
+	dir := t.TempDir()
+	backing := filepath.Join(dir, "backing.md")
+	if err := os.WriteFile(backing, []byte("previous report"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	outputPath := filepath.Join(dir, "daily.md")
+	if err := os.Symlink(backing, outputPath); err != nil {
+		t.Fatal(err)
+	}
+	bundle := generationBundle(t)
+	collector := &generationCollector{bundle: &bundle}
+	executor := &generationExecutor{}
+	notifier := &generationNotifier{}
+	result, err := GenerateDetailed(context.Background(), GenerateRequest{Config: generationConfig(), 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})
+	info, statErr := os.Lstat(outputPath)
+	data, readErr := os.ReadFile(backing)
+	if err == nil || result == nil || statErr != nil || info.Mode()&os.ModeSymlink == 0 || readErr != nil || string(data) != "previous report" || collector.called || executor.promptInspections != 0 || executor.called || notifier.calls != 0 {
+		t.Fatalf("GenerateDetailed() result/error/output/backing/collector/executor/notifier = %#v/%v/%#v (%v)/%q (%v)/%t/%#v/%#v", result, err, info, statErr, data, readErr, collector.called, executor, notifier)
 	}
 }