Implement catalog idempotent publish skips

internal/publish/plan.go

@@ -231,6 +231,7 @@ func planExistingCatalog(ctx context.Context, req Request, catalog state.Catalog
 		Action:                actionForWorkflow(workflow),
 		CatalogOutputsToWrite: catalogOutputsForPlan(req, outputs, catalog.Outputs, scope, now),
 	}
+	allPlannedOutputsMatch := catalogContainsMatchingOutputs(req, catalog.Outputs, outputs, scope)
 	for _, output := range catalog.Outputs {
 		if _, exists := planned[output.Path]; exists {
 			continue
@@ -241,9 +242,43 @@ func planExistingCatalog(ctx context.Context, req Request, catalog state.Catalog
 		}
 		details.CatalogOutputsToRetain = append(details.CatalogOutputsToRetain, output)
 	}
+	if allPlannedOutputsMatch && (workflow == config.WorkflowAdditive || len(details.CatalogOutputsToDelete) == 0) {
+		details.Action = ActionSkipSame
+		details.CatalogOutputsToWrite = nil
+		details.CatalogOutputsToDelete = nil
+	}
 	return details, nil
 }
 
+func catalogContainsMatchingOutputs(req Request, existing []state.CatalogOutputFile, outputs []Output, scope state.OwnerScope) bool {
+	for _, output := range outputs {
+		catalogOutput, ok := state.FindCatalogOutputByPath(existing, output.DestinationPath)
+		if !ok || !catalogOutputMatchesPlan(req, catalogOutput, output, scope) {
+			return false
+		}
+	}
+	return true
+}
+
+func catalogOutputMatchesPlan(req Request, catalogOutput state.CatalogOutputFile, output Output, scope state.OwnerScope) bool {
+	if catalogOutput.PipelineID != scope.PipelineID ||
+		catalogOutput.DestinationID != scope.DestinationID ||
+		catalogOutput.Source.ID != req.SourceBundle.Manifest.ID ||
+		catalogOutput.Source.Digest != req.SourceBundle.Manifest.Digest ||
+		!catalogOutput.Source.Created.Equal(req.SourceBundle.Manifest.Created) ||
+		catalogOutput.Path != output.DestinationPath ||
+		catalogOutput.Kind != output.Kind ||
+		catalogOutput.URL != output.URL ||
+		catalogOutput.SHA256 != output.SHA256 ||
+		catalogOutput.Size != output.Size {
+		return false
+	}
+	if output.Kind == state.OutputKindGenerated {
+		return catalogOutput.SourcePath == output.SourcePath && catalogOutput.Transform == output.Transform
+	}
+	return catalogOutput.SourcePath == "" && catalogOutput.Transform == ""
+}
+
 func planSupersededLegacy(req Request, outputs []Output, workflow string, scope state.OwnerScope, now time.Time) catalogPlanDetails {
 	details := catalogPlanDetails{
 		Action:                actionForWorkflow(workflow),