[#74316] add dry-run JSON WP mutations

Add parent-aware create dry-runs and schema-driven update
dry-runs for work packages, both with machine-readable JSON
output.

Keep the legacy typed update flags intact while adding --set,
--parent, --dry-run, and --json as the agent workflow surface.

https://community.openproject.org/projects/cli/work_packages/74316

Author: myabc

README.md

@@ -174,6 +174,10 @@ op update workpackage 42 --subject 'The new subject' --status 'In Progress' --ty
 
 # Uploading an attachment to a work package
 op update workpackage 42 --attach ./Downloads/Report.pdf
+
+# Resolving and validating field updates as JSON before applying them
+# This first slice supports schema-resolved custom fields via --set.
+op update workpackage 74316 --set 'Votes=3' --dry-run --json
 ```
 
 #### Inspecting
@@ -182,6 +186,9 @@ op update workpackage 42 --attach ./Downloads/Report.pdf
 # Inspecting a work package with more details,
 # then in the work package list command
 op inspect workpackage 42
+
+# Inspecting a work package and its direct children as machine-readable JSON
+op inspect workpackage 74316 --children --json
 ```
 
 ## Creating a release

cmd/create/create.go

@@ -16,7 +16,6 @@ func init() {
 		0,
 		"Project ID to create the work package in",
 	)
-	_ = createWorkPackageCmd.MarkFlagRequired("project")
 
 	createWorkPackageCmd.Flags().BoolVarP(
 		&shouldOpenWorkPackageInBrowser,
@@ -34,5 +33,26 @@ func init() {
 		"Change the work package type",
 	)
 
+	createWorkPackageCmd.Flags().Uint64Var(
+		&parentWorkPackageID,
+		"parent",
+		0,
+		"Create the work package as a child of an existing work package",
+	)
+
+	createWorkPackageCmd.Flags().BoolVar(
+		&printCreatedWorkPackageAsJSON,
+		"json",
+		false,
+		"Print machine-readable JSON output",
+	)
+
+	createWorkPackageCmd.Flags().BoolVar(
+		&dryRunCreateWorkPackage,
+		"dry-run",
+		false,
+		"Resolve and validate without persisting the work package",
+	)
+
 	RootCmd.AddCommand(createWorkPackageCmd)
 }

cmd/create/work_package.go

@@ -5,14 +5,19 @@ import (
 
 	"github.com/spf13/cobra"
 
+	componentErrors "github.com/opf/openproject-cli/components/errors"
 	"github.com/opf/openproject-cli/components/launch"
+	"github.com/opf/openproject-cli/components/presenter"
 	"github.com/opf/openproject-cli/components/printer"
 	"github.com/opf/openproject-cli/components/resources/work_packages"
 	"github.com/opf/openproject-cli/components/routes"
 )
 
 var projectId uint64
+var parentWorkPackageID uint64
 var shouldOpenWorkPackageInBrowser bool
+var printCreatedWorkPackageAsJSON bool
+var dryRunCreateWorkPackage bool
 var typeFlag string
 
 var createWorkPackageCmd = &cobra.Command{
@@ -24,14 +29,55 @@ var createWorkPackageCmd = &cobra.Command{
 
 func createWorkPackage(_ *cobra.Command, args []string) {
 	if len(args) != 1 {
-		printer.ErrorText(fmt.Sprintf("Expected 1 argument [subject], but got %d", len(args)))
+		printCreateError("invalid_argument", fmt.Sprintf("Expected 1 argument [subject], but got %d", len(args)))
+		return
+	}
+
+	if err := validateCreateWorkPackageFlags(); err != nil {
+		printCreateError("conflicting_arguments", err.Error())
 		return
 	}
 
 	subject := args[0]
-	workPackage, err := work_packages.Create(projectId, createOptions(subject))
+	options := createOptions(subject)
+
+	if dryRunCreateWorkPackage {
+		plan, err := work_packages.DryRunCreate(projectId, options)
+		if err != nil {
+			printCreateError(createErrorCode(err), err.Error())
+			return
+		}
+
+		data, err := presenter.MarshalJSON(plan)
+		if err != nil {
+			printer.Error(err)
+			return
+		}
+
+		printer.Info(string(data))
+		return
+	}
+
+	workPackage, err := work_packages.Create(projectId, options)
 	if err != nil {
-		printer.Error(err)
+		printCreateError(createErrorCode(err), err.Error())
+		return
+	}
+
+	if printCreatedWorkPackageAsJSON {
+		payload, err := work_packages.Inspect(workPackage.Id)
+		if err != nil {
+			printCreateError("post_apply_inspect_failed", err.Error())
+			return
+		}
+
+		data, err := presenter.MarshalJSON(payload)
+		if err != nil {
+			printer.Error(err)
+			return
+		}
+
+		printer.Info(string(data))
 		return
 	}
 
@@ -54,5 +100,44 @@ func createOptions(subject string) map[work_packages.CreateOption]string {
 		options[work_packages.CreateType] = typeFlag
 	}
 
+	if parentWorkPackageID > 0 {
+		options[work_packages.CreateParent] = fmt.Sprintf("%d", parentWorkPackageID)
+	}
+
 	return options
 }
+
+func validateCreateWorkPackageFlags() error {
+	if shouldOpenWorkPackageInBrowser && printCreatedWorkPackageAsJSON {
+		return fmt.Errorf("cannot use --open together with --json")
+	}
+
+	if dryRunCreateWorkPackage && !printCreatedWorkPackageAsJSON {
+		return fmt.Errorf("cannot use --dry-run without --json")
+	}
+
+	return nil
+}
+
+func printCreateError(code, message string) {
+	if !printCreatedWorkPackageAsJSON {
+		printer.ErrorText(message)
+		return
+	}
+
+	data, err := presenter.MarshalError(code, message)
+	if err != nil {
+		printer.Error(err)
+		return
+	}
+
+	printer.Info(string(data))
+}
+
+func createErrorCode(err error) string {
+	if componentErrors.IsCustom(err) {
+		return "invalid_argument"
+	}
+
+	return "api_error"
+}