feat: add descriptive error messages for missing positional arguments

Replace Cobra's generic "accepts N arg(s), received 0" errors with
contextual messages like "missing incident_id. Usage: flashduty
incident update <id>", helping CLI users understand what's needed.

Author: debidong

internal/cli/args.go

@@ -0,0 +1,22 @@
+package cli
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/spf13/cobra"
+)
+
+// requireArgs returns a positional argument validator that produces descriptive
+// error messages naming the missing arguments, e.g.:
+//
+//	"missing incident_id. Usage: flashduty incident update <id>"
+func requireArgs(argNames ...string) cobra.PositionalArgs {
+	return func(cmd *cobra.Command, args []string) error {
+		if len(args) < len(argNames) {
+			missing := argNames[len(args):]
+			return fmt.Errorf("missing %s. Usage: %s", strings.Join(missing, ", "), cmd.UseLine())
+		}
+		return nil
+	}
+}

internal/cli/config.go

@@ -44,7 +44,7 @@ func newConfigSetCmd() *cobra.Command {
 		Use:   "set <key> <value>",
 		Short: "Set a configuration value",
 		Long:  "Supported keys: app_key, base_url",
-		Args:  cobra.ExactArgs(2),
+		Args:  requireArgs("key", "value"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			key, value := args[0], args[1]
 

internal/cli/incident.go

@@ -108,7 +108,7 @@ func newIncidentGetCmd() *cobra.Command {
 	return &cobra.Command{
 		Use:   "get <id> [<id2> ...]",
 		Short: "Get incident details",
-		Args:  cobra.MinimumNArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -252,7 +252,7 @@ func newIncidentUpdateCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "update <id>",
 		Short: "Update an incident",
-		Args:  cobra.ExactArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -302,7 +302,7 @@ func newIncidentAckCmd() *cobra.Command {
 	return &cobra.Command{
 		Use:   "ack <id> [<id2> ...]",
 		Short: "Acknowledge incidents",
-		Args:  cobra.MinimumNArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -321,7 +321,7 @@ func newIncidentCloseCmd() *cobra.Command {
 	return &cobra.Command{
 		Use:   "close <id> [<id2> ...]",
 		Short: "Close incidents",
-		Args:  cobra.MinimumNArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -340,7 +340,7 @@ func newIncidentTimelineCmd() *cobra.Command {
 	return &cobra.Command{
 		Use:   "timeline <id>",
 		Short: "View incident timeline",
-		Args:  cobra.ExactArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -381,7 +381,7 @@ func newIncidentAlertsCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "alerts <id>",
 		Short: "View incident alerts",
-		Args:  cobra.ExactArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {
@@ -427,7 +427,7 @@ func newIncidentSimilarCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "similar <id>",
 		Short: "Find similar incidents",
-		Args:  cobra.ExactArgs(1),
+		Args:  requireArgs("incident_id"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := newClient()
 			if err != nil {