diff --git a/internal/cmd/customers.go b/internal/cmd/customers.go
index 63f6953..64d728c 100644
--- a/internal/cmd/customers.go
+++ b/internal/cmd/customers.go
@@ -101,6 +101,7 @@ func newCustomersCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "customer")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -168,6 +169,12 @@ type customerInputFlags struct {
 func (f *customerInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.name, "name", "", "Customer name")
 	cmd.Flags().StringVar(&f.externalCustomerID, "external-customer-id", "", "External customer ID")
+}
+
+// registerSlug adds --slug to create only. The API never renames a customer:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *customerInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "Customer slug")
 }
 
diff --git a/internal/cmd/deployment_zones.go b/internal/cmd/deployment_zones.go
index b77a09c..80bee94 100644
--- a/internal/cmd/deployment_zones.go
+++ b/internal/cmd/deployment_zones.go
@@ -101,6 +101,7 @@ func newDeploymentZonesCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "deployment zone")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -175,6 +176,12 @@ func (f *deploymentZoneInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.description, "description", "", "Deployment zone description")
 	cmd.Flags().StringVar(&f.metadata, "metadata-json", "", "Deployment zone metadata as inline JSON or YAML object")
 	cmd.Flags().StringVar(&f.releaseID, "release-id", "", "Release ID")
+}
+
+// registerSlug adds --slug to create only. The API never renames a deployment zone:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *deploymentZoneInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "Deployment zone slug")
 }
 
diff --git a/internal/cmd/entitlement_groups.go b/internal/cmd/entitlement_groups.go
index eb9770c..7a06930 100644
--- a/internal/cmd/entitlement_groups.go
+++ b/internal/cmd/entitlement_groups.go
@@ -104,6 +104,7 @@ func newEntitlementGroupsCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "entitlement group")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -251,6 +252,12 @@ type entitlementGroupInputFlags struct {
 func (f *entitlementGroupInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.name, "name", "", "Entitlement group name")
 	cmd.Flags().StringVar(&f.description, "description", "", "Entitlement group description")
+}
+
+// registerSlug adds --slug to create only. The API never renames an entitlement group:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *entitlementGroupInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "Entitlement group slug")
 }
 
diff --git a/internal/cmd/entitlements.go b/internal/cmd/entitlements.go
index d41c820..3c67830 100644
--- a/internal/cmd/entitlements.go
+++ b/internal/cmd/entitlements.go
@@ -101,6 +101,7 @@ func newEntitlementsCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "entitlement")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -175,6 +176,12 @@ func (f *entitlementInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.kind, "type", "", "Entitlement type")
 	cmd.Flags().StringVar(&f.aggregationMethod, "aggregation-method", "", "Entitlement aggregation method")
 	cmd.Flags().StringArrayVar(&f.groupSlugs, "group-slug", nil, "Entitlement group slug, repeat for multiple values")
+}
+
+// registerSlug adds --slug to create only. The API never renames an entitlement:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *entitlementInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "Entitlement slug")
 }
 
diff --git a/internal/cmd/exit_test.go b/internal/cmd/exit_test.go
index 8e7f73a..5f77a23 100644
--- a/internal/cmd/exit_test.go
+++ b/internal/cmd/exit_test.go
@@ -105,6 +105,10 @@ func TestExitCodeForUsageMistakes(t *testing.T) {
 			name: "unsupported config key",
 			args: []string{"config", "set", "bogus", "value"},
 		},
+		{
+			name: "a slug on the update of a resource the API never renames",
+			args: []string{"--base-url", "http://127.0.0.1:1", "entitlements", "update", "webhook", "--name", "webhook", "--slug", "webhooks"},
+		},
 		{
 			name: "destructive command with a non-interactive stdin and no --yes",
 			args: []string{"--base-url", "http://127.0.0.1:1", "customers", "delete", "acme"},
diff --git a/internal/cmd/input_sources_test.go b/internal/cmd/input_sources_test.go
index 0f3b36a..a2e581a 100644
--- a/internal/cmd/input_sources_test.go
+++ b/internal/cmd/input_sources_test.go
@@ -273,6 +273,40 @@ func TestInlineFlagsAreRecognisedByTheCommandThatRegistersThem(t *testing.T) {
 	})
 }
 
+// TestSlugFlagIsOfferedOnlyWhereTheAPIActsOnIt pins --slug to the commands where a slug
+// does something. Six resources are never renamed: their update accepts the slug already
+// in the path and refuses any other. The SDK dropped the field on those updates, so
+// "update webhook --slug webhooks" printed a success and left the slug alone. Components
+// and instances do take a slug on update, so they keep the flag there.
+func TestSlugFlagIsOfferedOnlyWhereTheAPIActsOnIt(t *testing.T) {
+	root := NewRootCommand()
+
+	for path, want := range map[string]bool{
+		"customers create":          true,
+		"customers update":          false,
+		"deployment-zones create":   true,
+		"deployment-zones update":   false,
+		"entitlement-groups create": true,
+		"entitlement-groups update": false,
+		"entitlements create":       true,
+		"entitlements update":       false,
+		"licenses create":           true,
+		"licenses update":           false,
+		"service-accounts create":   true,
+		"service-accounts update":   false,
+		"components update":         true,
+		"instances update":          true,
+	} {
+		cmd, _, err := root.Find(strings.Split(path, " "))
+		if err != nil {
+			t.Fatalf("Find(%q) error = %v", path, err)
+		}
+		if got := cmd.Flags().Lookup("slug") != nil; got != want {
+			t.Errorf("%q offers --slug = %t, want %t", path, got, want)
+		}
+	}
+}
+
 // placeholderArgs supplies one throwaway value per positional argument in the command's
 // Use line, so that argument validation is satisfied and the run reaches the input check.
 func placeholderArgs(cmd *cobra.Command) []string {
diff --git a/internal/cmd/licenses.go b/internal/cmd/licenses.go
index deb59c3..01cf5a5 100644
--- a/internal/cmd/licenses.go
+++ b/internal/cmd/licenses.go
@@ -102,6 +102,7 @@ func newLicensesCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "license")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -331,6 +332,12 @@ func (f *licenseInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.version, "version", "", "License version")
 	cmd.Flags().StringVar(&f.versionName, "version-name", "", "Human-readable license version name")
 	cmd.Flags().BoolVar(&f.isDefault, "default", false, "Whether the license is the default")
+}
+
+// registerSlug adds --slug to create only. The API never renames a license:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *licenseInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "License slug")
 }
 
diff --git a/internal/cmd/service_accounts.go b/internal/cmd/service_accounts.go
index 404b2d8..1573bfe 100644
--- a/internal/cmd/service_accounts.go
+++ b/internal/cmd/service_accounts.go
@@ -101,6 +101,7 @@ func newServiceAccountsCreateCommand() *cobra.Command {
 	}
 	addInputSourceFlags(cmd, &file, &payload, "service account")
 	inline.register(cmd)
+	inline.registerSlug(cmd)
 	return cmd
 }
 
@@ -238,6 +239,12 @@ type serviceAccountInputFlags struct {
 
 func (f *serviceAccountInputFlags) register(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.name, "name", "", "Service account name")
+}
+
+// registerSlug adds --slug to create only. The API never renames a service account:
+// its update accepts the slug already in the path and refuses any other, so the
+// flag could only restate the argument or be refused.
+func (f *serviceAccountInputFlags) registerSlug(cmd *cobra.Command) {
 	cmd.Flags().StringVar(&f.slug, "slug", "", "Service account slug")
 }