fix(signature-flow): block no-op default option on instance create

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/views/Settings/PolicyWorkbench/settings/signature-flow/SignatureFlowScalarRuleEditor.vue

@@ -11,15 +11,19 @@
 				:key="flow.value"
 				class="signature-flow-scalar-editor__option"
 				type="radio"
+				:disabled="flow.disabled"
 				:model-value="normalizedValue === flow.value"
 				name="signature-flow-scalar-editor"
-				@update:modelValue="onFlowChange(flow.value, $event)">
+				@update:modelValue="onFlowChange(flow.value, flow.disabled, $event)">
 				<div class="signature-flow-scalar-editor__copy">
 					<strong>{{ flow.label }}</strong>
 					<p>{{ flow.description }}</p>
 				</div>
 			</NcCheckboxRadioSwitch>
 		</div>
+		<p v-if="isInstanceCreateMode" class="signature-flow-scalar-editor__hint">
+			{{ t('libresign', 'To create an instance rule, choose Simultaneous or Sequential. "Let users choose" already matches the system default and is not saved as an instance override.') }}
+		</p>
 	</div>
 </template>
 
@@ -36,13 +40,15 @@ defineOptions({
 
 const props = defineProps<{
 	modelValue: EffectivePolicyValue
+	editorScope?: 'system' | 'group' | 'user'
+	editorMode?: 'create' | 'edit' | null
 }>()
 
 const emit = defineEmits<{
 	'update:modelValue': [value: EffectivePolicyValue]
 }>()
 
-const flows: Array<{ value: SignatureFlowMode | 'none', label: string, description: string }> = [
+const baseFlows: Array<{ value: SignatureFlowMode | 'none', label: string, description: string }> = [
 	{
 		value: 'parallel',
 		label: t('libresign', 'Simultaneous (Parallel)'),
@@ -60,6 +66,27 @@ const flows: Array<{ value: SignatureFlowMode | 'none', label: string, descripti
 	},
 ]
 
+const isInstanceCreateMode = computed(() => {
+	return props.editorScope === 'system' && props.editorMode === 'create'
+})
+
+const flows = computed(() => {
+	return baseFlows.map((flow) => {
+		if (flow.value === 'none' && isInstanceCreateMode.value) {
+			return {
+				...flow,
+				disabled: true,
+				description: t('libresign', 'Already the system default for this setting. Choose another option to create an explicit instance rule.'),
+			}
+		}
+
+		return {
+			...flow,
+			disabled: false,
+		}
+	})
+})
+
 const normalizedValue = computed<SignatureFlowMode | 'none' | null>(() => {
 	const value = props.modelValue
 	if (value === 'parallel' || value === 'ordered_numeric' || value === 'none') {
@@ -69,8 +96,8 @@ const normalizedValue = computed<SignatureFlowMode | 'none' | null>(() => {
 	return null
 })
 
-function onFlowChange(flow: SignatureFlowMode | 'none', selected?: unknown) {
-	if (selected === false) {
+function onFlowChange(flow: SignatureFlowMode | 'none', disabled: boolean, selected?: unknown) {
+	if (disabled || selected === false) {
 		return
 	}
 
@@ -99,6 +126,12 @@ function onFlowChange(flow: SignatureFlowMode | 'none', selected?: unknown) {
 		color: var(--color-text-maxcontrast);
 	}
 
+	&__hint {
+		margin: 0;
+		font-size: 0.84rem;
+		color: var(--color-text-maxcontrast);
+	}
+
 	:deep(.signature-flow-scalar-editor__option.checkbox-radio-switch) {
 		width: 100%;
 	}