Segments: Preserve segmented property values after save (closes #22166)

src/Umbraco.Web.UI.Client/src/packages/content/content/workspace/content-detail-workspace-base.ts

@@ -1,4 +1,4 @@
 import type { UmbContentDetailModel, UmbElementValueModel } from '../types.js';
 import { UmbContentCollectionManager } from '../collection/index.js';
 import { UmbContentWorkspaceDataManager } from '../manager/index.js';
 import { UmbMergeContentVariantDataController } from '../controller/merge-content-variant-data.controller.js';
@@ -500,7 +500,23 @@
 		data.values = dataValues;
 		*/
 
-		return { ...data, values: processedValues };
+		// Merge: start with processed values, then add any original server values
+		// that weren't covered by the preset builder's variant options.
+		// This prevents segment-specific values from being silently dropped
+		// when variant options don't cover all culture+segment combinations.
+		const mergedValues = [...processedValues];
+		const variantKey = (v: { alias: string; culture: string | null; segment: string | null }) =>
+			`${v.alias}|${UmbVariantId.Create(v).toString()}`;
+		const coveredKeys = new Set(processedValues.map(variantKey));
+		for (const serverValue of data.values) {
+			const key = variantKey(serverValue);
+			if (!coveredKeys.has(key)) {
+				coveredKeys.add(key);
+				mergedValues.push(serverValue);
+			}
+		}
+
+		return { ...data, values: mergedValues };
 	}
 
 	/**