fix: handle 'default' collection filter in cluster volumes page

- Update matchesCollection to recognize 'default' as filter for empty collection
- Remove incorrect conversion of 'default' to empty string in handlers
- Fixes issue where ?collection=default would show all collections instead of just default collection

weed/admin/dash/ec_shard_management.go

@@ -16,8 +16,8 @@ import (
 // matchesCollection checks if a volume/EC volume collection matches the filter collection.
 // Handles the special case where empty collection ("") represents the "default" collection.
 func matchesCollection(volumeCollection, filterCollection string) bool {
-	// Both empty means default collection matches default filter
-	if volumeCollection == "" && filterCollection == "" {
+	// Handle special case where "default" filter matches empty collection
+	if filterCollection == "default" && volumeCollection == "" {
 		return true
 	}
 	// Direct string match for named collections

weed/admin/handlers/cluster_handlers.go

@@ -170,12 +170,6 @@ func (h *ClusterHandlers) ShowCollectionDetails(c *gin.Context) {
 		return
 	}
 
-	// Map "default" collection to empty string for backend filtering
-	actualCollectionName := collectionName
-	if collectionName == "default" {
-		actualCollectionName = ""
-	}
-
 	// Parse query parameters
 	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "25"))
@@ -183,7 +177,7 @@ func (h *ClusterHandlers) ShowCollectionDetails(c *gin.Context) {
 	sortOrder := c.DefaultQuery("sort_order", "asc")
 
 	// Get collection details data (volumes and EC volumes)
-	collectionDetailsData, err := h.adminServer.GetCollectionDetails(actualCollectionName, page, pageSize, sortBy, sortOrder)
+	collectionDetailsData, err := h.adminServer.GetCollectionDetails(collectionName, page, pageSize, sortBy, sortOrder)
 	if err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to get collection details: " + err.Error()})
 		return