Fix: add persisted project folder deletion

Frontend/src/components/shell/WorkspaceSidebar/WorkspaceSidebar.tsx

@@ -581,6 +581,36 @@ export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 		}
 	};
 
+	const deletePersistedFolder = async (folderId: string): Promise<void> => {
+		const projectId = activeProject()?.id ?? "";
+		if (!folderId || !projectId || !isUuidString(projectId)) {
+			return;
+		}
+
+		try {
+			const response = await fetch(
+				`${resolveAPIBase()}/projects/${projectId}/tree/folders?folderId=${encodeURIComponent(folderId)}`,
+				{
+					method: "DELETE",
+					headers: {
+						Accept: "application/json",
+					},
+				},
+			);
+
+			const body = (await response.json()) as WorkspaceFoldersResponse;
+
+			if (!response.ok) {
+				throw new Error(body.message || "Failed to delete project tree folder.");
+			}
+
+			setPersistedFolders(readPersistedWorkspaceFolders(body));
+			setCollapsedFolderIds((current) => current.filter((id) => id !== folderId));
+		} catch (error) {
+			console.error(error);
+		}
+	};
+
 	const cancelPendingFolder = (): void => {
 		setPendingFolderDraft(null);
 		setPendingFolderName("");
@@ -639,20 +669,27 @@ export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 	};
 
 	const handleContextActionSelect = (action: WorkspaceContextMenuAction, target: WorkspaceContextMenuTarget): void => {
-		if (action.id !== "new-folder") {
-			return;
-		}
-
-			switch (target.kind) {
-			case "workspace":
-			case "home":
-				beginFolderDraft(null, 0);
+		switch (action.id) {
+			case "new-folder":
+				switch (target.kind) {
+					case "workspace":
+					case "home":
+						beginFolderDraft(null, 0);
+						return;
+					case "folder":
+						beginFolderDraft(target.id, (findTreeNodeDepth(workspaceTreeNodes(), target.id, workspaceTreeAdapter) ?? 0) + 1);
+						return;
+					case "settings":
+					case "item":
+						return;
+				}
 				return;
-			case "folder":
-				beginFolderDraft(target.id, (findTreeNodeDepth(workspaceTreeNodes(), target.id, workspaceTreeAdapter) ?? 0) + 1);
+			case "delete-folder":
+				if (target.kind === "folder") {
+					void deletePersistedFolder(target.id);
+				}
 				return;
-			case "settings":
-			case "item":
+			default:
 				return;
 		}
 	};