fix: #10783, do not purge files without a timestamp prefix

src/posts/uploads.js

@@ -98,6 +98,10 @@ module.exports = function (Posts) {
 		let files = await fs.readdir(_getFullPath('/files'));
 		files = files.filter(filename => filename !== '.gitignore');
 
+		// Exclude non-timestamped files (e.g. group covers; see gh#10783/gh#10705)
+		const tsPrefix = /^\d{13}\-/;
+		files = files.filter(filename => tsPrefix.test(filename));
+
 		files = await Promise.all(files.map(async filename => (await Posts.uploads.isOrphan(`files/${filename}`) ? `files/${filename}` : null)));
 		files = files.filter(Boolean);