fix: harden audit durability and fallback config writes

lib/upload-audit.js

@@ -6,6 +6,26 @@ function getUploadAuditLogPath(uploadLogPath, pathApi = nodePath) {
   return pathApi.join(pathApi.dirname(uploadLogPath), 'upload-audit.log');
 }
 
+async function appendDurably(fs, targetPath, line) {
+  const handle = await fs.promises.open(targetPath, 'a');
+  let appendError = null;
+  let closeError = null;
+  try {
+    await handle.appendFile(line, 'utf-8');
+    await handle.sync();
+  } catch (error) {
+    appendError = error;
+  }
+  try {
+    await handle.close();
+  } catch (error) {
+    closeError = error;
+  }
+  if (appendError && closeError) throw new AggregateError([appendError, closeError], 'Audit append and close failed');
+  if (appendError) throw appendError;
+  if (closeError) throw closeError;
+}
+
 function createUploadAuditWriter(options) {
   const source = options && typeof options === 'object' ? options : {};
   const fs = source.fs;
@@ -20,7 +40,7 @@ function createUploadAuditWriter(options) {
   const maxBackups = Number.isFinite(source.maxBackups) ? source.maxBackups : 2;
   let activePath = null;
 
-  if (!fs || !fs.promises || typeof fs.promises.appendFile !== 'function' || typeof resolveUploadLogTarget !== 'function') {
+  if (!fs || !fs.promises || typeof fs.promises.open !== 'function' || typeof resolveUploadLogTarget !== 'function') {
     throw new TypeError('createUploadAuditWriter requires fs and resolveUploadLogTarget');
   }
 
@@ -49,7 +69,7 @@ function createUploadAuditWriter(options) {
           }
         }
         rotateLogFile(targetPath, maxBytes, maxBackups);
-        await fs.promises.appendFile(targetPath, line, 'utf-8');
+        await appendDurably(fs, targetPath, line);
         activePath = targetPath;
         return true;
       } catch (error) {