race condition

qbo_helper.js

@@ -15,6 +15,7 @@ const path = require('path');
 
 let oauthClient = null;
 let _lastSavedAccessToken = null;
+let refreshInFlight = null; // single-flight lock for concurrent token refresh
 const tokenFile = path.join(__dirname, 'qbo_token.json');
 
 const getOAuthClient = () => {
@@ -110,12 +111,17 @@ async function makeQboApiCall(requestOptions) {
     }
 
     const doRefresh = async () => {
+        if (refreshInFlight) {
+            console.log(`[${ts()}] ⏳ Awaiting in-flight token refresh...`);
+            return refreshInFlight;
+        }
         console.log(`[${ts()}] 🔄 QBO Token Refresh...`);
         const refreshTokenStr = currentToken.refresh_token;
+        refreshInFlight = (async () => {
             try {
                 const authResponse = await client.refreshUsingToken(refreshTokenStr);
                 console.log(`[${ts()}] ✅ Token refreshed via refreshUsingToken()`);
-            saveTokens();  // saveTokens prüft selbst ob sich was geändert hat
+                saveTokens();
                 return authResponse;
             } catch (e) {
                 const errMsg = e.originalMessage || e.message || String(e);
@@ -128,7 +134,11 @@ async function makeQboApiCall(requestOptions) {
                     );
                 }
                 throw e;
+            } finally {
+                refreshInFlight = null;
             }
+        })();
+        return refreshInFlight;
     };
 
     try {