fix(simplefin): retry transient fetch failures (3 attempts, 1s/2s backoff)

services/simplefinService.js

@@ -83,6 +83,9 @@ async function claimSetupToken(setupToken) {
   return accessUrl;
 }
 
+const FETCH_RETRY_ATTEMPTS = 3;
+const FETCH_RETRY_DELAYS   = [1000, 2000]; // ms between attempts 1→2 and 2→3
+
 async function fetchAccountsAndTransactions(accessUrl, sinceEpoch) {
   let url;
   try {
@@ -95,18 +98,34 @@ async function fetchAccountsAndTransactions(accessUrl, sinceEpoch) {
   const baseUrl   = `${url.protocol}//${url.host}${url.pathname.replace(/\/?$/, '')}`;
   const endpoint  = `${baseUrl}/accounts?start-date=${Math.floor(sinceEpoch)}&version=2`;
 
-  let data;
+  let lastErr;
+  for (let attempt = 0; attempt < FETCH_RETRY_ATTEMPTS; attempt++) {
+    if (attempt > 0) await new Promise(r => setTimeout(r, FETCH_RETRY_DELAYS[attempt - 1]));
+
+    let res;
     try {
-    const res = await fetch(endpoint, {
+      res = await fetch(endpoint, {
         headers: { 'Authorization': `Basic ${basicAuth}` },
         signal: AbortSignal.timeout(30000),
       });
+    } catch (err) {
+      // Network error or timeout — retry unless this was the last attempt
+      if (attempt < FETCH_RETRY_ATTEMPTS - 1) { lastErr = err; continue; }
+      throw sanitizeError(err);
+    }
+
     if (res.status === 403) {
       throw Object.assign(new Error('SimpleFIN access has been revoked — please reconnect'), { code: 'SIMPLEFIN_REVOKED' });
     }
     if (!res.ok) {
-      throw new Error(`SimpleFIN fetch failed (HTTP ${res.status})`);
+      const err = new Error(`SimpleFIN fetch failed (HTTP ${res.status})`);
+      // Retry transient server errors; surface client errors immediately
+      if (attempt < FETCH_RETRY_ATTEMPTS - 1 && res.status >= 500) { lastErr = err; continue; }
+      throw sanitizeError(err);
     }
+
+    let data;
+    try {
       data = await res.json();
     } catch (err) {
       throw sanitizeError(err);
@@ -119,10 +138,12 @@ async function fetchAccountsAndTransactions(accessUrl, sinceEpoch) {
         .join('; ');
       data._errlistSummary = msgs;
     }
-
     return data;
   }
 
+  throw sanitizeError(lastErr);
+}
+
 function normalizeAccount(rawAccount, dataSourceId, userId) {
   const balance          = rawAccount.balance != null     ? Math.round(parseFloat(rawAccount.balance) * 100)           : null;
   const availableBalance = rawAccount['available-balance'] != null ? Math.round(parseFloat(rawAccount['available-balance']) * 100) : null;