feat: make mobile queue priority self-healing (Closes #1466)

frontend/dashboard.js

@@ -447,11 +447,10 @@
     },
     onChange: () => {
       renderMobileQueuePresentation();
-      void mobileQueuePriority.sync();
     },
   });
   mobileQueuePriority.start();
-  window.addEventListener('online', () => { void mobileQueuePriority.sync(); });
+  mobileQueuePriority.startLifecycle({window, document});
   let rR = null;
   function rRC() {
     if (rR) return rR;

frontend/mobile-queue-priority.js

@@ -11,8 +11,17 @@
   const prefix = 'stackchain-mobile-queue-priority-v1:';
   const labels = options.labels || {};
   const documentRef = options.document || (typeof document !== 'undefined' ? document : null);
+  const setTimer = options.setTimeout || setTimeout;
+  const clearTimer = options.clearTimeout || clearTimeout;
+  const debounceMs = Number.isFinite(options.debounceMs) ? Math.max(0, options.debounceMs) : 150;
+  const retryBaseMs = Number.isFinite(options.retryBaseMs) ? Math.max(1, options.retryBaseMs) : 1000;
+  const retryMaxMs = Number.isFinite(options.retryMaxMs) ? Math.max(retryBaseMs, options.retryMaxMs) : 30000;
   let memory = null;
   const syncFlights = new Map();
+  let debounceTimer = null;
+  let retryTimer = null;
+  let retryAccount = '';
+  let retryAttempts = 0;
 
   function key() {
     const login = String(getLogin() || '').trim().toLowerCase();
@@ -90,6 +99,45 @@
     if (!persist(value)) return false;
     options.onChange?.(order.slice());
     announce(value);
+    scheduleSync();
+    return true;
+  }
+
+  function scheduleSync() {
+    if (!fetchJson || !key()) return false;
+    if (debounceTimer) clearTimer(debounceTimer);
+    debounceTimer = setTimer(() => {
+      debounceTimer = null;
+      void sync();
+    }, debounceMs);
+    return true;
+  }
+
+  function clearRetry() {
+    if (retryTimer) clearTimer(retryTimer);
+    retryTimer = null;
+    retryAccount = '';
+    retryAttempts = 0;
+  }
+
+  function transient(error) {
+    const status = Number(error?.status) || 0;
+    return status === 0 || status === 408 || status === 425 || status === 429 || status >= 500;
+  }
+
+  function scheduleRetry(accountKey) {
+    if (retryTimer && retryAccount !== accountKey) clearRetry();
+    if (retryTimer || key() !== accountKey) return false;
+    const delay = Math.min(retryMaxMs, retryBaseMs * (2 ** retryAttempts));
+    retryAttempts += 1;
+    retryAccount = accountKey;
+    retryTimer = setTimer(() => {
+      retryTimer = null;
+      retryAccount = '';
+      const current = read();
+      if (key() !== accountKey || !current.pending || current.status === 'conflict') return;
+      void sync();
+    }, delay);
     return true;
   }
 
@@ -123,6 +171,7 @@
       throw new Error('Queue priority response is invalid.');
     }
     const value = {revision:snapshotValue.revision, order:snapshotValue.order.slice(), pending:false, status:'ready', remote:null};
+    clearRetry();
     persist(value);
     options.onChange?.(value.order.slice());
     announce(value);
@@ -180,10 +229,12 @@
         const latest = read();
         const remote = error?.status === 409 && error?.payload?.detail?.snapshot;
         if (remote && valid(remote.order) && Number.isInteger(remote.revision)) {
+          clearRetry();
           latest.status = 'conflict'; latest.pending = true;
           latest.remote = {revision:remote.revision, order:remote.order.slice()};
         } else {
           latest.status = 'pending'; latest.pending = true;
+          if (transient(error)) scheduleRetry(accountKey);
         }
         persist(latest); announce(latest); render();
         return snapshot();
@@ -193,6 +244,10 @@
   }
 
   function sync() {
+    if (debounceTimer) {
+      clearTimer(debounceTimer);
+      debounceTimer = null;
+    }
     const accountKey = key();
     const current = read();
     if (!fetchJson || !accountKey || !current.pending) return Promise.resolve(snapshot());
@@ -266,6 +321,20 @@
     return render();
   }
 
-  return {getOrder, move, reset, render, start, load, sync, useLocal, useRemote,
+  function startLifecycle(lifecycle = {}) {
+    const windowObject = lifecycle.window;
+    const lifecycleDocument = lifecycle.document;
+    const reconcile = () => {
+      if (!key()) return Promise.resolve(snapshot());
+      return read().pending ? sync() : load();
+    };
+    windowObject?.addEventListener?.('online', () => { void reconcile(); });
+    lifecycleDocument?.addEventListener?.('visibilitychange', () => {
+      if (!lifecycleDocument.hidden) void reconcile();
+    });
+    return reconcile;
+  }
+
+  return {getOrder, move, reset, render, start, startLifecycle, load, sync, scheduleSync, useLocal, useRemote,
     state:snapshot, defaultOrder:() => DEFAULT_ORDER.slice()};
 });