feat: share progressive live snapshot (Closes #1425)

frontend/index.html

@@ -2323,6 +2323,7 @@
 <script src="static/offline-work.js"></script>
 <script src="static/offline-today.js"></script>
 <script src="static/my-work.js"></script>
+<script src="static/progressive-live-snapshot.js"></script>
 <script src="static/progressive-my-work.js"></script>
 <script src="static/progressive-capture.js"></script>
 <script src="static/agenda-replan.js"></script>

frontend/progressive-human-gates.js

@@ -10,8 +10,10 @@ function createProgressiveHumanGates(options = {}) {
     if (!response.ok) throw new Error(payload.error || payload.detail?.message || payload.detail || 'Review request failed.');
     return payload;
   });
+  const liveSnapshot = options.liveSnapshot || null;
   const getIdentity = options.getIdentity || (async () => {
-    const response = await fetchJson('api/v1/live', {headers:{Accept:'application/json'}});
+    const response = liveSnapshot ? await liveSnapshot.acquire() :
+      await fetchJson('api/v1/live', {headers:{Accept:'application/json'}});
     const user = response?.context?.user || {};
     const login = String(user.login || '').trim();
     return {login, accountKey:login && user.id ? String(user.id) + ':' + login : login};
@@ -91,7 +93,9 @@ function createProgressiveHumanGates(options = {}) {
 }
 
 if (typeof window !== 'undefined' && typeof document !== 'undefined') {
-  window.stackchainProgressiveHumanGates = createProgressiveHumanGates({document});
+  window.stackchainProgressiveHumanGates = createProgressiveHumanGates({
+    document, liveSnapshot:window.stackchainProgressiveLiveSnapshot,
+  });
   void window.stackchainProgressiveHumanGates.start().catch(() => {});
 }
 if (typeof module !== 'undefined' && module.exports) {

frontend/progressive-live-snapshot.js

@@ -0,0 +1,40 @@
+function createProgressiveLiveSnapshot({fetchSnapshot}) {
+  let value = null;
+  let flight = null;
+
+  const acquire = () => {
+    if (value) return Promise.resolve(value);
+    if (flight) return flight;
+    flight = Promise.resolve().then(() => fetchSnapshot()).then(snapshot => {
+      value = snapshot;
+      flight = null;
+      return snapshot;
+    }, error => {
+      flight = null;
+      throw error;
+    });
+    return flight;
+  };
+
+  return {
+    acquire,
+    snapshot:() => value,
+    pending:() => flight,
+    identity() {
+      const user = value?.context?.user || {};
+      const login = String(user.login || '').trim();
+      return {login, accountKey:login && user.id ? String(user.id) + ':' + login : login};
+    },
+  };
+}
+
+if (typeof window !== 'undefined') {
+  window.stackchainProgressiveLiveSnapshot = createProgressiveLiveSnapshot({
+    fetchSnapshot:async () => {
+      const response = await fetch('api/v1/live', {headers:{Accept:'application/json'}});
+      if (!response.ok) throw new Error('HTTP ' + response.status);
+      return response.json();
+    },
+  });
+}
+if (typeof module !== 'undefined' && module.exports) module.exports = createProgressiveLiveSnapshot;

frontend/progressive-my-work.js

@@ -1,5 +1,6 @@
 function createProgressiveMyWork({
-  document, fetchSnapshot, pollerOptions = {}, lifecycleTarget = globalThis,
+  document, fetchSnapshot, liveSnapshot: snapshotBroker = null,
+  pollerOptions = {}, lifecycleTarget = globalThis,
 }) {
   const list = document.querySelector('#my-work-list');
   const status = document.querySelector('#my-work-status');
@@ -25,6 +26,9 @@ function createProgressiveMyWork({
   const deferredQueues = {
     today:'Today', agenda:'Agenda', later:'Later', draft:'Drafts',
   };
+  const fetchProgressiveSnapshot = (revisions = {}, options = {}) =>
+    snapshotBroker && Object.keys(revisions || {}).length === 0 ?
+      snapshotBroker.acquire() : fetchSnapshot(revisions, options);
 
   const escapeHtml = value => String(value || '').replace(/[&<>"']/g, character => ({
     '&':'&amp;', '<':'&lt;', '>':'&gt;', '"':'&quot;', "'":'&#39;',
@@ -128,7 +132,7 @@ function createProgressiveMyWork({
   if (typeof createContextPoller === 'function') {
     poller = createContextPoller({
       ...pollerOptions,
-      fetchContext: fetchSnapshot,
+      fetchContext: fetchProgressiveSnapshot,
       onSnapshot: applySnapshot,
       onError: () => {
         if (status && !stopped) status.textContent = 'Assigned work is reconnecting…';
@@ -175,7 +179,7 @@ function createProgressiveMyWork({
         ));
         return Boolean(await request);
       }
-      const request = Promise.resolve().then(() => fetchSnapshot());
+      const request = Promise.resolve().then(() => fetchProgressiveSnapshot());
       liveSnapshotPromise = request.then(snapshot => (
         snapshot && typeof snapshot === 'object' &&
         Object.prototype.hasOwnProperty.call(snapshot, 'context') ? snapshot : null
@@ -208,6 +212,7 @@ if (typeof window !== 'undefined' && typeof document !== 'undefined') {
   window.stackchainProgressiveMyWork = createProgressiveMyWork({
     document,
     lifecycleTarget: window,
+    liveSnapshot:window.stackchainProgressiveLiveSnapshot,
     fetchSnapshot: async (revisions = {}, { signal } = {}) => {
       const query = createContextPoller.buildRevisionQuery(revisions);
       const response = await fetch('api/v1/live' + (query ? '?' + query : ''), {

frontend/service-worker.js

@@ -1,7 +1,7 @@
 const BASE = new URL('./', self.location.href).pathname;
 importScripts(BASE + 'static/private-data-registry.js');
 importScripts(BASE + 'static/background-issue-sync.js');
-const CACHE = 'stackchain-dashboard-shell-v141';
+const CACHE = 'stackchain-dashboard-shell-v142';
 const OFFLINE_LEASE_URL = new URL(BASE + '__offline-session-lease', self.location.origin).href;
 const OUTAGE_STATUSES = new Set([500, 502, 503, 504]);
 const NAVIGATION_TIMEOUT_MS = self.__STACKCHAIN_NAVIGATION_TIMEOUT_MS || 4000;
@@ -188,6 +188,7 @@ const SHELL = [
   BASE + 'static/offline-work.js',
   BASE + 'static/offline-today.js',
   BASE + 'static/my-work.js',
+  BASE + 'static/progressive-live-snapshot.js',
   BASE + 'static/progressive-my-work.js',
   BASE + 'static/progressive-capture.js',
   BASE + 'static/agenda-replan.js',