feat: preserve mobile shares through sign-in (#313)

frontend/login.js

@@ -2,15 +2,33 @@
   if (typeof module === 'object' && module.exports) module.exports = factory;
   else root.createLoginController = factory;
 }(typeof self !== 'undefined' ? self : this, function createLoginController(options) {
+  function validShareContinuation(value) {
+    if (typeof value !== 'string' || !value.startsWith('./?') || value.includes('#')) return './';
+    const limits = { title: 200, text: 8000, url: 2048 };
+    const params = new URLSearchParams(value.slice(3));
+    const entries = Array.from(params.entries());
+    if (!entries.length) return './';
+    const invalid = entries.some(([name, content]) => (
+      !Object.prototype.hasOwnProperty.call(limits, name)
+      || !content
+      || content.length > limits[name]
+    ));
+    if (invalid) return './';
+    return value;
+  }
+
   const form = options.form;
   const status = options.status;
   const button = options.button;
   const fetchImpl = options.fetchImpl;
   const location = options.location;
+  const continuation = validShareContinuation(options.continuation);
   const setIntervalImpl = options.setIntervalImpl || setInterval;
   const clearIntervalImpl = options.clearIntervalImpl || clearInterval;
   let timer = null;
 
+  if (continuation !== './') status.textContent = 'Sign in to continue your shared capture.';
+
   function showReason(reason) {
     if (reason !== 'session-expired') return;
     status.textContent = 'Your session expired. Private drafts remain on this device. Sign in to continue.';
@@ -49,7 +67,7 @@
     }
     form.reset();
     if (response.ok) {
-      location.replace('./');
+      location.replace(continuation);
       return;
     }
     if (response.status === 429) {
@@ -66,14 +84,16 @@ if (typeof document !== 'undefined') {
   const form = document.getElementById('sign-in');
   const status = document.getElementById('status');
   const button = document.getElementById('submit-sign-in');
+  const loginParams = new URLSearchParams(window.location.search);
   const controller = createLoginController({
     form,
     status,
     button,
     fetchImpl: fetch.bind(window),
     location: window.location,
+    continuation: loginParams.get('continue'),
   });
-  controller.showReason(new URLSearchParams(window.location.search).get('reason'));
+  controller.showReason(loginParams.get('reason'));
   form.addEventListener('submit', event => {
     event.preventDefault();
     const accessToken = new FormData(form).get('access_token');

frontend/service-worker.js

@@ -1,6 +1,6 @@
 const BASE = new URL('./', self.location.href).pathname;
 importScripts(BASE + 'static/background-issue-sync.js');
-const CACHE = 'stackchain-dashboard-shell-v31';
+const CACHE = 'stackchain-dashboard-shell-v32';
 const OUTAGE_STATUSES = new Set([500, 502, 503, 504]);
 const SHELL = [
   BASE,
@@ -163,7 +163,9 @@ self.addEventListener('fetch', event => {
     event.respondWith(
       fetch(request).then(async response => {
         const cache = await caches.open(CACHE);
-        if (response.ok) {
+        const responseUrl = new URL(response.url || request.url);
+        const isDashboardShell = responseUrl.origin === self.location.origin && responseUrl.pathname === BASE;
+        if (response.ok && !response.redirected && isDashboardShell) {
           await cache.put(BASE, response.clone());
         } else if (OUTAGE_STATUSES.has(response.status)) {
           const cached = await cache.match(BASE);