feat: lazy-load issue capture workflow (Closes #537)

frontend/feature-loader.js

@@ -0,0 +1,60 @@
+function createFeatureLoader({ document, urls, timeoutMs = 10000 }) {
+  const pending = new Map();
+  const loaded = new Set();
+
+  function load(name) {
+    if (loaded.has(name)) return Promise.resolve();
+    if (pending.has(name)) return pending.get(name);
+    const url = urls[name];
+    if (!url) return Promise.reject(new Error('Unknown feature: ' + name));
+
+    const request = new Promise((resolve, reject) => {
+      const script = document.createElement('script');
+      let timeout;
+      const fail = () => {
+        clearTimeout(timeout);
+        script.remove();
+        pending.delete(name);
+        reject(new Error('Could not load ' + name.replace(/-/g, ' ') + '.'));
+      };
+      script.src = url;
+      script.async = true;
+      script.onload = () => {
+        clearTimeout(timeout);
+        pending.delete(name);
+        loaded.add(name);
+        resolve();
+      };
+      script.onerror = fail;
+      timeout = setTimeout(fail, timeoutMs);
+      document.head.appendChild(script);
+    });
+    pending.set(name, request);
+    return request;
+  }
+
+  async function run(name, elements, callback) {
+    const trigger = elements?.trigger;
+    const status = elements?.status;
+    if (trigger) trigger.disabled = true;
+    if (status) status.textContent = 'Loading ' + name.replace(/-/g, ' ') + '…';
+    try {
+      await load(name);
+      callback();
+      if (status) status.textContent = '';
+      return true;
+    } catch (_error) {
+      if (status) {
+        const label = name === 'issue-capture' ? 'Issue capture' : name.replace(/-/g, ' ');
+        status.textContent = label + ' could not load. Tap New issue to retry.';
+      }
+      return false;
+    } finally {
+      if (trigger) trigger.disabled = false;
+    }
+  }
+
+  return { load, run, ready: name => loaded.has(name) };
+}
+
+if (typeof module !== 'undefined' && module.exports) module.exports = createFeatureLoader;