stage 1

public/js/api.js

@@ -0,0 +1,50 @@
+/*
+ * API communication module. Centralizes fetch calls and service-worker
+ * registration so network details stay out of rendering and state logic.
+ */
+
+import { API_BASE } from './constants.js';
+
+/*
+ * Generic JSON fetcher. All frontend API calls pass through this function so
+ * error handling, header defaults, and base path are consistent everywhere.
+ */
+export async function fetchJson(path, options = {}) {
+  const url = path.startsWith('http') ? path : `${API_BASE}${path}`;
+
+  const requestOptions = {
+    ...options,
+    headers: {
+      Accept: 'application/json',
+      ...(options.headers || {})
+    }
+  };
+
+  const response = await fetch(url, requestOptions);
+
+  if (!response.ok) {
+    let message = `Request failed for ${url}: ${response.status}`;
+
+    try {
+      const errorPayload = await response.json();
+
+      if (errorPayload?.message) {
+        message = errorPayload.message;
+      }
+    } catch {
+      /* Ignore JSON parse errors for non-JSON responses. */
+    }
+
+    throw new Error(message);
+  }
+
+  return response.json();
+}
+
+export function registerServiceWorker() {
+  if ('serviceWorker' in navigator) {
+    navigator.serviceWorker.register('/sw.js').catch((error) => {
+      console.error('Service worker registration failed', error);
+    });
+  }
+}