fix(BUG-12/23): sw.js never caches API responses — static-only cache-first, API always network

frontend/sw.js

@@ -1,7 +1,14 @@
-const CACHE = "bharatgraph-v3";
-const STATIC = ["/","/index.html","/css/design-system.css",
-  "/css/components.css","/js/router.js","/js/api.js",
-  "/js/components.js","/js/graph.js","/js/timeline.js","/js/evidence_panel.js","/js/app.js"];
+// BUG-12/23 FIX: was caching API responses (health, search, stats) with cache-then-network.
+// Cold-start 503 responses were being served from cache for minutes.
+// Fix: static assets only (cache-first). API calls always network-first, no caching.
+// Never cache health, search, stats, investigate — these must always be fresh.
+const CACHE = "bharatgraph-v4";
+const STATIC = [
+  "/","/index.html",
+  "/css/design-system.css","/css/components.css",
+  "/js/router.js","/js/api.js","/js/components.js",
+  "/js/graph.js","/js/timeline.js","/js/evidence_panel.js","/js/app.js"
+];
 
 self.addEventListener("install", e => {
   e.waitUntil(caches.open(CACHE).then(c => c.addAll(STATIC)));
@@ -17,14 +24,19 @@ self.addEventListener("activate", e => {
 });
 
 self.addEventListener("fetch", e => {
-  const isApi = e.request.url.includes("hf.space") || e.request.url.includes("/api/");
+  const url = e.request.url;
+  // BUG-12/23 FIX: API calls NEVER cached — always fetch live from network
+  const isApi = url.includes("hf.space") || url.includes("/api/") ||
+                url.includes("/health") || url.includes("/stats") ||
+                url.includes("/search") || url.includes("/investigate");
   if (isApi) {
-    e.respondWith(
-      fetch(e.request)
-        .then(r => { if (r.ok) caches.open(CACHE).then(c => c.put(e.request, r.clone())); return r; })
-        .catch(() => caches.match(e.request))
-    );
+    // Network only — no cache fallback for API
+    e.respondWith(fetch(e.request).catch(() =>
+      new Response(JSON.stringify({error:"API temporarily unavailable"}),
+        {status:503, headers:{"Content-Type":"application/json"}})
+    ));
   } else {
+    // Static assets: cache-first
     e.respondWith(caches.match(e.request).then(r => r || fetch(e.request)));
   }
 });