diff --git a/src/client/api.ts b/src/client/api.ts
index 5612007..5cd1963 100644
--- a/src/client/api.ts
+++ b/src/client/api.ts
@@ -47,8 +47,15 @@ async function expectOk<T>(res: Response, fallback: string): Promise<T> {
 /**
  * Fetches the client-side app configuration from the worker.
  * GET /api/config
+ *
+ * If the worker injected the config via a <script> tag (window.__APP_CONFIG__),
+ * that is used immediately without a network round-trip.
  */
 export async function fetchConfig(): Promise<AppConfig> {
+  const injected = (globalThis as Record<string, unknown>).__APP_CONFIG__ as AppConfig | undefined;
+  if (injected?.supabaseUrl && injected?.supabasePublishableKey) {
+    return injected;
+  }
   const response = await fetch("/api/config");
   if (!response.ok) throw new Error("Config unavailable");
   return response.json() as Promise<AppConfig>;
diff --git a/src/worker/index.ts b/src/worker/index.ts
index 6aadf9a..c45f59d 100644
--- a/src/worker/index.ts
+++ b/src/worker/index.ts
@@ -140,7 +140,12 @@ export default {
         return await previewShare(request, env, ctx);
       }
 
-      return withDiscoveryHeaders(await env.ASSETS.fetch(request));
+      const assetResponse = await env.ASSETS.fetch(request);
+      const contentType = assetResponse.headers.get("content-type") ?? "";
+      if (contentType.includes("text/html") && request.method === "GET") {
+        return withDiscoveryHeaders(await injectConfig(assetResponse, env));
+      }
+      return withDiscoveryHeaders(assetResponse);
     } catch (error) {
       console.error(JSON.stringify({ event: "unhandled_error", message: errorMessage(error) }));
       return json({ error: "Internal server error" }, 500);
@@ -148,6 +153,25 @@ export default {
   }
 };
 
+/**
+ * Injects the Supabase client config into an HTML response so the browser
+ * can initialise the Supabase client without a separate /api/config fetch.
+ * The injected script sets window.__APP_CONFIG__ before any module scripts run.
+ */
+async function injectConfig(response: Response, env: Env): Promise<Response> {
+  const configScript = `<script>window.__APP_CONFIG__=${JSON.stringify({
+    supabaseUrl: env.SUPABASE_URL,
+    supabasePublishableKey: env.SUPABASE_PUBLISHABLE_KEY
+  })}</script>`;
+  const html = await response.text();
+  const injected = html.replace("</head>", `${configScript}</head>`);
+  return new Response(injected, {
+    status: response.status,
+    statusText: response.statusText,
+    headers: response.headers
+  });
+}
+
 function discoveryRoute(request: Request, url: URL): Response | null {
   if (request.method !== "GET" && request.method !== "HEAD") {
     return null;