fix: support idempotent actions over HTTP

backend/static/js/app.js

@@ -17,6 +17,32 @@ function csrfToken() {
   return match ? decodeURIComponent(match[1]) : "";
 }
 
+function createIdempotencyKey() {
+  const cryptoApi = globalThis.crypto;
+  if (typeof cryptoApi?.randomUUID === "function") {
+    return cryptoApi.randomUUID();
+  }
+
+  const bytes = new Uint8Array(16);
+  if (typeof cryptoApi?.getRandomValues === "function") {
+    cryptoApi.getRandomValues(bytes);
+  } else {
+    for (let index = 0; index < bytes.length; index += 1) {
+      bytes[index] = Math.floor(Math.random() * 256);
+    }
+  }
+  bytes[6] = (bytes[6] & 0x0f) | 0x40;
+  bytes[8] = (bytes[8] & 0x3f) | 0x80;
+  const hex = [...bytes].map((value) => value.toString(16).padStart(2, "0"));
+  return [
+    hex.slice(0, 4).join(""),
+    hex.slice(4, 6).join(""),
+    hex.slice(6, 8).join(""),
+    hex.slice(8, 10).join(""),
+    hex.slice(10).join(""),
+  ].join("-");
+}
+
 async function api(path, options = {}) {
   const headers = { Accept: "application/json", ...(options.headers || {}) };
   if (options.body && typeof options.body !== "string") {
@@ -165,7 +191,7 @@ function renderStoryNode(run) {
         try {
           const next = await api(`math-life/runs/${run.run_id}/choice/`, {
             method: "POST",
-            headers: { "Idempotency-Key": crypto.randomUUID() },
+            headers: { "Idempotency-Key": createIdempotencyKey() },
             body: { choice_index: choice.index },
           });
           renderStoryNode(next);
@@ -341,7 +367,7 @@ function renderAttempt(attempt) {
     try {
       const result = await api(`contests/attempts/${attempt.attempt_id}/submit/`, {
         method: "POST",
-        headers: { "Idempotency-Key": crypto.randomUUID() },
+        headers: { "Idempotency-Key": createIdempotencyKey() },
         body: { answers },
       });
       renderAttempt(result);