Merge fix/client-id-insecure-context for client-side ids

src/frontend/utils/client-id.ts

@@ -0,0 +1,27 @@
+/**
+ * Creates a random RFC 4122 version 4 UUID for new entities built in the
+ * browser.
+ *
+ * crypto.randomUUID() exists only in secure contexts (HTTPS or localhost).
+ * The app is also opened over plain HTTP from other machines in the LAN, where
+ * it is undefined, so fall back to crypto.getRandomValues(), which is
+ * available in every context.
+ */
+export function createClientId(
+  source: Pick<Crypto, "getRandomValues"> & Partial<Pick<Crypto, "randomUUID">> = crypto
+): string {
+  if (typeof source.randomUUID === "function") {
+    return source.randomUUID();
+  }
+  const bytes = source.getRandomValues(new Uint8Array(16));
+  bytes[6] = (bytes[6] & 0x0f) | 0x40; // version 4
+  bytes[8] = (bytes[8] & 0x3f) | 0x80; // RFC 4122 variant
+  const hex = Array.from(bytes, (byte) => byte.toString(16).padStart(2, "0")).join("");
+  return [
+    hex.slice(0, 8),
+    hex.slice(8, 12),
+    hex.slice(12, 16),
+    hex.slice(16, 20),
+    hex.slice(20),
+  ].join("-");
+}