Initial commit: Add project files

frontend/src/shared/commands/idempotency.ts

@@ -0,0 +1,11 @@
+export interface IdempotentCommand<T> {
+  readonly idempotencyKey: string
+  readonly request: T
+}
+
+/**
+ * Create once per user intent. Retries must reuse the returned envelope rather than call this again.
+ */
+export function createIdempotentCommand<T>(request: T): IdempotentCommand<T> {
+  return Object.freeze({ idempotencyKey: crypto.randomUUID(), request })
+}