feat: add project management features including open/save functionality and recovery support

platform/browser/projectFiles.ts

@@ -0,0 +1,55 @@
+import type { RecoveryStorage } from "@platform/projectStorage";
+
+export const browserRecoveryStorage: RecoveryStorage = {
+  async read(key) {
+    return request<string | undefined>("readonly", (store) => store.get(key)).then((value) => value ?? null);
+  },
+  async write(key, value) {
+    await request("readwrite", (store) => store.put(value, key));
+  },
+  async remove(key) {
+    await request("readwrite", (store) => store.delete(key));
+  },
+};
+
+const RECOVERY_DATABASE = "image-studio";
+const RECOVERY_STORE = "recovery";
+
+function openRecoveryDatabase(): Promise<IDBDatabase> {
+  return new Promise((resolve, reject) => {
+    const open = indexedDB.open(RECOVERY_DATABASE, 1);
+    open.onupgradeneeded = () => {
+      if (!open.result.objectStoreNames.contains(RECOVERY_STORE)) open.result.createObjectStore(RECOVERY_STORE);
+    };
+    open.onsuccess = () => resolve(open.result);
+    open.onerror = () => reject(open.error ?? new Error("Could not open recovery storage."));
+  });
+}
+
+async function request<T>(mode: IDBTransactionMode, operation: (store: IDBObjectStore) => IDBRequest<T>): Promise<T> {
+  const database = await openRecoveryDatabase();
+  return new Promise((resolve, reject) => {
+    const transaction = database.transaction(RECOVERY_STORE, mode);
+    const databaseRequest = operation(transaction.objectStore(RECOVERY_STORE));
+    databaseRequest.onsuccess = () => resolve(databaseRequest.result);
+    databaseRequest.onerror = () => reject(databaseRequest.error ?? new Error("Recovery storage operation failed."));
+    transaction.oncomplete = () => database.close();
+    transaction.onerror = () => {
+      database.close();
+      reject(transaction.error ?? new Error("Recovery storage transaction failed."));
+    };
+  });
+}
+
+export function downloadProjectFile(source: string, fileName: string): void {
+  const url = URL.createObjectURL(new Blob([source], { type: "application/json" }));
+  const link = document.createElement("a");
+  link.href = url;
+  link.download = fileName;
+  link.click();
+  URL.revokeObjectURL(url);
+}
+
+export function readProjectFile(file: File): Promise<string> {
+  return file.text();
+}

platform/projectStorage.ts

@@ -0,0 +1,5 @@
+export type RecoveryStorage = {
+  read(key: string): Promise<string | null>;
+  write(key: string, value: string): Promise<void>;
+  remove(key: string): Promise<void>;
+};