refactor: extract flagged storage file loader

Author: ndycode

lib/storage.ts

@@ -21,6 +21,7 @@ import {
 	buildMetadataSection,
 } from "./storage/backup-metadata.js";
 import { formatStorageErrorHint } from "./storage/error-hints.js";
+import { loadFlaggedAccountsFromFile } from "./storage/flagged-storage-file.js";
 import {
 	collectNamedBackups,
 	type NamedBackupSummary,
@@ -507,9 +508,10 @@ function isCacheLikeBackupArtifactName(entryName: string): boolean {
 async function loadFlaggedAccountsFromPath(
 	path: string,
 ): Promise<FlaggedAccountStorageV1> {
-	const content = await fs.readFile(path, "utf-8");
-	const data = JSON.parse(content) as unknown;
-	return normalizeFlaggedStorage(data);
+	return loadFlaggedAccountsFromFile(path, {
+		readFile: fs.readFile,
+		normalizeFlaggedStorage,
+	});
 }
 
 type AccountsJournalEntry = {

lib/storage/flagged-storage-file.ts

@@ -0,0 +1,13 @@
+import type { FlaggedAccountStorageV1 } from "../storage.js";
+
+export async function loadFlaggedAccountsFromFile(
+	path: string,
+	deps: {
+		readFile: typeof import("node:fs").promises.readFile;
+		normalizeFlaggedStorage: (data: unknown) => FlaggedAccountStorageV1;
+	},
+): Promise<FlaggedAccountStorageV1> {
+	const content = await deps.readFile(path, "utf-8");
+	const data = JSON.parse(content) as unknown;
+	return deps.normalizeFlaggedStorage(data);
+}