diff --git a/lib/storage.ts b/lib/storage.ts
index b8a9ea56..cb7d705f 100644
--- a/lib/storage.ts
+++ b/lib/storage.ts
@@ -23,6 +23,16 @@ export {
 } from "./storage/identity.js";
 
 import { normalizeEmailKey } from "./storage/identity.js";
+import {
+	ACCOUNTS_BACKUP_SUFFIX,
+	ACCOUNTS_WAL_SUFFIX,
+	getFlaggedAccountsPath as buildFlaggedAccountsPath,
+	getAccountsBackupPath,
+	getAccountsBackupRecoveryCandidates,
+	getAccountsWalPath,
+	getIntentionalResetMarkerPath,
+	RESET_MARKER_SUFFIX,
+} from "./storage/file-paths.js";
 import {
 	type AccountMetadataV1,
 	type AccountMetadataV3,
@@ -54,12 +64,8 @@ const log = createLogger("storage");
 const ACCOUNTS_FILE_NAME = "openai-codex-accounts.json";
 const FLAGGED_ACCOUNTS_FILE_NAME = "openai-codex-flagged-accounts.json";
 const LEGACY_FLAGGED_ACCOUNTS_FILE_NAME = "openai-codex-blocked-accounts.json";
-const ACCOUNTS_BACKUP_SUFFIX = ".bak";
-const ACCOUNTS_WAL_SUFFIX = ".wal";
-const ACCOUNTS_BACKUP_HISTORY_DEPTH = 3;
 const BACKUP_COPY_MAX_ATTEMPTS = 5;
 const BACKUP_COPY_BASE_DELAY_MS = 10;
-const RESET_MARKER_SUFFIX = ".reset-intent";
 let storageBackupEnabled = true;
 let lastAccountsSaveTimestamp = 0;
 
@@ -367,25 +373,6 @@ export function setStorageBackupEnabled(enabled: boolean): void {
 	storageBackupEnabled = enabled;
 }
 
-function getAccountsBackupPath(path: string): string {
-	return `${path}${ACCOUNTS_BACKUP_SUFFIX}`;
-}
-
-function getAccountsBackupPathAtIndex(path: string, index: number): string {
-	if (index <= 0) {
-		return getAccountsBackupPath(path);
-	}
-	return `${path}${ACCOUNTS_BACKUP_SUFFIX}.${index}`;
-}
-
-function getAccountsBackupRecoveryCandidates(path: string): string[] {
-	const candidates: string[] = [];
-	for (let i = 0; i < ACCOUNTS_BACKUP_HISTORY_DEPTH; i += 1) {
-		candidates.push(getAccountsBackupPathAtIndex(path, i));
-	}
-	return candidates;
-}
-
 async function getAccountsBackupRecoveryCandidatesWithDiscovery(
 	path: string,
 ): Promise<string[]> {
@@ -425,10 +412,6 @@ async function getAccountsBackupRecoveryCandidatesWithDiscovery(
 	return [...knownCandidates, ...discoveredOrdered];
 }
 
-function getAccountsWalPath(path: string): string {
-	return `${path}${ACCOUNTS_WAL_SUFFIX}`;
-}
-
 async function copyFileWithRetry(
 	sourcePath: string,
 	destinationPath: string,
@@ -605,10 +588,6 @@ function computeSha256(value: string): string {
 	return createHash("sha256").update(value).digest("hex");
 }
 
-function getIntentionalResetMarkerPath(path: string): string {
-	return `${path}${RESET_MARKER_SUFFIX}`;
-}
-
 function createEmptyStorageWithMetadata(
 	restoreEligible: boolean,
 	restoreReason: RestoreReason,
@@ -996,11 +975,14 @@ export async function exportNamedBackup(
 }
 
 export function getFlaggedAccountsPath(): string {
-	return join(dirname(getStoragePath()), FLAGGED_ACCOUNTS_FILE_NAME);
+	return buildFlaggedAccountsPath(getStoragePath(), FLAGGED_ACCOUNTS_FILE_NAME);
 }
 
 function getLegacyFlaggedAccountsPath(): string {
-	return join(dirname(getStoragePath()), LEGACY_FLAGGED_ACCOUNTS_FILE_NAME);
+	return buildFlaggedAccountsPath(
+		getStoragePath(),
+		LEGACY_FLAGGED_ACCOUNTS_FILE_NAME,
+	);
 }
 
 async function migrateLegacyProjectStorageIfNeeded(
diff --git a/lib/storage/file-paths.ts b/lib/storage/file-paths.ts
new file mode 100644
index 00000000..e151afe7
--- /dev/null
+++ b/lib/storage/file-paths.ts
@@ -0,0 +1,42 @@
+import { dirname, join } from "node:path";
+
+export const ACCOUNTS_BACKUP_SUFFIX = ".bak";
+export const ACCOUNTS_WAL_SUFFIX = ".wal";
+const ACCOUNTS_BACKUP_HISTORY_DEPTH = 3;
+export const RESET_MARKER_SUFFIX = ".reset-intent";
+
+export function getAccountsBackupPath(path: string): string {
+	return `${path}${ACCOUNTS_BACKUP_SUFFIX}`;
+}
+
+function getAccountsBackupPathAtIndex(path: string, index: number): string {
+	if (index <= 0) return getAccountsBackupPath(path);
+	return `${path}${ACCOUNTS_BACKUP_SUFFIX}.${index}`;
+}
+
+export function getAccountsBackupRecoveryCandidates(path: string): string[] {
+	const candidates: string[] = [];
+	for (let i = 0; i < ACCOUNTS_BACKUP_HISTORY_DEPTH; i += 1) {
+		candidates.push(getAccountsBackupPathAtIndex(path, i));
+	}
+	return candidates;
+}
+
+export function getAccountsWalPath(path: string): string {
+	return `${path}${ACCOUNTS_WAL_SUFFIX}`;
+}
+
+export function getIntentionalResetMarkerPath(path: string): string {
+	return `${path}${RESET_MARKER_SUFFIX}`;
+}
+
+export function getFlaggedAccountsPath(
+	storagePath: string,
+	fileName: string,
+): string {
+	return buildSiblingStoragePath(storagePath, fileName);
+}
+
+function buildSiblingStoragePath(storagePath: string, fileName: string): string {
+	return join(dirname(storagePath), fileName);
+}
diff --git a/test/storage-file-paths.test.ts b/test/storage-file-paths.test.ts
new file mode 100644
index 00000000..9a9cda23
--- /dev/null
+++ b/test/storage-file-paths.test.ts
@@ -0,0 +1,56 @@
+import { dirname, join } from "node:path";
+import { describe, expect, it } from "vitest";
+import {
+	ACCOUNTS_BACKUP_SUFFIX,
+	ACCOUNTS_WAL_SUFFIX,
+	getAccountsBackupPath,
+	getAccountsBackupRecoveryCandidates,
+	getAccountsWalPath,
+	getFlaggedAccountsPath,
+	getIntentionalResetMarkerPath,
+	RESET_MARKER_SUFFIX,
+} from "../lib/storage/file-paths.js";
+
+describe("storage file paths", () => {
+	it("builds the primary backup, wal, and reset marker paths", () => {
+		const storagePath = "/tmp/openai-codex-accounts.json";
+
+		expect(getAccountsBackupPath(storagePath)).toBe(
+			`${storagePath}${ACCOUNTS_BACKUP_SUFFIX}`,
+		);
+		expect(getAccountsWalPath(storagePath)).toBe(
+			`${storagePath}${ACCOUNTS_WAL_SUFFIX}`,
+		);
+		expect(getIntentionalResetMarkerPath(storagePath)).toBe(
+			`${storagePath}${RESET_MARKER_SUFFIX}`,
+		);
+	});
+
+	it("returns backup recovery candidates for the base backup and history slots", () => {
+		const storagePath = "/tmp/openai-codex-accounts.json";
+
+		expect(getAccountsBackupRecoveryCandidates(storagePath)).toEqual([
+			`${storagePath}.bak`,
+			`${storagePath}.bak.1`,
+			`${storagePath}.bak.2`,
+		]);
+	});
+
+	it("builds flagged storage paths next to the active storage file", () => {
+		const storagePath = "/tmp/config/openai-codex-accounts.json";
+		const fileName = "openai-codex-flagged-accounts.json";
+
+		expect(getFlaggedAccountsPath(storagePath, fileName)).toBe(
+			join(dirname(storagePath), fileName),
+		);
+	});
+
+	it("uses dirname/join semantics consistently for windows-like storage paths", () => {
+		const storagePath = String.raw`C:\Users\user\.codex\openai-codex-accounts.json`;
+		const fileName = "openai-codex-blocked-accounts.json";
+
+		expect(getFlaggedAccountsPath(storagePath, fileName)).toBe(
+			join(dirname(storagePath), fileName),
+		);
+	});
+});