From 19d84d9f657dcd5c46f89aca08c52267294921b8 Mon Sep 17 00:00:00 2001
From: ferhat elmas <elmas.ferhat@gmail.com>
Date: Mon, 16 Feb 2026 14:37:45 +0100
Subject: [PATCH] fix(file-backend): return correct last modified in head
 object

closes #858

Signed-off-by: ferhat elmas <elmas.ferhat@gmail.com>
---
 src/storage/backend/file.ts   | 14 ++++-----
 src/test/file-backend.test.ts | 57 +++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 8 deletions(-)

diff --git a/src/storage/backend/file.ts b/src/storage/backend/file.ts
index 89d5110f..5a2ff3ff 100644
--- a/src/storage/backend/file.ts
+++ b/src/storage/backend/file.ts
@@ -89,15 +89,14 @@ export class FileBackend implements StorageBackendAdapter {
     const eTag = await this.etag(file, data)
     const fileSize = data.size
     const { cacheControl, contentType } = await this.getFileMetadata(file)
-    const lastModified = new Date(0)
-    lastModified.setUTCMilliseconds(data.mtimeMs)
+    const lastModified = data.mtime
 
     if (headers?.ifNoneMatch && headers.ifNoneMatch === eTag) {
       return {
         metadata: {
           cacheControl: cacheControl || 'no-cache',
           mimetype: contentType || 'application/octet-stream',
-          lastModified: lastModified,
+          lastModified,
           httpStatusCode: 304,
           size: data.size,
           eTag,
@@ -115,7 +114,7 @@ export class FileBackend implements StorageBackendAdapter {
           metadata: {
             cacheControl: cacheControl || 'no-cache',
             mimetype: contentType || 'application/octet-stream',
-            lastModified: lastModified,
+            lastModified,
             httpStatusCode: 304,
             size: data.size,
             eTag,
@@ -155,7 +154,7 @@ export class FileBackend implements StorageBackendAdapter {
         metadata: {
           cacheControl: cacheControl || 'no-cache',
           mimetype: contentType || 'application/octet-stream',
-          lastModified: lastModified,
+          lastModified,
           httpStatusCode: 200,
           size: data.size,
           eTag,
@@ -319,8 +318,7 @@ export class FileBackend implements StorageBackendAdapter {
 
     const data = await fs.stat(file)
     const { cacheControl, contentType } = await this.getFileMetadata(file)
-    const lastModified = new Date(0)
-    lastModified.setUTCMilliseconds(data.mtimeMs)
+    const lastModified = data.mtime
     const eTag = await this.etag(file, data)
 
     return {
@@ -329,7 +327,7 @@ export class FileBackend implements StorageBackendAdapter {
       cacheControl: cacheControl || 'no-cache',
       mimetype: contentType || 'application/octet-stream',
       eTag,
-      lastModified: data.birthtime,
+      lastModified,
       contentLength: data.size,
     }
   }
diff --git a/src/test/file-backend.test.ts b/src/test/file-backend.test.ts
index 88fff428..cc1da895 100644
--- a/src/test/file-backend.test.ts
+++ b/src/test/file-backend.test.ts
@@ -157,3 +157,60 @@ describe('FileBackend xattr metadata', () => {
     }
   })
 })
+
+describe('FileBackend lastModified', () => {
+  let tmpDir: string
+  let backend: FileBackend
+  let originalStoragePath: string | undefined
+  let originalFilePath: string | undefined
+
+  beforeEach(async () => {
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'storage-file-backend-'))
+    originalStoragePath = process.env.STORAGE_FILE_BACKEND_PATH
+    originalFilePath = process.env.FILE_STORAGE_BACKEND_PATH
+    process.env.STORAGE_FILE_BACKEND_PATH = tmpDir
+    process.env.FILE_STORAGE_BACKEND_PATH = tmpDir
+    getConfig({ reload: true })
+    backend = new FileBackend()
+  })
+
+  afterEach(async () => {
+    if (originalStoragePath === undefined) {
+      delete process.env.STORAGE_FILE_BACKEND_PATH
+    } else {
+      process.env.STORAGE_FILE_BACKEND_PATH = originalStoragePath
+    }
+    if (originalFilePath === undefined) {
+      delete process.env.FILE_STORAGE_BACKEND_PATH
+    } else {
+      process.env.FILE_STORAGE_BACKEND_PATH = originalFilePath
+    }
+    await fs.remove(tmpDir)
+  })
+
+  it('headObject/getObject should return mtime as lastModified', async () => {
+    const bucket = 'test-bucket'
+    const key = 'test-file.txt'
+    const version = 'v1'
+
+    await backend.uploadObject(
+      bucket,
+      key,
+      version,
+      Readable.from('initial content'),
+      'text/plain',
+      'no-cache'
+    )
+
+    const filePath = path.join(tmpDir, withOptionalVersion(`${bucket}/${key}`, version))
+    const stat = await fs.stat(filePath)
+    const knownMtime = new Date(stat.birthtimeMs + 60_000) // mtime must be in the future
+    await fs.utimes(filePath, knownMtime, knownMtime)
+
+    const headResult = await backend.headObject(bucket, key, version)
+    expect(headResult.lastModified).toEqual(knownMtime)
+
+    const getResult = await backend.getObject(bucket, key, version)
+    expect(getResult.metadata.lastModified).toEqual(knownMtime)
+  })
+})