From c7276621eb44d2a1d898d3aee2c725154a2b4633 Mon Sep 17 00:00:00 2001
From: Josef Zweck <josef@zweck.dev>
Date: Wed, 18 Feb 2026 23:32:23 +0100
Subject: [PATCH] Add metadata validation for missing backup files in OneDrive
 backup agent (#163072)

---
 homeassistant/components/onedrive/backup.py   | 15 +++++++++++
 .../onedrive_for_business/backup.py           |  2 +-
 tests/components/onedrive/test_backup.py      | 25 +++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/homeassistant/components/onedrive/backup.py b/homeassistant/components/onedrive/backup.py
index 232e8b1ad12..a76d6df820a 100644
--- a/homeassistant/components/onedrive/backup.py
+++ b/homeassistant/components/onedrive/backup.py
@@ -257,9 +257,24 @@ class OneDriveBackupAgent(BackupAgent):
             )
 
         items = await self._client.list_drive_items(self._folder_id)
+
+        # Build a set of backup filenames to check for orphaned metadata
+        backup_filenames = {
+            item.name for item in items if item.name and item.name.endswith(".tar")
+        }
+
         metadata_files: dict[str, AgentBackup] = {}
         for item in items:
             if item.name and item.name.endswith(".metadata.json"):
+                # Check if corresponding backup file exists
+                backup_filename = f"{item.name[: -len('.metadata.json')]}.tar"
+                if backup_filename not in backup_filenames:
+                    _LOGGER.warning(
+                        "Backup file %s not found for metadata %s",
+                        backup_filename,
+                        item.name,
+                    )
+                    continue
                 if metadata := await _download_metadata(item.id):
                     metadata_files[metadata.backup_id] = metadata
 
diff --git a/homeassistant/components/onedrive_for_business/backup.py b/homeassistant/components/onedrive_for_business/backup.py
index 661b616f3cb..52ce8af8941 100644
--- a/homeassistant/components/onedrive_for_business/backup.py
+++ b/homeassistant/components/onedrive_for_business/backup.py
@@ -255,7 +255,7 @@ class OneDriveBackupAgent(BackupAgent):
         for item in items:
             if item.name and item.name.endswith(".metadata.json"):
                 # Check if corresponding backup file exists
-                backup_filename = item.name.replace(".metadata.json", ".tar")
+                backup_filename = f"{item.name[: -len('.metadata.json')]}.tar"
                 if backup_filename not in backup_filenames:
                     _LOGGER.warning(
                         "Backup file %s not found for metadata %s",
diff --git a/tests/components/onedrive/test_backup.py b/tests/components/onedrive/test_backup.py
index 78e8964bcc8..d15cfcfa6c6 100644
--- a/tests/components/onedrive/test_backup.py
+++ b/tests/components/onedrive/test_backup.py
@@ -157,6 +157,31 @@ async def test_agents_get_backup(
     }
 
 
+async def test_agents_get_backup_missing_file(
+    hass: HomeAssistant,
+    hass_ws_client: WebSocketGenerator,
+    mock_config_entry: MockConfigEntry,
+    mock_onedrive_client: MagicMock,
+    mock_metadata_file: File,
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Test what happens when only metadata exists."""
+    mock_onedrive_client.list_drive_items.return_value = [mock_metadata_file]
+
+    backup_id = BACKUP_METADATA["backup_id"]
+    client = await hass_ws_client(hass)
+    await client.send_json_auto_id({"type": "backup/details", "backup_id": backup_id})
+    response = await client.receive_json()
+
+    assert response["success"]
+    assert response["result"]["agent_errors"] == {}
+    assert response["result"]["backup"] is None
+    assert (
+        "Backup file 23e64aec.tar not found for metadata 23e64aec.metadata.json"
+        in caplog.text
+    )
+
+
 async def test_agents_delete(
     hass: HomeAssistant,
     hass_ws_client: WebSocketGenerator,