Verify deletion actually removed the file before reporting success

MeTube's /delete only unlinks the file when it's configured with
DELETE_FILE_ON_TRASHCAN=true; otherwise it just drops the entry from its
own "done" list and returns {"status": "ok"} regardless -- we were trusting
that response and marking the job "deleted" (offering a re-download) while
the file was still sitting on mediaVM's disk the whole time.

Now HEAD-check the media_url right after the delete call. If the file is
still reachable, leave the job's status untouched (still "completed", still
playable) and surface a clear 409 explaining MeTube's own config is why,
rather than lying about local state.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/api/videos.py

@@ -9,6 +9,7 @@ from app.models.channel import Channel
 from app.models.download_job import DownloadJob
 from app.models.video import Video
 from app.services.download_jobs import (
+    DeleteDidNotRemoveFile,
     DeleteNotAllowed,
     MeTubeRejected,
     delete_local_copy,
@@ -78,6 +79,14 @@ def delete_download(youtube_video_id: str, db: Session = Depends(get_db)) -> dic
         job = delete_local_copy(db, video)
     except DeleteNotAllowed as exc:
         raise HTTPException(status_code=400, detail=str(exc))
+    except DeleteDidNotRemoveFile:
+        raise HTTPException(
+            status_code=409,
+            detail=(
+                "MeTube убрал запись из своего списка, но файл остался на диске "
+                "(на mediaVM выключена настройка DELETE_FILE_ON_TRASHCAN)"
+            ),
+        )
     except Exception:
         logger.exception("Failed to delete local copy for %s", youtube_video_id)
         raise HTTPException(status_code=502, detail="MeTube is unavailable")

backend/app/services/download_jobs.py

@@ -19,6 +19,15 @@ class DeleteNotAllowed(Exception):
     pass
 
 
+class DeleteDidNotRemoveFile(Exception):
+    """MeTube accepted the /delete request but the file is still reachable
+    afterwards -- its DELETE_FILE_ON_TRASHCAN setting is very likely off on
+    that instance, which is outside this app's control (see AGENTS.md
+    constraint 11: never touch MeTube's own config/source)."""
+
+    pass
+
+
 def get_latest_job(db: Session, video_id: int) -> DownloadJob | None:
     return (
         db.query(DownloadJob)
@@ -69,7 +78,18 @@ def delete_local_copy(db: Session, video: Video) -> DownloadJob:
     if not job.metube_job_id:
         raise DeleteNotAllowed("Missing MeTube job id, cannot request deletion")
 
-    MeTubeClient().delete_download(job.metube_job_id)
+    client = MeTubeClient()
+    client.delete_download(job.metube_job_id)
+
+    # MeTube's /delete only unlinks the file if it's configured with
+    # DELETE_FILE_ON_TRASHCAN=true -- otherwise it just drops the entry from
+    # its own "done" list and the file stays put. We don't control that
+    # instance's config, so verify rather than trust the "ok" response.
+    if job.media_url and client.check_media(job.media_url):
+        raise DeleteDidNotRemoveFile(
+            "MeTube removed the entry but the file is still on disk "
+            "(its DELETE_FILE_ON_TRASHCAN setting is likely off)"
+        )
 
     job.status = "deleted"
     job.media_url = None

frontend/src/components/DownloadButton.tsx

@@ -75,6 +75,11 @@ function DownloadButton({ video }: Props) {
         >
           Удалить
         </button>
+        {deleteMutation.isError && (
+          <span className="download-badge error" title={(deleteMutation.error as Error).message}>
+            {(deleteMutation.error as Error).message}
+          </span>
+        )}
       </span>
     )
   }

tests/test_videos.py

@@ -184,6 +184,7 @@ def test_delete_download_success(client, db_session, monkeypatch):
         "app.services.metube_client.MeTubeClient.delete_download",
         lambda self, metube_job_id: calls.setdefault("id", metube_job_id) or {"status": "ok"},
     )
+    monkeypatch.setattr("app.services.metube_client.MeTubeClient.check_media", lambda self, url: False)
 
     resp = client.delete(f"/api/videos/{video.youtube_video_id}/download")
 
@@ -195,3 +196,32 @@ def test_delete_download_success(client, db_session, monkeypatch):
     db_session.refresh(job)
     assert job.status == "deleted"
     assert job.media_url is None
+
+
+def test_delete_download_file_still_present_returns_409(client, db_session, monkeypatch):
+    """MeTube can accept /delete and still leave the file on disk if its own
+    DELETE_FILE_ON_TRASHCAN config is off -- we must not lie about that."""
+    from app.models.download_job import DownloadJob
+
+    video = _seed_single_video(db_session)
+    job = DownloadJob(
+        video_id=video.id,
+        status="completed",
+        metube_job_id="vid1.vid1",
+        media_url="http://metube.local/download/f.mp4",
+    )
+    db_session.add(job)
+    db_session.commit()
+
+    monkeypatch.setattr(
+        "app.services.metube_client.MeTubeClient.delete_download", lambda self, metube_job_id: {"status": "ok"}
+    )
+    monkeypatch.setattr("app.services.metube_client.MeTubeClient.check_media", lambda self, url: True)
+
+    resp = client.delete(f"/api/videos/{video.youtube_video_id}/download")
+
+    assert resp.status_code == 409
+
+    db_session.refresh(job)
+    assert job.status == "completed"
+    assert job.media_url == "http://metube.local/download/f.mp4"