fix(downloads): a download larger than the space left says so, not "processing failed"

yt-dlp refuses a file announced over `max_filesize` by logging one line and returning with no file
(measured, and pinned in test_formats against a local server): the worker found no output and
failed the job as `postprocess`. `formats.watching_size_cap` now sees that line through our yt-dlp
logger, and the download (and, should it ever happen, a YouTube clip's range fetch) fails as the
owner's refusal with DOWNLOAD_TOO_BIG_MESSAGE, classified `quota_exceeded`. The download's quota
copy says it does not fit in what is left — true at a full cap too — instead of "Storage full".
A pre-existing type error the change touched is fixed (baseline down by one).

backend/tests/test_clip.py

@@ -15,7 +15,7 @@ from app import worker as workermod
 from app.config import settings
 from app.downloads import clip as clipmod
 from app.downloads import errors as dlerrors
-from app.downloads import pipeline, quota, runner, service
+from app.downloads import formats, pipeline, quota, runner, service
 from app.downloads import probe as probemod
 from app.downloads.edit import INPUT_GUARD
 from app.models import Channel, DownloadJob, MediaAsset, PlexItem, PlexLibrary, PlexShow, Video
@@ -705,6 +705,30 @@ def test_a_clip_larger_than_what_its_owner_has_left_is_refused_and_not_placed(
     )
 
 
+def test_a_youtube_clip_range_yt_dlp_refuses_for_its_cap_says_it_is_too_big(
+    db, make_user, as_user, yt_video, worker, monkeypatch
+):
+    # Should yt-dlp's own `max_filesize` refuse the range, it returns with no file (test_formats):
+    # the owner's storage, not a processing fault, and nothing is cut.
+    def refused(*_a, max_bytes=None, **_k):
+        formats._YDL_LOG.debug(
+            f"[download] File is larger than max-filesize (9000 bytes > {max_bytes} bytes). Aborting."
+        )
+        return {"requested_downloads": [{}]}
+
+    monkeypatch.setattr(pipeline, "_extract_with_fallback", refused)
+    job = _clip(as_user(make_user()), source="youtube", ref=yt_video).json()
+    monkeypatch.setattr(quota, "remaining_bytes", lambda _db, _uid: 500)
+    job, asset = worker["run"](job)
+    assert (job.status, job.error_code, job.error, asset.status) == (
+        "error",
+        "quota_exceeded",
+        dlerrors.CLIP_TOO_BIG_MESSAGE,
+        "pending",
+    )
+    assert "cmd" not in worker
+
+
 def test_a_plex_clip_of_a_silent_file_is_cut_silent(db, make_user, as_user, plex_episode, worker):
     # The player names the track it plays 0 even when the file has none.
     worker["probe"] = {"streams": [{"codec_type": "video"}]}