feat: let a subscription carry clip bounds (closes #1049)

A subscription already carries every other download option and applies it to
each video it queues. Clip bounds were the one exception: 4f83174 added them
for one-off downloads and carved subscriptions out, rejecting the fields in the
subscribe route and stripping them in the UI before the request was built. So
the fields sat visible in the shared advanced-options panel while quietly doing
nothing for a subscription.

Carry them like the rest: two fields on SubscriptionInfo, threaded through the
check flow to add_entry. Stored records that predate the fields take the
defaults, since _from_stored filters by field name.

One thing does not carry over. parse_download_options reads a YouTube t=
timestamp from the URL and turns it into a clip start, which is right when you
paste a link to a moment in a video you want. A subscription URL is a channel
or a playlist, so a timestamp left on it says nothing about the videos that
feed will yield, and honouring it would silently truncate every future
download. The subscribe route therefore takes clip bounds only when the caller
sent the fields explicitly; the t= param is still stripped from the stored URL.

Worth knowing when using this: the range is a fixed offset applied to every
video, so it suits feeds with a consistent shape - a standing intro, a fixed
sponsor read - and will cut in the wrong place on a feed without one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/tests/test_subscriptions.py

@@ -409,6 +409,76 @@ class SubscriptionPersistenceTests(unittest.IsolatedAsyncioTestCase):
             self.assertEqual(sub.seen_ids[:2], ["v2", "v1"])
             self.assertEqual([entry["webpage_url"] for entry, _, _ in queue.entries], ["https://example.com/v2"])
 
+    async def test_check_now_applies_subscription_clip_bounds(self):
+        """Issue #1049: clip bounds were the one download option a subscription
+        could not carry, so they must reach every entry it queues."""
+        with tempfile.TemporaryDirectory() as tmp:
+            queue = _Queue()
+            mgr = SubscriptionManager(_Config(tmp), queue, _Notifier())
+
+            with patch(
+                "subscriptions.extract_flat_playlist",
+                side_effect=[
+                    (
+                        {"_type": "channel", "title": "Channel"},
+                        [{"id": "v1", "title": "One", "webpage_url": "https://example.com/v1"}],
+                    ),
+                    (
+                        {"_type": "channel", "title": "Channel"},
+                        [
+                            {"id": "v2", "title": "Two", "webpage_url": "https://example.com/v2"},
+                            {"id": "v1", "title": "One", "webpage_url": "https://example.com/v1"},
+                        ],
+                    ),
+                ],
+            ):
+                result = await mgr.add_subscription(
+                    "https://example.com/channel",
+                    check_interval_minutes=60,
+                    download_type="video",
+                    codec="auto",
+                    format="any",
+                    quality="best",
+                    folder="",
+                    custom_name_prefix="",
+                    auto_start=True,
+                    playlist_item_limit=0,
+                    split_by_chapters=False,
+                    chapter_template="",
+                    subtitle_language="en",
+                    subtitle_mode="prefer_manual",
+                    clip_start=30.0,
+                    clip_end=90.0,
+                )
+                sub_id = result["subscription"]["id"]
+                self.assertEqual(mgr.get(sub_id).clip_start, 30.0)
+                self.assertEqual(mgr.get(sub_id).clip_end, 90.0)
+                await mgr.check_now([sub_id])
+
+            self.assertEqual(len(queue.entries), 1)
+            _entry, args, _kwargs = queue.entries[0]
+            # add_entry(entry, download_type, ..., ytdl_options_overrides, clip_start, clip_end)
+            self.assertEqual(args[-2], 30.0)
+            self.assertEqual(args[-1], 90.0)
+
+    async def test_clip_bounds_survive_reload_and_default_to_none(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            cfg = _Config(tmp)
+            queue = _Queue()
+            mgr = SubscriptionManager(cfg, queue, _Notifier())
+            sub_id = await self._add_one_subscription(mgr)
+            # Records written before these fields existed simply take the defaults.
+            self.assertIsNone(mgr.get(sub_id).clip_start)
+            self.assertIsNone(mgr.get(sub_id).clip_end)
+
+            mgr.get(sub_id).clip_start = 12.5
+            async with mgr._lock:
+                mgr._save_locked()
+
+            reloaded = SubscriptionManager(cfg, _Queue(), _Notifier())
+            self.assertEqual(reloaded.get(sub_id).clip_start, 12.5)
+            self.assertIsNone(reloaded.get(sub_id).clip_end)
+
     async def test_check_now_queues_subscriber_only_when_skip_disabled(self):
         with tempfile.TemporaryDirectory() as tmp:
             queue = _Queue()