Build ytstream: catalogue, retention, subscription mirror, proxy

Phases 1-4 of plan.md §13. Forked from youtube-automate as planned rather than
written from scratch: naming, NFO, auth, the admin UI, settings and the DB layer
came across largely unchanged, download.py is gone, and the pieces that only make
sense for a streaming library are new.

  api.py       YouTube Data API v3 client. The whole metadata path.
  strm.py      Materialising: a .strm, an .nfo and a thumbnail. Replaces the
               330-line download.py, because the job is writing a URL to a file.
  subsync.py   The subscription mirror, most of which is refusals.
  reap.py      Retention, rewritten around the 30-day window and min_keep_videos.
  discovery.py RSS polling plus an API-backed, resumable, bounded backfill.
  proxy/       The verified PoC, moved in with a systemd unit.

330 tests, all passing, no network and no yt-dlp in any of them. The suite leans
towards the failure paths, because that is where this design can actually hurt
someone: a 403 that looks like an unsubscribe, a video that ages out and comes
back, a title that never arrives. tests/test_proxy.py replaces the two standalone
scripts under proxy/ and now drives the real make_handler(mgr, ...) rather than the
PoC's make_handler(path, done), so routing and video-id validation are covered too.

Ran it end to end against the live API and it found three real bugs.

The first was mine and the tests caught it: strm.remove pruned empty directories
up to the media root, so a channel directory whose tvshow.nfo happened to be
missing would be deleted along with the season. It only looked safe because
tvshow.nfo normally stops the walk. The prune boundary is now the channel
directory explicitly.

The other two only showed up against real data, and they compounded. The backfill
inserted rows with no title and left the RSS poll to fill them in — but RSS returns
15 entries, which for Pitch Side spans 23 days against a 30-day window, so five of
twenty episodes were named after their video ids. Worse, strm.materialise wrote
that fallback back to the database as the title, which made the row look titled and
permanently disabled the repair path. Both fixed: playlistItems.list now requests
snippet as well as contentDetails, which costs the same single quota unit and
carries the title alongside the exact publish date, and the fallback is used for the
filename without being persisted. A title that does arrive late now also removes the
badly-named files and re-queues, so the episode is rewritten rather than keeping its
video-id name forever. Verified against the live API: all twenty Pitch Side episodes
now carry real titles.

Measured on the real account: 119 subscriptions queued for approval and none added
on the first sync, then a two-channel run backfilled and materialised 26 episodes in
under seven seconds.

Two deliberate departures from plan.md, both recorded there:

min_keep_videos defaults to 5 rather than being left as an open question. Without
it 52 of 117 measured channels are empty Jellyfin series that flicker in and out as
their single video crosses the retention line, and the plan already recommended it.

The Jellyfin refresh is a bare /Library/Refresh with a comment explaining why it
must stay that way. A normal scan makes zero media probes; FullRefresh does probe,
and at 400 episodes that is 400 cold starts.

Not yet done: no systemd units are installed (needs root — deploy/deploy.sh), the
admin UI has no routes for sources or the approval queue yet, and nothing has been
pointed at the real media root.

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

tests/test_channels.py

@@ -0,0 +1,151 @@
+"""Channel subscribe/unsubscribe, and the API-only sync path."""
+
+from __future__ import annotations
+
+import pytest
+
+from ytstream import api, channels, config
+
+from conftest import CHANNEL_ID, FakeApi, add_channel, add_video
+
+
+def test_normalise_url_accepts_every_reference_form():
+    assert channels.normalise_url(CHANNEL_ID).endswith("/channel/" + CHANNEL_ID)
+    assert channels.normalise_url("@clabretro") == "https://www.youtube.com/@clabretro"
+    assert channels.normalise_url("clabretro") == "https://www.youtube.com/@clabretro"
+    assert channels.normalise_url("https://youtube.com/x") == "https://youtube.com/x"
+    assert channels.normalise_url("youtube.com/x") == "https://youtube.com/x"
+
+
+def test_normalise_url_rejects_nonsense():
+    with pytest.raises(channels.ResolutionError):
+        channels.normalise_url("")
+    with pytest.raises(channels.ResolutionError):
+        channels.normalise_url("not a handle!!")
+
+
+def test_uulf_playlist_id():
+    assert channels.uulf_playlist_id(CHANNEL_ID) == "UULF" + CHANNEL_ID[2:]
+
+
+# ---------------------------------------------------------- subscribe_from_sync
+
+
+@pytest.fixture()
+def api_channel(monkeypatch):
+    """Patch channels' lazily-imported api module."""
+    fake = FakeApi(channel={"channel_id": "UC" + "a" * 22, "title": "Alpha Channel",
+                            "description": "About alpha", "handle": "@alpha",
+                            "avatar_url": None})
+    monkeypatch.setattr(api, "Api", lambda *a, **kw: fake)
+    return fake
+
+
+def test_subscribe_from_sync_never_calls_yt_dlp(conn, settings, media_root,
+                                                api_channel, monkeypatch):
+    """119 channels' worth of yt-dlp resolution is the request burst this design
+    exists to avoid."""
+    monkeypatch.setattr(channels.ytdlp, "run_json",
+                        lambda *a, **k: pytest.fail("yt-dlp must not be called"))
+
+    row = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Alpha")
+
+    assert row["title"] == "Alpha Channel"
+    assert row["source"] == "youtube"
+
+
+def test_subscribe_from_sync_uses_the_api_description(conn, settings, media_root,
+                                                      api_channel):
+    row = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Alpha")
+    assert row["description"] == "About alpha"
+
+
+def test_subscribe_from_sync_is_idempotent(conn, settings, media_root, api_channel):
+    first = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Alpha")
+    second = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Alpha")
+    assert first["id"] == second["id"]
+    assert conn.execute("SELECT COUNT(*) FROM channel").fetchone()[0] == 1
+
+
+def test_subscribe_from_sync_survives_a_metadata_failure(conn, settings, media_root,
+                                                         monkeypatch):
+    """A channel we cannot describe is still a channel we can mirror."""
+    class Failing(FakeApi):
+        def channel(self, channel_id):
+            raise api.ApiError(500, "backendError", "boom")
+
+    monkeypatch.setattr(api, "Api", lambda *a, **kw: Failing())
+
+    row = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Fallback Name")
+
+    assert row["title"] == "Fallback Name"
+
+
+def test_subscribe_from_sync_makes_no_directory(conn, settings, media_root,
+                                                monkeypatch):
+    """The tree appears with the first episode, so a channel with nothing inside
+    the window leaves no empty series behind."""
+    class NoArt(FakeApi):
+        def channel(self, channel_id):
+            return {"channel_id": channel_id, "title": "Quiet", "description": "",
+                    "handle": None, "avatar_url": None}
+
+    monkeypatch.setattr(api, "Api", lambda *a, **kw: NoArt())
+
+    row = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Quiet")
+
+    assert not (media_root / row["dir_name"]).exists()
+
+
+def test_directory_names_are_deduplicated(conn, settings, media_root, monkeypatch):
+    """Two channels can legitimately share a title; dir_name is UNIQUE."""
+    class Same(FakeApi):
+        def channel(self, channel_id):
+            return {"channel_id": channel_id, "title": "Same Name",
+                    "description": "", "handle": None, "avatar_url": None}
+
+    monkeypatch.setattr(api, "Api", lambda *a, **kw: Same())
+
+    first = channels.subscribe_from_sync(conn, settings, "UC" + "a" * 22, "Same Name")
+    second = channels.subscribe_from_sync(conn, settings, "UC" + "b" * 22, "Same Name")
+
+    assert first["dir_name"] == "Same Name"
+    assert second["dir_name"] == "Same Name (2)"
+
+
+# ------------------------------------------------------------------ unsubscribe
+
+
+def test_unsubscribe_removes_the_tree_and_the_rows(conn, media_root, channel):
+    tree = media_root / "clabretro"
+    (tree / "Season 2026").mkdir(parents=True)
+    (tree / "tvshow.nfo").write_text("<tvshow/>")
+    add_video(conn, channel["id"], "vid00000001")
+
+    title = channels.unsubscribe(conn, channel["id"])
+
+    assert title == "clabretro"
+    assert not tree.exists()
+    assert conn.execute("SELECT COUNT(*) FROM channel").fetchone()[0] == 0
+    assert conn.execute("SELECT COUNT(*) FROM video").fetchone()[0] == 0
+
+
+def test_unsubscribe_rejects_an_unknown_id(conn):
+    with pytest.raises(LookupError):
+        channels.unsubscribe(conn, 999)
+
+
+def test_lookup_helpers(conn, channel):
+    assert channels.get(conn, channel["id"])["title"] == "clabretro"
+    assert channels.get_by_channel_id(conn, CHANNEL_ID)["id"] == channel["id"]
+    assert channels.get(conn, 999) is None
+    assert channels.get_by_channel_id(conn, "UCnope") is None
+
+
+def test_all_channels_is_sorted_case_insensitively(conn):
+    add_channel(conn, "UC" + "a" * 22, "zebra", "zebra")
+    add_channel(conn, "UC" + "b" * 22, "Apple", "Apple")
+
+    titles = [row["title"] for row in channels.all_channels(conn)]
+
+    assert titles == ["Apple", "zebra"]