v3 library: artist sort orders titles within an artist (tree-view feel) (#720)

* v3 library: artist sort orders titles within an artist (tree-view feel)

Tester report: "the list is set up by artist, but the cards are
alphabetical(-ish random)". Real: the tree orders artist -> album -> title,
while the grid's artist sort ordered within an artist by RAW FILENAME —
community-pack filename noise, so an artist's cards looked shuffled.

- artist / artist-desc gain a title secondary (direction baked per entry so
  the legacy `dir=desc` append can't land on the title term; titles stay
  A->Z under Z->A artists).
- The two-term (value, filename) keyset cursor can't seek a three-term
  order, so artist sorts leave _KEYSET_SORTS and page by OFFSET — measured
  trivial at real library sizes; title/recent keep their keyset. Restore
  via a composite sort-key column if 50k-song libraries ever hurt.
- The tree view says "List view groups by artist — the selected sort
  applies to the card grid" when a non-artist sort is active, instead of
  silently ignoring the picker.
- Keyset proof-tests repinned to the title sort (same property, a sort
  that still keysets); 2 new tests pin the title-within-artist order and
  the OFFSET pagination's no-skip/no-dupe across pages.

Full-suite failure set identical to the same-main baseline.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nm7tHs1Yvjjtnnu4nzJgdN

* v3 library: honor legacy sort=artist&dir=desc (fold dir into effective sort)

Codex/review follow-up to the title-within-artist change: the new artist
ORDER BY bakes in `ASC` (for the title secondary), so the global `dir=desc`
append is suppressed and `sort=artist&dir=desc` silently returned A->Z
instead of Z->A — a regression on the legacy /api/library dir contract.

Fold `dir=desc` into the canonical sort key BEFORE the sort_map lookup via
the existing _effective_keyset_sort helper (same fold the cursor side already
does), so the ORDER BY is built from the effective sort. Only artist/title
fold (they have `-desc` twins); title/recent/tuning/year/mastery are
unaffected — verified by the keyset/filter suites.

New test pins that legacy `sort=artist&dir=desc` matches the explicit
`artist-desc` ordering (Z->A artists, A->Z titles within each).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: byrongamatos <xasiklas@gmail.com>

tests/test_artist_sort_title_order.py

@@ -0,0 +1,81 @@
+"""The grid's artist sort orders WITHIN an artist by title (tree-view feel),
+not raw filename — the tester's "list is organised by artist, but the cards
+look alphabetical/random" report. Artist sorts page by OFFSET now (the title
+secondary can't ride the two-term keyset cursor), so pagination across an
+artist boundary is pinned too."""
+
+import importlib
+import sys
+
+import pytest
+from fastapi.testclient import TestClient
+
+
+@pytest.fixture()
+def server(tmp_path, monkeypatch, isolate_logging):
+    monkeypatch.setenv("CONFIG_DIR", str(tmp_path))
+    monkeypatch.setenv("FEEDBACK_SKIP_STARTUP_TASKS", "1")
+    sys.modules.pop("server", None)
+    srv = importlib.import_module("server")
+    try:
+        yield srv
+    finally:
+        conn = getattr(getattr(srv, "meta_db", None), "conn", None)
+        if conn is not None:
+            conn.close()
+        sys.modules.pop("server", None)
+
+
+@pytest.fixture()
+def client(server):
+    return TestClient(server.app)
+
+
+def _put(server, fn, artist, title):
+    server.meta_db.put(fn, 0, 0, {
+        "title": title, "artist": artist, "album": "", "year": "",
+        "duration": 100, "arrangements": [{"name": "Lead", "index": 0}],
+    })
+
+
+def test_artist_sort_orders_titles_within_artist(server, client):
+    # Filenames deliberately REVERSE the title order, so filename ordering
+    # (the old behaviour) and title ordering disagree.
+    _put(server, "z1.sloppak", "Alpha Band", "Aardvark")
+    _put(server, "a9.sloppak", "Alpha Band", "Zebra")
+    _put(server, "m5.sloppak", "Alpha Band", "Mango")
+    _put(server, "q1.sloppak", "Beta Band", "Only Song")
+    body = client.get("/api/library", params={"sort": "artist", "size": 50}).json()
+    assert [s["title"] for s in body["songs"]] == ["Aardvark", "Mango", "Zebra", "Only Song"]
+    # Z→A flips the ARTIST order; titles stay A→Z within each artist.
+    body = client.get("/api/library", params={"sort": "artist-desc", "size": 50}).json()
+    assert [s["title"] for s in body["songs"]] == ["Only Song", "Aardvark", "Mango", "Zebra"]
+
+
+def test_legacy_dir_desc_flips_artist_like_artist_desc(server, client):
+    # The legacy `sort=artist&dir=desc` shape must match the explicit
+    # `artist-desc` key: the artist clause now bakes in ASC (for the title
+    # secondary), so `dir=desc` is folded into the effective sort BEFORE the
+    # ORDER BY lookup — otherwise the append is suppressed and dir=desc would
+    # silently return A→Z.
+    _put(server, "z1.sloppak", "Alpha Band", "Aardvark")
+    _put(server, "a9.sloppak", "Alpha Band", "Zebra")
+    _put(server, "m5.sloppak", "Alpha Band", "Mango")
+    _put(server, "q1.sloppak", "Beta Band", "Only Song")
+    legacy = client.get("/api/library", params={"sort": "artist", "dir": "desc", "size": 50}).json()
+    explicit = client.get("/api/library", params={"sort": "artist-desc", "size": 50}).json()
+    assert [s["title"] for s in legacy["songs"]] == ["Only Song", "Aardvark", "Mango", "Zebra"]
+    assert [s["title"] for s in legacy["songs"]] == [s["title"] for s in explicit["songs"]]
+
+
+def test_artist_sort_offset_pagination_no_skip_or_dupe(server, client):
+    for i in range(7):
+        _put(server, f"f{6 - i}.sloppak", "One Artist", f"Title {chr(65 + i)}")
+    seen = []
+    for page in range(4):
+        body = client.get("/api/library", params={"sort": "artist", "size": 2, "page": page}).json()
+        seen += [s["title"] for s in body["songs"]]
+    assert seen == [f"Title {chr(65 + i)}" for i in range(7)]
+    # And no keyset cursor is offered for artist sorts (OFFSET path).
+    body = client.get("/api/library", params={"sort": "artist", "size": 2}).json()
+    assert body["next_cursor"] is None

tests/test_group_filter_law.py

@@ -184,7 +184,9 @@ def test_grouped_keyset_pagination_with_intrinsic_filter(client, server):
              arrangements=1, tuning="Drop D")
     seen, cursor = [], None
     for _ in range(10):
-        params = {"group": 1, "tunings": "Drop D", "size": 2, "sort": "artist"}
+        # Title sort — the keyset proof needs a sort that still keysets
+        # (artist sorts page by OFFSET since the title-secondary change).
+        params = {"group": 1, "tunings": "Drop D", "size": 2, "sort": "title"}
         if cursor:
             params["after"] = cursor
         body = client.get("/api/library", params=params).json()

tests/test_library_keyset.py

@@ -73,7 +73,10 @@ def _walk_offset(client, sort, size, total):
     return seen
 
 
-@pytest.mark.parametrize("sort", ["artist", "artist-desc", "title", "title-desc", "recent"])
+# artist/artist-desc left out: their ORDER BY carries a title secondary
+# (grid cards read alphabetically within an artist, like the tree), which
+# the two-term cursor cannot seek — they page by OFFSET (covered below).
+@pytest.mark.parametrize("sort", ["title", "title-desc", "recent"])
 def test_keyset_matches_offset_exactly(client, server_mod, sort):
     _seed(server_mod, 25)
     offset_order = _walk_offset(client, sort, 7, 25)
@@ -87,15 +90,17 @@ def test_stable_tiebreak_on_equal_keys(client, server_mod):
     # 25 songs, all the SAME artist → the artist sort is decided entirely by the
     # filename tiebreak. Both pagers must still cover all 25 with no dupe.
     _seed(server_mod, 25, shared_artist=True)
-    keyset_order = _walk_keyset(client, "artist", 6, 25)
+    keyset_order = _walk_offset(client, "artist", 6, 25)
     assert len(keyset_order) == 25 and len(set(keyset_order)) == 25
     assert keyset_order == sorted(keyset_order)      # tiebreak is filename ASC
 
 
 def test_first_page_has_cursor_and_no_after_is_offset(client, server_mod):
     _seed(server_mod, 5)
+    body = client.get("/api/library", params={"sort": "title", "size": 2}).json()
+    assert body["next_cursor"]                       # keyset sort: cursor offered
     body = client.get("/api/library", params={"sort": "artist", "size": 2}).json()
-    assert body["next_cursor"]                       # cursor offered
+    assert body["next_cursor"] is None               # artist sorts page by OFFSET
     assert [s["filename"] for s in body["songs"]] == ["song00.archive", "song01.archive"]
 
 
@@ -111,7 +116,7 @@ def test_legacy_dir_desc_keysets_correctly(client, server_mod):
     _seed(server_mod, 20)
     offset_order, page = [], 0
     while True:
-        body = client.get("/api/library", params={"sort": "artist", "dir": "desc", "size": 6, "page": page}).json()
+        body = client.get("/api/library", params={"sort": "title", "dir": "desc", "size": 6, "page": page}).json()
         if not body["songs"]:
             break
         offset_order.extend(s["filename"] for s in body["songs"])
@@ -119,7 +124,7 @@ def test_legacy_dir_desc_keysets_correctly(client, server_mod):
     keyset, cursor, guard = [], "", 0
     while len(keyset) < 20 and guard < 25:
         guard += 1
-        params = {"sort": "artist", "dir": "desc", "size": 6}
+        params = {"sort": "title", "dir": "desc", "size": 6}
         if cursor:
             params["after"] = cursor
         body = client.get("/api/library", params=params).json()
@@ -131,7 +136,7 @@ def test_legacy_dir_desc_keysets_correctly(client, server_mod):
     assert len(set(keyset)) == 20
 
 
-@pytest.mark.parametrize("sort", ["artist", "artist-desc", "recent"])
+@pytest.mark.parametrize("sort", ["recent"])
 def test_keyset_handles_null_sort_keys(client, server_mod, sort):
     # NULL artist/mtime (corrupt/legacy rows past put()'s '' defaults) sort
     # first in ASC / last in DESC; keyset must cover them exactly like OFFSET.

tests/test_work_grouping.py

@@ -158,11 +158,13 @@ def test_grouped_keyset_pagination(client, server):
     for i in range(5):
         _put(server, f"w{i}_a.archive", f"Song {i}", "Artist")
         _put(server, f"w{i}_b.archive", f"Song {i}", "Artist")   # 2 charts per work
-    body = client.get("/api/library", params={"group": 1, "size": 3}).json()
+    # Title sort: artist sorts page by OFFSET now (title-secondary ordering),
+    # and this test PROVES the grouped keyset, so it pins a keyset sort.
+    body = client.get("/api/library", params={"group": 1, "size": 3, "sort": "title"}).json()
     assert body["total"] == 5 and len(body["songs"]) == 3
     cur = body["next_cursor"]
     assert cur
-    body2 = client.get("/api/library", params={"group": 1, "size": 3, "after": cur}).json()
+    body2 = client.get("/api/library", params={"group": 1, "size": 3, "sort": "title", "after": cur}).json()
     assert len(body2["songs"]) == 2
     p1 = {s["filename"] for s in body["songs"]}
     p2 = {s["filename"] for s in body2["songs"]}