README.md

@@ -174,17 +174,40 @@ An artist neither key resolves is recorded as fetched with no tags, so the next
 pass does not spend a request on it again. A genuine failure — a rate limit, a
 bad key — is *not* recorded, so that one is retried.
 
-The built-in moods are chosen for this library rather than as a general
-taxonomy:
+The built-in moods are built from the **tag distribution of this library**,
+measured, rather than from a general taxonomy:
 
 | Mood | Selected on |
-| ------------------ | ------------------------------------------------- |
-| `80s-synths` | synthpop, new wave, synthwave — released 1975-1992 |
-| `high-energy-rock` | hard rock, punk, pop punk, alternative |
-| `screamo` | screamo, post-hardcore, metalcore, emo |
-| `drum-and-bass` | drum and bass, liquid funk, neurofunk, jungle |
-| `dance` | house, big room, hardstyle, trance, dubstep |
-| `classic-rock` | classic rock, prog, psychedelic, blues rock |
+| --------------- | -------------------------------------------------------- |
+| `drum-and-bass` | drum and bass and its six spellings, liquid funk, neurofunk, jungle, techstep, hospital records |
+| `bass` | dubstep, brostep, grime, trip-hop, big beat |
+| `dance` | house and its variants, trance, techno, electro, rave |
+| `pop-punk` | pop punk, punk, emo, emocore, easycore, power pop |
+| `screamo` | screamo, post-hardcore, metalcore, melodic hardcore, trancecore |
+| `heavy-metal` | heavy metal, thrash, speed, power, death, prog, NWOBHM |
+| `hair-metal` | hair metal, glam metal, glam rock, arena rock, AOR — 1975-1994 |
+| `nu-metal` | nu metal, alternative metal, rapcore, industrial |
+| `classic-rock` | classic rock, prog, psychedelic, blues rock, 70s, 60s |
+| `80s-synths` | synthpop, electropop, new wave, post-punk — 1975-1992 |
+| `indie` | indie, indie rock, indie pop, britpop, singer-songwriter |
+
+Measuring first mattered. `synthwave`, `edm`, `big room` and `hardstyle` are
+plausible tags that carry **nothing at all** here, while `techstep`, `easycore`
+and `hospital records` carry real weight. Guessing produces the first list.
+
+Three kinds of tag are never used, and there is a test enforcing it:
+
+- **Nationality** — `american` alone spans 241 artists. A passport is not a
+  sound.
+- **`rock` and `electronic`** — 340 and 275 artists, most of the library. A
+  mood that matches everything is not a mood.
+- **Artist names** — Last.fm's most popular tag for an artist is frequently
+  their own name. `green day`, `paramore` and `queen` are single-artist
+  playlists waiting to happen.
+
+`80s-synths` deliberately excludes the bare `80s` tag, which in this library
+sits on Def Leppard and Bon Jovi rather than on anything with a synthesiser in
+it. Those belong to `hair-metal`, which is why that mood now exists.
 
 An artist qualifies when their tag weights inside a mood sum to at least 30 out
 of Last.fm's 0-100 scale. One low-weight tag is not a genre, it is somebody's

music_curator.py

@@ -1242,49 +1242,97 @@ PLAYLISTS = (
 # `years` filters on the album's release date, which is what separates eighties
 # synth records from everything a synthpop tag would otherwise drag in.
 DEFAULT_VIBES = (
+    # Built from the tag distribution of this library rather than from a general
+    # taxonomy, which is why some obvious-looking tags are absent and some
+    # unobvious ones are here. `synthwave`, `edm`, `big room` and `hardstyle`
+    # carry nothing at all; `techstep`, `easycore` and `hospital records` carry
+    # real weight.
+    #
+    # Three kinds of tag are deliberately never used. Nationality -- american,
+    # british, swedish -- describes a passport, not a sound, and `american`
+    # alone spans 241 artists. `rock` and `electronic` span 340 and 275, which
+    # is most of the library and therefore no mood at all. And Last.fm's most
+    # popular tag for an artist is frequently their own name, so `green day`,
+    # `paramore` and `queen` are single-artist playlists waiting to happen.
     {
-        "name": "80s-synths",
+        "name": "drum-and-bass",
         "tags": [
-            "synthpop", "synth pop", "synth-pop", "new wave", "synthwave",
-            "new romantic", "electropop", "80s", "1980s",
+            "drum and bass", "dnb", "drum n bass", "drum'n'bass", "drum & bass",
+            "drum 'n' bass", "liquid funk", "neurofunk", "jungle", "techstep",
+            "darkstep", "drumstep", "breakbeat", "hospital records",
         ],
-        "years": [1975, 1992],
     },
     {
-        "name": "high-energy-rock",
+        "name": "bass",
+        "tags": ["dubstep", "brostep", "grime", "trip-hop", "big beat"],
+    },
+    {
+        "name": "dance",
         "tags": [
-            "hard rock", "punk rock", "pop punk", "punk", "alternative rock",
-            "rock", "garage rock", "skate punk",
+            "house", "electro house", "progressive house", "tech house", "trance",
+            "techno", "electro", "rave", "dance", "minimal",
+        ],
+    },
+    {
+        "name": "pop-punk",
+        "tags": [
+            "pop punk", "pop-punk", "punk rock", "punk", "skate punk", "emo",
+            "emocore", "easycore", "powerpop", "power pop", "post-grunge",
         ],
     },
     {
         "name": "screamo",
         "tags": [
-            "screamo", "post-hardcore", "metalcore", "emo", "hardcore",
-            "melodic hardcore", "emocore",
+            "screamo", "post-hardcore", "metalcore", "melodic metalcore",
+            "melodic hardcore", "hardcore", "trancecore", "deathcore",
         ],
     },
     {
-        "name": "drum-and-bass",
+        "name": "heavy-metal",
         "tags": [
-            "drum and bass", "drum n bass", "dnb", "liquid funk", "neurofunk",
-            "jungle", "breakbeat",
+            "heavy metal", "metal", "thrash metal", "thrash", "speed metal",
+            "power metal", "death metal", "progressive metal", "nwobhm",
+            "classic metal",
         ],
     },
     {
-        "name": "dance",
+        "name": "hair-metal",
         "tags": [
-            "electro house", "house", "big room", "electronic dance music",
-            "edm", "hardstyle", "trance", "dubstep", "electro",
+            "hair metal", "glam metal", "glam rock", "arena rock", "aor",
+            "rock and roll", "rock n roll",
+        ],
+        "years": [1975, 1994],
+    },
+    {
+        "name": "nu-metal",
+        "tags": [
+            "nu metal", "nu-metal", "alternative metal", "rapcore",
+            "industrial metal", "industrial rock", "industrial",
         ],
     },
     {
         "name": "classic-rock",
         "tags": [
-            "classic rock", "progressive rock", "psychedelic rock",
-            "blues rock", "70s", "60s",
+            "classic rock", "progressive rock", "psychedelic rock", "psychedelic",
+            "blues rock", "blues", "southern rock", "art rock", "space rock",
+            "british invasion", "folk rock", "70s", "60s",
         ],
     },
+    {
+        "name": "80s-synths",
+        # Without the bare `80s` tag, which in this library sits on Def Leppard
+        # and Bon Jovi rather than on anything with a synthesiser in it. The
+        # year window is kept as a second filter, not as the only one.
+        "tags": [
+            "synthpop", "electropop", "new wave", "post-punk",
+            "post-punk revival", "new romantic",
+        ],
+        "years": [1975, 1992],
+    },
+    {
+        "name": "indie",
+        "tags": ["indie", "indie rock", "indie pop", "britpop", "singer-songwriter"],
+    },
 )
 
 

tests/test_music_curator.py

@@ -1198,3 +1198,37 @@ def test_a_real_failure_is_not_recorded_so_the_next_pass_retries(tmp_path):
 
     # One artist failed hard and must still be pending.
     assert store.scalar("SELECT COUNT(*) FROM artist_tag_fetched") == 1
+
+
+# Tags that carry real weight in a real library, against tags that describe a
+# passport, span most of the collection, or are somebody's artist name.
+USELESS_TAGS = {
+    "american", "british", "australian", "canadian", "swedish", "dutch", "german",
+    "scottish", "english", "uk", "usa", "canada",
+    "rock", "electronic", "pop", "alternative", "metal ", "all", "heavy",
+    "female vocalists", "male vocalists", "female vocalist",
+    "my top songs", "cover", "covers", "not emo",
+    "green day", "paramore", "queen", "bon jovi", "shinedown", "aerosmith",
+    "journey", "fleetwood mac",
+}
+
+
+def test_no_mood_selects_on_a_useless_tag():
+    """Nationality is not a sound; `rock` and `electronic` span most of the
+    library; and Last.fm's top tag for an artist is often their own name."""
+    for vibe in music_curator.DEFAULT_VIBES:
+        overlap = {tag.casefold() for tag in vibe["tags"]} & USELESS_TAGS
+        assert not overlap, f"{vibe['name']} selects on {overlap}"
+
+
+def test_mood_names_are_unique():
+    names = [vibe["name"] for vibe in music_curator.DEFAULT_VIBES]
+    assert len(names) == len(set(names))
+
+
+def test_the_eighties_mood_does_not_lean_on_the_bare_decade_tag():
+    """In this library `80s` sits on Def Leppard and Bon Jovi, not on
+    synthesisers. The hair-metal mood is where those belong."""
+    synths = next(v for v in music_curator.DEFAULT_VIBES if v["name"] == "80s-synths")
+    assert "80s" not in synths["tags"]
+    assert synths["years"] == [1975, 1992]