Remove the Quallenalarm (jellyfish) typing minigame

Letters-round lessons only had bubbles and jellyfish as eligible arcade
modes; with jellyfish gone, bubbles is now always used instead of the
two alternating - no lessons need to be dropped.

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

python-backend/musicmouse/tippen/curriculum.py

@@ -38,7 +38,7 @@ __all__ = [
 ]
 
 type LessonKind = Literal["letters", "fragments", "words", "sentences"]
-type ModeId = Literal["dive", "bubbles", "jellyfish", "feed", "race"]
+type ModeId = Literal["dive", "bubbles", "feed", "race"]
 type CreatureId = Literal["clownfish", "octopus", "seahorse", "turtle", "pearlmussel"]
 
 #: In world order - see ``tippen/src/lib/aquarium.ts``, the one place this list is
@@ -52,9 +52,9 @@ CREATURE_IDS: Final[tuple[CreatureId, ...]] = (
 )
 
 #: Which modes make sense for a kind - letters rounds are single keys, so only the
-#: arcade modes fit; only words and sentences are long enough for a race.
+#: arcade mode fits; only words and sentences are long enough for a race.
 ELIGIBLE_MODES: Final[dict[LessonKind, tuple[ModeId, ...]]] = {
-    "letters": ("bubbles", "jellyfish"),
+    "letters": ("bubbles",),
     "fragments": ("dive", "feed"),
     "words": ("dive", "feed", "race"),
     "sentences": ("dive", "race"),
@@ -230,9 +230,6 @@ def _build_lessons(worlds: tuple[_YamlWorld, ...]) -> tuple[Lesson, ...]:
     lessons: list[Lesson] = []
     active: set[str] = set()
     seen_before: set[str] = set()
-    # Letters rounds alternate bubbles/jellyfish across the whole course, so the arcade
-    # game never repeats twice in a row even across a fragments/words lesson in between.
-    last_arcade: ModeId = "jellyfish"  # so lesson 1 opens on bubbles
 
     for world in worlds:
         for entry in world.lessons:
@@ -260,16 +257,10 @@ def _build_lessons(worlds: tuple[_YamlWorld, ...]) -> tuple[Lesson, ...]:
             else:
                 emphasis = "mixed"
 
-            primary_mode: ModeId
-            if kind == "letters":
-                default_arcade: ModeId = "jellyfish" if last_arcade == "bubbles" else "bubbles"
-                primary_mode = entry.mode or default_arcade
-                last_arcade = primary_mode
-            else:
-                primary_mode = entry.mode or "dive"
+            primary_mode: ModeId = entry.mode or ("bubbles" if kind == "letters" else "dive")
 
             # Bonus replays are only ever feed/race - dive is the plain default, and
-            # bubbles/jellyfish already alternate on their own.
+            # bubbles is the only letters-round arcade mode.
             bonus_modes = tuple(
                 mode
                 for mode in ELIGIBLE_MODES[kind]

python-backend/tests/test_tippen_curriculum.py

@@ -244,11 +244,10 @@ def test_plays_a_mode_that_fits_its_kind(curriculum) -> None:
             assert mode in ELIGIBLE_MODES[lesson.kind], where
 
 
-def test_never_plays_the_same_arcade_game_twice_in_a_row(curriculum) -> None:
-    arcade = [lesson for lesson in curriculum.lessons if lesson.kind == "letters"]
-    for i in range(1, len(arcade)):
-        where = f"{arcade[i].number}: {arcade[i].title}"
-        assert arcade[i].primary_mode != arcade[i - 1].primary_mode, where
+def test_letters_rounds_always_play_bubbles(curriculum) -> None:
+    for lesson in curriculum.lessons:
+        if lesson.kind == "letters":
+            assert lesson.primary_mode == "bubbles", f"{lesson.number}: {lesson.title}"
 
 
 def test_offers_every_eligible_mode_not_gated_on_as_a_bonus(curriculum) -> None: