mechanic: use upstream's exponential level curve

pqcli/mechanic.py

@@ -59,8 +59,9 @@ class SignalMixin:
 
 
 def level_up_time(level: int) -> int:
-    # seconds
-    return 20 * level * 60
+    # seconds: 20 minutes for level 1, exponential increase after that.
+    # floor(x + 0.5) mirrors JS Math.round, unlike Python's round().
+    return math.floor((20 + 1.15**level) * 60 + 0.5)
 
 
 class Bar(SignalMixin):

tests/test_mechanic.py

@@ -0,0 +1,9 @@
+from pqcli.mechanic import level_up_time
+
+
+def test_level_up_time_matches_upstream() -> None:
+    # Math.round((20 + Math.pow(1.15, level)) * 60), pq-web 5cd39f1
+    assert level_up_time(1) == 1269
+    assert level_up_time(10) == 1443
+    assert level_up_time(30) == 5173
+    assert level_up_time(100) == 70460007