Add scoring and pool validation

app/scoring.py

@@ -1 +1,40 @@
 """Score functions."""
+
+from __future__ import annotations
+
+from collections.abc import Callable
+
+ScoreFn = Callable[[bool, int, int], int]
+SCORE_FNS: dict[str, ScoreFn] = {}
+
+
+def register(name: str) -> Callable[[ScoreFn], ScoreFn]:
+    def decorator(func: ScoreFn) -> ScoreFn:
+        SCORE_FNS[name] = func
+        return func
+
+    return decorator
+
+
+@register("linear_decay")
+def linear_decay(correct: bool, elapsed_ms: int, time_limit_ms: int) -> int:
+    if not correct:
+        return 0
+    elapsed_ms = max(0, min(elapsed_ms, time_limit_ms))
+    return round(1000 * (1 - 0.5 * elapsed_ms / time_limit_ms))
+
+
+@register("flat")
+def flat(correct: bool, elapsed_ms: int, time_limit_ms: int) -> int:
+    return 1000 if correct else 0
+
+
+@register("exponential_decay")
+def exponential_decay(correct: bool, elapsed_ms: int, time_limit_ms: int) -> int:
+    if not correct:
+        return 0
+    import math
+
+    elapsed_ms = max(0, min(elapsed_ms, time_limit_ms))
+    decay = math.exp(-2 * elapsed_ms / time_limit_ms)
+    return round(1000 * (0.5 + 0.5 * decay))