server/tasks/task1/grader.py

"""
grader.py  (Task 1 – Targeted Vulnerability Detection)
-------------------------------------------------------
Deterministic grader. Grade range: (0, 1)
"""

from __future__ import annotations
from typing import Dict
from utils import SemanticMatcher

class Task1Grader:
    def __init__(self, target_function: str, vulnerability_issue: str, n: int) -> None:
        self.target_function     = target_function.lower()
        self.vulnerability_issue = vulnerability_issue
        
        # Log of No. of functions (n) is a heurisitic used to decided the size of contract code
        self.n = n
        self._decay = 0.75
    
    def _clamp(self, reward: float) -> float:
        return max(0.001, min(0.999, reward))

    def grade(self, submitted_function: str, submitted_vuln_type: str, steps: int, cummulative_cost: int) -> float:
        """Returns grade strictly in (0, 1)."""
        func_match = submitted_function.strip().lower() == self.target_function
        issue_match = SemanticMatcher().matchscore(self.vulnerability_issue, submitted_vuln_type)
        
        # Score formula
        free_budget = (cummulative_cost / steps) * (self.n + 2)
        reward = (func_match * 0.5) + (issue_match * 0.5) + (self._decay ** max(0, cummulative_cost - free_budget))
        return self._clamp(reward)
        
    def get_canonical_answer(self) -> Dict[str, str]:
        return {"function": self.target_function, "vulnerability": self.vulnerability_issue}