def score(candidate: dict) -> float:
                                    
    signals = candidate.get("redrob_signals", {}) or {}
    gh = signals.get("github_activity_score")

    if gh is None or gh == -1:
        return 0.25

    gh = float(gh)
    if gh < 0:
        return 0.25
    elif gh <= 69.0:
        return round(gh / 100.0, 6)
    else:
                                                      
        return round(0.80 + (gh - 70.0) / 30.0 * 0.20, 6)