To calculate the 3BV (Boulder, Bomb, and Victory) metric for a Minesweeper board represented as a 2D grid, we can define a function in Python that iterates through the grid and counts the three components: boulders, bombs, and victory squares. Below is a sample implementation of the function:

def calculate_3bv(board):
    boulders = 0
    bombs = 0
    victory_squares = 0
    
    rows = len(board)
    cols = len(board[0]) if rows > 0 else 0

    for i in range(rows):
        for j in range(cols):
            if board[i][j] == -1:  # Assuming -1 represents a bomb
                bombs += 1
            elif board[i][j] == 0:  # Assuming 0 represents a boulder
                boulders += 1
                # Check for victory squares by revealing adjacent squares
                victory_squares += reveal_victory_squares(board, i, j)

    total_3bv = boulders + bombs + victory_squares
    return total_3bv

def reveal_victory_squares(board, x, y):
    # Placeholder function for revealing victory squares logic
    # Implement logic to count additional victory squares if needed
    return 1  # Simplified assumption that each boulder can be a victory square
    

In this code, we scan the board for bombs and boulders, counting them directly. The function reveal_victory_squares is a placeholder where you can implement logic to determine specific victory squares based on your game’s rules. Edge cases to consider include boards entirely filled with bombs (where the count of bombs would be equal to the grid size) and completely empty boards (where both boulders and bombs would be zero). Make sure to adjust the bomb and boulder definitions based on how you represent them in your grid (e.g., using -1 for bombs, 0 for boulders, and positive numbers for numbered squares indicating bomb proximity).