CREATE TABLE IF NOT EXISTS document_revisions (
    id INT AUTO_INCREMENT PRIMARY KEY,
    category VARCHAR(64) NOT NULL,
    filename VARCHAR(128) NOT NULL,
    author_email VARCHAR(255),
    author_name VARCHAR(255),
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    reverse_diff MEDIUMTEXT NOT NULL,
    INDEX idx_doc (category, filename, created_at)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;