CREATE TABLE lead_message_reads (
    id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
    lead_id INT UNSIGNED NOT NULL,
    user_id INT UNSIGNED NOT NULL,
    last_read_at DATETIME NOT NULL,
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    UNIQUE KEY uq_lead_message_reads (lead_id, user_id),
    INDEX idx_lead_message_reads_user (user_id),
    CONSTRAINT fk_lead_message_reads_lead FOREIGN KEY (lead_id) REFERENCES leads (id) ON DELETE CASCADE,
    CONSTRAINT fk_lead_message_reads_user FOREIGN KEY (user_id) REFERENCES users (id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;