CREATE TABLE IF NOT EXISTS wa_push_subscriptions (
    id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    agent_id BIGINT UNSIGNED NOT NULL,
    endpoint_hash CHAR(64) NOT NULL,
    endpoint TEXT NOT NULL,
    public_key VARCHAR(255) NOT NULL,
    auth_token VARCHAR(255) NOT NULL,
    content_encoding VARCHAR(20) NOT NULL DEFAULT 'aes128gcm',
    user_agent VARCHAR(500) NULL,
    enabled TINYINT(1) NOT NULL DEFAULT 1,
    last_success_at DATETIME NULL,
    last_error TEXT NULL,
    created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    UNIQUE KEY uq_push_endpoint_hash (endpoint_hash),
    KEY idx_push_agent_enabled (agent_id, enabled),
    CONSTRAINT fk_push_subscription_agent FOREIGN KEY (agent_id) REFERENCES wa_agents(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;