May 2026: Delivered a security-focused upgrade to the wp-calypso login flow by integrating a Challenge Widget via the Blackbox SDK. Implemented a dedicated challenge state component and a singleton SDK loader, moved loading to the client side, and gated login submissions during challenge initialization for robust security and better UX. Refined session management to reset on remount/back-navigation and added onChallengeFailure handling; extended load/collect timeouts to 5s to improve reliability on slow networks; enhanced TypeScript typings (Window.Blackbox) and logging for easier debugging and cross-team collaboration. Business impact: stronger authentication, reduced risk of stale or blocked logins, and smoother user experience across diverse network conditions.