February 2026 (PyPSA/PyPSA) monthly summary: - Key features delivered include a Secant-based Transmission Loss Approximation with error control for power flow optimization, increasing loss estimation accuracy used in dispatch. Internal constraints were added to support the new loss model, and documentation was updated to reflect the new capabilities. - Major bugs fixed: none reported this month; focus was on feature delivery and documentation improvements. - Overall impact: enhances model fidelity and optimization robustness, enabling more cost-aware dispatch decisions and potential fuel/transmission cost reductions through improved loss estimation. - Technologies/skills demonstrated: numerical methods (secant-based error control), integration with optimization workflow, documentation practices, and collaborative code contributions (commit 391870d643cfc2f8655e56d96e013d1aa076f437; Line losses with error control #1495).