March 2026 monthly summary for espressif/esp-matter. Focused on enabling cluster-level simulation to accelerate testing and development of Matter applications. Key feature delivered this month: mock delegates for cluster simulation in the all-device-types app, allowing device behavior to be simulated without actual implementations. Key achievements: - Merged mock_delegates_1 into main, adding empty mock delegates for cluster simulation across the all-device-types app. - Created and wired empty mock delegates for various clusters to support testing workflows without hardware. - Integrated changes into the main branch with reference to app-frameworks/esp-matter!1221 and commit 6e6b39721b087031997e7cf8d3596b9c13a92315. - This work reduces testing friction, accelerates development cycles, and improves readiness for end-to-end Matter testing. Major bugs fixed: - None documented for this month; effort focused on feature scaffolding and test doubles. Overall impact and accomplishments: - Significantly improved testability and development velocity by enabling cluster-level simulations without hardware, aligning with the project roadmap for modular testing. - Demonstrated solid Git workflows, merge processes, and collaboration with cross-team MR references. Technologies/skills demonstrated: - C/C++ development in ESP-IDF, cluster/Matter concepts, and test scaffolding. - Git merge workflows, code review, and branch management. - Test-driven development patterns and simulation-based testing approaches.