April 2025 monthly summary: Focused on delivering extensible data-type support in xtdb/arrow-java by implementing Arrow Java ExtensionWriter for custom extension types. This enables writing of extension values and type-specific writers via configurable factories, including handling for unknown vector and value types to enhance flexibility and resilience in data representation. The work lays the groundwork for interoperable, extensible data types across Arrow pipelines and downstream consumers, aligning with performance and data fidelity goals. No major bugs reported fixed this month; primary emphasis on feature delivery and architecture groundwork. Technologies/skills demonstrated include Java, Arrow Java SDK, ExtensionWriter API, and factory-pattern design, with clear commit traceability (see 437612c07e04fb0283010961a836de22521fa759).