Worked on the dafny-lang/dafny repository to deliver a foundational feature enabling plugin development through a mutable Abstract Syntax Tree (AST) surface. By making AST node fields writable in C#, this change allowed plugins to perform AST rewrites, unlocking new opportunities for extensibility and future tooling. The approach focused on AST manipulation and compiler development, establishing a clear and maintainable interface for plugin authors. This work laid the groundwork for a richer plugin ecosystem and future analyses, improving the flexibility and maintainability of the compiler’s architecture while supporting ongoing enhancements in plugin development and related tooling within the Dafny project.