You ask Claude Code to change one function, and it greps for the name, opens a 900-line file, reads half of it, opens three more files, and your context window is gone before the first edit. Then the rename it does is a dozen fragile find-and-replace edits that still miss a call site. Serena fixes that by giving the agent the tools your IDE already has. It can jump straight to a symbol, list every reference to it, rename it across the project, or replace one function body without reading th...