extract-modulelisted

Carve a bloated, multi-responsibility file into a handful of focused modules without breaking a thing. The skill first maps what the file actually does and where the seams are — clusters of functions that share state, types, or a single reason to change — then designs each new module's public surface before touching code, and moves the clusters out one at a time so every intermediate state still compiles and passes tests. ## When to use this skill - A single file has grown past what one person holds in their head, and unrelated edits keep colliding in it. - One file mixes responsibilities — HTTP handling, business rules, and persistence; or parsing, validation, and formatting — that change for different reasons. - The file is a chronic merge-conflict hotspot because every feature touches it. - You need a *safe, incremental* split with a green build at each step, not a big-bang rewrite. > [!WARNING] > Do not split by line count. "This file is 1,200 lines, cut it in half" produces two arbitrarily-severed files that still share state and import each other constantly — worse than one. Split by **cohesion**: a module is a set of functions and types with one reason to change and a small interface to everything else. If a proposed boundary would expose more than a handful of symbols, the seam is in the wrong place. ## Instructions 1. **Map responsibilities before touching code.** Read the whole file and list every top-level function/class with its one-line purpose and what stat