code-quality

Apply a small set of **type-driven** quality techniques when writing or refactoring code. Each technique has its own reference — the principle, a real before/after from this repo, and the smells to grep for. **Read the reference(s) that match the code in front of you; don't apply all five blindly.** ## When this fires A request to _refactor / clean up / improve / harden / tighten_ code or an API — or when you're about to write a new module/type/public export and want it right the first time. Not a bug hunt (use `/code-review`). ## The techniques — read the matching reference | Smell in front of you | Technique | Reference | | --------------------------------------------------------------------------------------------------------------------------- | --------------------------------------- | -------------------------------------------------------------------------------------------------------- | | a magic `0` / `""` / `-1`; the same primitive re-validated at many sites; `"x" in obj` repeated | **Parse, don't validate** | [`references/parse-dont-validate.md`](references/parse-dont-validate.md) | | a field that's always `""`; boolean-flag soup; a sentinel standing in for "absent...