mutationslisted

# Mutations A mutation is a change to expected behaviour, data, logic, workflow, configuration or output. It is worth exactly one thing: **the observation that says what it actually did.** **The deliverable is an entry in `MUTATIONS.md` that is OPEN until that observation exists**, and then closed with a disposition and a citation of wherever the outcome was recorded. A change whose effect nobody looked at is otherwise indistinguishable from one that was checked and behaved — that indistinguishability is the whole subject of this skill, and `MU-0001` is it, measured. ## When this fires Three gates. Any one of them fires this skill, and the work in hand pauses until the mutation is assessed. | Gate | Fires when | |---|---| | **Mutation** | a change is proposed or detected that affects behaviour, data integrity, configuration, security, dependencies, interfaces or expected outputs | | **Oops** | a mutation produces an unexpected result, side effect or regression | | **Mistake** | a mutation stems from an incorrect assumption, invalid action, missed requirement or preventable process failure | The Oops and Mistake gates are **hand-offs, not duplicates**: they fire this skill to record the mutation and its observation, and they fire `oops` / `mistake-to-gate` to record the occurrence and build the guard. One event, two records, joined by a citation — see the boundary below. ### Which gate is mechanical The Mutation gate. `mistakes-check.sh` refuses an entry whose `Actual