wc-archetype-mutation — bounded exploration

The mutation operator from the genetic loop (evolution-protocol.md). After recombination has fused the best blocks, mutation explores the neighbourhood of each offspring — small perturbations that might find a slightly better local arrangement or, when the diversity governor raises the rate, push an offspring away from a collapsed template. It is the explore side of the explore/exploit dial.

Inputs

An offspring candidate (post-crossover, feasible) with block tags.
mutation_rate (default low, e.g. ~1 perturbation per offspring; raised by wc-population-diversity to ~2–3 when collapse is detected).
Live constraints (budget, nation cap, phase) for the feasibility guard.

Mutation moves (pick per the rate; each must keep feasibility)

Move	What it does	When apt
Differential swap	replace one BB4 pick with an adjacent-price, similar-EV alternative of lower ownership	exploring the rank axis; diversity-injection toward differential
Enabler nudge	swap a BB5 enabler for an equal-price guaranteed starter with a marginally better fixture	freeing optionality without touching value blocks
Captain-ladder shift	reorder one step of MB2 (promote a different day-2 captain candidate)	matchday plans; exploring captaincy variance
Bench reorder	re-rank MB3 bench by a refined kickoff/likely-points read	improving manual-sub optionality
Fixture-swing transfer	for a transfer plan, try one alternative in→out pair targeting a steeper fixture delta	exploring A4-style edges
Formation flex	shift the XI between two valid formations (e.g. 3-4-3 ↔ 3-5-2) the same 15 supports	exploring attack/defence balance