evolve — breed the best forward

Breed candidates from the best versions so far, gate them, let a blind judge score the whole pool, carry the top two forward. The first round that does not raise the best score ends the run.

Read ../_shared/tournament.md first. It defines the loop and binds this skill — gate, parallel builders, one blind pooled judge, red lines, pre-crown check, apply and verify — except for these overrides:

• §1 — R0 is also gated and scored alone by the judge as the curve's baseline (§1 below).
• §4.1-§4.2 ideas — candidates are bred from the leader (§2 below), not built from fresh ideas.
• §4.4 pool — both parents, leader and runner-up, sit in the pool as anchors, not one champion.
• §4.6-§4.8 throne — ranks 1 and 2 carry forward; the best candidate must strictly beat the best parent of the same pass (§3-§4 below).
• §5 cap — 6 rounds; the end sentence reads no increase at round N or round 6 reached.

0. Target and rubric

The argument is the target (/evolve the pathfinding cache); without one, ask one question: which file, function, screen or document. Pick the rubric by what is improved and freeze it with the target (tournament.md §1):

For the interface rows, also freeze what compose / humanize freeze in their §0, render at the round's viewports (tournament.md §4.3) and load the design skill they name. Their red lines are written against "the champion"; here read the best parent in the same pass for it. Every parent, leader or runner-up, went through the pre-crown check before it was carried and stays capped by its findings.

1. Round 0

Work folder <scratchpad>/evolve/<target-slug>/. R0 is the current version in r0/, gated and scored alone by the blind judge (§3) as the curve's baseline. If nothing exists yet, there is no R0: round 1 builds three fresh candidates from the frozen target, as tournament.md §1.1 and §4.1-§4.2, judged with no parent in the pool and no stop comparison. Down the ranking (§4.7 there), the first candidate to survive its pre-crown check is crowned leader and the next survivor becomes runner-up; leader and parent comparisons start at round 2. None survives → stop, nothing applied.

2. The round

Parents of round N: the leader (rank 1 of the previous pass) and the runner-up (rank 2). Round 1 has only R0 (or no parent at all, §1).

Breed three candidates in r<N>/c<k>/, all from the leader, each with one move written down before any edit: two fixes aimed at the leader's weakest criteria, and one graft of the runner-up's idea where it beat the leader (a third fix when there is none). No move already tried in an earlier round. Builders run in parallel as in tournament.md §4.2, each handed the leader and its own move instead of a fresh idea.

Gate each candidate (the table's gate column, tournament.md §3). All out → no increase (§4).

3. The judging pass

tournament.md §4.4-§4.6, with the surviving candidates plus both parents in the pool, no hint which is a parent. Ties go to the parent. Before ranks 1 and 2 are fixed, each candidate in line for either goes through the row's pre-crown check (§4.7 there), highest-ranked first; its caps re-rank it, and the check moves down the pool until both places hold checked versions. Ranks 1 and 2 become the next leader and runner-up, parent or candidate.

Write the leader's new score beside its old one; the gap is the judge's drift.

4. Stopping

Compare the best candidate with the best parent in the same pass:

• Strictly higher → the score rose; next round.
• Not higher (lower, tied, red-lined, every candidate pulled back by the pre-crown check, all gated out) → stop; the best parent is champion.
• Round 6 finished → stop, even if still rising.

Append each round to rounds.md before the next: round, moves, gate, the pass's ranking with scores, pre-crown check, carried forward. Then apply and verify as tournament.md §5 steps 1-4; a champion of R0 changes nothing, and say so.

5. Final analysis

tournament.md §6, with one row per round:

A parent's score is the one from that round's pass. How we did it traces the winner's lineage back to R0 — the move each generation added, which graft survived. Possible mistakes names at least judge drift, the local optimum of building on one line (no blank-canvas run — compose or humanize does that), and whatever the gate could not check. The sentence after the table: no increase at round N, or round 6 reached.