296 set pools kinds folds shared leaf

// ASPIRATIONAL (design capture 2026-09-06 — red until the surface lands).
// The `set` surface as designed: a POOL over `kind` declarations. A kind is
// shape + kind identity with NO storage and NO capacity slot; the set owns
// the capacity; inserts route through the kind (the kind name IS the kind);
// shared leaves fold into one contiguous extent, private leaves per-kind.
// The current implementation of `set` is a view over new stores (sequential
// loops, no shared extent) — this test pins the TARGET, not that behavior.
// Flips green when `std/store:kind` + the pooled `std/store:set` land.
// DEPENDENCY (Lars, 2026-09-06): the kind layer is an ABSTRACT/VIRTUAL shape
// — `kind(Player)` declares shape + identity with no storage, and the pooled
// set's dispatch (inserts route through the kind; queries dispatch over kind
// identities) needs that abstract/virtual machinery, not just a fold. There
// is no abstract/virtual surface in the language today; the set waits on it.
// Currently red: `no std/store:new(Player) found` — today's `set` is a view
// over new stores, and the pool's `kind` declarations have no `new` to
// resolve. Output is identical to 690_287 (same program, new surface).
// WHEN `std/store:kind` LANDS, mint alongside (ruled in DESIGN.md, unpinnable
// until the surface exists): kind(Player) + new(Player) refused (one binding
// per name); claims take layer-1 declarations only (no set-in-set); set/union/
// view each need >= 2 members. Open ruling to settle with the set: flat pool
// (per-row tag) vs per-kind segmentation (no tag, split extent) — the flat
// end's coexistence tax is measured vs the view in the 006 benchmark.
import std/io
import std/proto
import std/store

std/proto:i64(Strength)
std/proto:i64(Mana)
std/proto:i64(Armor)

std/proto(Player) {
    str: Strength
    mana: Mana
}

std/proto(Enemy) {
    str: Strength
    armor: Armor
}

std/store:kind(Player) { Player }
std/store:kind(Enemy) { Enemy }

std/store:set(Entities, capacity: 16) {
    Player
    Enemy
}

std/store:insert(Player) { str: 18, mana: 12 }
std/store:insert(Enemy) { str: 10, armor: 5 }

std/store:query(Entities)
! query e |> std/io:print.ln("entity {{ e.str:d }}")

std/store:query(Entities)
! query e when e is Player |> std/io:print.ln("player {{ e.str:d }} {{ e.mana:d }}")

std/store:query(Entities)
! query e when e is Enemy |> std/io:print.ln("enemy {{ e.str:d }} {{ e.armor:d }}")