feedback7 R22-RENDER: an enemy standing out its attack recovery is drawn standing — the snapshot carries stand / standCut and the interpolator holds the position until the recovery ends (PR #381 by @ZiyueW1116, supersedes #307 / #314); golden: unchanged

Since 0.2.0 the sim stands an unblocked enemy for the rest of its attack clip (ai.js attackStand → atkStandUntil),
but render/interp.js lerped x/y over the whole snapshot gap, so the view slid through a recovery the sim held
(repro: a real 隐形弩手, snapshots 4.9 / 5.0, stand until 4.934 — sampled at 4.917 it slid at vx −0.2).

The snapshot now carries, only when non-empty, `stand: [[id, until]]` (atkStandUntil of enemies alive, deployed,
visible, neither feared nor stunned) and `standCut: [[id, at]]` (the latest time each listed enemy's recovery was cut
or ignored: a displacement, fear, a stun, hiding, leaving — Battle._cutAttackStand, display metadata the battle never
reads). sample() holds the older position until `until` and interpolates the rest (HP / SP keep the whole interval),
stays linear when the newer snapshot records a cut inside the interval, and extrapolates nothing for a newest snapshot
that shows a stand, a death, a stun or a block. Teleports and redeploys still snap first; old snapshots without the
fields interpolate as before.

Substantially @ZiyueW1116's code (PR #381), authored as theirs. Changed on review: the docs (SIM §9, design/network.md)
and code comments in English like the rest of them; the snapshot builds its listed-id set only when an enemy has a cut
to report.

Golden: unchanged — the digest canon hashes neither field and the sim's timing does not move (all 283 scenarios match).

Tests: test/render/attack-recovery-interp.test.js (new, 25: metadata validation, hold-then-slide, cuts, legacy
snapshots, extrapolation guards, real 隐形弩手 / Weedy push-kill / stun / freeze / sleep / levitate / block / fear
battles) 25/25; render/interp 16/16; sim battle, perf, robustness, downelem 69/69.

docs/SIM.md

@@ -1296,7 +1296,7 @@ Unknown subprofessions fall back to the profession default (test `professions.te
 
 ## 9. Wire format (snapshot.js, DESIGN §8.2)
 
-- `snapshot()` → `{ fieldId, t, units: [[id, x, y, hp, maxHp, sp, spMax, flags, anim]], dp, killed, total, dps?, boss?, down?, elem? }`.
+- `snapshot()` → `{ fieldId, t, units: [[id, x, y, hp, maxHp, sp, spMax, flags, anim]], dp, killed, total, dps?, boss?, down?, elem?, stand?, standCut? }`.
   `sp/spMax` show remaining duration/ammo as a draining bar while a timed skill is active (ammo: `ammoLeft / ammoMax`, the
   activation's real total — 拉特兰's and 逃犯引渡手续's extra bullets included, community report #35). Units in DIE state stay 0.8 s.
   Active finite zero-SP duration skills display `timeLeft/duration` using `duration` as `spMax`; after end they show
@@ -1309,6 +1309,19 @@ Unknown subprofessions fall back to the profession default (test `professions.te
   knocked-out operator's tile, §1; `row, col` = the tile it lies on and comes back on, `unit.body`); `elem: [[id, element, fill,
   cooldownEnd, cooldown]]` (only when non-empty) = `elementView` of every unit with a gauge or a running 爆发冷却 (§3).
   `fieldMeta()` lists the knocked-out operators too (a client joining mid-battle shows them; DESIGN §18.3).
+  `stand: [[id, until]]` (only when non-empty) = the game time each enemy's attack recovery ends (`atkStandUntil`: it
+  stands for the rest of its attack clip, §1.2 `attackStand`) — enemies alive, deployed, visible, neither feared nor stunned;
+  display metadata the battle never reads (PR #381). When `until` falls between two snapshots the renderer holds the older
+  position until then and interpolates the rest of the interval (HP / SP keep the whole interval); a newer snapshot that
+  moved before `until` is interpolated linearly; while the newest snapshot still holds a stand nothing is extrapolated
+  (the next one confirms the move). A snapshot without the field interpolates over the whole interval, a teleport or a
+  redeploy still snaps first, and nothing is inferred from the attack animation. `standCut: [[id, at]]` (only when
+  non-empty) = the latest game time each enemy's recovery was cut or ignored (a displacement — 失衡 —, fear, a stun, hiding,
+  leaving the field), one per enemy: an interval whose newer snapshot carries a cut inside it is interpolated linearly even
+  when the older stand ended inside it too, and an older cut leaves a later stand alone. It covers the enemies listed in
+  `units` (the 0.8 s death window included), never a hidden or unlisted one. The newest snapshot showing a death, a stun
+  (freeze, sleep, 浮空 included) or a block is not extrapolated until a later snapshot shows it moving again; the
+  extrapolated velocity uses the same moving span as the interpolation (the stand is not in its denominator).
 - `drainEvents()` tuples: `['spawn', UnitInfo]` (first appearance), `['deploy', id]` (every (re)deploy and 【移动】 — the client plays the deploy and its interpolation snaps instead of sliding), `['atk', src, tgt, projKind]`
   (`none|arrow|bolt|bomb|lob|orb|drone|enemy|boomerang|droneBomb|chain|chainHeal`; a boomerang's way back has no event — the
   renderer flies it back to the thrower at `BOOMERANG_RETURN_SPEED`; an enemy's `profile.shot` may name another kind,