feedback7 R22-FIELDS: the Hidden Core 铳's 碎铳之簧 chase the casting gun for the whole 5 s of 末日布道 instead of stopping on arrival; each gun keeps its data timer, the later call takes the springs (PR #347 by @CXUtk, its pair stagger and lock not taken); golden: hidden-boss_9-pair, hidden-boss_9-solo, coop2-ABYSS-10-boosted

PR #347 by @CXUtk, applied with changes. Kept: 追逐模式 lasts the gain's whole 5 s — PRTS 假想敌：铳 末日布道 "令全场的
“碎铳之簧”获得5秒增益…增益期间切换为追逐模式", “碎铳之簧” 追逐模式 "持续追踪令其进入该形态的场上的假想敌：铳移动" (no
arrival clause, unlike the 铳's own 冲锋模式, which ends "到达目标所在位置后"); data skill 2: cooldown 45, initCooldown 20,
dog_duration 5, move_speed 8. kitSpring no longer ends the chase when it reaches the gun or comes within 1 tile; with no
gun left on the field the spring holds still until the gain ends (until 0.2.1 that ended the chase at once).
Not taken (the maintainer's decision on the Grok triage): the second gun's half-cooldown first-call delay and the cond
that refused a call while any spring was chasing — neither is in the data, and the lock contradicts the handbook's
「持续召唤场上所有“碎铳之簧”向自身移动」 (a call takes every spring to its caster). Both guns keep their data timers, so on a
pair field the mirrored gun's call, a tick after the first, retargets the springs for a new 5 s.

Measured (notes repro-347.mjs): a spring 0.2 tile from the gun chased 0.03 s, one 5 tiles away 2.97 s; now 5.03 s both.

Tests: test/content/hidden-gun-pursuit.test.js (new, 5; the arena harness and two tests are the PR's): the full 5 s
next to a moving gun and with no gun left fail on the parent; the pair timing (20 s after each gun's spawn, then every
45 s, the two calls a tick apart), a mid-chase call retargeting the springs for a new 5 s and the solo timing guard
against the stagger / lock. test/sim/feedback1e-healers.test.js E2 audit: the fields whose leaders / parts a healer must
block run 200 s instead of 120 — on the solo 铳 field the springs now first meet a healer at 145 s (at 21 s until now).

Golden (on top of the portal commit):
- fields hidden-boss_9-pair: the springs spend 5 s invulnerable per call, so they take less (actrpa 855522 → 722451,
  actrpb 798033 → 660498, actrpc 1384683 → 1168947) and pass less on; leader left 3511007 → 3747749; p2's deaths
  7 → 12 (longer tramples); still 8 / 8 kills, no leak.
- fields hidden-boss_9-solo: leader left 1932856 → 2011732; the springs take less; 隐德来希's candles (5601_entlec, an
  enemy-side summon) 6 → 8.
- matches coop2-ABYSS-10-boosted (hidden boss_9): still cleared at 800 LP; the seats' leader damage shifts
  (7523075 / 6369365 → 6992346 / 6900614).

docs/SIM.md

@@ -205,7 +205,11 @@ Leader parts (`tag:'part'`) pass damage to their leader with `loseHp(leader, sha
 (无来源, credited to the attacker's `bossDamage`): `PART_TRANSFER` 1 for 斩胄之剑 / 破胄之锤 (`BLADE_TRANSFER`, the same
 constant) and 碎铳之簧 (PRTS "受到伤害时令假想敌：胄/铳受到等量的无来源生命流失"; DESIGN §20.10, §20.13). Content may replace a part mid-battle: every 剑/锤 sortie (content/bosses.js `kitBlade`)
 ends by spawning a new 初始模式 copy on its level branch route (`left_hand_origin` / `right_hand_origin`) with the old
-HP, then `kill(old, null)` — uncounted, no bounty; the client sees a `die` and a `spawn`.
+HP, then `kill(old, null)` — uncounted, no bounty; the client sees a `die` and a `spawn`. The Hidden Core 铳's 【末日布道】
+puts every 碎铳之簧 into 追逐模式 for its whole 5 s gain (`dog_duration`; invulnerable, no ordinary attacks): the spring
+keeps following the casting gun after reaching it (PR #347; until 0.2.1 arrival or 1 tile ended the chase), and each
+gun casts on its own data timer (20 s after it spawns, then every 45 s), so on a pair field the later call retargets
+every spring to that gun for a new 5 s (PRTS: 「持续召唤场上所有“碎铳之簧”向自身移动」).
 
 WALK legs pathfind on the stage grid inside the rect with the official flow field (grid.js: 4-direction SPFA from the
 destination, crates cost 1000, then Bresenham line-of-sight smoothing — research 08 §3.4). The official route stays