0.2.5-dev: community round 30 and follow-ups

- Stock: fixed trait gifts (缪尔赛思 / 变形者集群 变形同构体, 耶拉 不融冰, 蜜蜡 / 卡涅利安 迅捷作战粮, 诗怀雅 盟约之币) still occupy stock but are granted past the cap; an operator card already shown in the shop or a reward can be taken after the pool runs out and overdraws (GitHub #498, the owner's decision); item buys and item rewards keep the stock check. 洛洛 / 焰尾 sub-pools use the measured weights (PR #497 by @2321Robin; the occupancy idea of PR #496 by @2321Robin re-implemented differently).
- Boss pairs are drawn at random once per match and fixed to battle start; the Hidden Core reuses them; a leaver does not split a full pair (the owner's decision).
- 阿戈尔 in 联防 no longer re-applies the opening devour HP loss or a false revive; Touch's team medic stays for the match after its holder leaves (owner-approved, official lifetime unverified).
- Auto-skill ranges: 司霆惊蛰 S2, 斩业星熊 S3 against air, 予愿安洁莉娜 S3; 自在's post-rebirth invulnerability is also untargetable (#510); Horn / Clementia / catapult / 忍冬 first hit (PR #502 by @Xinglan233); 不融冰 / tear gas trigger on real damage.
- Bond layer-up sound in round start / draft / prep / battle (#482): one channel, a new cue replaces the old, no extra cooldown; a prep update that adds layers and activates a bond plays one cue.
- Client: multi-swing fix (#506), refresh single-flight (PR #507 by @robll-v1), LP tower keeps the settled value with a −N tick (PR #504 by @robll-v1), export with only 潜能 / 练度 changes (PR #503 by @Xinglan233), spectator rosters list DIY members (PR #505 by @Xinglan233), banned members beside bond tooltips (PR #494 by @YuriRestia), recovery action above the away overlay (PR #511 by @RainoutOvO), the /dev/sim-check.html consistency page (PR #492 by @Cloudnyco), Korean (PR #490 by @D-Roote) and English Victoria wording (PR #499 by @YuriRestia).
- golden: 45 of 287 scenarios move against 0.2.4 (roster 17, bonds 3, fields 6, matches 17, standins 2), each attributed in docs/history/0.2.5.md §30.9 / §30.16.

server/match/finalAssault.js

@@ -3,7 +3,8 @@
 //
 //   * Merged LP: teamLp = Σ LP of the alive players at the start of the Final Assault (no cap); the Hidden Core
 //     continues with what is left.
-//   * Pairing: alive players by seat → (1,2), (3,4); an odd player is alone on its own field with the `_s` template
+//   * Pairing: shuffled once per match before Final Assault prep; Hidden Core keeps those pairs. If players leave,
+//     intact pairs stay together and the remaining single players pair up. An odd player uses the `_s` template
 //     (solo modes always use `_s`). Field ids 'b1', 'b2'. In a pair the first player is the LEFT side, the second the
 //     RIGHT side (the sim mirrors the right side: board col c → field col 20 − c with the piece direction RIGHT ↔
 //     LEFT, UP / DOWN unchanged (DESIGN §3, research 09 §1.2 ConvertChessPositionInfoToBossMap); board rows 9–12 →
@@ -55,11 +56,22 @@ export function bossFieldPlacement(side, row, col, dir = 'RIGHT') {
   return side === 'R' ? { row: r, col: COLS - 1 - col, dir: mirrorDir(d) } : { row: r, col, dir: d };
 }
 
-/** Pair alive players by seat: [[a, b], [c, d]] / [[a, b], [c]] / [[a]]. */
-export function pairPlayers(alive) {
+/** Seeded initial pairing; `previous` carries player-id pairs through prep, combat and Hidden Core. */
+export function pairPlayers(alive, rng, previous = null) {
   const sorted = alive.slice().sort((a, b) => a.seat - b.seat);
   const groups = [];
-  for (let i = 0; i < sorted.length; i += 2) groups.push(sorted.slice(i, i + 2));
+  let singles;
+  if (Array.isArray(previous)) {
+    const remaining = new Map(sorted.map(p => [p.playerId, p]));
+    singles = [];
+    for (const ids of previous) {
+      const group = [];
+      for (const id of ids) if (remaining.has(id)) { group.push(remaining.get(id)); remaining.delete(id); }
+      if (group.length === 2) groups.push(group); else singles.push(...group);
+    }
+    singles.push(...remaining.values());
+  } else singles = sorted.length > 1 ? rng.shuffle(sorted) : sorted;
+  for (let i = 0; i < singles.length; i += 2) groups.push(singles.slice(i, i + 2));
   return groups;
 }