feedback5 CB5: the boss round's prep shows both players of a pair together — the partner's pieces on the other half, as the battle places them — and frames the pair's two avatars in the official green (community report of 2026-10-06, item 51)

The own half was already the official one (the right-hand player on the right half with the
right_boss_*_camera_param camera, its layout mirrored col c -> 20 - c with RIGHT <-> LEFT, so its operators
face the leader as before: research 09 §1.2, DESIGN §15); the partner's half stood empty and nothing framed
the pair.
Server: in a boss round's prep m.private.bossMate { playerId, side, units } = the partner's board as UnitInfo
on its half (Match.bossMateView, finalAssault.js bossFieldPlacement); markPrivate marks the partner's
m.private with the mover's, so it follows live; a scout of either player (Match.prepFieldMeta) carries both
halves (`mate`), and its signature covers the partner's board.
Client: render/app.js syncMates draws the partner's units read-only ('m:<uid>' views: never picked, dragged
or swept with the own pieces) and the whole boss field is lit; the team panel frames the pair's avatars
(gameLogic teamFrameIds: the players still in by seat, two by two, as prepCamera — the boss field in the
fight) from the round start through the Final Assault / Hidden Core, with the official ui/battle
bg_team_border tinted the autochess green (#4ed8af; a plain ring without the local art); none for a lone
player, an eliminated player, a spectator seat, or 联防.
Overlap with PR #191 (same-field frames, issue #190; not merged): it published m.public bossPairing and
framed the partner alone in gold, 联防 included, plus a banner naming the partner; here the pairing is read
as the prep camera already does, both avatars get the official green frame, boss rounds only.
[ASSUMED] the partner's bench is not shown; one frame per avatar.

Golden unchanged. Tests: test/match/feedback5-boss-pair-prep.test.js (new, 4), the item 55 test now checks
the scouted player's own pieces (the partner's stand on the other half); SP_E2E
test/ui/feedback5-boss-pair.e2e.test.js (new, 2: both halves and the frames in prep and fight; item 55's
eliminated guest on the boss field with the leader). Docs: design/client.md §10 / §15, design/network.md,
PLAYING.md.

server/match/match/messaging.js

@@ -52,8 +52,17 @@ export class MatchMessaging {
   }
 
   markPublic() { this._pubDirty = true; }
-  /** A player's state changed: its m.private and (throttled, deduplicated) m.public (level, board, bonds…). */
-  markPrivate(ps) { if (ps) { this._privDirty.add(ps); this._pubDirty = true; } }
+  /**
+   * A player's state changed: its m.private and (throttled, deduplicated) m.public (level, board, bonds…) — in a boss
+   * round's prep also its pair partner's m.private, which shows this board on its other half (bossMate, item 51).
+   */
+  markPrivate(ps) {
+    if (!ps) return;
+    this._privDirty.add(ps);
+    this._pubDirty = true;
+    const m = this._bossMateOf(ps);
+    if (m) this._privDirty.add(m.mate);
+  }
 
   /** Send pending m.private (per player, only when changed) and m.public (throttled ≤ 10/s). */
   flush(forcePublic = false) {