feedback5 CB5: an eliminated player (and a spectator seat) follows a player through every phase reset — the one it last watched, else the first player still in — instead of being sent back to its own empty board each round (community report of 2026-10-06, item 56; the idea of PR #189)

Official: research 09 §3.1 — after elimination the client keeps observing (self_dead_dialog KEEP_WATCH,
DeadAutoObDn { obIndex, state, preparation }, FindFirstAvailObTarget). Until 0.2.0 every phase reset cleared
an eliminated player's watch: in 回合开始 / 机变 / 休整期 it saw its own empty board, in battle the first field.

Server (server/match/match/watch.js): Match.watchPref (viewer → the player of its last manual g.watch: a prep
scout, a single-player field, or the new optional g.watch playerId on a shared 联防 / boss pair field — PR
#189's review point); _watchTargetOf = that player while still in, else the first player still in (seat
order, AI seats included); startRound scouts its board (_followScout, kept through 机变 and 休整期), both
combat modes and the boss fields start on its field, a resync / a spectator joining in prep gets the board,
a followed player who quits hands over at once. Client: the screen adopts the pushed board like a 前往查看 tap
(battle/observe.js followedScout; the stale-field fix of PR #189), keeps it through the prep phases (no camera
flight home and back), a spectator no longer asks for the first player itself; g.watch sends the tapped row.
Overlap with PR #189 (not merged): the same preference chain; differences — the fallback includes AI seats
(a lone human with AI teammates had nobody to follow), shared fields record the tapped playerId.

Golden unchanged. Tests: test/match/feedback5-watch-follow.test.js (new, 9), spectator.test.js updated (the
spectator follows the player it scouted). Docs: design/network.md, PLAYING.md.

shared/protocol.js

@@ -368,7 +368,9 @@ export const C2S = {
   'g.choice': { idx: (v) => isInt(v, 0, 5) },
   'g.ready': { ready: isBool },
   'g.emote': { id: (v) => EMOTES.includes(v) },
-  'g.watch': { fieldId: (v) => isStr(v, 32) },
+  // playerId: the player tapped in the team panel (a 联防 / boss pair field shows two) — what an eliminated viewer or a
+  // spectator seat follows from then on (Match.watchPref; community report of 2026-10-06, item 56)
+  'g.watch': { fieldId: (v) => isStr(v, 32), playerId: isId, $optional: ['playerId'] },
   'g.autoplay': { on: isBool },
   // solo pause (official PauseUp / ResumeUp, DESIGN §14): freezes the running battle (field clock, deadlines, the
   // browser's local runner) — solo matches only (co-op ⇒ WRONG_PHASE), only while a battle runs; m.public.paused