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.

docs/design/network.md

@@ -15,7 +15,7 @@ Platform additions (implemented): `welcome.{resumed, version}`, `welcome.diyKitt
 **Spectator seats** (a remake feature — the official room has none; community report #26, owner's decision 2026-10-04; the spectator-seat subsection of §23): `room.spectate {code}` takes one of a co-op room's `MAX_SPECTATORS` (2) spectator seats, in its lobby or during its match; `room.removeSpectator {playerId}` (host) frees one (`room.closed {reason:'kicked'}` to it); `room.state.spectators: [{playerId, name, connected}]`. A spectator is never a player (not in `seats`, not counted for the start, never host, keeps no room alive — `room.closed {empty}` when the last human leaves), receives the room's broadcasts and watches like an eliminated player (`Match.addSpectator`: `b.start` watch / `m.field`, never `m.private`); it may only `g.watch`, leave, and store a `room.loadout` — anything else answers `error SPECTATOR`. Its seat is kept and given back on reconnect like a player's.
 
 ### 8.2 Match
-C→S (all carry `rid`): `g.infoReady` · `g.band {bandId}` · `g.bandSkip` · `g.bandFocus {bandId?}` (the strategy highlighted in the draft screen — what a timed-out turn takes; absent / null clears it; `WRONG_PHASE` outside BAND_DRAFT, `ALREADY` after the pick, `BAD_TARGET` for a band not allowed; §18.2) · `g.buy {slot}` · `g.refresh` · `g.freeze` · `g.levelUp` · `g.sell {uid}` · `g.move {uid, to:{area:'board', row, col}|{area:'hand', idx}, dir?}` · `g.equip {itemUid, targetUid, replaceUid?}` (`replaceUid`: which equipped item a third one replaces, §6.2) · `g.art {itemUid, row, col, dir?}` (`dir` ∈ UP|RIGHT|DOWN|LEFT from the deploy wheel, §3; absent ⇒ `to.dir`, then RIGHT; `g.move` onto the piece's own tile re-orients it; board pieces in `m.private` / `m.field {prep:true}` carry `dir`) · `g.destroy {uid}` (hand / temp items only; equipped items are locked, §6.2) · `g.reward {idx}` · `g.choice {idx}` · `g.ready {ready}` · `g.emote {id}` · `g.watch {fieldId}` · `g.autoplay {on}` · `g.pause {on}` (solo battles only, §14 Solo pause) · `g.unitStats {seq?}` (ROUND_START / SP_DRAFT / PREP, else `WRONG_PHASE`; eliminated: `ELIMINATED`) → push `m.unitStats` (§18.5) · `g.leave`
+C→S (all carry `rid`): `g.infoReady` · `g.band {bandId}` · `g.bandSkip` · `g.bandFocus {bandId?}` (the strategy highlighted in the draft screen — what a timed-out turn takes; absent / null clears it; `WRONG_PHASE` outside BAND_DRAFT, `ALREADY` after the pick, `BAD_TARGET` for a band not allowed; §18.2) · `g.buy {slot}` · `g.refresh` · `g.freeze` · `g.levelUp` · `g.sell {uid}` · `g.move {uid, to:{area:'board', row, col}|{area:'hand', idx}, dir?}` · `g.equip {itemUid, targetUid, replaceUid?}` (`replaceUid`: which equipped item a third one replaces, §6.2) · `g.art {itemUid, row, col, dir?}` (`dir` ∈ UP|RIGHT|DOWN|LEFT from the deploy wheel, §3; absent ⇒ `to.dir`, then RIGHT; `g.move` onto the piece's own tile re-orients it; board pieces in `m.private` / `m.field {prep:true}` carry `dir`) · `g.destroy {uid}` (hand / temp items only; equipped items are locked, §6.2) · `g.reward {idx}` · `g.choice {idx}` · `g.ready {ready}` · `g.emote {id}` · `g.watch {fieldId, playerId?}` (`playerId`: the player tapped — a shared 联防 / boss pair field shows two; what an eliminated viewer follows, §25) · `g.autoplay {on}` · `g.pause {on}` (solo battles only, §14 Solo pause) · `g.unitStats {seq?}` (ROUND_START / SP_DRAFT / PREP, else `WRONG_PHASE`; eliminated: `ELIMINATED`) → push `m.unitStats` (§18.5) · `g.leave`
 S→C:
 - `m.public` — full public state on every change (throttled ≤ 10/s): `{ phase, round, lastRound, deadline, serverNow, modeId, difficulty, stageId, factions, disabledBonds, bannedChess, bossId, hiddenBossId?, teamLp?, bossHp?:{hp,max}, overtimeAt? /* FA / HC: ms epoch the overtime drain starts, §4 */, paused /* solo pause, §14 */, draft?:{order,turn,picks,skipsLeft,turnDeadline,turnSeconds /* one turn's length, 0 untimed; deadline = turnDeadline (§18.2) */,untimed}, sp?:{family,cards /* bounty cards carry descRaw?, §20.6 */,turn,picks}, players:[{playerId, seat, name, isBot, connected, alive, lp, bandId, shopLevel, boardCount, ready, bonds:[{bondId,count,active,tier,layers,harmony? /* 调和's +1 is in count, §21.26 */}], fieldId, status, pendingLp? /* COMBAT / 联防 of a normal round: the LP the player's own battle will cost at settlement so far, min(lpCapPerRound, counted leaks) — in 联防 min(lpCapPerRound, uniteLeft) — omitted when 0 and in every other phase (§17.5 live LP) */, uniteLeft? /* 联防: the leaker's enemies still standing — not spawned yet + alive + counted leaks, uncapped, live (§20.6) */}] , fields:[{fieldId, kind, players:[playerId...]}] }`
 - `m.private` — the recipient's full PlayerState view (§6.2 minus server-only data) on every change.
@@ -75,7 +75,7 @@ Piece = { uid, kind: 'chess'|'item'|'token', id, golden: bool, tier, items: [ {
 
 **Protocol (additions; `shared/protocol.js` is normative).**
 - `battleId` = `<prefix>.<round>.<seq>.<fieldId>` (`Match._ccField`; `<prefix>` = the match seed in base 36 plus `-<matchNo>`, the room's match number the lobby passes as `opts.matchNo`; `<seq>` counts every battle of the match; the informational `.<fieldId>` is dropped when the id would exceed the protocol's 64 chars): unique for the whole match although field ids repeat (`n:<pid>` every round, `u`, `b1`/`b2` in both boss rounds), and across the matches of one room. The client runner keys its local battles by it (the same id again = the same battle, no rebuild) and the server matches reports by it, so a late `b.progress` / `b.result` of a finished battle — or one that crossed into the room's next match on the same socket — is ignored instead of being credited to another battle.
-- S→C `b.start { battleId, fieldId, kind, spec, authoritative, startAt, serverNow, elapsed, speed, watch, done }` — sent at COMBAT/UNITE/FINAL_ASSAULT/HIDDEN start to every human in the field (联防: to every human; COMBAT and boss rounds: eliminated humans get the first field as a display replica — research 09 "keep-watching auto-observes the first available field"), on `g.watch`, and on reconnect/resync. `elapsed` = game seconds on the field clock (a finished field: its end time); the client fast-forwards to it. `speed` = game seconds per real second (2; tests/tools may speed up).
+- S→C `b.start { battleId, fieldId, kind, spec, authoritative, startAt, serverNow, elapsed, speed, watch, done }` — sent at COMBAT/UNITE/FINAL_ASSAULT/HIDDEN start to every human in the field (联防: to every human; COMBAT and boss rounds: eliminated humans and spectator seats get the field of the player they follow as a display replica — the one they last watched with `g.watch`, else the first player still in; research 09 "keep-watching auto-observes the first available field", 0.2.0 item 56), on `g.watch`, and on reconnect/resync. `elapsed` = game seconds on the field clock (a finished field: its end time); the client fast-forwards to it. `speed` = game seconds per real second (2; tests/tools may speed up).
 - C→S `b.progress { battleId, gt, killed, total, leaks?, left?, bossDmg?, by?, done? }` — authoritative clients, ~1 Hz (boss fields 4 Hz). Normal/联防: `leaks` = counted leaks so far; 联防: `left` = per leaker its enemies still standing (`spec.js uniteLeft`, clamped by the server to `fields.js uniteBillBounds`; §20.6). Boss: `bossDmg` = cumulative damage of this field to the shared pool, `by` = the same per player, `leaks` = the field's cumulative LP cost (leaks × `lpr` + leader "扣除目标生命" effects; `spec.js attachLpMeter`). The server applies deltas (never twice). Stale reports (unknown battle, not the authority, after the match ended) are ignored, never answered with an error; the platform never answers a rid-less `b.progress` with an error frame (it would surface as a toast).
 - C→S `b.result { battleId, result }` — authoritative client at battle end; `result` = `compactResult(BattleResult)` (the fields the match consumes; ≤ 4 players, ≤ 400 leaks, ≤ 64 unitsEnd, ≤ 160 unitStats, ≤ 40 layer gains; `fitResult` keeps the frame ≤ 60 KB: unit statistics, then leak mods, then — boss only — leak entries go first). Structural checks in `isBattleResult`; `server/net.js` routes `b.*` frames to the match (lobby `routeGame`).
 - S→C `b.pool { hp, max, teamLp, acked: { [fieldId]: cumulative damage counted } }` (boss rounds, ≤ 4 Hz; exact numbers, never rounded) — clients reconcile their `LocalBossPool`: displayed pool = server hp − (local cumulative damage − acked). Pools never hold less than 1 HP (`BOSS_POOL_MIN_HP`: `SharedBossPool` and `LocalBossPool`; a browser pool reads any finite rest below 1 as 0 — §20.5); the 'cleared'-result dust rule (a boss field whose client result is `'cleared'` while < 1 HP is left on the server empties the pool) only catches noise at that boundary.
@@ -89,7 +89,7 @@ Piece = { uid, kind: 'chess'|'item'|'token', id, golden: bool, tier, items: [ {
 
 **Solo pause (official `PauseUp` / `ResumeUp`; `Match.setPause`).** C→S `g.pause { on }`: solo matches only (co-op → `WRONG_PHASE 'co-op battles never pause'`), and `on: true` only while a battle runs (COMBAT / FINAL_ASSAULT / HIDDEN_CORE with a live field, not once the Final Assault is ending — else `WRONG_PHASE 'no battle running'`); `on: false` is always accepted. While `m.public.paused` is true everything of the battle is frozen: the field clock (`b.start elapsed`, the boss plausibility budgets and the overtime drain), the authority deadline and the server-run release timers, the boss clock, the HUD `deadline` / `overtimeAt` (shifted by the paused time on resume) and the server-run pacers (FieldRunner / HeadlessPacer skip their intervals); the browser's runner stops its local clock. In solo battles the top bar shows a 暂停 / 继续作战 button (`ui/hud.js PauseButton`, `ui/matchStatus.js pauseAvailable`; `Space` toggles it), a paused overlay offers 继续作战 / 放弃模拟, and the HUD clocks freeze at the pause moment. A disconnect or leave resumes (the server takes the field over — nobody is left to resume it); the battle phase ending drops the pause.
 
-**Spectating (research 09 §3.1 / §6.3).** No live spectating while your own normal battle runs (`g.watch` → `WRONG_PHASE 'own battle running'`; the UI toasts "作战中无法查看队友"). After your own battle ends you see "⌛ 作战结束，等待队友完成作战" with each teammate's live progress (`m.public.fields[].progress`); tapping a teammate's avatar expands **前往查看** → `g.watch` → `b.start` (display replica fast-forwarded to the field clock); the own row shows **返回战场**. Prep: the same flow shows the teammate's board (`m.field` with `prep: true`) and sends it again when that board changes (GitHub #87). The scout is framed by the prep camera in its shop-folded form and renders the teammate’s hand (整备区) and 临时整备区 as units on their rows — the own prep bench’s exact look (user playtest #2 item 1, the GitHub #44 suggestion; the spectator seat's scout view is the same, §23.19's never-a-private-view staying the no-`m.private` rule). While scouting, the 本局信息 drawer shows the watched player's 策略 in place of one's own (`game.js scoutPid` → `enemyDrawer.js InfoTab bandId / bandOwner`, labelled "X 的策略"; user playtest #2 item 2), and the right effects column follows the watched field too: the scout meta carries the player's effects view, a display-replica battle derives it from the spec's `playerEffects` (`battle/observe.js spectateEffects`) — undefined (empty column, never one's own) for 联防 / boss pair fields and server-run watched fields. 联防: every human receives the unite spec (helpers + observers). Final Assault: each human sees its own pair field; the other pair → `BAD_TARGET 'other group hidden'`. In 联防/FA fields the ‹ › pill switches the camera LEFT half / 全景 / RIGHT half ("你自己" / "👁 name" / "全景" / "无人在家"); there is **no** view switcher during normal combat. Eliminated players start each combat phase on the first field (auto-observe) and may watch any field.
+**Spectating (research 09 §3.1 / §6.3).** No live spectating while your own normal battle runs (`g.watch` → `WRONG_PHASE 'own battle running'`; the UI toasts "作战中无法查看队友"). After your own battle ends you see "⌛ 作战结束，等待队友完成作战" with each teammate's live progress (`m.public.fields[].progress`); tapping a teammate's avatar expands **前往查看** → `g.watch` → `b.start` (display replica fast-forwarded to the field clock); the own row shows **返回战场**. Prep: the same flow shows the teammate's board (`m.field` with `prep: true`) and sends it again when that board changes (GitHub #87). The scout is framed by the prep camera in its shop-folded form and renders the teammate’s hand (整备区) and 临时整备区 as units on their rows — the own prep bench’s exact look (user playtest #2 item 1, the GitHub #44 suggestion; the spectator seat's scout view is the same, §23.19's never-a-private-view staying the no-`m.private` rule). While scouting, the 本局信息 drawer shows the watched player's 策略 in place of one's own (`game.js scoutPid` → `enemyDrawer.js InfoTab bandId / bandOwner`, labelled "X 的策略"; user playtest #2 item 2), and the right effects column follows the watched field too: the scout meta carries the player's effects view, a display-replica battle derives it from the spec's `playerEffects` (`battle/observe.js spectateEffects`) — undefined (empty column, never one's own) for 联防 / boss pair fields and server-run watched fields. 联防: every human receives the unite spec (helpers + observers). Final Assault: each human sees its own pair field; the other pair → `BAD_TARGET 'other group hidden'`. In 联防/FA fields the ‹ › pill switches the camera LEFT half / 全景 / RIGHT half ("你自己" / "👁 name" / "全景" / "无人在家"); there is **no** view switcher during normal combat. Eliminated players and spectator seats follow a player through every phase reset (0.2.0, community report item 56; the official DeadAutoObDn { obIndex, state, preparation }; the idea of PR #189): the player they last watched with a manual `g.watch` (`Match.watchPref`; a shared field records the `playerId` tapped, else nobody), else the first player still in (seat order, AI seats included) — the round start pushes that player's prep board (`Match._followScout`, adopted by the screen like a 前往查看 tap: `battle/observe.js followedScout`; kept through 机变 and 休整期), each battle starts on that player's field, a resync / a spectator joining in prep gets the board again; they may watch any field.
 
 **Client runner.** `public/js/battle/runner.js` owns the local Battles: fixed-step clock at the battle speed (60 ticks per real second at 2×, at most `max(8, 4·speed)` ticks per frame, bounded fast-forward of ≤ 240 ticks per frame when far behind; a new battle is caught up silently before it is shown), feeds the existing renderer through the same `snapshot()`/`drainEvents()` wire formats every frame (`view.setLocalFeed` shrinks the interpolation buffer to ~2 frames), publishes the field meta (m.field shape + `local`, `battleId`, `players`, `sides`, `speed`) into `store.match.field` and its state into `store.match.battle` (with `leaks: { [fieldId]: counted leaks so far }` of every normal field it simulates and, while the 联防 field is on screen, `uniteLeft` per leaker (§20.6), authoritative or display replica — the settle rule's count, `/sim/spec.js battleProgress`; published in the frame a count changes: the live LP of §17.5), sends `b.progress`/`b.result` when authoritative (results retried once on timeout; a result lost with the socket — the request failed `DISCONNECTED` / `OFFLINE` or timed out twice — is kept and sent again when the session is back online and whenever a `b.start` still names that finished battle `authoritative: true`; the server answers a duplicate `ok` and changes nothing; a server refusal is final), follows `m.public.paused` (solo pause: every local clock stands still, resume shifts it by the paused time), handles `b.pool`/`b.end`, fast-forwards on reconnect/observe, and survives tab backgrounding (a 250 ms interval pump keeps authoritative battles on their clock while hidden; the server deadline + takeover cover extreme cases). Catch-up frames keep the state events and every enemy form fx (`keepsState`); while hidden, the battle on screen holds them for the first frame back (`hold`; past `HELD_MAX` the superseded status / skill toggles are dropped, `compactHeld`, and only a backlog still past it re-enters the view from the field meta), and a battle that ended while hidden delivers them when the tab is shown; a catch-up frame or a hidden step drains its events every `EV_SLICE` (15) ticks, each batch stamped with its own game time (`gt`), so a late form fx reaches the render engine as late as it is; the game screen's pre-entry buffer (`keepEarly`, also while a re-sent field meta re-enters the field on screen) and the render engine's event queue (`render/interp.js isCosmeticEvent`) never drop a form fx either (§21.4). Sim content errors are logged as console warnings (the server logs its own). The sim loader fetches the ten data files (one retry each) and fails when any is missing — a battle on partial data would report a plausible wrong result — so the next `b.start` retries and the server's deadline covers the field meanwhile. `public/js/battle/observe.js` holds the observing rules and labels.