Shrink the per-tick worker → main update payload by ~90% (#4244)

Stacked on #4243 (the `perf:client` harness) — first step of fixing the
every-100ms main-thread stutter: make the per-tick burst small before
spreading what remains across frames.

## Problem

The harness showed the main-thread burst was dominated by
`structuredClone` of the `updates` object, and the clone was dominated
by two kinds of per-tick churn that re-sent object payloads every tick:

- `gold` / `troops` / `tilesOwned` change for nearly every alive player
every tick → ~278 partial `PlayerUpdate` objects per tick (world/400
bots), ~508 on giantworldmap.
- Attack troop counts tick down every tick → whole
`outgoingAttacks`/`incomingAttacks` arrays re-cloned for every fighting
player every tick.
- `playerNameViewData` (an all-players record) was cloned every tick but
only recomputed every 30 ticks.

## Change

Three additions to the worker → main protocol (all transferable,
zero-clone):

1. **`packedPlayerUpdates`** — `[smallID, tilesOwned, gold, troops]`
float64 quads for players whose stats changed. These fields no longer
appear in `PlayerUpdate` diffs (first emissions still carry the full
snapshot). Gold is exact in a float64 (game values ≪ 2^53).
2. **`packedAttackUpdates`** — `[ownerSmallID, direction, index,
troops]` quads. Attack arrays are only resent when
membership/order/retreating changes — which is exactly the condition
that keeps the patch indexes valid (a tick either resends an array or
patches it, never both).
3. **`playerNameViewData` is now optional** — attached only on
placement-rebuild ticks (spawn ticks, first ticks, every 30th, spawn
end). The client keeps the last applied values; dead players' name
placements freeze at death (matching the previous effective behavior).

On the client, `GameView.populateFrame` now also rebuilds `names` /
`relationMatrix` / `allianceClusters` only when their inputs changed
that tick — field presence on a partial `PlayerUpdate` marks them dirty.
(`playerStatus`, nuke telegraphs, and attack rings still recompute every
tick; they're tick- or unit-dependent.)

## Results (perf:client, this machine; low-end devices ~5–20× slower)

Default run (world, 400 bots, 1800 ticks):

| stage | before | after |
|---|---|---|
| clone (serialize+deserialize) | 1.02ms | **0.09ms** |
| GameView.update | 0.62ms | **0.29ms** |
| WebGLFrameBuilder.update | 0.04ms | 0.04ms |
| **TOTAL burst mean** | **1.67ms** | **0.42ms** |
| TOTAL p99 / max | 3.47 / 10.3ms | **1.21 / 3.92ms** |

giantworldmap/600t: 2.54 → 0.68ms mean. Player update objects: 278 → 6.5
per tick (world), 508 → 12 (giant). The remaining burst is mostly tile
apply + per-tick derivations — the part that frame-spreading (next step)
addresses.

## Verification

- **Sim final hash unchanged** on all three reference configs
(`5607618202213430`, `29309648281599524`, `39945089450032050`) — no
simulation behavior change.
- **View hash unchanged** on all three configs (`942106e9`, `a3aae227`,
`cbaaf265`) — the rendered view state is provably identical
tick-for-tick, including the name-freeze semantics.
- New tests: `tests/PackedPlayerUpdates.test.ts` (drain + GameRunner
cadence), packed-channel and freeze-at-death cases in
`tests/client/view/GameView.test.ts`, `packAttackTroopDeltas` unit tests
and updated diff contract in `tests/GameUpdateUtils.test.ts` /
`tests/PlayerUpdateDiff.test.ts`.
- `npm test` (1490 tests), `eslint`, `prettier`, `tsc --noEmit` all
pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/client/TransformHandler.ts

@@ -227,8 +227,9 @@ export class TransformHandler {
   centerCamera() {
     this.clearTarget();
     const player = this.game.myPlayer();
-    if (!player || !player.nameLocation()) return;
-    this.target = new Cell(player.nameLocation().x, player.nameLocation().y);
+    const nameLocation = player?.nameLocation();
+    if (!nameLocation) return;
+    this.target = new Cell(nameLocation.x, nameLocation.y);
     this.intervalID = setInterval(() => this.goTo(), GOTO_INTERVAL_MS);
   }
 

src/client/view/GameView.ts

@@ -16,6 +16,7 @@ import {
   GameUpdateViewData,
   SpawnPhaseEndUpdate,
 } from "../../core/game/GameUpdates";
+import { ATTACK_DELTA_OUTGOING } from "../../core/game/GameUpdateUtils";
 import {
   MotionPlanRecord,
   unpackMotionPlans,
@@ -100,6 +101,17 @@ export class GameView implements GameMap {
 
   private _myPlayer: PlayerView | null = null;
 
+  // ── populateFrame dirty flags ──────────────────────────────────────────
+  // The derived structures below only depend on rarely-changing player
+  // fields, so they're rebuilt only when one of their inputs arrived this
+  // tick (PlayerUpdates are partial — field presence means "changed").
+  /** Names: nameData record applied, or a player was added. */
+  private _namesDirty = true;
+  /** Relation matrix: allies/embargoes changed, or a player was added. */
+  private _relationsDirty = true;
+  /** Alliance clusters: allies changed, or a player was added. */
+  private _clustersDirty = true;
+
   private unitGrid: UnitGrid;
   private unitMotionPlans = new Map<
     number,
@@ -290,6 +302,21 @@ export class GameView implements GameMap {
       this._myClanTag,
     );
 
+    // Name placements arrive only on ticks where the worker recomputed them
+    // (see GameUpdateViewData.playerNameViewData). Apply to existing alive
+    // players here; dead players keep their last placement (names freeze at
+    // death), and new players get theirs via the PlayerView constructor in
+    // pass 1 below.
+    if (gu.playerNameViewData !== undefined) {
+      for (const id in gu.playerNameViewData) {
+        const pv = this._players.get(id);
+        if (pv !== undefined && pv.state.isAlive) {
+          pv.nameData = gu.playerNameViewData[id];
+        }
+      }
+      this._namesDirty = true;
+    }
+
     // Pass 1: ensure every player exists with up-to-date PlayerState. We need
     // all smallIDs registered before pass 2 can translate embargo PlayerIDs.
     // PlayerUpdate is now partial: only `id` is guaranteed; everything else
@@ -311,9 +338,19 @@ export class GameView implements GameMap {
         this.smallIDToID.set(pu.smallID, pu.id);
       }
 
+      // Derived-data dirty tracking: field presence on a partial update
+      // means the field changed this tick.
+      if (pu.allies !== undefined) {
+        this._relationsDirty = true;
+        this._clustersDirty = true;
+      }
+      if (pu.embargoes !== undefined) {
+        this._relationsDirty = true;
+      }
+
       if (existing !== undefined) {
         existing.applyUpdate(pu);
-        const nextNameData = gu.playerNameViewData[pu.id];
+        const nextNameData = gu.playerNameViewData?.[pu.id];
         if (nextNameData !== undefined) {
           existing.nameData = nextNameData;
         }
@@ -321,7 +358,7 @@ export class GameView implements GameMap {
         const player = new PlayerView(
           this,
           pu,
-          gu.playerNameViewData[pu.id],
+          gu.playerNameViewData?.[pu.id],
           // First check human by clientID, then check nation by name.
           this._cosmetics.get(pu.clientID ?? "") ??
             this._cosmetics.get(pu.name!) ??
@@ -333,6 +370,9 @@ export class GameView implements GameMap {
         if (team !== null) {
           this._teams.set(pu.smallID!, team);
         }
+        this._namesDirty = true;
+        this._relationsDirty = true;
+        this._clustersDirty = true;
       }
     });
 
@@ -353,6 +393,43 @@ export class GameView implements GameMap {
       player.setEmbargoSmallIDs(smallIDs);
     });
 
+    // Packed per-player stats: [smallID, tilesOwned, gold, troops] quads for
+    // every player whose stats changed this tick (the per-tick churn that no
+    // longer travels in PlayerUpdate objects). Applied after pass 1 so
+    // first-emission players exist; their quad carries the same values as
+    // the full update, so double-applying is harmless.
+    const packedStats = gu.packedPlayerUpdates;
+    if (packedStats !== undefined) {
+      for (let i = 0; i + 3 < packedStats.length; i += 4) {
+        const state = this._playerStates.get(packedStats[i]);
+        if (state === undefined) continue;
+        state.tilesOwned = packedStats[i + 1];
+        state.gold = packedStats[i + 2];
+        state.troops = packedStats[i + 3];
+      }
+    }
+
+    // Packed attack troop counts: [ownerSmallID, direction, index, troops]
+    // quads. The attack arrays themselves are only resent when membership/
+    // order changes, which is also what keeps these indexes valid — a tick
+    // either resends an array (fresh troops included) or patches it, never
+    // both. See packAttackTroopDeltas.
+    const packedAttacks = gu.packedAttackUpdates;
+    if (packedAttacks !== undefined) {
+      for (let i = 0; i + 3 < packedAttacks.length; i += 4) {
+        const state = this._playerStates.get(packedAttacks[i]);
+        if (state === undefined) continue;
+        const attacks =
+          packedAttacks[i + 1] === ATTACK_DELTA_OUTGOING
+            ? state.outgoingAttacks
+            : state.incomingAttacks;
+        const attack = attacks[packedAttacks[i + 2]];
+        if (attack !== undefined) {
+          attack.troops = packedAttacks[i + 3];
+        }
+      }
+    }
+
     if (this._myClientID) {
       this._myPlayer ??= this.playerByClientID(this._myClientID);
     }
@@ -441,16 +518,20 @@ export class GameView implements GameMap {
       this._changedTilesScratch.push({ ref: this.updatedTiles[i], state: 0 });
     }
 
-    // Names map — rebuilt every tick. Cheap (one entry per player, no big
-    // arrays). Entry order is irrelevant for the renderer.
-    this._names.clear();
-    for (const p of this._players.values()) {
-      this._names.set(p.id(), {
-        playerID: p.id(),
-        x: p.nameData?.x ?? 0,
-        y: p.nameData?.y ?? 0,
-        size: p.nameData?.size ?? 0,
-      });
+    // Names map — rebuilt only when a placement record arrived or a player
+    // was added (nameData values cannot change between those ticks). Entry
+    // order is irrelevant for the renderer.
+    if (this._namesDirty) {
+      this._namesDirty = false;
+      this._names.clear();
+      for (const p of this._players.values()) {
+        this._names.set(p.id(), {
+          playerID: p.id(),
+          x: p.nameData?.x ?? 0,
+          y: p.nameData?.y ?? 0,
+          size: p.nameData?.size ?? 0,
+        });
+      }
     }
 
     // FrameEvents — clear arrays, then re-populate from this tick's updates.
@@ -478,16 +559,29 @@ export class GameView implements GameMap {
       isTransitiveTarget: (sid) =>
         this._myPlayer?.hasTransitiveTarget(sid) ?? false,
     });
-    const rel = buildRelationMatrix(this._playerStates, this._teams);
-    f.relationMatrix = rel.matrix;
-    f.relationSize = rel.size;
-    f.allianceClusters = computeAllianceClusters(this._playerStates);
+    // Relations + clusters depend only on allies/embargoes/teams, which
+    // change rarely (teams only when a player is added) — recompute only
+    // when one of those inputs arrived this tick. buildRelationMatrix
+    // writes into a reusable module-level buffer, so skipping the call
+    // leaves f.relationMatrix's contents intact.
+    if (this._relationsDirty) {
+      this._relationsDirty = false;
+      const rel = buildRelationMatrix(this._playerStates, this._teams);
+      f.relationMatrix = rel.matrix;
+      f.relationSize = rel.size;
+    }
+    if (this._clustersDirty) {
+      this._clustersDirty = false;
+      f.allianceClusters = computeAllianceClusters(this._playerStates);
+    }
     f.nukeTelegraphs = extractNukeTelegraphs(
       this._unitStates,
       this._map.width(),
       this._myPlayer?.smallID() ?? 0,
-      rel.matrix,
-      rel.size,
+      // The latest relation matrix — recomputed above when dirty, otherwise
+      // carried over on the frame from the last rebuild.
+      f.relationMatrix,
+      f.relationSize,
     );
     f.attackRings = this._myPlayer
       ? extractAttackRings(
@@ -535,6 +629,7 @@ export class GameView implements GameMap {
       const conquered = this._players.get(c.conqueredId);
       if (conquered === undefined) continue;
       const loc = conquered.nameLocation();
+      if (loc === undefined) continue;
       ev.conquestEvents.push({
         x: loc.x,
         y: loc.y,

src/client/view/PlayerView.ts

@@ -123,7 +123,8 @@ export class PlayerView {
   constructor(
     private game: GameView,
     data: PlayerUpdate,
-    public nameData: NameViewData,
+    // Undefined until the worker's first name placement for this player.
+    public nameData: NameViewData | undefined,
     public cosmetics: PlayerCosmetics,
   ) {
     this.state = stateFromUpdate(data);
@@ -405,7 +406,7 @@ export class PlayerView {
       .filter((u) => u.owner().smallID() === this.smallID());
   }
 
-  nameLocation(): NameViewData {
+  nameLocation(): NameViewData | undefined {
     return this.nameData;
   }
 

src/core/GameRunner.ts

@@ -160,6 +160,11 @@ export class GameRunner {
       return false;
     }
 
+    // Track whether placements were recomputed this tick — the record is
+    // only attached to the update when it could have changed, so the main
+    // thread doesn't structured-clone an identical ~all-players record on
+    // every other tick.
+    let viewDataChanged = false;
     if (this.game.inSpawnPhase()) {
       for (const p of this.game.players()) {
         if (p.type() !== PlayerType.Human && p.type() !== PlayerType.Nation) {
@@ -167,6 +172,7 @@ export class GameRunner {
         }
         if (p.spawnTile() === undefined) continue;
         this.playerViewData[p.id()] = placeSpawnName(this.game, p);
+        viewDataChanged = true;
       }
     }
 
@@ -179,17 +185,22 @@ export class GameRunner {
       for (const p of this.game.players()) {
         this.playerViewData[p.id()] = placeName(this.game, p);
       }
+      viewDataChanged = true;
     }
 
     const packedTileUpdates = this.game.drainPackedTileUpdates();
     const packedMotionPlans = this.game.drainPackedMotionPlans();
+    const packedPlayerUpdates = this.game.drainPackedPlayerUpdates();
+    const packedAttackUpdates = this.game.drainPackedAttackUpdates();
 
     this.callBack({
       tick: this.game.ticks(),
       packedTileUpdates,
       ...(packedMotionPlans ? { packedMotionPlans } : {}),
+      ...(packedPlayerUpdates ? { packedPlayerUpdates } : {}),
+      ...(packedAttackUpdates ? { packedAttackUpdates } : {}),
       updates: updates,
-      playerNameViewData: this.playerViewData,
+      ...(viewDataChanged ? { playerNameViewData: this.playerViewData } : {}),
       tickExecutionDuration: tickExecutionDuration,
       pendingTurns: pendingTurns ?? 0,
     });

src/core/game/Game.ts

@@ -666,7 +666,10 @@ export interface Player {
   executeRetreat(attackID: string): void;
 
   // Misc
-  toUpdate(): PlayerUpdate | null;
+  toUpdate(
+    statsOut?: number[],
+    attackTroopsOut?: number[],
+  ): PlayerUpdate | null;
   playerProfile(): PlayerProfile;
   // WARNING: this operation is expensive.
   bestTransportShipSpawn(tile: TileRef): TileRef | false;
@@ -720,6 +723,8 @@ export interface Game extends GameMap {
   drainPackedTileUpdates(): Uint32Array;
   recordMotionPlan(record: MotionPlanRecord): void;
   drainPackedMotionPlans(): Uint32Array | null;
+  drainPackedPlayerUpdates(): Float64Array | null;
+  drainPackedAttackUpdates(): Float64Array | null;
   setWinner(winner: Player | Team, allPlayersStats: AllPlayersStats): void;
   getWinner(): Player | Team | null;
   config(): Config;

src/core/game/GameImpl.ts

@@ -95,6 +95,10 @@ export class GameImpl implements Game {
 
   private updates: GameUpdates = createGameUpdatesMap();
   private tileUpdatePairs: number[] = [];
+  /** [smallID, tilesOwned, gold, troops] quads — see PlayerImpl.toUpdate. */
+  private playerStatsQuads: number[] = [];
+  /** [smallID, direction, index, troops] quads — see packAttackTroopDeltas. */
+  private attackTroopsQuads: number[] = [];
   private motionPlanRecords: MotionPlanRecord[] = [];
   private planDrivenUnitIds = new Set<number>();
   private unitGrid: UnitGrid;
@@ -451,7 +455,10 @@ export class GameImpl implements Game {
     this.execs.push(...inited);
     this.unInitExecs = unInited;
     for (const player of this._players.values()) {
-      const update = player.toUpdate();
+      const update = player.toUpdate(
+        this.playerStatsQuads,
+        this.attackTroopsQuads,
+      );
       if (update !== null) this.addUpdate(update);
     }
     if (this.ticks() % 10 === 0) {
@@ -489,6 +496,22 @@ export class GameImpl implements Game {
     return packed;
   }
 
+  drainPackedPlayerUpdates(): Float64Array | null {
+    const quads = this.playerStatsQuads;
+    if (quads.length === 0) return null;
+    const packed = Float64Array.from(quads);
+    quads.length = 0;
+    return packed;
+  }
+
+  drainPackedAttackUpdates(): Float64Array | null {
+    const quads = this.attackTroopsQuads;
+    if (quads.length === 0) return null;
+    const packed = Float64Array.from(quads);
+    quads.length = 0;
+    return packed;
+  }
+
   recordMotionPlan(record: MotionPlanRecord): void {
     switch (record.kind) {
       case "grid":

src/core/game/GameUpdateUtils.ts

@@ -20,6 +20,12 @@ import {
  * PlayerUpdate, you MUST add a matching setIfDifferent(...) line here, and an
  * apply line in applyStateUpdate below. A field missing here is never diffed,
  * so its changes silently never reach the main thread after the first update.
+ *
+ * EXCEPTION: tilesOwned / gold / troops are deliberately NOT diffed here.
+ * They change for nearly every alive player every tick, so they travel on
+ * the transferable `GameUpdateViewData.packedPlayerUpdates` channel instead
+ * (see PlayerImpl.toUpdate) and appear in PlayerUpdate objects only on a
+ * player's first (full) emission.
  */
 export function diffPlayerUpdate(
   prev: PlayerUpdate,
@@ -46,9 +52,7 @@ export function diffPlayerUpdate(
   setIfDifferent("playerType", prev.playerType === next.playerType);
   setIfDifferent("isAlive", prev.isAlive === next.isAlive);
   setIfDifferent("isDisconnected", prev.isDisconnected === next.isDisconnected);
-  setIfDifferent("tilesOwned", prev.tilesOwned === next.tilesOwned);
-  setIfDifferent("gold", prev.gold === next.gold);
-  setIfDifferent("troops", prev.troops === next.troops);
+  // tilesOwned / gold / troops intentionally absent — see EXCEPTION above.
   setIfDifferent("isTraitor", prev.isTraitor === next.isTraitor);
   setIfDifferent(
     "traitorRemainingTicks",
@@ -76,13 +80,17 @@ export function diffPlayerUpdate(
     "outgoingEmojis",
     emojiArrayEqual(prev.outgoingEmojis, next.outgoingEmojis),
   );
+  // Attack arrays are compared WITHOUT troop counts: troops change every
+  // tick for every active attack and travel via packedAttackUpdates (see
+  // packAttackTroopDeltas below). The arrays are only resent when
+  // membership/order/retreating changes.
   setIfDifferent(
     "outgoingAttacks",
-    attackArrayEqual(prev.outgoingAttacks, next.outgoingAttacks),
+    attackArrayMembershipEqual(prev.outgoingAttacks, next.outgoingAttacks),
   );
   setIfDifferent(
     "incomingAttacks",
-    attackArrayEqual(prev.incomingAttacks, next.incomingAttacks),
+    attackArrayMembershipEqual(prev.incomingAttacks, next.incomingAttacks),
   );
   setIfDifferent(
     "alliances",
@@ -159,7 +167,17 @@ function stringSetEqual(a?: Set<string>, b?: Set<string>): boolean {
   return true;
 }
 
-function attackArrayEqual(a?: AttackUpdate[], b?: AttackUpdate[]): boolean {
+/**
+ * Attack-array equality ignoring troop counts: same attacks, same order,
+ * same retreating flags. When this holds, only troop counts can differ, and
+ * those travel as packed quads (packAttackTroopDeltas) addressed by index —
+ * which stays valid precisely because any membership/order change makes
+ * this false and resends the whole array.
+ */
+function attackArrayMembershipEqual(
+  a?: AttackUpdate[],
+  b?: AttackUpdate[],
+): boolean {
   if (a === b) return true;
   if (!a || !b) return false;
   if (a.length !== b.length) return false;
@@ -169,7 +187,6 @@ function attackArrayEqual(a?: AttackUpdate[], b?: AttackUpdate[]): boolean {
     if (
       x.attackerID !== y.attackerID ||
       x.targetID !== y.targetID ||
-      x.troops !== y.troops ||
       x.id !== y.id ||
       x.retreating !== y.retreating
     ) {
@@ -179,6 +196,38 @@ function attackArrayEqual(a?: AttackUpdate[], b?: AttackUpdate[]): boolean {
   return true;
 }
 
+/**
+ * Direction lane of a `packedAttackUpdates` quad: which of the owner's attack
+ * arrays the index addresses. Encoder (PlayerImpl.toUpdate →
+ * packAttackTroopDeltas) and decoder (client GameView.update) must both use
+ * these.
+ */
+export const ATTACK_DELTA_OUTGOING = 0;
+export const ATTACK_DELTA_INCOMING = 1;
+
+/**
+ * Push a `[ownerSmallID, direction, index, troops]` quad onto `out` for each
+ * attack whose troop count changed between `prev` and `next`. No-op when the
+ * arrays are not membership-equal — diffPlayerUpdate resends the whole array
+ * that tick (carrying fresh troop counts), so patches would be redundant and
+ * their indexes unreliable.
+ */
+export function packAttackTroopDeltas(
+  prev: AttackUpdate[] | undefined,
+  next: AttackUpdate[] | undefined,
+  ownerSmallID: number,
+  direction: typeof ATTACK_DELTA_OUTGOING | typeof ATTACK_DELTA_INCOMING,
+  out: number[],
+): void {
+  if (prev === next || !prev || !next) return;
+  if (!attackArrayMembershipEqual(prev, next)) return;
+  for (let i = 0; i < next.length; i++) {
+    if (prev[i].troops !== next[i].troops) {
+      out.push(ownerSmallID, direction, i, next[i].troops);
+    }
+  }
+}
+
 function allianceArrayEqual(a?: AllianceView[], b?: AllianceView[]): boolean {
   if (a === b) return true;
   if (!a || !b) return false;

src/core/game/GameUpdates.ts

@@ -33,7 +33,35 @@ export interface GameUpdateViewData {
    * (similar to `packedTileUpdates`) to avoid structured-clone copies.
    */
   packedMotionPlans?: Uint32Array;
-  playerNameViewData: Record<string, NameViewData>;
+  /**
+   * Packed per-player numeric stats as `[smallID, tilesOwned, gold, troops]`
+   * float64 quads — the fields that change for nearly every alive player
+   * every tick. They travel here (transferred, not structured-cloned) instead
+   * of in `PlayerUpdate` object diffs, which only carry them on a player's
+   * first emission. Gold is exact in a float64 (game values stay far below
+   * 2^53). Absent when no player's stats changed.
+   */
+  packedPlayerUpdates?: Float64Array;
+  /**
+   * Packed attack troop-count changes as
+   * `[ownerSmallID, direction, index, troops]` float64 quads, where
+   * `direction` is 0 for the owner's outgoingAttacks and 1 for
+   * incomingAttacks, and `index` addresses that array. Troop counts change
+   * every tick for every active attack, so they travel here instead of
+   * re-sending whole attack arrays in PlayerUpdate diffs; the arrays
+   * themselves are only resent when membership/order/retreating changes —
+   * which also guarantees the receiver's indexes line up (see
+   * packAttackTroopDeltas). Absent when no attack troop count changed.
+   */
+  packedAttackUpdates?: Float64Array;
+  /**
+   * Name placement per player. Only present on ticks where the worker
+   * recomputed placements (spawn ticks, the first ticks, every 30th tick,
+   * spawn end) — between those the values wouldn't change, so the record is
+   * omitted instead of re-cloned every tick. Consumers keep the last applied
+   * values.
+   */
+  playerNameViewData?: Record<string, NameViewData>;
   tickExecutionDuration?: number;
   pendingTurns?: number;
 }

src/core/game/PlayerImpl.ts

@@ -41,7 +41,12 @@ import {
 } from "./Game";
 import { GameImpl } from "./GameImpl";
 import { andFN, manhattanDistFN, TileRef } from "./GameMap";
-import { diffPlayerUpdate } from "./GameUpdateUtils";
+import {
+  ATTACK_DELTA_INCOMING,
+  ATTACK_DELTA_OUTGOING,
+  diffPlayerUpdate,
+  packAttackTroopDeltas,
+} from "./GameUpdateUtils";
 import {
   AllianceView,
   AttackUpdate,
@@ -154,13 +159,53 @@ export class PlayerImpl implements Player {
    * return only fields that changed since the previous call (a partial
    * `{ type, id, ...changedFields }`), or `null` if nothing changed.
    *
+   * tilesOwned / gold / troops are excluded from partial updates (they churn
+   * for every alive player every tick): when any of them changed, a
+   * `[smallID, tilesOwned, gold, troops]` quad is pushed to `statsOut`
+   * instead, which GameImpl drains into the transferable
+   * `packedPlayerUpdates` buffer. Attack troop counts likewise go to
+   * `attackTroopsOut` as `[smallID, direction, index, troops]` quads
+   * (→ `packedAttackUpdates`) instead of re-sending whole attack arrays.
+   *
    * `lastSentUpdate` is updated to the full snapshot on every call.
    */
-  toUpdate(): PlayerUpdate | null {
+  toUpdate(
+    statsOut?: number[],
+    attackTroopsOut?: number[],
+  ): PlayerUpdate | null {
     const full = this.toFullUpdate();
     const prev = this.lastSentUpdate;
     this.lastSentUpdate = full;
     if (prev === undefined) return full;
+    if (
+      statsOut !== undefined &&
+      (prev.tilesOwned !== full.tilesOwned ||
+        prev.gold !== full.gold ||
+        prev.troops !== full.troops)
+    ) {
+      statsOut.push(
+        full.smallID!,
+        full.tilesOwned!,
+        Number(full.gold),
+        full.troops!,
+      );
+    }
+    if (attackTroopsOut !== undefined) {
+      packAttackTroopDeltas(
+        prev.outgoingAttacks,
+        full.outgoingAttacks,
+        full.smallID!,
+        ATTACK_DELTA_OUTGOING,
+        attackTroopsOut,
+      );
+      packAttackTroopDeltas(
+        prev.incomingAttacks,
+        full.incomingAttacks,
+        full.smallID!,
+        ATTACK_DELTA_INCOMING,
+        attackTroopsOut,
+      );
+    }
     return diffPlayerUpdate(prev, full);
   }
 

src/core/worker/Worker.worker.ts

@@ -113,6 +113,12 @@ function sendGameUpdateBatch(gameUpdates: GameUpdateViewData[]): void {
     if (gu.packedMotionPlans) {
       transfers.push(gu.packedMotionPlans.buffer);
     }
+    if (gu.packedPlayerUpdates) {
+      transfers.push(gu.packedPlayerUpdates.buffer);
+    }
+    if (gu.packedAttackUpdates) {
+      transfers.push(gu.packedAttackUpdates.buffer);
+    }
   }
 
   ctx.postMessage(

tests/GameUpdateUtils.test.ts

@@ -4,8 +4,13 @@ import { PlayerType } from "../src/core/game/Game";
 import {
   applyStateUpdate,
   diffPlayerUpdate,
+  packAttackTroopDeltas,
 } from "../src/core/game/GameUpdateUtils";
-import { GameUpdateType, PlayerUpdate } from "../src/core/game/GameUpdates";
+import {
+  AttackUpdate,
+  GameUpdateType,
+  PlayerUpdate,
+} from "../src/core/game/GameUpdates";
 import { makePlayerUpdate } from "./util/viewStubs";
 
 function makePlayerState(overrides: Partial<PlayerState> = {}): PlayerState {
@@ -41,24 +46,30 @@ describe("diffPlayerUpdate", () => {
   });
 
   it("returns a diff with only changed primitives plus type+id", () => {
-    const prev = makePlayerUpdate({ gold: 100n });
-    const next = makePlayerUpdate({ gold: 250n });
+    const prev = makePlayerUpdate({ betrayals: 0 });
+    const next = makePlayerUpdate({ betrayals: 1 });
     const diff = diffPlayerUpdate(prev, next);
     expect(diff).not.toBeNull();
     expect(diff).toEqual({
       type: GameUpdateType.Player,
       id: "player-a",
-      gold: 250n,
+      betrayals: 1,
     });
   });
 
   it("includes every changed primitive in a single diff", () => {
-    const prev = makePlayerUpdate({ gold: 100n, troops: 50, tilesOwned: 5 });
-    const next = makePlayerUpdate({ gold: 200n, troops: 75, tilesOwned: 5 });
+    const prev = makePlayerUpdate({ betrayals: 0, isTraitor: false });
+    const next = makePlayerUpdate({ betrayals: 1, isTraitor: true });
     const diff = diffPlayerUpdate(prev, next)!;
-    expect(diff.gold).toBe(200n);
-    expect(diff.troops).toBe(75);
-    expect(diff.tilesOwned).toBeUndefined();
+    expect(diff.betrayals).toBe(1);
+    expect(diff.isTraitor).toBe(true);
+    expect(diff.hasSpawned).toBeUndefined();
+  });
+
+  it("ignores tilesOwned/gold/troops — they travel via packedPlayerUpdates", () => {
+    const prev = makePlayerUpdate({ gold: 100n, troops: 50, tilesOwned: 5 });
+    const next = makePlayerUpdate({ gold: 200n, troops: 75, tilesOwned: 9 });
+    expect(diffPlayerUpdate(prev, next)).toBeNull();
   });
 
   it("detects allies array additions", () => {
@@ -94,7 +105,22 @@ describe("diffPlayerUpdate", () => {
     expect(diffPlayerUpdate(prev, next)).toBeNull();
   });
 
-  it("detects outgoingAttacks element changes", () => {
+  it("detects outgoingAttacks membership/retreating changes", () => {
+    const prev = makePlayerUpdate({
+      outgoingAttacks: [
+        { attackerID: 1, targetID: 2, troops: 10, id: "a", retreating: false },
+      ],
+    });
+    const next = makePlayerUpdate({
+      outgoingAttacks: [
+        { attackerID: 1, targetID: 2, troops: 10, id: "a", retreating: true },
+      ],
+    });
+    const diff = diffPlayerUpdate(prev, next)!;
+    expect(diff.outgoingAttacks).toEqual(next.outgoingAttacks);
+  });
+
+  it("ignores attack troop-count changes — they travel via packedAttackUpdates", () => {
     const prev = makePlayerUpdate({
       outgoingAttacks: [
         { attackerID: 1, targetID: 2, troops: 10, id: "a", retreating: false },
@@ -105,8 +131,7 @@ describe("diffPlayerUpdate", () => {
         { attackerID: 1, targetID: 2, troops: 20, id: "a", retreating: false },
       ],
     });
-    const diff = diffPlayerUpdate(prev, next)!;
-    expect(diff.outgoingAttacks).toEqual(next.outgoingAttacks);
+    expect(diffPlayerUpdate(prev, next)).toBeNull();
   });
 
   it("detects alliance list changes", () => {
@@ -143,14 +168,76 @@ describe("diffPlayerUpdate", () => {
   });
 
   it("always includes type and id on a non-null diff", () => {
-    const prev = makePlayerUpdate({ gold: 100n });
-    const next = makePlayerUpdate({ gold: 200n });
+    const prev = makePlayerUpdate({ betrayals: 0 });
+    const next = makePlayerUpdate({ betrayals: 1 });
     const diff = diffPlayerUpdate(prev, next)!;
     expect(diff.type).toBe(GameUpdateType.Player);
     expect(diff.id).toBe(next.id);
   });
 });
 
+describe("packAttackTroopDeltas", () => {
+  const attack = (
+    troops: number,
+    id = "a",
+    retreating = false,
+  ): AttackUpdate => ({
+    attackerID: 1,
+    targetID: 2,
+    troops,
+    id,
+    retreating,
+  });
+
+  it("emits [owner, direction, index, troops] quads for changed troop counts", () => {
+    const out: number[] = [];
+    packAttackTroopDeltas(
+      [attack(10, "a"), attack(20, "b")],
+      [attack(10, "a"), attack(15, "b")],
+      7,
+      1,
+      out,
+    );
+    expect(out).toEqual([7, 1, 1, 15]);
+  });
+
+  it("emits nothing when arrays are not membership-equal (diff resends them)", () => {
+    const out: number[] = [];
+    packAttackTroopDeltas(
+      [attack(10, "a")],
+      [attack(15, "a"), attack(5, "b")],
+      7,
+      0,
+      out,
+    );
+    expect(out).toEqual([]);
+  });
+
+  it("a retreat flip suppresses quads even when troops also changed", () => {
+    // retreating is part of membership equality, so the whole array resends
+    // (with fresh troops) and patches must NOT be emitted — a tick resends
+    // or patches, never both.
+    const out: number[] = [];
+    packAttackTroopDeltas(
+      [attack(10, "a", false)],
+      [attack(5, "a", true)],
+      7,
+      0,
+      out,
+    );
+    expect(out).toEqual([]);
+  });
+
+  it("emits nothing for identical references or missing arrays", () => {
+    const out: number[] = [];
+    const arr = [attack(10)];
+    packAttackTroopDeltas(arr, arr, 7, 0, out);
+    packAttackTroopDeltas(undefined, arr, 7, 0, out);
+    packAttackTroopDeltas(arr, undefined, 7, 0, out);
+    expect(out).toEqual([]);
+  });
+});
+
 describe("applyStateUpdate", () => {
   it("applies every field from a full update", () => {
     const target = makePlayerState();
@@ -276,18 +363,10 @@ describe("applyStateUpdate", () => {
 
 describe("diff + apply round-trip", () => {
   it("emitting full first + diff second reconstructs final state", () => {
-    const v0 = makePlayerUpdate({
-      gold: 0n,
-      troops: 100,
-      tilesOwned: 0,
-      allies: [],
-    });
-    const v1 = makePlayerUpdate({
-      gold: 200n,
-      troops: 150,
-      tilesOwned: 5,
-      allies: [2],
-    });
+    // tilesOwned/gold/troops round-trip via packedPlayerUpdates instead
+    // (covered in tests/client/view/GameView.test.ts).
+    const v0 = makePlayerUpdate({ betrayals: 0, allies: [] });
+    const v1 = makePlayerUpdate({ betrayals: 2, allies: [2] });
 
     // Initial state: receiver applies the full update.
     const target = makePlayerState();
@@ -298,9 +377,7 @@ describe("diff + apply round-trip", () => {
     expect(diff).not.toBeNull();
     applyStateUpdate(target, diff);
 
-    expect(target.gold).toBe(200);
-    expect(target.troops).toBe(150);
-    expect(target.tilesOwned).toBe(5);
+    expect(target.betrayals).toBe(2);
     expect(target.allies).toEqual([2]);
   });
 

tests/PackedPlayerUpdates.test.ts

@@ -0,0 +1,155 @@
+/**
+ * The worker→main tick payload: per-tick numeric stat churn travels on the
+ * transferable `packedPlayerUpdates` quad buffer (drained from GameImpl),
+ * and `playerNameViewData` is attached only on ticks where the worker
+ * recomputed name placements. See GameUpdateViewData in GameUpdates.ts.
+ */
+import { Executor } from "../src/core/execution/ExecutionManager";
+import { SpawnExecution } from "../src/core/execution/SpawnExecution";
+import { Game, Player, PlayerInfo, PlayerType } from "../src/core/game/Game";
+import {
+  GameUpdateType,
+  GameUpdateViewData,
+} from "../src/core/game/GameUpdates";
+import { GameRunner } from "../src/core/GameRunner";
+import { setup } from "./util/Setup";
+
+const gameID = "game_id";
+
+describe("packedPlayerUpdates (GameImpl drain)", () => {
+  let game: Game;
+  let alice: Player;
+
+  beforeEach(async () => {
+    game = await setup("plains", {});
+    const aliceInfo = new PlayerInfo(
+      "alice",
+      PlayerType.Human,
+      "alice_client",
+      "alice_id",
+    );
+    game.addPlayer(aliceInfo);
+    game.addExecution(new SpawnExecution(gameID, aliceInfo, game.ref(10, 10)));
+    game.executeNextTick();
+    game.executeNextTick();
+    alice = game.player("alice_id");
+    game.drainPackedPlayerUpdates(); // discard spawn-time churn
+  });
+
+  test("a stat change is drained as a [smallID, tiles, gold, troops] quad", () => {
+    alice.addGold(500n);
+    game.executeNextTick();
+    const packed = game.drainPackedPlayerUpdates();
+    expect(packed).not.toBeNull();
+    // Find alice's quad (other players may have churned too).
+    let quad: number[] | undefined;
+    for (let i = 0; i + 3 < packed!.length; i += 4) {
+      if (packed![i] === alice.smallID()) {
+        quad = Array.from(packed!.subarray(i, i + 4));
+      }
+    }
+    expect(quad).toEqual([
+      alice.smallID(),
+      alice.numTilesOwned(),
+      Number(alice.gold()),
+      alice.troops(),
+    ]);
+  });
+
+  test("drain returns null when no stats changed and resets between drains", () => {
+    alice.addGold(500n);
+    game.executeNextTick();
+    expect(game.drainPackedPlayerUpdates()).not.toBeNull();
+    // Drained — a second drain without a tick has nothing.
+    expect(game.drainPackedPlayerUpdates()).toBeNull();
+  });
+});
+
+describe("GameRunner payload cadence", () => {
+  let game: Game;
+  let byTick: Map<number, GameUpdateViewData>;
+  let tick: () => void;
+
+  beforeEach(async () => {
+    game = await setup(
+      "plains",
+      {},
+      [],
+      undefined,
+      undefined,
+      false, // keep the spawn phase under the test's control
+    );
+    const aliceInfo = new PlayerInfo(
+      "alice",
+      PlayerType.Human,
+      "alice_client",
+      "alice_id",
+    );
+    game.addPlayer(aliceInfo);
+    game.addExecution(new SpawnExecution(gameID, aliceInfo, game.ref(10, 10)));
+    byTick = new Map();
+    const runner = new GameRunner(
+      game,
+      new Executor(game, gameID, "alice_client"),
+      (gu) => {
+        if (!("errMsg" in gu)) byTick.set(gu.tick, gu);
+      },
+    );
+    // No runner.init(): no SpawnTimerExecution — the game stays in the spawn
+    // phase until the test ends it manually.
+    let turn = 0;
+    tick = () => {
+      runner.addTurn({ turnNumber: turn++, intents: [] });
+      runner.executeNextTick();
+    };
+  });
+
+  test("playerNameViewData is attached only on placement-rebuild ticks", () => {
+    tick(); // 1
+    tick(); // 2
+    game.endSpawnPhase();
+    for (let t = 3; t <= 61; t++) tick();
+
+    // ticks < 3 always rebuild; every 30th tick rebuilds; everything else
+    // omits the record. (The in-tick spawn-end rebuild also sets the flag,
+    // but ending the spawn phase between ticks doesn't exercise it here.)
+    expect(byTick.get(1)!.playerNameViewData).toBeDefined();
+    expect(byTick.get(2)!.playerNameViewData).toBeDefined();
+    expect(byTick.get(4)!.playerNameViewData).toBeUndefined();
+    expect(byTick.get(29)!.playerNameViewData).toBeUndefined();
+    expect(byTick.get(30)!.playerNameViewData).toBeDefined();
+    expect(byTick.get(31)!.playerNameViewData).toBeUndefined();
+    expect(byTick.get(60)!.playerNameViewData).toBeDefined();
+  });
+
+  test("stat churn arrives as packedPlayerUpdates quads on the view data", () => {
+    tick(); // 1
+    tick(); // 2
+    game.endSpawnPhase();
+    tick(); // 3 — flush spawn churn
+
+    const alice = game.player("alice_id");
+    alice.addGold(500n);
+    tick(); // 4
+    const gu = byTick.get(game.ticks())!;
+    const packed = gu.packedPlayerUpdates;
+    expect(packed).toBeDefined();
+    expect(packed!.length % 4).toBe(0);
+    let quad: number[] | undefined;
+    for (let i = 0; i + 3 < packed!.length; i += 4) {
+      if (packed![i] === alice.smallID()) {
+        quad = Array.from(packed!.subarray(i, i + 4));
+      }
+    }
+    expect(quad).toEqual([
+      alice.smallID(),
+      alice.numTilesOwned(),
+      Number(alice.gold()),
+      alice.troops(),
+    ]);
+    // And the object channel no longer carries the stat fields: alice must
+    // not appear in this tick's PlayerUpdates for a gold-only change.
+    const playerUpdates = gu.updates[GameUpdateType.Player];
+    expect(playerUpdates.find((u) => u.id === "alice_id")).toBeUndefined();
+  });
+});

tests/PlayerUpdateDiff.test.ts

@@ -72,10 +72,10 @@ describe("Player update diffing (toUpdate)", () => {
 
   test("primitive changes appear in the diff without unchanged collections", () => {
     alice.toUpdate();
-    alice.addGold(123n);
+    alice.markTraitor();
     const diff = alice.toUpdate();
     expect(diff).not.toBeNull();
-    expect(diff!.gold).toBe(alice.gold());
+    expect(diff!.isTraitor).toBe(true);
     // Unchanged collection fields must be absent from the diff.
     expect(diff!.allies).toBeUndefined();
     expect(diff!.embargoes).toBeUndefined();
@@ -83,6 +83,52 @@ describe("Player update diffing (toUpdate)", () => {
     expect(diff!.alliances).toBeUndefined();
   });
 
+  test("stat churn (gold/troops/tilesOwned) travels via statsOut, not the diff", () => {
+    const statsOut: number[] = [];
+    alice.toUpdate(statsOut);
+    statsOut.length = 0;
+
+    alice.addGold(123n);
+    const diff = alice.toUpdate(statsOut);
+    // No object diff — gold alone must not put the player on the object
+    // channel (that's the whole point of the packed stats channel).
+    expect(diff).toBeNull();
+    expect(statsOut).toEqual([
+      alice.smallID(),
+      alice.numTilesOwned(),
+      Number(alice.gold()),
+      alice.troops(),
+    ]);
+
+    // Nothing changed → no quad, no diff.
+    statsOut.length = 0;
+    expect(alice.toUpdate(statsOut)).toBeNull();
+    expect(statsOut).toEqual([]);
+
+    // A non-stat change produces an object diff but no quad.
+    alice.markTraitor();
+    expect(alice.toUpdate(statsOut)).not.toBeNull();
+    expect(statsOut).toEqual([]);
+  });
+
+  test("first emission carries the stats in the full snapshot, not statsOut", () => {
+    const info = new PlayerInfo(
+      "dora",
+      PlayerType.Human,
+      "dora_client",
+      "dora_id",
+    );
+    game.addPlayer(info);
+    const dora = game.player("dora_id");
+    const statsOut: number[] = [];
+    const full = dora.toUpdate(statsOut);
+    expect(full).not.toBeNull();
+    expect(full!.gold).toBe(dora.gold());
+    expect(full!.troops).toBe(dora.troops());
+    expect(full!.tilesOwned).toBe(dora.numTilesOwned());
+    expect(statsOut).toEqual([]);
+  });
+
   test("adding and removing an embargo shows up in consecutive diffs", () => {
     alice.toUpdate();
     alice.addEmbargo(bob, false);
@@ -156,17 +202,33 @@ describe("Player update diffing (toUpdate)", () => {
       alice.smallID(),
     );
 
-    // As the attack progresses, troop counts change and must keep flowing
-    // through subsequent diffs.
+    // As the attack progresses, troop counts change — but attack arrays are
+    // NOT resent for troop-only changes. Troops flow as packed
+    // [ownerSmallID, direction, index, troops] quads instead.
+    game.drainPackedAttackUpdates(); // discard quads from earlier ticks
     const nextUpdates = game.executeNextTick();
     const nextPlayerUpdates = nextUpdates[
       GameUpdateType.Player
     ] as PlayerUpdate[];
     const next = nextPlayerUpdates.find((u) => u.id === "alice_id");
-    expect(next).toBeDefined();
-    expect(
-      next!.outgoingAttacks!.some((a) => a.targetID === bob.smallID()),
-    ).toBe(true);
+    if (next !== undefined) {
+      // Alice may appear for other field changes, but not for attack arrays.
+      expect(next.outgoingAttacks).toBeUndefined();
+    }
+    const packed = game.drainPackedAttackUpdates();
+    expect(packed).not.toBeNull();
+    // Find alice's outgoing quads and check one matches her current attack.
+    const aliceQuads: number[][] = [];
+    for (let i = 0; i + 3 < packed!.length; i += 4) {
+      if (packed![i] === alice.smallID() && packed![i + 1] === 0) {
+        aliceQuads.push(Array.from(packed!.subarray(i, i + 4)));
+      }
+    }
+    expect(aliceQuads.length).toBeGreaterThan(0);
+    const aliceAttacks = alice.outgoingAttacks();
+    for (const [, , index, troops] of aliceQuads) {
+      expect(troops).toBe(aliceAttacks[index].troops());
+    }
   });
 
   test("in-worker mutation of shared empty collections fails loudly", () => {

tests/client/view/GameView.test.ts

@@ -27,9 +27,11 @@ function withPlayers(
 ) {
   const gu = makeEmptyGu(tick);
   gu.updates[GameUpdateType.Player] = players;
+  const nameViewData: NonNullable<typeof gu.playerNameViewData> = {};
   for (const p of players) {
-    gu.playerNameViewData[p.id] = nameDataMap[p.id] ?? makeNameViewData();
+    nameViewData[p.id] = nameDataMap[p.id] ?? makeNameViewData();
   }
+  gu.playerNameViewData = nameViewData;
   return gu;
 }
 
@@ -140,6 +142,288 @@ describe("GameView.update — players", () => {
   });
 });
 
+describe("GameView.update — packed channels", () => {
+  it("packedPlayerUpdates quads update tilesOwned/gold/troops in place", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [
+        makePlayerUpdate({ id: "alice", smallID: 1, troops: 100, gold: 5n }),
+      ]),
+    );
+
+    const gu = makeEmptyGu(2);
+    // [smallID, tilesOwned, gold, troops]
+    gu.packedPlayerUpdates = new Float64Array([1, 42, 999, 250]);
+    game.update(gu);
+
+    const alice = game.player("alice");
+    expect(alice.numTilesOwned()).toBe(42);
+    expect(alice.gold()).toBe(999n);
+    expect(alice.troops()).toBe(250);
+  });
+
+  it("packedAttackUpdates patches troop counts by direction and index", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [
+        makePlayerUpdate({
+          id: "alice",
+          smallID: 1,
+          outgoingAttacks: [
+            {
+              attackerID: 1,
+              targetID: 2,
+              troops: 500,
+              id: "a1",
+              retreating: false,
+            },
+            {
+              attackerID: 1,
+              targetID: 3,
+              troops: 300,
+              id: "a2",
+              retreating: false,
+            },
+          ],
+          incomingAttacks: [
+            {
+              attackerID: 4,
+              targetID: 1,
+              troops: 80,
+              id: "a3",
+              retreating: false,
+            },
+          ],
+        }),
+      ]),
+    );
+
+    const gu = makeEmptyGu(2);
+    // [ownerSmallID, direction (0=outgoing, 1=incoming), index, troops]
+    gu.packedAttackUpdates = new Float64Array([1, 0, 1, 290, 1, 1, 0, 75]);
+    game.update(gu);
+
+    const alice = game.player("alice");
+    expect(alice.outgoingAttacks().map((a) => a.troops)).toEqual([500, 290]);
+    expect(alice.incomingAttacks().map((a) => a.troops)).toEqual([75]);
+  });
+
+  it("quads for unknown smallIDs and out-of-range attack indexes are ignored", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [makePlayerUpdate({ id: "alice", smallID: 1 })]),
+    );
+    const gu = makeEmptyGu(2);
+    gu.packedPlayerUpdates = new Float64Array([99, 1, 1, 1]);
+    gu.packedAttackUpdates = new Float64Array([1, 0, 5, 123, 99, 1, 0, 7]);
+    expect(() => game.update(gu)).not.toThrow();
+  });
+
+  it("same-tick array resend and patch on different directions both apply", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [
+        makePlayerUpdate({
+          id: "alice",
+          smallID: 1,
+          outgoingAttacks: [
+            {
+              attackerID: 1,
+              targetID: 2,
+              troops: 500,
+              id: "a1",
+              retreating: false,
+            },
+          ],
+          incomingAttacks: [
+            {
+              attackerID: 4,
+              targetID: 1,
+              troops: 80,
+              id: "a3",
+              retreating: false,
+            },
+          ],
+        }),
+      ]),
+    );
+
+    // Outgoing membership changed → full array resent with fresh troops;
+    // incoming membership unchanged → troops arrive as a patch. The patch
+    // must land on the long-lived incoming array and not interfere with the
+    // resent outgoing array (a tick resends or patches each array, never
+    // both — but different directions can mix on one tick).
+    const gu = makeEmptyGu(2);
+    gu.updates[GameUpdateType.Player] = [
+      {
+        type: GameUpdateType.Player,
+        id: "alice",
+        outgoingAttacks: [
+          {
+            attackerID: 1,
+            targetID: 2,
+            troops: 450,
+            id: "a1",
+            retreating: false,
+          },
+          {
+            attackerID: 1,
+            targetID: 3,
+            troops: 100,
+            id: "a2",
+            retreating: false,
+          },
+        ],
+      },
+    ];
+    gu.packedAttackUpdates = new Float64Array([1, 1, 0, 75]);
+    game.update(gu);
+
+    const alice = game.player("alice");
+    expect(alice.outgoingAttacks().map((a) => a.troops)).toEqual([450, 100]);
+    expect(alice.incomingAttacks().map((a) => a.troops)).toEqual([75]);
+  });
+
+  it("gold survives the float64 quad exactly, including > 2^32 values", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [makePlayerUpdate({ id: "alice", smallID: 1 })]),
+    );
+    const bigGold = 2 ** 52 + 11; // integer, exactly representable in f64
+    const gu = makeEmptyGu(2);
+    gu.packedPlayerUpdates = new Float64Array([1, 0, bigGold, 0]);
+    game.update(gu);
+    expect(game.player("alice").gold()).toBe(BigInt(bigGold));
+  });
+
+  it("nameData persists across ticks without a playerNameViewData record", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [makePlayerUpdate({ id: "alice", smallID: 1 })], {
+        alice: { x: 7, y: 9, size: 3 },
+      }),
+    );
+    expect(game.frameData().names.get("alice")).toMatchObject({ x: 7, y: 9 });
+
+    // Tick without a record (worker omits it between placement rebuilds) —
+    // even with a player update present, the old placement must survive.
+    const gu = makeEmptyGu(2);
+    gu.updates[GameUpdateType.Player] = [
+      makePlayerUpdate({ id: "alice", smallID: 1 }),
+    ];
+    game.update(gu);
+    expect(game.frameData().names.get("alice")).toMatchObject({ x: 7, y: 9 });
+
+    // A new record updates the placement (alice is alive).
+    const gu3 = makeEmptyGu(3);
+    gu3.playerNameViewData = { alice: { x: 11, y: 13, size: 4 } };
+    game.update(gu3);
+    expect(game.frameData().names.get("alice")).toMatchObject({ x: 11, y: 13 });
+  });
+
+  it("dead players keep their last name placement (freeze at death)", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [makePlayerUpdate({ id: "alice", smallID: 1 })], {
+        alice: { x: 7, y: 9, size: 3 },
+      }),
+    );
+
+    // Alice dies.
+    const gu2 = makeEmptyGu(2);
+    gu2.updates[GameUpdateType.Player] = [
+      makePlayerUpdate({ id: "alice", smallID: 1, isAlive: false }),
+    ];
+    game.update(gu2);
+
+    // A later record must not move her name.
+    const gu3 = makeEmptyGu(3);
+    gu3.playerNameViewData = { alice: { x: 0, y: 0, size: 0 } };
+    game.update(gu3);
+    expect(game.frameData().names.get("alice")).toMatchObject({ x: 7, y: 9 });
+  });
+});
+
+describe("GameView.update — derived-data dirty flags", () => {
+  function twoPlayers() {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [
+        makePlayerUpdate({ id: "alice", smallID: 1 }),
+        makePlayerUpdate({ id: "bob", smallID: 2 }),
+      ]),
+    );
+    return game;
+  }
+
+  it("relationMatrix recomputes when allies arrive on a partial update", () => {
+    const game = twoPlayers();
+    const size = game.frameData().relationSize;
+    expect(game.frameData().relationMatrix[1 * size + 2]).toBe(0); // neutral
+
+    const gu = makeEmptyGu(2);
+    gu.updates[GameUpdateType.Player] = [
+      { type: GameUpdateType.Player, id: "alice", allies: [2] },
+    ];
+    game.update(gu);
+    // friendly, both directions
+    expect(game.frameData().relationMatrix[1 * size + 2]).toBe(1);
+    expect(game.frameData().relationMatrix[2 * size + 1]).toBe(1);
+  });
+
+  it("relationMatrix recomputes when embargoes arrive on a partial update", () => {
+    const game = twoPlayers();
+    const size = game.frameData().relationSize;
+
+    const gu = makeEmptyGu(2);
+    gu.updates[GameUpdateType.Player] = [
+      {
+        type: GameUpdateType.Player,
+        id: "alice",
+        embargoes: new Set(["bob"]),
+      },
+    ];
+    game.update(gu);
+    expect(game.frameData().relationMatrix[1 * size + 2]).toBe(2); // embargo
+  });
+
+  it("allianceClusters keep identity on clean ticks and recompute on allies change", () => {
+    const game = twoPlayers();
+    const before = game.frameData().allianceClusters;
+    expect(before.get(1)).not.toBe(before.get(2)); // separate clusters
+
+    // Clean tick: no relation inputs changed → cached object, untouched.
+    game.update(makeEmptyGu(2));
+    expect(game.frameData().allianceClusters).toBe(before);
+
+    // Alliance forms → recomputed: alice and bob share a cluster root.
+    const gu = makeEmptyGu(3);
+    gu.updates[GameUpdateType.Player] = [
+      { type: GameUpdateType.Player, id: "alice", allies: [2] },
+      { type: GameUpdateType.Player, id: "bob", allies: [1] },
+    ];
+    game.update(gu);
+    const after = game.frameData().allianceClusters;
+    expect(after).not.toBe(before);
+    expect(after.get(1)).toBe(after.get(2));
+  });
+
+  it("names map keeps identity and content on ticks without a record", () => {
+    const game = makeGameView();
+    game.update(
+      withPlayers(1, [makePlayerUpdate({ id: "alice", smallID: 1 })], {
+        alice: { x: 7, y: 9, size: 3 },
+      }),
+    );
+    const names = game.frameData().names;
+    const entry = names.get("alice");
+
+    game.update(makeEmptyGu(2));
+    expect(game.frameData().names).toBe(names); // long-lived map
+    expect(game.frameData().names.get("alice")).toBe(entry); // not rebuilt
+  });
+});
+
 describe("GameView.update — units", () => {
   it("creates a UnitView on first sighting and reuses it after", () => {
     const game = makeGameView();

tests/perf/client/ClientUpdatePerf.ts

@@ -424,6 +424,12 @@ async function main(): Promise<void> {
     if (gu.packedMotionPlans) {
       transfers.push(gu.packedMotionPlans.buffer);
     }
+    if (gu.packedPlayerUpdates) {
+      transfers.push(gu.packedPlayerUpdates.buffer);
+    }
+    if (gu.packedAttackUpdates) {
+      transfers.push(gu.packedAttackUpdates.buffer);
+    }
     start = performance.now();
     const cloned = structuredClone(gu, { transfer: transfers });
     const cloneMs = performance.now() - start;

tests/util/viewStubs.ts

@@ -204,7 +204,9 @@ export function makeEmptyGu(
     tick,
     updates,
     packedTileUpdates: new Uint32Array(0),
-    playerNameViewData: {},
+    // playerNameViewData deliberately absent — production omits it on every
+    // tick between placement rebuilds, so the stub default must exercise the
+    // absent path. Tests that need placements set it explicitly.
     ...overrides,
   };
 }