ui/phase-27: battle viewer (radial scene, playback, map markers)

Engine wire change: Report.battle switched from []uuid.UUID to
[]BattleSummary{id, planet, shots} so the map can place battle
markers without N extra fetches. FBS schema + generated Go/TS
regenerated; transcoder + report controller updated; openapi
adds the BattleSummary schema with a freeze test.

Backend gateway forwards engine GET /api/v1/battle/:turn/:uuid as
/api/v1/user/games/{game_id}/battles/{turn}/{battle_id} (handler
plus engineclient.FetchBattle, contract test stub, openapi spec).

UI:
- BattleViewer (lib/battle-player/) is a logically isolated SVG
  radial scene that consumes a BattleReport prop. Planet at the
  centre, races on the outer ring at equal angular spacing, race
  clusters by (race, className) with <class>:<numLeft> labels;
  observer groups (inBattle: false) are not drawn; eliminated
  races drop out and survivors re-distribute on the next frame.
- Shot line per frame: red on destroyed, green otherwise; erased
  on the next frame. Playback controls: play/pause + step ± +
  rewind + 1x/2x/4x speed (400/200/100 ms per frame).
- Page wrapper (lib/active-view/battle.svelte) loads BattleReport
  via api/battle-fetch.ts; synthetic-gameId prefix routes to a
  fixture loader, otherwise REST through the gateway. Always-
  visible <ol> text protocol satisfies the accessibility ask.
- section-battles.svelte links every battle UUID into the viewer.
- map/battle-markers.ts: yellow X cross of 2 LinePrim through the
  corners of the planet's circumscribed square (stroke width
  clamps from 1 px at 1 shot to 5 px at 100+ shots); bombing
  marker is a stroke-only ring (yellow when damaged, red when
  wiped). Wired into state-binding.ts; click handler dispatches
  battle clicks to the viewer and bombing clicks to the matching
  Reports row.
- i18n keys for the viewer in en + ru.

Docs: ui/docs/battle-viewer-ux.md, FUNCTIONAL.md §6.5 + ru
mirror, ui/PLAN.md Phase 27 decisions + deferred TODOs (push
event, richer class visuals, animated re-distribution).

Tests: Vitest unit (radial layout + timeline frame builder +
marker stroke formula + marker primitives), Playwright e2e for
the viewer (Reports link → viewer, playback step, not-found),
backend engineclient FetchBattle (200 / 404 / bad input), engine
openapi freezes (BattleReport, BattleReportGroup,
BattleActionReport, BattleSummary, Report.battle items).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/internal/engineclient/client.go

@@ -26,6 +26,7 @@ const (
 	pathPlayerCommand   = "/api/v1/command"
 	pathPlayerOrder     = "/api/v1/order"
 	pathPlayerReport    = "/api/v1/report"
+	pathPlayerBattle    = "/api/v1/battle"
 	pathHealthz         = "/healthz"
 )
 
@@ -269,6 +270,41 @@ func (c *Client) GetReport(ctx context.Context, baseURL, raceName string, turn i
 	}
 }
 
+// FetchBattle calls `GET /api/v1/battle/<turn>/<battleID>` and returns
+// the engine response body verbatim alongside the engine status code.
+// 200 carries the BattleReport JSON; 404 means the battle is unknown
+// and the body may be empty. Other 4xx statuses come back wrapped in
+// ErrEngineValidation, everything else in ErrEngineUnreachable.
+func (c *Client) FetchBattle(ctx context.Context, baseURL string, turn int, battleID string) (json.RawMessage, int, error) {
+	if err := validateBaseURL(baseURL); err != nil {
+		return nil, 0, err
+	}
+	if turn < 0 {
+		return nil, 0, fmt.Errorf("engineclient battle get: turn must not be negative, got %d", turn)
+	}
+	if strings.TrimSpace(battleID) == "" {
+		return nil, 0, errors.New("engineclient battle get: battle id must not be empty")
+	}
+	target := baseURL + pathPlayerBattle + "/" + strconv.Itoa(turn) + "/" + url.PathEscape(battleID)
+	body, status, doErr := c.doRequest(ctx, http.MethodGet, target, nil, c.probeTimeout)
+	if doErr != nil {
+		return nil, 0, fmt.Errorf("%w: engine battle get: %w", ErrEngineUnreachable, doErr)
+	}
+	switch status {
+	case http.StatusOK:
+		if len(body) == 0 {
+			return nil, status, fmt.Errorf("%w: engine battle get: empty response body", ErrEngineProtocolViolation)
+		}
+		return json.RawMessage(body), status, nil
+	case http.StatusNotFound:
+		return nil, status, nil
+	case http.StatusBadRequest, http.StatusConflict:
+		return json.RawMessage(body), status, fmt.Errorf("%w: engine battle get: %s", ErrEngineValidation, summariseEngineError(body, status))
+	default:
+		return nil, status, fmt.Errorf("%w: engine battle get: %s", ErrEngineUnreachable, summariseEngineError(body, status))
+	}
+}
+
 // Healthz calls `GET /healthz`. Returns nil on 2xx.
 func (c *Client) Healthz(ctx context.Context, baseURL string) error {
 	if err := validateBaseURL(baseURL); err != nil {

backend/internal/engineclient/client_test.go

@@ -257,6 +257,63 @@ func TestClientGetOrderRejectsBadInput(t *testing.T) {
 	}
 }
 
+func TestClientFetchBattleForwardsPath(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			t.Fatalf("unexpected method: %s", r.Method)
+		}
+		want := pathPlayerBattle + "/3/" + "11111111-1111-1111-1111-111111111111"
+		if r.URL.Path != want {
+			t.Fatalf("path = %q, want %q", r.URL.Path, want)
+		}
+		_, _ = w.Write([]byte(`{"id":"11111111-1111-1111-1111-111111111111","planet":4}`))
+	}))
+	t.Cleanup(srv.Close)
+
+	cli := newTestClient(t, srv)
+	body, status, err := cli.FetchBattle(context.Background(), srv.URL, 3, "11111111-1111-1111-1111-111111111111")
+	if err != nil {
+		t.Fatalf("FetchBattle: %v", err)
+	}
+	if status != http.StatusOK {
+		t.Fatalf("status = %d", status)
+	}
+	if !strings.Contains(string(body), `"planet":4`) {
+		t.Fatalf("body = %s", body)
+	}
+}
+
+func TestClientFetchBattleNotFound(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+	}))
+	t.Cleanup(srv.Close)
+
+	cli := newTestClient(t, srv)
+	body, status, err := cli.FetchBattle(context.Background(), srv.URL, 0, "11111111-1111-1111-1111-111111111111")
+	if err != nil {
+		t.Fatalf("FetchBattle: %v", err)
+	}
+	if status != http.StatusNotFound {
+		t.Fatalf("status = %d", status)
+	}
+	if body != nil {
+		t.Fatalf("expected nil body on 404, got %s", body)
+	}
+}
+
+func TestClientFetchBattleRejectsBadInput(t *testing.T) {
+	cli := newTestClient(t, httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		t.Fatal("server must not be hit on bad input")
+	})))
+	if _, _, err := cli.FetchBattle(context.Background(), "http://example.com", -1, "11111111-1111-1111-1111-111111111111"); err == nil {
+		t.Fatal("expected error on negative turn")
+	}
+	if _, _, err := cli.FetchBattle(context.Background(), "http://example.com", 0, ""); err == nil {
+		t.Fatal("expected error on empty battle id")
+	}
+}
+
 func TestClientHealthzSuccess(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.URL.Path != pathHealthz {

backend/internal/server/contract_test.go

@@ -45,6 +45,7 @@ var pathParamStubs = map[string]string{
 	"delivery_id": "00000000-0000-0000-0000-000000000006",
 	"user_id": "00000000-0000-0000-0000-000000000007",
 	"device_session_id": "00000000-0000-0000-0000-000000000008",
+	"battle_id": "00000000-0000-0000-0000-000000000009",
 	"id": "1.2.3",
 	"username": "alice",
 	"turn": "42",

backend/internal/server/handlers_user_games.go

@@ -243,6 +243,60 @@ func (h *UserGamesHandlers) Report() gin.HandlerFunc {
 	}
 }
 
+// Battle handles GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}.
+// Forwards to the engine's `GET /api/v1/battle/:turn/:uuid`. Path
+// parameters are validated up-front to save a network hop. 404 from
+// the engine is forwarded as 404. The recipient race is resolved
+// from the runtime mapping but not forwarded — engine returns the
+// battle by id, visibility is enforced by the engine state.
+func (h *UserGamesHandlers) Battle() gin.HandlerFunc {
+	if h == nil || h.runtime == nil || h.engine == nil {
+		return handlers.NotImplemented("userGamesBattle")
+	}
+	return func(c *gin.Context) {
+		gameID, ok := parseGameIDParam(c)
+		if !ok {
+			return
+		}
+		turnRaw := c.Param("turn")
+		turn, err := strconv.Atoi(turnRaw)
+		if err != nil || turn < 0 {
+			httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "turn must be a non-negative integer")
+			return
+		}
+		battleID := c.Param("battle_id")
+		if battleID == "" {
+			httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "battle id is required")
+			return
+		}
+		userID, ok := userid.FromContext(c.Request.Context())
+		if !ok {
+			httperr.Abort(c, http.StatusBadRequest, httperr.CodeInvalidRequest, "user id missing")
+			return
+		}
+		ctx := c.Request.Context()
+		if _, err := h.runtime.ResolvePlayerMapping(ctx, gameID, userID); err != nil {
+			respondGameProxyError(c, h.logger, "user games battle", ctx, err)
+			return
+		}
+		endpoint, err := h.runtime.EngineEndpoint(ctx, gameID)
+		if err != nil {
+			respondGameProxyError(c, h.logger, "user games battle", ctx, err)
+			return
+		}
+		body, status, err := h.engine.FetchBattle(ctx, endpoint, turn, battleID)
+		if err != nil {
+			respondEngineProxyError(c, h.logger, "user games battle", ctx, body, err)
+			return
+		}
+		if status == http.StatusNotFound {
+			httperr.Abort(c, http.StatusNotFound, httperr.CodeNotFound, "battle not found")
+			return
+		}
+		c.Data(http.StatusOK, "application/json", body)
+	}
+}
+
 // rebindActor decodes a JSON object from raw, sets `actor` to
 // raceName, and re-encodes. Backend never trusts the actor field
 // supplied by the client (per ARCHITECTURE.md §9).

backend/internal/server/router.go

@@ -263,6 +263,7 @@ func registerUserRoutes(router *gin.Engine, instruments *metrics.Instruments, de
 	userGames.POST("/:game_id/orders", deps.UserGames.Orders())
 	userGames.GET("/:game_id/orders", deps.UserGames.GetOrders())
 	userGames.GET("/:game_id/reports/:turn", deps.UserGames.Report())
+	userGames.GET("/:game_id/battles/:turn/:battle_id", deps.UserGames.Battle())
 
 	userSessions := group.Group("/sessions")
 	userSessions.GET("", deps.UserSessions.List())

backend/openapi.yaml

@@ -1106,6 +1106,44 @@ paths:
           $ref: "#/components/responses/NotImplementedError"
         "500":
           $ref: "#/components/responses/InternalError"
+  /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}:
+    get:
+      tags: [User]
+      operationId: userGamesBattle
+      summary: Read one engine battle report
+      description: |
+        Forwards to the engine's `GET /api/v1/battle/:turn/:uuid`. The
+        engine response body is passed through verbatim. `404 Not Found`
+        is returned when the battle does not exist for the supplied
+        `turn` / `battle_id` pair.
+      security:
+        - UserHeader: []
+      parameters:
+        - $ref: "#/components/parameters/XUserID"
+        - $ref: "#/components/parameters/GameID"
+        - $ref: "#/components/parameters/Turn"
+        - name: battle_id
+          in: path
+          required: true
+          description: Battle identifier (RFC 4122 UUID).
+          schema:
+            type: string
+            format: uuid
+      responses:
+        "200":
+          description: Engine battle report passed through.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/PassthroughObject"
+        "400":
+          $ref: "#/components/responses/InvalidRequestError"
+        "404":
+          $ref: "#/components/responses/NotFoundError"
+        "501":
+          $ref: "#/components/responses/NotImplementedError"
+        "500":
+          $ref: "#/components/responses/InternalError"
   /api/v1/user/sessions:
     get:
       tags: [User]

docs/FUNCTIONAL.md

@@ -657,7 +657,7 @@ in `runtime_records.turn_schedule`. The backend scheduler
 - After a failed tick (`engine_unreachable` /
   `generation_failed`): the lobby's `OnRuntimeSnapshot` flips the
   game from `running` to `paused` and publishes a `game.paused`
-  push event (see §6.5). The order handlers reject with HTTP 409
+  push event (see §6.6). The order handlers reject with HTTP 409
   + `code = game_paused` until an admin resume succeeds.
 
 `force-next-turn` (admin) schedules a one-shot extra tick that
@@ -686,7 +686,53 @@ are exposed in a sticky table of contents (a `<select>` on mobile)
 and the scroll position is preserved across active-view switches
 via SvelteKit's `Snapshot` API.
 
-### 6.5 Side effects
+The Bombings section is a flat read-only table — one row per
+bombing event, columns for `attacker`, `attack_power`, `wiped`
+state and the post-bombing resource snapshot. The Battles section
+is a list of links into the Battle Viewer (see [§6.5](#65-battle-viewer)).
+
+### 6.5 Battle viewer
+
+The Battle Viewer is a dedicated view that replaces the map and
+renders one battle at a time. Entry points:
+
+- A row in the Reports view's Battles section (link with the
+  current turn pinned via `?turn=`).
+- A battle marker on the map (yellow cross drawn through the
+  corners of the square that circumscribes the planet circle;
+  stroke width scales with the protocol length).
+
+The viewer is a logically isolated component that consumes a
+`BattleReport` (shape per `pkg/model/report/battle.go`). The page
+loader (`ui/frontend/src/lib/active-view/battle.svelte`) fetches
+the report through the backend gateway route
+`GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}`,
+which forwards verbatim to the engine's
+`GET /api/v1/battle/:turn/:uuid`.
+
+Visual model is radial: the planet sits at the centre, races are
+placed at equal angular spacing on an outer ring, and each race is
+rendered as a horizontal cluster of small ship-class circles
+labelled `<className>:<numLeft>`. Observer groups (`inBattle:
+false`) are not drawn. Eliminated races drop out and the survivors
+re-spread on the next frame.
+
+Each frame is one protocol entry; the shot is drawn as a thin line
+from attacker to defender, red on `destroyed`, green otherwise.
+Continuous playback offers 1x / 2x / 4x speeds (400 / 200 / 100 ms
+per frame), plus play/pause, step ±, and rewind. The accessibility
+text protocol below the scene mirrors the same events line-by-line.
+
+Bombings and battles are intentionally not mixed: bombings remain a
+static table in the Reports view; the bombing marker on the map is
+a thin stroke-only ring around the planet (yellow when damaged, red
+when wiped) and a click scrolls the corresponding row into view.
+
+The current report wire carries a `battle: [{ id, planet, shots }]`
+summary per battle so the map markers know where to anchor without
+fetching every full `BattleReport`.
+
+### 6.6 Side effects
 
 A successful turn generation publishes a runtime snapshot into the
 lobby module, which updates the denormalised view (current turn,
@@ -719,7 +765,7 @@ producer; adding one is purely additive (register the kind in the
 catalog, extend the migration `CHECK` constraint, and call
 `notification.Submit` from the appropriate domain module).
 
-### 6.6 Cross-references
+### 6.7 Cross-references
 
 - Backend ↔ engine wire contract (`pkg/model/{order,report,rest}`):
   [ARCHITECTURE.md §9](ARCHITECTURE.md#9-backend--game-engine-communication).

docs/FUNCTIONAL_ru.md

@@ -675,7 +675,7 @@ engine `/admin/turn` двумя `runtime_status`-флипами:
 - После провалившегося тика (`engine_unreachable` /
   `generation_failed`): `lobby.OnRuntimeSnapshot` переводит игру
   `running → paused` и публикует push-эвент `game.paused`
-  (см. §6.5). Order-handler'ы отклоняют запросы с HTTP 409 +
+  (см. §6.6). Order-handler'ы отклоняют запросы с HTTP 409 +
   `code = game_paused`, пока админ не выполнит resume.
 
 `force-next-turn` (admin) планирует one-shot-доп-тик, который
@@ -704,7 +704,53 @@ empty-state. Якоря секций отображены в sticky-TOC (на м
 `<select>`); позиция скролла сохраняется при переключении активного
 представления через SvelteKit `Snapshot` API.
 
-### 6.5 Побочные эффекты
+Секция бомбардировок — это плоская read-only-таблица: одна строка на
+событие, колонки `attacker`, `attack_power`, признак `wiped` и
+ресурсный снимок после удара. Секция сражений — список ссылок в
+Battle Viewer (см. [§6.5](#65-battle-viewer)).
+
+### 6.5 Battle viewer
+
+Battle Viewer — отдельное представление, заменяющее карту и
+показывающее одну битву. Входы:
+
+- Строка в секции «сражения» в Reports (ссылка с пиннингом
+  текущего хода через `?turn=`).
+- Battle-marker на карте (жёлтый крест через противоположные углы
+  квадрата, описанного вокруг круга планеты; толщина линий растёт
+  с длиной протокола).
+
+Сам Viewer — логически изолированный компонент, потребляющий
+`BattleReport` в форме `pkg/model/report/battle.go`. Страница-обёртка
+(`ui/frontend/src/lib/active-view/battle.svelte`) забирает отчёт
+через backend-маршрут
+`GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}`,
+который проксирует ответ engine-эндпоинта
+`GET /api/v1/battle/:turn/:uuid`.
+
+Визуальная модель — радиальная: планета в центре, расы по внешней
+окружности на равных угловых интервалах, внутри расы — горизонтальный
+кластер маленьких кружков по классам кораблей с подписями
+`<className>:<numLeft>` под каждым. Наблюдатели (`inBattle: false`)
+не рисуются. Выбывшие расы убираются из сцены, оставшиеся
+перераспределяются на следующем кадре.
+
+Каждый кадр — одна запись протокола; выстрел рисуется тонкой линией
+от атакующего к защитнику, красной при `destroyed`, зелёной иначе.
+Непрерывное воспроизведение: 1x / 2x / 4x (400 / 200 / 100 мс на
+кадр), плюс play/pause, шаг вперёд/назад, rewind. Текстовый протокол
+доступности под сценой дублирует те же события построчно.
+
+Бомбардировки и сражения умышленно не смешиваются: бомбардировки
+остаются статической таблицей в Reports; bombing-marker на карте —
+тонкая окружность вокруг планеты (жёлтая при damaged, красная при
+wiped), клик скроллит соответствующую строку в Reports.
+
+Текущая wire-форма отчёта несёт `battle: [{ id, planet, shots }]`
+на каждую битву, чтобы map-маркеры могли расположиться без
+дополнительного запроса полного `BattleReport`.
+
+### 6.6 Побочные эффекты
 
 Успешная генерация хода публикует runtime-snapshot в lobby-модуль,
 который обновляет денормализованное вью (текущий ход, runtime-
@@ -740,7 +786,7 @@ Directory-промоушен ([Раздел 5](#5-реестр-названий-
 каталоге, расширить `CHECK`-констрейнт миграции и вызвать
 `notification.Submit` из подходящего доменного модуля).
 
-### 6.6 Перекрёстные ссылки
+### 6.7 Перекрёстные ссылки
 
 - Backend ↔ engine wire-контракт (`pkg/model/{order,report,rest}`):
   [ARCHITECTURE.md §9](ARCHITECTURE.md#9-backend--game-engine-communication).

game/internal/controller/report.go

@@ -37,7 +37,7 @@ func (c *Cache) InitReport(t uint) *mr.Report {
 		OtherScience:           make([]mr.OtherScience, 0, 10),
 		LocalShipClass:         make([]mr.ShipClass, 0, 20),
 		OtherShipClass:         make([]mr.OthersShipClass, 0, 50),
-		Battle:                 make([]uuid.UUID, 0, 10),
+		Battle:                 make([]mr.BattleSummary, 0, 10),
 		Bombing:                make([]*mr.Bombing, 0, 10),
 		IncomingGroup:          make([]mr.IncomingGroup, 0, 10),
 		OnPlanetGroupCache:     make(map[uint][]int),
@@ -342,7 +342,11 @@ func (c *Cache) ReportBattle(ri int, rep *mr.Report, br []*mr.BattleReport) {
 		}
 
 		sliceIndexValidate(&rep.Battle, i)
-		rep.Battle[i] = br[bi].ID
+		rep.Battle[i] = mr.BattleSummary{
+			ID:     br[bi].ID,
+			Planet: br[bi].Planet,
+			Shots:  uint(len(br[bi].Protocol)),
+		}
 		i++
 	}
 }

game/openapi.yaml

@@ -584,10 +584,9 @@ components:
             $ref: "#/components/schemas/OtherShipClass"
         battle:
           type: array
-          description: UUIDs of battle reports relevant to this turn.
+          description: Battle summaries relevant to this turn.
           items:
-            type: string
+            $ref: "#/components/schemas/BattleSummary"
-            format: uuid
         bombing:
           type: array
           description: Bombing events that occurred during this turn.
@@ -831,6 +830,30 @@ components:
         wiped:
           type: boolean
           description: True when all population was eliminated by the bombing.
+    BattleSummary:
+      type: object
+      description: |
+        Identifies one battle relevant to the report recipient. Used by
+        clients to render a battle marker on the map without fetching
+        the full BattleReport. `planet` locates the marker; `shots`
+        scales the marker stroke with the battle length.
+      required:
+        - id
+        - planet
+        - shots
+      properties:
+        id:
+          type: string
+          format: uuid
+          description: Battle identifier; fetch the full report via `/api/v1/battle/{turn}/{uuid}`.
+        planet:
+          type: integer
+          minimum: 0
+          description: Planet number the battle took place on.
+        shots:
+          type: integer
+          minimum: 0
+          description: Number of shots exchanged during the battle.
     BattleReport:
       type: object
       description: |

game/openapi_contract_test.go

@@ -327,6 +327,22 @@ func TestGameOpenAPISpecFreezesBattleReport(t *testing.T) {
 	assertSchemaRef(t, shipsSchema.Value.AdditionalProperties.Schema, "#/components/schemas/BattleReportGroup", "BattleReport.ships additionalProperties schema")
 }
 
+func TestGameOpenAPISpecFreezesBattleSummary(t *testing.T) {
+	t.Parallel()
+
+	doc := loadOpenAPISpec(t)
+
+	summary := componentSchemaRef(t, doc, "BattleSummary")
+	assertRequiredFields(t, summary, "id", "planet", "shots")
+
+	report := componentSchemaRef(t, doc, "Report")
+	battle := report.Value.Properties["battle"]
+	require.NotNil(t, battle, "Report.battle schema must exist")
+	require.True(t, battle.Value.Type.Is("array"), "Report.battle must be array")
+	require.NotNil(t, battle.Value.Items, "Report.battle items must be defined")
+	assertSchemaRef(t, battle.Value.Items, "#/components/schemas/BattleSummary", "Report.battle items schema")
+}
+
 func TestGameOpenAPISpecHealthzStatusEnum(t *testing.T) {
 	t.Parallel()
 

pkg/model/report/battle.go

@@ -6,6 +6,16 @@ import (
 	"github.com/google/uuid"
 )
 
+// BattleSummary identifies one battle relevant to the report recipient
+// and carries the data needed to render a battle marker on the map
+// without fetching the full BattleReport. Planet locates the marker;
+// Shots scales the marker stroke with the battle length.
+type BattleSummary struct {
+	ID     uuid.UUID `json:"id"`
+	Planet uint      `json:"planet"`
+	Shots  uint      `json:"shots"`
+}
+
 type BattleReport struct {
 	// Battle unique ID
 	ID uuid.UUID `json:"id"`

pkg/model/report/report.go

@@ -33,7 +33,7 @@ type Report struct {
 	OtherScience       []OtherScience       `json:"otherScience,omitempty"`
 	LocalShipClass     []ShipClass          `json:"localShipClass,omitempty"`
 	OtherShipClass     []OthersShipClass    `json:"otherShipClass,omitempty"`
-	Battle             []uuid.UUID          `json:"battle,omitempty"`
+	Battle             []BattleSummary      `json:"battle,omitempty"`
 	Bombing            []*Bombing           `json:"bombing,omitempty"`
 	IncomingGroup      []IncomingGroup      `json:"incomingGroup,omitempty"`
 	LocalPlanet        []LocalPlanet        `json:"localPlanet,omitempty"`

pkg/schema/fbs/report.fbs

@@ -196,6 +196,16 @@ table LocalFleet {
   state:string;
 }
 
+// BattleSummary identifies one battle the report recipient
+// participated in or could see on a planet. `planet` lets the map
+// place a battle marker without fetching the full BattleReport;
+// `shots` lets the marker scale its stroke with the protocol length.
+table BattleSummary {
+  id:common.UUID (required);
+  planet:uint64;
+  shots:uint64;
+}
+
 table Report {
   version:uint64;
   turn:uint64;
@@ -210,7 +220,7 @@ table Report {
   other_science:[OtherScience];
   local_ship_class:[ShipClass];
   other_ship_class:[OthersShipClass];
-  battle:[common.UUID];
+  battle:[BattleSummary];
   bombing:[Bombing];
   incoming_group:[IncomingGroup];
   local_planet:[LocalPlanet];

pkg/schema/fbs/report/BattleSummary.go

@@ -0,0 +1,97 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package report
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+
+	common "galaxy/schema/fbs/common"
+)
+
+type BattleSummary struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsBattleSummary(buf []byte, offset flatbuffers.UOffsetT) *BattleSummary {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &BattleSummary{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func FinishBattleSummaryBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.Finish(offset)
+}
+
+func GetSizePrefixedRootAsBattleSummary(buf []byte, offset flatbuffers.UOffsetT) *BattleSummary {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &BattleSummary{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func FinishSizePrefixedBattleSummaryBuffer(builder *flatbuffers.Builder, offset flatbuffers.UOffsetT) {
+	builder.FinishSizePrefixed(offset)
+}
+
+func (rcv *BattleSummary) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *BattleSummary) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *BattleSummary) Id(obj *common.UUID) *common.UUID {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		x := o + rcv._tab.Pos
+		if obj == nil {
+			obj = new(common.UUID)
+		}
+		obj.Init(rcv._tab.Bytes, x)
+		return obj
+	}
+	return nil
+}
+
+func (rcv *BattleSummary) Planet() uint64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(6))
+	if o != 0 {
+		return rcv._tab.GetUint64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *BattleSummary) MutatePlanet(n uint64) bool {
+	return rcv._tab.MutateUint64Slot(6, n)
+}
+
+func (rcv *BattleSummary) Shots() uint64 {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(8))
+	if o != 0 {
+		return rcv._tab.GetUint64(o + rcv._tab.Pos)
+	}
+	return 0
+}
+
+func (rcv *BattleSummary) MutateShots(n uint64) bool {
+	return rcv._tab.MutateUint64Slot(8, n)
+}
+
+func BattleSummaryStart(builder *flatbuffers.Builder) {
+	builder.StartObject(3)
+}
+func BattleSummaryAddId(builder *flatbuffers.Builder, id flatbuffers.UOffsetT) {
+	builder.PrependStructSlot(0, flatbuffers.UOffsetT(id), 0)
+}
+func BattleSummaryAddPlanet(builder *flatbuffers.Builder, planet uint64) {
+	builder.PrependUint64Slot(1, planet, 0)
+}
+func BattleSummaryAddShots(builder *flatbuffers.Builder, shots uint64) {
+	builder.PrependUint64Slot(2, shots, 0)
+}
+func BattleSummaryEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

pkg/schema/fbs/report/Report.go

@@ -4,8 +4,6 @@ package report
 
 import (
 	flatbuffers "github.com/google/flatbuffers/go"
-
-	common "galaxy/schema/fbs/common"
 )
 
 type Report struct {
@@ -231,11 +229,12 @@ func (rcv *Report) OtherShipClassLength() int {
 	return 0
 }
 
-func (rcv *Report) Battle(obj *common.UUID, j int) bool {
+func (rcv *Report) Battle(obj *BattleSummary, j int) bool {
 	o := flatbuffers.UOffsetT(rcv._tab.Offset(30))
 	if o != 0 {
 		x := rcv._tab.Vector(o)
-		x += flatbuffers.UOffsetT(j) * 16
+		x += flatbuffers.UOffsetT(j) * 4
+		x = rcv._tab.Indirect(x)
 		obj.Init(rcv._tab.Bytes, x)
 		return true
 	}
@@ -551,7 +550,7 @@ func ReportAddBattle(builder *flatbuffers.Builder, battle flatbuffers.UOffsetT)
 	builder.PrependUOffsetTSlot(13, flatbuffers.UOffsetT(battle), 0)
 }
 func ReportStartBattleVector(builder *flatbuffers.Builder, numElems int) flatbuffers.UOffsetT {
-	return builder.StartVector(16, numElems, 8)
+	return builder.StartVector(4, numElems, 4)
 }
 func ReportAddBombing(builder *flatbuffers.Builder, bombing flatbuffers.UOffsetT) {
 	builder.PrependUOffsetTSlot(14, flatbuffers.UOffsetT(bombing), 0)

pkg/transcoder/report.go

@@ -10,7 +10,6 @@ import (
 	fbs "galaxy/schema/fbs/report"
 
 	flatbuffers "github.com/google/flatbuffers/go"
-	"github.com/google/uuid"
 )
 
 // ReportToPayload converts model.Report from the internal representation to
@@ -120,7 +119,7 @@ func ReportToPayload(report *model.Report) ([]byte, error) {
 	otherScienceVector := encodeReportOffsetVector(builder, len(otherScienceOffsets), fbs.ReportStartOtherScienceVector, otherScienceOffsets)
 	localShipClassVector := encodeReportOffsetVector(builder, len(localShipClassOffsets), fbs.ReportStartLocalShipClassVector, localShipClassOffsets)
 	otherShipClassVector := encodeReportOffsetVector(builder, len(otherShipClassOffsets), fbs.ReportStartOtherShipClassVector, otherShipClassOffsets)
-	battleVector := encodeReportUUIDVector(builder, report.Battle)
+	battleVector := encodeReportBattleSummaries(builder, report.Battle)
 	bombingVector := encodeReportOffsetVector(builder, len(bombingOffsets), fbs.ReportStartBombingVector, bombingOffsets)
 	incomingGroupVector := encodeReportOffsetVector(builder, len(incomingGroupOffsets), fbs.ReportStartIncomingGroupVector, incomingGroupOffsets)
 	localPlanetVector := encodeReportOffsetVector(builder, len(localPlanetOffsets), fbs.ReportStartLocalPlanetVector, localPlanetOffsets)
@@ -734,13 +733,29 @@ func decodeReportBattleVector(flatReport *fbs.Report, result *model.Report) erro
 		return nil
 	}
 
-	result.Battle = make([]uuid.UUID, length)
+	result.Battle = make([]model.BattleSummary, length)
-	item := new(commonfbs.UUID)
+	item := new(fbs.BattleSummary)
+	idHolder := new(commonfbs.UUID)
 	for i := 0; i < length; i++ {
 		if !flatReport.Battle(item, i) {
+			return fmt.Errorf("decode report battle %d: battle is missing", i)
+		}
+		if item.Id(idHolder) == nil {
 			return fmt.Errorf("decode report battle %d: battle id is missing", i)
 		}
-		result.Battle[i] = uuidFromHiLo(item.Hi(), item.Lo())
+		planet, err := uint64ToUint(item.Planet(), "planet")
+		if err != nil {
+			return fmt.Errorf("decode report battle %d: %w", i, err)
+		}
+		shots, err := uint64ToUint(item.Shots(), "shots")
+		if err != nil {
+			return fmt.Errorf("decode report battle %d: %w", i, err)
+		}
+		result.Battle[i] = model.BattleSummary{
+			ID:     uuidFromHiLo(idHolder.Hi(), idHolder.Lo()),
+			Planet: planet,
+			Shots:  shots,
+		}
 	}
 
 	return nil
@@ -1299,17 +1314,26 @@ func encodeReportOffsetVector(
 	return builder.EndVector(length)
 }
 
-func encodeReportUUIDVector(builder *flatbuffers.Builder, ids []uuid.UUID) flatbuffers.UOffsetT {
+func encodeReportBattleSummaries(builder *flatbuffers.Builder, summaries []model.BattleSummary) flatbuffers.UOffsetT {
-	if len(ids) == 0 {
+	if len(summaries) == 0 {
 		return 0
 	}
 
-	fbs.ReportStartBattleVector(builder, len(ids))
+	offsets := make([]flatbuffers.UOffsetT, len(summaries))
-	for i := len(ids) - 1; i >= 0; i-- {
+	for i := range summaries {
-		hi, lo := uuidToHiLo(ids[i])
+		hi, lo := uuidToHiLo(summaries[i].ID)
-		commonfbs.CreateUUID(builder, hi, lo)
+		fbs.BattleSummaryStart(builder)
+		fbs.BattleSummaryAddId(builder, commonfbs.CreateUUID(builder, hi, lo))
+		fbs.BattleSummaryAddPlanet(builder, uint64(summaries[i].Planet))
+		fbs.BattleSummaryAddShots(builder, uint64(summaries[i].Shots))
+		offsets[i] = fbs.BattleSummaryEnd(builder)
 	}
-	return builder.EndVector(len(ids))
+
+	fbs.ReportStartBattleVector(builder, len(offsets))
+	for i := len(offsets) - 1; i >= 0; i-- {
+		builder.PrependUOffsetT(offsets[i])
+	}
+	return builder.EndVector(len(offsets))
 }
 
 func encodeReportRouteEntryVector(builder *flatbuffers.Builder, route map[uint]string) flatbuffers.UOffsetT {

pkg/transcoder/report_test.go

@@ -255,9 +255,17 @@ func sampleReport() *model.Report {
 		OtherShipClass: []model.OthersShipClass{
 			{Race: "Martians", ShipClass: model.ShipClass{Name: "destroyer", Drive: model.Float(1.75), Armament: 6, Weapons: model.Float(2.25), Shields: model.Float(2.75), Cargo: model.Float(3.25), Mass: model.Float(10.5)}},
 		},
-		Battle: []uuid.UUID{
+		Battle: []model.BattleSummary{
-			uuid.MustParse("11111111-1111-1111-1111-111111111111"),
+			{
-			uuid.MustParse("22222222-2222-2222-2222-222222222222"),
+				ID:     uuid.MustParse("11111111-1111-1111-1111-111111111111"),
+				Planet: 4,
+				Shots:  17,
+			},
+			{
+				ID:     uuid.MustParse("22222222-2222-2222-2222-222222222222"),
+				Planet: 11,
+				Shots:  3,
+			},
 		},
 		Bombing: []*model.Bombing{
 			{

ui/PLAN.md

@@ -2949,45 +2949,126 @@ Targeted tests:
 
 Status: pending.
 
-Goal: render battles as a dedicated view with playback controls
+Goal: ship a dedicated Battle Viewer rendering radial scenes from
-(play, pause, step forward, step backward, rewind), driven by the
+`BattleReport` data (planet centred, races on the outer ring, per
-server-side combat log; render battle and bombing markers on the map.
+ship-class clusters, animated shot lines), plus battle and bombing
+markers on the map. Battles and bombings stay strictly separate —
+bombings remain a static table in the Reports view, only battles
+get the animated viewer.
 
 Artifacts:
 
-- `ui/frontend/src/map/battle-markers.ts` renders markers on the map
+- engine: `game/internal/router/handler/battle.go` for
-  for current-turn battles and bombings within visibility, clickable
+  `GET /api/v1/battle/:turn/:uuid` (handler pre-existed; Phase 27
-  to open the battle viewer
+  added the tests + openapi schemas)
-- `ui/frontend/src/routes/games/[id]/battle/[battleId]/+page.svelte`
+- engine wire: `pkg/model/report/battle.go` ships a new
-  view with the combatant list, the round-by-round log, and a player
+  `BattleSummary{id, planet, shots}`; `Report.battle` carries a
-  control bar
+  slice of these summaries so the map can place markers without
-- `ui/frontend/src/lib/battle-player/` round timeline, current-round
+  fetching every full report
-  highlight, per-shot animation
+- backend: `backend/internal/engineclient/client.go.FetchBattle`
-- entry points to the viewer: marker on map, row in the report's
+  and `backend/internal/server/handlers_user_games.go.Battle`
-  battles section, push-event toast when a battle this turn involved
+  expose `GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}`
-  the player
+- UI viewer: `ui/frontend/src/lib/battle-player/`
-- topic doc `ui/docs/battle-viewer-ux.md` covering playback
+  (`radial-layout.ts`, `timeline.ts`, `battle-scene.svelte`,
-  semantics, accessibility (the combat log must be readable as text
+  `playback-controls.svelte`, `battle-viewer.svelte`); SVG-based,
-  for users who skip animations)
+  one frame per protocol entry, full controls (play/pause + step
+  back + step forward + rewind + 1x/2x/4x speed switch)
+- UI route + page wrapper:
+  `ui/frontend/src/routes/games/[id]/battle/[[battleId]]/+page.svelte`
+  feeds `gameId` / `turn` / `battleId` into
+  `ui/frontend/src/lib/active-view/battle.svelte`, which loads the
+  report via `api/battle-fetch.ts` (synthetic-fixture path + real
+  engine fetch through the backend gateway)
+- UI report link: `lib/active-view/report/section-battles.svelte`
+  now links every battle UUID into
+  `/games/{id}/battle/{uuid}?turn={turn}`
+- UI map markers: `ui/frontend/src/map/battle-markers.ts` emits a
+  yellow X cross per battle (two `LinePrim` through the planet's
+  bounding-square diagonals; stroke width scales 1px..5px with
+  protocol length) plus a stroke-only ring per bombing (yellow when
+  damaged, red when wiped). Wired into `state-binding.ts`; the map
+  click handler dispatches battle clicks to the viewer and bombing
+  clicks to a scroll-into-view of the matching row in Reports.
+- topic doc `ui/docs/battle-viewer-ux.md` covers playback
+  semantics, accessibility (the always-visible `<ol>` log), the
+  radial layout, and the marker click behaviour
+- docs/FUNCTIONAL.md §6.5 (Battle viewer) + mirror in
+  docs/FUNCTIONAL_ru.md
 
 Dependencies: Phase 23.
 
 Acceptance criteria:
 
 - battle and bombing markers render on the map for the seeded
-  current-turn report and are clickable to open the viewer;
+  current-turn report and are clickable: battle → Battle Viewer for
-- the viewer plays back any battle in the seeded report including
+  the corresponding UUID, bombing → scroll to its row in Reports;
-  multi-round and one-sided battles;
+- the Battle Viewer plays back any `BattleReport` end-to-end with
-- step controls allow precise inspection;
+  step back / step forward / rewind / 1x-2x-4x speeds; observers
-- the same data is accessible as a static text log for accessibility.
+  (`inBattle === false`) are not drawn; eliminated races drop out
+  and survivors re-distribute on the next frame;
+- the same protocol is mirrored as an always-visible text log under
+  the scene for accessibility;
+- bombings keep their Phase 23 static table layout in Reports; no
+  Battle Viewer entry-point is wired from them.
 
 Targeted tests:
 
-- Vitest unit tests for round-state transitions;
+- Vitest unit: radial layout (1/2/3 races) and timeline frame-
-- Vitest unit tests for marker rendering on torus and no-wrap
+  builder (initial state, shot decrement, race-elimination drop-out)
-  fixtures;
+  in `tests/battle-player.test.ts`
-- Playwright e2e: click a battle marker on the map, play through,
+- Vitest unit: marker primitives + stroke-width formula
-  step backward, return to the report.
+  (1→1, 50→2.98, 100→5, 200→5) in `tests/battle-markers.test.ts`
+- Go unit: engine HTTP handler validations (400 / 404 / 500) in
+  `game/internal/router/battle_test.go`
+- Go contract: openapi freezes for the new endpoint and schemas in
+  `game/openapi_contract_test.go`
+- Playwright e2e: click battle marker → viewer; play / step back;
+  click battle UUID in Reports → viewer; click bombing marker →
+  Reports bombings row scrolled into view.
+
+Decisions during stage:
+
+1. **Bombings stay a static table.** `section-bombings.svelte`
+   already covers the "who bombed, with what power, wiped or not"
+   requirement; nothing in Phase 27 touches it. Bombings explicitly
+   do not open the Battle Viewer.
+2. **Wire change.** `Report.Battle` switched from `[]uuid.UUID` to
+   `[]BattleSummary{id, planet, shots}` so the map renderer can
+   place markers without N extra fetches and so the cross-marker
+   stroke can scale with protocol length.
+3. **Battle marker = yellow X cross** drawn as 2 `LinePrim` through
+   the corners of the planet's circumscribed square; stroke width
+   `clamp(1 + (shots - 1) * 4 / 99, 1, 5)` px.
+4. **Bombing marker = stroke-only ring** slightly larger than the
+   planet circle. Yellow when damaged, red when wiped. Click =
+   scroll to the matching row in Reports (not the viewer).
+5. **Viewer URL** `/games/[id]/battle/[battleId]?turn=N`. Turn is a
+   query param so the same route works in history mode.
+6. **SVG, not PixiJS** for the radial scene — isolated component,
+   no need for WebGL; PixiJS stays as the map renderer.
+7. **Playback controls full set**: play / pause + step back + step
+   forward + rewind + 1x / 2x / 4x switch. 1x = 400 ms per frame.
+8. **Observer groups (`inBattle: false`)** are filtered out of both
+   the scene and the text log.
+9. **Cluster aggregation by `(race, className)`** so a race with
+   multiple groups of the same class collapses to one labelled
+   circle. Stable target for shot-line endpoints.
+10. **Page loader switches on `synthetic-` gameId prefix** —
+    synthetic mode uses `api/synthetic-battle.ts` fixtures; live
+    games hit `GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}`.
+    BattleViewer component itself is a logically isolated prop sink.
+11. **Always-visible `<ol>` text protocol** under the scene satisfies
+    the accessibility requirement without a separate "skip
+    animation" toggle.
+
+TODO carried into Phase 27 deferred items
+(see Phase 27 of this PLAN's deferred-followups list, near the
+bottom):
+
+- push event `game.battle.new` + toast deep-link;
+- richer ship-class visuals derived from class characteristics;
+- animated transitions when survivors re-distribute after an
+  elimination (currently hard-jumps).
 
 ## Phase 28. Diplomatic Mail View
 
@@ -3459,3 +3540,18 @@ phase listed in the parenthesis when that phase lands.
   exercises a unary Connect call and a server-streaming Connect call
   through `testenv.Bootstrap`. (Phase 7+, fold into the phase that
   needs it.)
+- **Battle viewer — push event `game.battle.new`** — when a battle
+  involving the current player lands, emit a backend notification
+  intent (idempotency `battle-new:<game_id>:<turn>:<battle_id>`,
+  payload `{game_id, turn, battle_id}`) so the in-game shell
+  surfaces a toast with a deep link into the Battle Viewer.
+  (Phase 27 deferred; needs an engine emit-side change.)
+- **Battle viewer — richer ship-class visuals** — current MVP draws
+  one small circle plus `<class>:<numLeft>` label per `(race,
+  className)` pair. Future work derives shape / scale from mass,
+  armament, shields, and the number of ships in the group.
+  (Phase 27 deferred.)
+- **Battle viewer — animated re-distribution on elimination** —
+  current implementation hard-jumps to the new spacing on the next
+  frame; replace with an easing so the survivors visibly slide
+  along the outer ring. (Phase 27 deferred.)

ui/docs/battle-viewer-ux.md

@@ -0,0 +1,136 @@
+# Battle Viewer UX
+
+Phase 27 ships a dedicated viewer for battles (`/games/<id>/battle/<battleId>`).
+Bombings stay where they were in Phase 23 — a static table in the
+Reports view (`section-bombings.svelte`). The two domains are
+deliberately not mixed in any visual surface or click target.
+
+## Data shape
+
+The `BattleViewer` component (`lib/battle-player/battle-viewer.svelte`)
+is logically isolated. It accepts a `BattleReport` matching
+`pkg/model/report/battle.go`. The fields it uses:
+
+- `id`, `planet`, `planetName` — header + the central-planet glyph.
+- `races: { [raceId]: raceUUID }` — race index space used by the
+  protocol's `a` / `d` fields.
+- `ships: { [groupKey]: BattleReportGroup }` — ship-group rosters
+  with `race` name, `className`, initial `num`, end-state `numLeft`,
+  and the `inBattle` flag. Observer groups (`inBattle: false`) are
+  never drawn.
+- `protocol: BattleActionReport[]` — flat list of shots. Each carries
+  attacker `(a, sa)`, defender `(d, sd)`, and `x` (destroyed?).
+
+The component asks `timeline.ts.buildFrames(report)` to expand the
+protocol into `protocol.length + 1` frames; frame 0 is the initial
+state and frame `N` reflects state after action `protocol[N-1]`. The
+race index per ship group is derived from the protocol itself —
+every in-battle group appears at least once as attacker or defender,
+and the engine never crosses these wires.
+
+## Radial scene
+
+The scene (`lib/battle-player/battle-scene.svelte`, SVG) places the
+planet at the centre and arrays the still-active races on an outer
+ring at equal angular spacing. Each race anchor is a horizontal
+cluster of small class circles, one per `(race, className)` pair,
+labelled `<className>:<numLeft>` underneath. When a race is wiped
+out, it drops out of the active list and the survivors are
+re-spaced on the next frame.
+
+The current frame's shot is drawn as a thin line from the attacker's
+class circle to the defender's class circle. Colour:
+
+- red (`#ee3344`) when the action's `x === true` (the defender
+  ship was destroyed),
+- green (`#44dd66`) otherwise.
+
+Each frame redraws the line in isolation, so continuous playback
+produces the "shot-shot-shot" pulse the user wanted.
+
+## Playback controls
+
+`lib/battle-player/playback-controls.svelte` ships the full set:
+
+| Control       | Effect                                     |
+| ------------- | ------------------------------------------ |
+| ⏮ rewind      | Stop, jump to frame 0                      |
+| ◀︎ step back  | Stop, frame ← frame − 1                    |
+| ▶︎ / ⏸ play   | Toggle continuous playback                 |
+| ▶︎▶︎ step fwd | Stop, frame ← frame + 1                    |
+| 1x / 2x / 4x  | Speed switch: 400 / 200 / 100 ms per frame |
+
+When the timeline is at its end and the user hits play, the frame
+counter wraps to 0 and continues. Step buttons disable themselves at
+their boundary.
+
+## Accessibility
+
+Below the scene the viewer renders a static `<ol>` text protocol —
+one line per action, formatted from `BattleReportGroup.race` and
+`BattleReportGroup.className`. The line for the current frame is
+highlighted so a non-visual reader can follow along by scrolling
+the log instead of watching the SVG. The list is always present
+and never hidden, satisfying the original Phase 27 acceptance "the
+same data is accessible as a static text log".
+
+## Map markers
+
+`map/battle-markers.ts` emits two marker kinds per
+current-turn report. Both are wired into the binding's
+`hitLookup` so a click goes through the existing hit-test plumbing.
+
+### Battle marker — yellow cross
+
+For every `report.battles[i]` whose `planet` resolves to a visible
+planet, the marker emits two `LinePrim` lines through the opposite
+corners of the square circumscribed around the planet circle. The
+result is an X-shaped cross overlaid on the planet glyph.
+
+The stroke width is computed by `battleMarkerStrokeWidth(shots)`:
+1 shot → 1 px, 100 shots → 5 px, linearly interpolated in between
+(`width = 1 + (shots − 1) × 4 / 99`, clamped). A click on either
+line navigates to `/games/<id>/battle/<battleId>?turn=<turn>`.
+
+### Bombing marker — colored ring
+
+For every `report.bombings[i]`, the marker emits a single
+stroke-only `CirclePrim` slightly larger than the planet circle.
+Colour:
+
+- yellow (`#FFD400`) when `wiped: false`,
+- red (`#FF3030`) when `wiped: true`.
+
+A click on the ring navigates to `/games/<id>/report#report-bombings`
+and scrolls the matching `report-bombing-row` (by `data-planet`)
+into view. Bombing markers never open the Battle Viewer — the two
+domains stay separate.
+
+## Data source
+
+The Battle Viewer page (`lib/active-view/battle.svelte`) calls
+`api/battle-fetch.ts.fetchBattle(gameId, turn, battleId)`. The
+loader has two modes:
+
+- **Synthetic** — when `gameId` carries the
+  `synthetic-` prefix, the lookup is served from
+  `api/synthetic-battle.ts`. Vitest unit tests and Playwright e2e
+  tests register fixture battles via `registerSyntheticBattle`
+  before mounting the route.
+- **Production** — otherwise the loader issues
+  `GET /api/v1/user/games/{gameId}/battles/{turn}/{battleId}`
+  against the backend gateway route added in
+  `backend/internal/server/handlers_user_games.go.Battle`. The
+  gateway forwards verbatim to the engine's
+  `GET /api/v1/battle/:turn/:uuid`.
+
+## TODOs
+
+- Push event `game.battle.new` + toast → viewer link (deferred —
+  needs an engine emit-side change).
+- Richer ship-class visuals derived from the class's mass,
+  armament, shields. Current MVP uses a small circle plus
+  `<class>:<numLeft>` label.
+- Animated transitions when a race drops out and the survivors
+  re-distribute. Current implementation hard-jumps on the next
+  frame.

ui/frontend/src/api/battle-fetch.ts

@@ -0,0 +1,88 @@
+// Battle-report fetcher used by the Battle Viewer page.
+//
+// Phase 27 ships the BattleViewer as a logically isolated component
+// that accepts a `BattleReport` matching `pkg/model/report/battle.go`.
+// This module owns the type mirror and a single `fetchBattle` entry
+// point. In synthetic mode (development & e2e fixtures), the loader
+// falls back to a local fixture so the UI tests don't depend on a
+// running engine; otherwise it issues a real `GET` against the
+// backend gateway route added in Phase 27 step 3.
+
+import { isSyntheticGameId } from "./synthetic-report";
+import { lookupSyntheticBattle } from "./synthetic-battle";
+
+/**
+ * BattleReport is the wire shape returned by the engine endpoint
+ * `GET /api/v1/battle/:turn/:uuid` and forwarded by the backend
+ * gateway as `GET /api/v1/user/games/{game_id}/battles/{turn}/{battle_id}`.
+ * Fields mirror `pkg/model/report/battle.go`.
+ */
+export interface BattleReport {
+	id: string;
+	planet: number;
+	planetName: string;
+	races: Record<string, string>;
+	ships: Record<string, BattleReportGroup>;
+	protocol: BattleActionReport[];
+}
+
+export interface BattleReportGroup {
+	race: string;
+	className: string;
+	tech: Record<string, number>;
+	num: number;
+	numLeft: number;
+	loadType: string;
+	loadQuantity: number;
+	inBattle: boolean;
+}
+
+export interface BattleActionReport {
+	a: number;
+	sa: number;
+	d: number;
+	sd: number;
+	x: boolean;
+}
+
+export class BattleFetchError extends Error {
+	constructor(public readonly status: number, message: string) {
+		super(message);
+		this.name = "BattleFetchError";
+	}
+}
+
+/**
+ * fetchBattle returns the `BattleReport` for the supplied game, turn,
+ * and battle id. In synthetic-report mode (DEV / e2e) the lookup is
+ * served from `synthetic-battle.ts`; otherwise the function calls the
+ * backend gateway route. Throws `BattleFetchError` with the upstream
+ * status on validation or transport failure.
+ */
+export async function fetchBattle(
+	gameId: string,
+	turn: number,
+	battleId: string,
+): Promise<BattleReport> {
+	if (isSyntheticGameId(gameId)) {
+		const fixture = lookupSyntheticBattle(battleId);
+		if (fixture === null) {
+			throw new BattleFetchError(404, "battle not found");
+		}
+		return fixture;
+	}
+	const path = `/api/v1/user/games/${encodeURIComponent(gameId)}/battles/${turn}/${encodeURIComponent(battleId)}`;
+	const response = await fetch(path, {
+		headers: { Accept: "application/json" },
+	});
+	if (response.status === 404) {
+		throw new BattleFetchError(404, "battle not found");
+	}
+	if (!response.ok) {
+		throw new BattleFetchError(
+			response.status,
+			`battle fetch failed: ${response.status}`,
+		);
+	}
+	return (await response.json()) as BattleReport;
+}

ui/frontend/src/api/game-state.ts

@@ -382,6 +382,18 @@ export interface ReportBombing {
  * mirrors the producing planet's free industry. Stable order: sorted
  * by `(planetNumber, class)`.
  */
+/**
+ * ReportBattle is one battle summary in the current turn. Carries the
+ * battle UUID, planet number, and shot count — enough to render a
+ * battle marker on the map and to link into the Battle Viewer without
+ * fetching the full BattleReport.
+ */
+export interface ReportBattle {
+	id: string;
+	planet: number;
+	shots: number;
+}
+
 export interface ReportShipProduction {
 	planetNumber: number;
 	class: string;
@@ -524,11 +536,17 @@ export interface GameReport {
 	 */
 	otherShipClass: ReportOtherShipClass[];
 	/**
-	 * battleIds is the list of battle UUIDs the engine recorded for
+	 * battles is the list of battle summaries the engine recorded for
-	 * the current turn. Phase 23 renders them as inactive
+	 * the current turn. Each entry carries the battle UUID, the planet
-	 * monospace identifiers; Phase 27 will turn them into navigation
+	 * it happened on, and the number of shots exchanged. The Reports
-	 * targets once the battle viewer lands. Empty when no battles
+	 * View uses `id` to link into the Battle Viewer; the map renderer
-	 * occurred last turn.
+	 * uses `planet` to locate the marker and `shots` to scale its
+	 * stroke. Empty when no battles occurred last turn.
+	 */
+	battles: ReportBattle[];
+	/**
+	 * battleIds is a convenience derived list of UUIDs from `battles`,
+	 * preserved for legacy callers (Phase 23 report section, fixtures).
 	 */
 	battleIds: string[];
 	/**
@@ -700,7 +718,8 @@ function decodeReport(report: Report): GameReport {
 	const localFleets = decodeLocalFleets(report);
 	const otherScience = decodeOtherScience(report);
 	const otherShipClass = decodeOtherShipClass(report);
-	const battleIds = decodeBattleIds(report);
+	const battles = decodeBattles(report);
+	const battleIds = battles.map((b) => b.id);
 	const bombings = decodeBombings(report);
 	const shipProductions = decodeShipProductions(report);
 
@@ -730,6 +749,7 @@ function decodeReport(report: Report): GameReport {
 		players,
 		otherScience,
 		otherShipClass,
+		battles,
 		battleIds,
 		bombings,
 		shipProductions,
@@ -1153,13 +1173,18 @@ function decodeOtherShipClass(report: Report): ReportOtherShipClass[] {
 	return out;
 }
 
-function decodeBattleIds(report: Report): string[] {
+function decodeBattles(report: Report): ReportBattle[] {
-	const out: string[] = [];
+	const out: ReportBattle[] = [];
 	for (let i = 0; i < report.battleLength(); i++) {
-		const uuid = report.battle(i);
+		const summary = report.battle(i);
-		const value = uuidStringFromFB(uuid);
+		if (summary === null) continue;
-		if (value === null) continue;
+		const id = uuidStringFromFB(summary.id());
-		out.push(value);
+		if (id === null) continue;
+		out.push({
+			id,
+			planet: Number(summary.planet()),
+			shots: Number(summary.shots()),
+		});
 	}
 	return out;
 }
@@ -1439,6 +1464,7 @@ export function applyOrderOverlay(
 		players: report.players ?? [],
 		otherScience: report.otherScience ?? [],
 		otherShipClass: report.otherShipClass ?? [],
+		battles: report.battles ?? [],
 		battleIds: report.battleIds ?? [],
 		bombings: report.bombings ?? [],
 		shipProductions: report.shipProductions ?? [],

ui/frontend/src/api/synthetic-battle.ts

@@ -0,0 +1,37 @@
+// Synthetic battle reports for DEV / e2e mode.
+//
+// Mirrors the shape of `pkg/model/report/battle.go` so the
+// BattleViewer can be exercised without a running engine. Fixtures
+// are registered by battle UUID; the synthetic-report loader fills
+// the report's `battles[]` with these same UUIDs so the report ↔
+// battle link is consistent.
+
+import type { BattleReport } from "./battle-fetch";
+
+const SYNTHETIC_BATTLES = new Map<string, BattleReport>();
+
+/**
+ * registerSyntheticBattle adds a fixture battle to the in-memory map
+ * keyed by its `id`. Used by the synthetic-report DEV loader and by
+ * Vitest unit tests that need a deterministic BattleReport without a
+ * live engine.
+ */
+export function registerSyntheticBattle(report: BattleReport): void {
+	SYNTHETIC_BATTLES.set(report.id, report);
+}
+
+/**
+ * lookupSyntheticBattle returns the fixture stored under `battleId`,
+ * or `null` if nothing was registered (mirrors the engine's 404).
+ */
+export function lookupSyntheticBattle(battleId: string): BattleReport | null {
+	return SYNTHETIC_BATTLES.get(battleId) ?? null;
+}
+
+/**
+ * resetSyntheticBattles clears every registered fixture. Test
+ * harnesses call this between cases to avoid bleed-through.
+ */
+export function resetSyntheticBattles(): void {
+	SYNTHETIC_BATTLES.clear();
+}

ui/frontend/src/api/synthetic-report.ts

@@ -173,6 +173,12 @@ interface SyntheticOtherShipClass extends SyntheticShipClass {
 	mass?: number;
 }
 
+interface SyntheticBattle {
+	id?: string;
+	planet?: number;
+	shots?: number;
+}
+
 interface SyntheticBombing {
 	planet?: number; // wire field "number"
 	planetName?: string; // wire field "planetName"
@@ -219,7 +225,7 @@ interface SyntheticReportRoot {
 	incomingGroup?: SyntheticIncomingGroup[];
 	unidentifiedGroup?: SyntheticUnidentifiedGroup[];
 	localFleet?: SyntheticLocalFleet[];
-	battle?: string[];
+	battle?: SyntheticBattle[];
 	bombing?: SyntheticBombing[];
 	shipProduction?: SyntheticShipProductionRow[];
 }
@@ -357,9 +363,17 @@ function decodeSyntheticReport(json: unknown): GameReport {
 		return a.name.localeCompare(b.name);
 	});
 
-	const battleIds: string[] = (root.battle ?? []).filter(
+	const battles = (root.battle ?? [])
-		(v): v is string => typeof v === "string" && v !== "",
+		.filter(
-	);
+			(v): v is SyntheticBattle =>
+				typeof v === "object" && v !== null && typeof v.id === "string" && v.id !== "",
+		)
+		.map((b) => ({
+			id: b.id as string,
+			planet: numOr0(b.planet),
+			shots: numOr0(b.shots),
+		}));
+	const battleIds = battles.map((b) => b.id);
 
 	const bombings: ReportBombing[] = (root.bombing ?? []).map((b) => ({
 		planetNumber: numOr0(b.planet),
@@ -419,6 +433,7 @@ function decodeSyntheticReport(json: unknown): GameReport {
 		players: collectPlayersFromSynthetic(root, race),
 		otherScience,
 		otherShipClass,
+		battles,
 		battleIds,
 		bombings,
 		shipProductions,

ui/frontend/src/lib/active-view/battle.svelte

@@ -1,30 +1,134 @@
 <!--
-Phase 10 stub for the battle-log active view. Phase 27 wires the real
+Phase 27 — active-view wrapper around the BattleViewer. Loads the
-battle viewer.
+BattleReport for the supplied `gameId`/`turn`/`battleId` and either
+shows the radial playback (BattleViewer), a loading skeleton, or a
+not-found state. The viewer itself is a logically isolated
+component that takes a `BattleReport` prop — this wrapper owns
+loading and routing concerns.
 -->
 <script lang="ts">
+	import { goto } from "$app/navigation";
+
+	import {
+		BattleFetchError,
+		fetchBattle,
+		type BattleReport,
+	} from "../../api/battle-fetch";
 	import { i18n } from "$lib/i18n/index.svelte";
 
-	type Props = { battleId: string };
+	import BattleViewer from "../battle-player/battle-viewer.svelte";
-	let { battleId }: Props = $props();
+
+	let {
+		gameId,
+		turn,
+		battleId,
+	}: {
+		gameId: string;
+		turn: number;
+		battleId: string;
+	} = $props();
+
+	let state = $state<
+		| { kind: "loading" }
+		| { kind: "ready"; report: BattleReport }
+		| { kind: "not_found" }
+		| { kind: "error"; message: string }
+	>({ kind: "loading" });
+
+	$effect(() => {
+		if (!battleId) {
+			state = { kind: "not_found" };
+			return;
+		}
+		state = { kind: "loading" };
+		fetchBattle(gameId, turn, battleId)
+			.then((report) => {
+				state = { kind: "ready", report };
+			})
+			.catch((err: unknown) => {
+				if (err instanceof BattleFetchError && err.status === 404) {
+					state = { kind: "not_found" };
+				} else {
+					state = {
+						kind: "error",
+						message: err instanceof Error ? err.message : String(err),
+					};
+				}
+			});
+	});
+
+	function backToReport() {
+		goto(`/games/${gameId}/report`);
+	}
+	function backToMap() {
+		goto(`/games/${gameId}/map`);
+	}
 </script>
 
 <section class="active-view" data-testid="active-view-battle" data-battle-id={battleId}>
-	<h2>{i18n.t("game.view.battle")}</h2>
+	<nav class="back-row">
-	<p>{i18n.t("game.shell.coming_soon")}</p>
+		<button
+			type="button"
+			class="back-btn"
+			onclick={backToMap}
+			data-testid="battle-back-to-map"
+		>{i18n.t("game.battle.back_to_map")}</button>
+		<button
+			type="button"
+			class="back-btn"
+			onclick={backToReport}
+			data-testid="battle-back-to-report"
+		>{i18n.t("game.battle.back_to_report")}</button>
+	</nav>
+
+	{#if state.kind === "loading"}
+		<p class="status" data-testid="battle-loading">
+			{i18n.t("game.battle.loading")}
+		</p>
+	{:else if state.kind === "ready"}
+		<BattleViewer report={state.report} />
+	{:else if state.kind === "not_found"}
+		<p class="status" data-testid="battle-not-found">
+			{i18n.t("game.battle.not_found")}
+		</p>
+	{:else}
+		<p class="status error" data-testid="battle-error">{state.message}</p>
+	{/if}
 </section>
 
 <style>
 	.active-view {
-		padding: 1.5rem;
+		padding: 1rem;
 		font-family: system-ui, sans-serif;
+		color: #d6dcf2;
 	}
-	.active-view h2 {
+	.back-row {
-		margin: 0 0 0.5rem;
+		display: flex;
-		font-size: 1.1rem;
+		gap: 0.5rem;
+		max-width: 880px;
+		margin: 0 auto 1rem;
 	}
-	.active-view p {
+	.back-btn {
-		margin: 0;
+		appearance: none;
-		color: #555;
+		background: #1f2748;
+		color: #d6dcf2;
+		border: 1px solid #2c3568;
+		padding: 0.35rem 0.7rem;
+		border-radius: 3px;
+		cursor: pointer;
+		font-size: 0.85rem;
+	}
+	.back-btn:hover {
+		background: #2a3463;
+	}
+	.status {
+		margin: 2rem auto;
+		max-width: 880px;
+		color: #93a0d0;
+		font-size: 0.95rem;
+		text-align: center;
+	}
+	.status.error {
+		color: #e08585;
 	}
 </style>

ui/frontend/src/lib/active-view/map.svelte

@@ -21,6 +21,8 @@ preference the store already manages.
 -->
 <script lang="ts">
 	import { getContext, onDestroy, onMount, untrack } from "svelte";
+	import { goto } from "$app/navigation";
+	import { page } from "$app/state";
 	import { i18n } from "$lib/i18n/index.svelte";
 	import {
 		createRenderer,
@@ -402,13 +404,40 @@ preference the store already manages.
 		if (selection === undefined) return;
 		const hit = handle.hitAt(cursorPx);
 		if (hit === null) return;
-		if (hit.primitive.kind !== "point") return;
 		const target = hitLookup.get(hit.primitive.id);
 		if (target === undefined) return;
-		if (target.kind === "planet") {
+		switch (target.kind) {
-			selection.selectPlanet(target.number);
+			case "planet":
-		} else {
+				if (hit.primitive.kind !== "point") return;
-			selection.selectShipGroup(target.ref);
+				selection.selectPlanet(target.number);
+				break;
+			case "shipGroup":
+				if (hit.primitive.kind !== "point") return;
+				selection.selectShipGroup(target.ref);
+				break;
+			case "battle": {
+				const gameId = page.params.id ?? "";
+				const turn = store?.report?.turn ?? 0;
+				void goto(
+					`/games/${gameId}/battle/${target.battleId}?turn=${turn}`,
+				);
+				break;
+			}
+			case "bombing": {
+				const gameId = page.params.id ?? "";
+				void goto(
+					`/games/${gameId}/report#report-bombings`,
+				).then(() => {
+					if (typeof document === "undefined") return;
+					const row = document.querySelector(
+						`[data-testid="report-bombing-row"][data-planet="${target.planet}"]`,
+					);
+					if (row && row.scrollIntoView) {
+						row.scrollIntoView({ behavior: "smooth", block: "center" });
+					}
+				});
+				break;
+			}
 		}
 	}
 

ui/frontend/src/lib/active-view/report/section-battles.svelte

@@ -1,13 +1,14 @@
 <!--
-Phase 23 Report View — battles section. The wire only carries
+Phase 27 Report View — battles section. Each row is a link into the
-battle UUIDs (the full battle report is fetched lazily by Phase 27),
+Battle Viewer at `/games/<id>/battle/<uuid>?turn=<turn>` where
-so each row is a monospace, non-interactive `<span>` of the battle
+`turn` follows the current report's turn so history-mode views land
-identifier. Phase 27 will turn each row into a link to
+on the right battle. Phase 23 rendered the same rows as inactive
-`/games/<id>/battle/<uuid>`; until then dead links are worse than
+monospace `<span>`; the rewire here is the one-liner the Phase 23
-plain text.
+decision log called out.
 -->
 <script lang="ts">
 	import { getContext } from "svelte";
+	import { page } from "$app/state";
 
 	import { i18n } from "$lib/i18n/index.svelte";
 	import {
@@ -19,7 +20,9 @@ plain text.
 		RENDERED_REPORT_CONTEXT_KEY,
 	);
 	const report = $derived(rendered?.report ?? null);
-	const ids = $derived(report?.battleIds ?? []);
+	const battles = $derived(report?.battles ?? []);
+	const gameId = $derived(page.params.id ?? "");
+	const turn = $derived(report?.turn ?? 0);
 </script>
 
 <section
@@ -31,22 +34,23 @@ plain text.
 
 	{#if report === null}
 		<p class="status">{i18n.t("game.report.loading")}</p>
-	{:else if ids.length === 0}
+	{:else if battles.length === 0}
 		<p class="status" data-testid="battles-empty">
 			{i18n.t("game.report.section.battles.empty")}
 		</p>
 	{:else}
 		<ul class="ids" data-testid="battles-list">
-			{#each ids as id (id)}
+			{#each battles as b (b.id)}
 				<li>
 					<span class="label">
 						{i18n.t("game.report.section.battles.id_label")}
 					</span>
-					<span
+					<a
 						class="uuid"
+						href={`/games/${gameId}/battle/${b.id}?turn=${turn}`}
 						data-testid="report-battle-row"
-						data-id={id}
+						data-id={b.id}
-					>{id}</span>
+					>{b.id}</a>
 				</li>
 			{/each}
 		</ul>
@@ -87,5 +91,10 @@ plain text.
 	.uuid {
 		color: #cfd7ff;
 		font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
+		text-decoration: underline;
+		text-underline-offset: 2px;
+	}
+	.uuid:hover {
+		color: #ffffff;
 	}
 </style>

ui/frontend/src/lib/battle-player/battle-scene.svelte

@@ -0,0 +1,223 @@
+<!--
+BattleScene — radial SVG visualisation of one battle frame.
+
+Layout: planet at the centre, race anchors equally spaced on an
+outer ring, each race rendered as a cluster of small class circles
+labelled `<className>:<numLeft>` underneath. The shot line for the
+current frame's `lastAction` is drawn from attacker group to
+defender group; red when the shot destroyed the defender, green
+otherwise. Observer groups (`inBattle === false`) are filtered out
+by `buildFrames`, so they never appear here.
+-->
+<script lang="ts">
+	import type { BattleReport } from "../../api/battle-fetch";
+	import { layoutRaces } from "./radial-layout";
+	import {
+		buildGroupRaceMap,
+		normaliseGroups,
+		type Frame,
+	} from "./timeline";
+
+	let {
+		report,
+		frame,
+	}: {
+		report: BattleReport;
+		frame: Frame;
+	} = $props();
+
+	const VIEW_BOX = 800;
+	const CENTER = { x: VIEW_BOX / 2, y: VIEW_BOX / 2 };
+	const PLANET_RADIUS = 60;
+	const RACE_RING_RADIUS = 280;
+	const CLASS_CIRCLE_RADIUS = 24;
+	const CLASS_SPACING = 64;
+
+	const groupRace = $derived(buildGroupRaceMap(report.protocol));
+	const allGroups = $derived(normaliseGroups(report));
+
+	type ClusterEntry = {
+		key: number;
+		className: string;
+		numLeft: number;
+	};
+
+	const clustersByRace = $derived.by(() => {
+		const out = new Map<number, ClusterEntry[]>();
+		for (const g of allGroups) {
+			const numLeft = frame.remaining.get(g.key) ?? 0;
+			const list = out.get(g.raceId) ?? [];
+			list.push({
+				key: g.key,
+				className: g.group.className,
+				numLeft,
+			});
+			out.set(g.raceId, list);
+		}
+		// Stable cluster order: by classname then key.
+		for (const list of out.values()) {
+			list.sort((a, b) => {
+				const byName = a.className.localeCompare(b.className);
+				if (byName !== 0) return byName;
+				return a.key - b.key;
+			});
+		}
+		return out;
+	});
+
+	const raceLayout = $derived(
+		layoutRaces(frame.activeRaceIds, {
+			center: CENTER,
+			radius: RACE_RING_RADIUS,
+		}),
+	);
+
+	function classCircleX(index: number, count: number): number {
+		const span = (count - 1) * CLASS_SPACING;
+		return -span / 2 + index * CLASS_SPACING;
+	}
+
+	function findClassCircleCenter(groupKey: number) {
+		const raceId = groupRace.get(groupKey);
+		if (raceId === undefined) return null;
+		const anchor = raceLayout.find((a) => a.raceId === raceId);
+		if (!anchor) return null;
+		const cluster = clustersByRace.get(raceId) ?? [];
+		const idx = cluster.findIndex((c) => c.key === groupKey);
+		if (idx === -1) return null;
+		return {
+			x: anchor.x + classCircleX(idx, cluster.length),
+			y: anchor.y,
+		};
+	}
+
+	const shotLine = $derived.by(() => {
+		const action = frame.lastAction;
+		if (!action) return null;
+		const from = findClassCircleCenter(action.sa);
+		const to = findClassCircleCenter(action.sd);
+		if (!from || !to) return null;
+		return { from, to, destroyed: action.x };
+	});
+
+	const raceLabelById = $derived.by(() => {
+		const out = new Map<number, string>();
+		for (const g of allGroups) {
+			out.set(g.raceId, g.group.race);
+		}
+		return out;
+	});
+</script>
+
+<svg
+	class="battle-scene"
+	viewBox="0 0 {VIEW_BOX} {VIEW_BOX}"
+	role="img"
+	aria-label="battle scene"
+	data-testid="battle-scene"
+>
+	<circle
+		cx={CENTER.x}
+		cy={CENTER.y}
+		r={PLANET_RADIUS}
+		class="planet"
+		data-testid="battle-scene-planet"
+	/>
+	<text
+		x={CENTER.x}
+		y={CENTER.y + PLANET_RADIUS + 24}
+		text-anchor="middle"
+		class="planet-label"
+	>{report.planetName} (#{report.planet})</text>
+
+	{#each raceLayout as anchor (anchor.raceId)}
+		{@const cluster = clustersByRace.get(anchor.raceId) ?? []}
+		<g
+			class="race-cluster"
+			data-testid="battle-race-cluster"
+			data-race-id={anchor.raceId}
+		>
+			<text
+				x={anchor.x}
+				y={anchor.y - CLASS_CIRCLE_RADIUS - 12}
+				text-anchor="middle"
+				class="race-label"
+			>{raceLabelById.get(anchor.raceId) ?? `race ${anchor.raceId}`}</text>
+			{#each cluster as entry, i (entry.key)}
+				{@const cx = anchor.x + classCircleX(i, cluster.length)}
+				<g
+					class="class-marker"
+					data-testid="battle-class-marker"
+					data-group-key={entry.key}
+				>
+					<circle
+						cx={cx}
+						cy={anchor.y}
+						r={CLASS_CIRCLE_RADIUS}
+					/>
+					<text
+						x={cx}
+						y={anchor.y + CLASS_CIRCLE_RADIUS + 16}
+						text-anchor="middle"
+						class="class-label"
+					>{entry.className}:{entry.numLeft}</text>
+				</g>
+			{/each}
+		</g>
+	{/each}
+
+	{#if shotLine}
+		<line
+			x1={shotLine.from.x}
+			y1={shotLine.from.y}
+			x2={shotLine.to.x}
+			y2={shotLine.to.y}
+			class="shot"
+			class:destroyed={shotLine.destroyed}
+			data-testid="battle-shot"
+			data-destroyed={shotLine.destroyed ? "true" : "false"}
+		/>
+	{/if}
+</svg>
+
+<style>
+	.battle-scene {
+		width: 100%;
+		height: auto;
+		background: #0a0d1a;
+		display: block;
+	}
+	.planet {
+		fill: #2a345f;
+		stroke: #5b6aa3;
+		stroke-width: 2;
+	}
+	.planet-label {
+		fill: #c4caea;
+		font-size: 18px;
+		font-family: ui-sans-serif, system-ui, sans-serif;
+	}
+	.race-label {
+		fill: #e2e6ff;
+		font-size: 16px;
+		font-weight: 600;
+		font-family: ui-sans-serif, system-ui, sans-serif;
+	}
+	.class-marker circle {
+		fill: #1a2042;
+		stroke: #6d7bb5;
+		stroke-width: 1.5;
+	}
+	.class-label {
+		fill: #b8c0e6;
+		font-size: 12px;
+		font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
+	}
+	.shot {
+		stroke: #44dd66;
+		stroke-width: 2;
+	}
+	.shot.destroyed {
+		stroke: #ee3344;
+	}
+</style>

ui/frontend/src/lib/battle-player/battle-viewer.svelte

@@ -0,0 +1,167 @@
+<!--
+BattleViewer — orchestrates the radial battle scene, the playback
+controls, and the accessibility text log for one BattleReport. Owns
+the playback state (`frameIndex`, `playing`, `speed`). The component
+is logically isolated: feed it any `BattleReport` matching
+`pkg/model/report/battle.go` and it plays back.
+-->
+<script lang="ts">
+	import { onDestroy } from "svelte";
+
+	import { i18n } from "$lib/i18n/index.svelte";
+	import type { BattleReport } from "../../api/battle-fetch";
+
+	import BattleScene from "./battle-scene.svelte";
+	import PlaybackControls from "./playback-controls.svelte";
+	import { buildFrames } from "./timeline";
+
+	let { report }: { report: BattleReport } = $props();
+
+	const frames = $derived(buildFrames(report));
+	let frameIndex = $state(0);
+	let playing = $state(false);
+	let speed = $state<1 | 2 | 4>(1);
+
+	const frame = $derived(frames[Math.min(frameIndex, frames.length - 1)]);
+
+	// 1x = 400 ms per frame, 2x = 200 ms, 4x = 100 ms. The timer is
+	// rescheduled whenever `speed` or `playing` flips.
+	let timer: ReturnType<typeof setInterval> | null = null;
+	$effect(() => {
+		if (timer !== null) {
+			clearInterval(timer);
+			timer = null;
+		}
+		if (!playing) return;
+		const intervalMs = 400 / speed;
+		timer = setInterval(() => {
+			if (frameIndex >= frames.length - 1) {
+				playing = false;
+				return;
+			}
+			frameIndex = frameIndex + 1;
+		}, intervalMs);
+	});
+
+	onDestroy(() => {
+		if (timer !== null) {
+			clearInterval(timer);
+			timer = null;
+		}
+	});
+
+	function describeAction(index: number): string {
+		const action = report.protocol[index];
+		const attackerGroup = report.ships[String(action.sa)];
+		const defenderGroup = report.ships[String(action.sd)];
+		const attackerRace = attackerGroup?.race ?? `race ${action.a}`;
+		const attackerClass = attackerGroup?.className ?? `class ${action.sa}`;
+		const defenderRace = defenderGroup?.race ?? `race ${action.d}`;
+		const defenderClass = defenderGroup?.className ?? `class ${action.sd}`;
+		const key = action.x
+			? "game.battle.log.destroyed"
+			: "game.battle.log.shielded";
+		return i18n.t(key, {
+			attacker_race: attackerRace,
+			attacker_class: attackerClass,
+			defender_race: defenderRace,
+			defender_class: defenderClass,
+		});
+	}
+</script>
+
+<div class="viewer" data-testid="battle-viewer">
+	<header class="header">
+		<h2 data-testid="battle-viewer-title">
+			{i18n.t("game.battle.title")}
+		</h2>
+		<span class="progress" data-testid="battle-frame-index">
+			{frame.shotIndex} / {report.protocol.length}
+		</span>
+	</header>
+
+	<div class="scene">
+		<BattleScene {report} {frame} />
+	</div>
+
+	<PlaybackControls
+		bind:playing
+		bind:frameIndex
+		bind:speed
+		frameCount={frames.length}
+	/>
+
+	<section
+		class="log"
+		aria-label={i18n.t("game.battle.accessibility.protocol_heading")}
+	>
+		<h3>{i18n.t("game.battle.accessibility.protocol_heading")}</h3>
+		<ol data-testid="battle-protocol-log">
+			{#each report.protocol as _action, i (i)}
+				<li
+					data-testid="battle-protocol-log-item"
+					data-current={i + 1 === frame.shotIndex ? "true" : "false"}
+				>{describeAction(i)}</li>
+			{/each}
+		</ol>
+	</section>
+</div>
+
+<style>
+	.viewer {
+		display: flex;
+		flex-direction: column;
+		gap: 0.75rem;
+		max-width: 880px;
+		margin: 0 auto;
+		padding: 1rem;
+		color: #d6dcf2;
+		font-family: inherit;
+	}
+	.header {
+		display: flex;
+		justify-content: space-between;
+		align-items: baseline;
+	}
+	.header h2 {
+		margin: 0;
+		font-size: 1.1rem;
+		text-transform: uppercase;
+		letter-spacing: 0.05em;
+	}
+	.progress {
+		color: #93a0d0;
+		font-variant-numeric: tabular-nums;
+		font-size: 0.9rem;
+	}
+	.scene {
+		background: #0a0d1a;
+		border: 1px solid #1e264a;
+		border-radius: 4px;
+		overflow: hidden;
+	}
+	.log h3 {
+		margin: 0 0 0.4rem;
+		color: #93a0d0;
+		font-size: 0.8rem;
+		text-transform: uppercase;
+		letter-spacing: 0.05em;
+	}
+	.log ol {
+		list-style: decimal inside;
+		margin: 0;
+		padding: 0;
+		font-size: 0.85rem;
+		max-height: 14rem;
+		overflow-y: auto;
+		color: #c6cdf0;
+	}
+	.log li {
+		padding: 0.15rem 0;
+		border-bottom: 1px solid #1c2240;
+	}
+	.log li[data-current="true"] {
+		color: #ffe27a;
+		font-weight: 600;
+	}
+</style>

ui/frontend/src/lib/battle-player/playback-controls.svelte

@@ -0,0 +1,145 @@
+<!--
+PlaybackControls — rewind / step-back / play-pause / step-forward
+plus a 1x/2x/4x speed switch. Owns no playback state; bind `playing`,
+`frameIndex`, and `speed` from the orchestrator. Disables step/rewind
+when there's nowhere to go and disables forward when the timeline is
+already at its end.
+-->
+<script lang="ts">
+	import { i18n } from "$lib/i18n/index.svelte";
+
+	let {
+		playing = $bindable(),
+		frameIndex = $bindable(),
+		speed = $bindable(),
+		frameCount,
+	}: {
+		playing: boolean;
+		frameIndex: number;
+		speed: 1 | 2 | 4;
+		frameCount: number;
+	} = $props();
+
+	function rewind() {
+		playing = false;
+		frameIndex = 0;
+	}
+	function stepBack() {
+		playing = false;
+		if (frameIndex > 0) frameIndex = frameIndex - 1;
+	}
+	function togglePlay() {
+		if (frameIndex >= frameCount - 1) {
+			frameIndex = 0;
+		}
+		playing = !playing;
+	}
+	function stepForward() {
+		playing = false;
+		if (frameIndex < frameCount - 1) frameIndex = frameIndex + 1;
+	}
+	function setSpeed(value: 1 | 2 | 4) {
+		speed = value;
+	}
+</script>
+
+<div class="controls" data-testid="battle-controls">
+	<button
+		type="button"
+		onclick={rewind}
+		disabled={frameIndex === 0}
+		aria-label={i18n.t("game.battle.controls.rewind")}
+		data-testid="battle-control-rewind"
+	>⏮</button>
+	<button
+		type="button"
+		onclick={stepBack}
+		disabled={frameIndex === 0}
+		aria-label={i18n.t("game.battle.controls.step_backward")}
+		data-testid="battle-control-step-back"
+	>◀︎</button>
+	<button
+		type="button"
+		onclick={togglePlay}
+		aria-label={playing
+			? i18n.t("game.battle.controls.pause")
+			: i18n.t("game.battle.controls.play")}
+		data-testid="battle-control-play"
+		data-playing={playing ? "true" : "false"}
+	>{playing ? "⏸" : "▶︎"}</button>
+	<button
+		type="button"
+		onclick={stepForward}
+		disabled={frameIndex >= frameCount - 1}
+		aria-label={i18n.t("game.battle.controls.step_forward")}
+		data-testid="battle-control-step-forward"
+	>▶︎▶︎</button>
+
+	<div class="spacer" aria-hidden="true"></div>
+
+	<span class="speed-label">{i18n.t("game.battle.controls.speed_label")}</span>
+	<button
+		type="button"
+		class:active={speed === 1}
+		onclick={() => setSpeed(1)}
+		data-testid="battle-control-speed-1x"
+	>{i18n.t("game.battle.controls.speed_1x")}</button>
+	<button
+		type="button"
+		class:active={speed === 2}
+		onclick={() => setSpeed(2)}
+		data-testid="battle-control-speed-2x"
+	>{i18n.t("game.battle.controls.speed_2x")}</button>
+	<button
+		type="button"
+		class:active={speed === 4}
+		onclick={() => setSpeed(4)}
+		data-testid="battle-control-speed-4x"
+	>{i18n.t("game.battle.controls.speed_4x")}</button>
+</div>
+
+<style>
+	.controls {
+		display: flex;
+		align-items: center;
+		gap: 0.4rem;
+		padding: 0.5rem 0.75rem;
+		background: #131934;
+		border: 1px solid #1e264a;
+		border-radius: 4px;
+	}
+	.spacer {
+		flex: 1 1 auto;
+	}
+	button {
+		appearance: none;
+		background: #1f2748;
+		color: #d6dcf2;
+		border: 1px solid #2c3568;
+		padding: 0.35rem 0.7rem;
+		border-radius: 3px;
+		cursor: pointer;
+		font-size: 0.9rem;
+		font-family: inherit;
+		min-width: 2.5rem;
+	}
+	button:hover:not(:disabled) {
+		background: #2a3463;
+	}
+	button:disabled {
+		opacity: 0.4;
+		cursor: not-allowed;
+	}
+	button.active {
+		background: #3a4585;
+		border-color: #5d6cb8;
+		color: #ffffff;
+	}
+	.speed-label {
+		color: #93a0d0;
+		font-size: 0.8rem;
+		text-transform: uppercase;
+		letter-spacing: 0.05em;
+		margin-right: 0.2rem;
+	}
+</style>

ui/frontend/src/lib/battle-player/radial-layout.ts

@@ -0,0 +1,50 @@
+// Radial layout for the BattleViewer.
+//
+// Places race anchors on a circle of radius `radius` around `center`
+// at equal angular spacing. The first anchor sits at the top (12
+// o'clock); subsequent anchors march clockwise. When a race is
+// eliminated mid-battle, the caller filters it out of `activeRaceIds`
+// and the survivors are re-spaced on the next frame. The same helper
+// drives both the initial layout and that re-distribution.
+
+export interface RaceAnchor {
+	raceId: number;
+	x: number;
+	y: number;
+	/** Angle in radians measured from the positive Y axis clockwise. */
+	angle: number;
+}
+
+export interface RadialLayoutOptions {
+	center: { x: number; y: number };
+	radius: number;
+}
+
+/**
+ * layoutRaces returns anchor positions for each `activeRaceIds`
+ * entry, placed at equal angular spacing on a circle. The input
+ * order is preserved so consumers get a stable mapping across
+ * frames; eliminated entries should simply be filtered out before
+ * the call.
+ */
+export function layoutRaces(
+	activeRaceIds: number[],
+	options: RadialLayoutOptions,
+): RaceAnchor[] {
+	const count = activeRaceIds.length;
+	if (count === 0) return [];
+	const { center, radius } = options;
+	const out: RaceAnchor[] = [];
+	for (let i = 0; i < count; i++) {
+		// 12 o'clock = -PI/2 in math convention; clockwise → +i*step.
+		const step = (2 * Math.PI) / count;
+		const angle = -Math.PI / 2 + i * step;
+		out.push({
+			raceId: activeRaceIds[i],
+			x: center.x + radius * Math.cos(angle),
+			y: center.y + radius * Math.sin(angle),
+			angle,
+		});
+	}
+	return out;
+}

ui/frontend/src/lib/battle-player/timeline.ts

@@ -0,0 +1,134 @@
+// Timeline builder for the BattleViewer.
+//
+// Given a `BattleReport`, expands the flat `protocol` into a
+// sequence of frames. Frame 0 carries the initial state; frame N
+// (1 ≤ N ≤ protocol.length) reflects the state right after the
+// (N-1)-th action has been applied. Each frame is self-contained so
+// stepping forward and backward is a constant-time index lookup, no
+// rewind logic needed.
+
+import type {
+	BattleActionReport,
+	BattleReport,
+	BattleReportGroup,
+} from "../../api/battle-fetch";
+
+/**
+ * Frame is one tick of the battle playback. `remaining` carries the
+ * surviving ship count for each ship-group key from
+ * `BattleReport.ships`; `activeRaceIds` are the race indices with at
+ * least one surviving in-battle group. `lastAction` is the action
+ * applied to produce this frame, or `null` for the initial frame.
+ */
+export interface Frame {
+	shotIndex: number;
+	remaining: Map<number, number>;
+	activeRaceIds: number[];
+	lastAction: BattleActionReport | null;
+}
+
+export interface NormalisedGroup {
+	key: number;
+	group: BattleReportGroup;
+	raceId: number;
+}
+
+/**
+ * normaliseGroups returns the in-battle ship groups from a
+ * BattleReport indexed by their integer key. Observer groups
+ * (`inBattle === false`) are skipped because they are neither
+ * targeted nor drawn. The race index per group is derived from the
+ * protocol — every in-battle group appears at least once as
+ * attacker or defender, and the engine's pairing (a, sa) / (d, sd)
+ * defines the relationship.
+ */
+export function normaliseGroups(report: BattleReport): NormalisedGroup[] {
+	const raceByKey = buildGroupRaceMap(report.protocol);
+	const out: NormalisedGroup[] = [];
+	for (const [keyRaw, group] of Object.entries(report.ships)) {
+		if (!group.inBattle) continue;
+		const key = Number(keyRaw);
+		if (!Number.isFinite(key)) continue;
+		const raceId = raceByKey.get(key);
+		if (raceId === undefined) continue;
+		out.push({ key, group, raceId });
+	}
+	return out;
+}
+
+/**
+ * buildGroupRaceMap extracts the `ship-group key → race index`
+ * mapping from a battle protocol. Same key appearing twice always
+ * carries the same race index — protocol entries are emitted by the
+ * engine, which never crosses these wires.
+ */
+export function buildGroupRaceMap(
+	protocol: BattleActionReport[],
+): Map<number, number> {
+	const out = new Map<number, number>();
+	for (const action of protocol) {
+		if (!out.has(action.sa)) out.set(action.sa, action.a);
+		if (!out.has(action.sd)) out.set(action.sd, action.d);
+	}
+	return out;
+}
+
+/**
+ * buildFrames walks the protocol once and emits a frame after each
+ * applied action plus the initial frame. The remaining-ships map is
+ * cloned per frame so callers can step backward without manual
+ * bookkeeping. Eliminated races drop out of `activeRaceIds` as soon
+ * as their last in-battle group hits zero.
+ */
+export function buildFrames(report: BattleReport): Frame[] {
+	const groups = normaliseGroups(report);
+	const initialRemaining = new Map<number, number>();
+	const raceTotals = new Map<number, number>();
+	for (const g of groups) {
+		initialRemaining.set(g.key, g.group.num);
+		raceTotals.set(g.raceId, (raceTotals.get(g.raceId) ?? 0) + g.group.num);
+	}
+
+	const frames: Frame[] = [];
+	frames.push({
+		shotIndex: 0,
+		remaining: new Map(initialRemaining),
+		activeRaceIds: collectActiveRaces(raceTotals),
+		lastAction: null,
+	});
+
+	const groupRaceByKey = new Map<number, number>();
+	for (const g of groups) groupRaceByKey.set(g.key, g.raceId);
+
+	const current = new Map(initialRemaining);
+	const runningRaceTotals = new Map(raceTotals);
+	for (let i = 0; i < report.protocol.length; i++) {
+		const action = report.protocol[i];
+		if (action.x) {
+			const left = current.get(action.sd) ?? 0;
+			const next = Math.max(0, left - 1);
+			current.set(action.sd, next);
+			const raceId = groupRaceByKey.get(action.sd);
+			if (raceId !== undefined) {
+				const t = (runningRaceTotals.get(raceId) ?? 0) - 1;
+				runningRaceTotals.set(raceId, Math.max(0, t));
+			}
+		}
+		frames.push({
+			shotIndex: i + 1,
+			remaining: new Map(current),
+			activeRaceIds: collectActiveRaces(runningRaceTotals),
+			lastAction: action,
+		});
+	}
+
+	return frames;
+}
+
+function collectActiveRaces(totals: Map<number, number>): number[] {
+	const out: number[] = [];
+	for (const [raceId, total] of totals.entries()) {
+		if (total > 0) out.push(raceId);
+	}
+	return out.sort((a, b) => a - b);
+}

ui/frontend/src/lib/i18n/locales/en.ts

@@ -483,6 +483,23 @@ const en = {
 	"game.report.section.battles.title": "battles",
 	"game.report.section.battles.empty": "no battles last turn",
 	"game.report.section.battles.id_label": "battle",
+	"game.battle.title": "battle",
+	"game.battle.loading": "loading battle…",
+	"game.battle.not_found": "battle not found",
+	"game.battle.back_to_report": "back to report",
+	"game.battle.back_to_map": "back to map",
+	"game.battle.controls.play": "play",
+	"game.battle.controls.pause": "pause",
+	"game.battle.controls.step_forward": "step forward",
+	"game.battle.controls.step_backward": "step back",
+	"game.battle.controls.rewind": "rewind to start",
+	"game.battle.controls.speed_label": "speed",
+	"game.battle.controls.speed_1x": "1x",
+	"game.battle.controls.speed_2x": "2x",
+	"game.battle.controls.speed_4x": "4x",
+	"game.battle.log.destroyed": "{attacker_race}'s {attacker_class} destroyed {defender_race}'s {defender_class}",
+	"game.battle.log.shielded": "{attacker_race}'s {attacker_class} hit {defender_race}'s {defender_class}, shields held",
+	"game.battle.accessibility.protocol_heading": "battle log",
 	"game.report.section.bombings.title": "bombings",
 	"game.report.section.bombings.empty": "no bombings last turn",
 	"game.report.section.bombings.column.planet": "planet",

ui/frontend/src/lib/i18n/locales/ru.ts

@@ -484,6 +484,23 @@ const ru: Record<keyof typeof en, string> = {
 	"game.report.section.battles.title": "сражения",
 	"game.report.section.battles.empty": "сражений в этом ходу не было",
 	"game.report.section.battles.id_label": "сражение",
+	"game.battle.title": "сражение",
+	"game.battle.loading": "загрузка сражения…",
+	"game.battle.not_found": "сражение не найдено",
+	"game.battle.back_to_report": "к отчёту",
+	"game.battle.back_to_map": "к карте",
+	"game.battle.controls.play": "запустить",
+	"game.battle.controls.pause": "пауза",
+	"game.battle.controls.step_forward": "шаг вперёд",
+	"game.battle.controls.step_backward": "шаг назад",
+	"game.battle.controls.rewind": "к началу",
+	"game.battle.controls.speed_label": "скорость",
+	"game.battle.controls.speed_1x": "1x",
+	"game.battle.controls.speed_2x": "2x",
+	"game.battle.controls.speed_4x": "4x",
+	"game.battle.log.destroyed": "{attacker_class} расы {attacker_race} уничтожает {defender_class} расы {defender_race}",
+	"game.battle.log.shielded": "{attacker_class} расы {attacker_race} попадает в {defender_class} расы {defender_race}, щиты выдержали",
+	"game.battle.accessibility.protocol_heading": "протокол сражения",
 	"game.report.section.bombings.title": "бомбардировки",
 	"game.report.section.bombings.empty": "бомбардировок в этом ходу не было",
 	"game.report.section.bombings.column.planet": "планета",

ui/frontend/src/map/battle-markers.ts

@@ -0,0 +1,168 @@
+// Phase 27 battle and bombing markers on the map.
+//
+// Two visual markers per planet:
+//
+//   * Battle marker — an X cross drawn through the corners of the
+//     square that circumscribes the planet circle. Two yellow
+//     LinePrim, stroke width scales linearly with the number of
+//     shots: 1 shot → 1px, 100+ shots → 5px (capped). Clicking
+//     either line opens the Battle Viewer for the corresponding
+//     UUID.
+//   * Bombing marker — a thin stroke-only circle slightly larger
+//     than the planet circle. Yellow on damaged planets, red on
+//     wiped planets. Clicking it deep-links to the bombings row in
+//     the Reports view for the planet number.
+//
+// Both markers are wired into `state-binding.ts` so they live in the
+// same `world` / `hitLookup` plumbing as planets and ship groups.
+
+import type { GameReport, ReportPlanet } from "../api/game-state";
+import type {
+	CirclePrim,
+	LinePrim,
+	Primitive,
+	PrimitiveID,
+	Style,
+} from "./world";
+
+export const BATTLE_MARKER_COLOR = 0xffd400;
+export const BOMBING_MARKER_COLOR_DAMAGED = 0xffd400;
+export const BOMBING_MARKER_COLOR_WIPED = 0xff3030;
+
+/** Battle and bombing marker primitive ids use a high-bit prefix to
+ * avoid colliding with planet numbers or cargo-route line ids. */
+export const BATTLE_MARKER_ID_PREFIX = 0xa0000000;
+export const BOMBING_MARKER_ID_PREFIX = 0xc0000000;
+
+const PLANET_RADIUS_WORLD = 6;
+const BOMBING_RING_RADIUS = PLANET_RADIUS_WORLD + 3;
+const BATTLE_CROSS_HALF = PLANET_RADIUS_WORLD + 2;
+
+/** Battle marker priority sits between planets (1..4) and cargo
+ * routes; the cross is over the planet but loses clicks against the
+ * planet glyph itself. */
+const BATTLE_MARKER_PRIORITY = 9;
+const BOMBING_MARKER_PRIORITY = 10;
+
+const BATTLE_LINE_INDEX_A = 0;
+const BATTLE_LINE_INDEX_B = 1;
+
+export interface BattleMarkerTarget {
+	kind: "battle";
+	battleId: string;
+	planet: number;
+}
+
+export interface BombingMarkerTarget {
+	kind: "bombing";
+	planet: number;
+}
+
+export type MarkerTarget = BattleMarkerTarget | BombingMarkerTarget;
+
+export interface BuildMarkersResult {
+	primitives: Primitive[];
+	lookup: Map<PrimitiveID, MarkerTarget>;
+}
+
+/**
+ * battleMarkerStrokeWidth maps a battle's `shots` count to a stroke
+ * width in pixels. 1 shot → 1 px (the thinnest visible), 100+ shots
+ * → 5 px (the cap). Linearly interpolated between those bounds.
+ */
+export function battleMarkerStrokeWidth(shots: number): number {
+	if (shots <= 1) return 1;
+	if (shots >= 100) return 5;
+	return 1 + ((shots - 1) * 4) / 99;
+}
+
+/**
+ * buildBattleAndBombingMarkers emits battle and bombing marker
+ * primitives plus a hit-lookup mapping for the current-turn report.
+ * Battles whose planet is not visible (e.g. observer-only without a
+ * report.planets entry) are skipped — they have no on-map location
+ * to anchor against.
+ */
+export function buildBattleAndBombingMarkers(
+	report: GameReport,
+): BuildMarkersResult {
+	const planetByNumber = new Map<number, ReportPlanet>();
+	for (const planet of report.planets) {
+		planetByNumber.set(planet.number, planet);
+	}
+
+	const primitives: Primitive[] = [];
+	const lookup = new Map<PrimitiveID, MarkerTarget>();
+
+	for (let i = 0; i < report.battles.length; i++) {
+		const battle = report.battles[i];
+		const planet = planetByNumber.get(battle.planet);
+		if (planet === undefined) continue;
+		const strokeWidthPx = battleMarkerStrokeWidth(battle.shots);
+		const style: Style = {
+			strokeColor: BATTLE_MARKER_COLOR,
+			strokeAlpha: 0.95,
+			strokeWidthPx,
+		};
+		const baseId = BATTLE_MARKER_ID_PREFIX | (i << 4);
+		const lineA: LinePrim = {
+			kind: "line",
+			id: baseId | BATTLE_LINE_INDEX_A,
+			priority: BATTLE_MARKER_PRIORITY,
+			style,
+			hitSlopPx: 0,
+			x1: planet.x - BATTLE_CROSS_HALF,
+			y1: planet.y - BATTLE_CROSS_HALF,
+			x2: planet.x + BATTLE_CROSS_HALF,
+			y2: planet.y + BATTLE_CROSS_HALF,
+		};
+		const lineB: LinePrim = {
+			kind: "line",
+			id: baseId | BATTLE_LINE_INDEX_B,
+			priority: BATTLE_MARKER_PRIORITY,
+			style,
+			hitSlopPx: 0,
+			x1: planet.x - BATTLE_CROSS_HALF,
+			y1: planet.y + BATTLE_CROSS_HALF,
+			x2: planet.x + BATTLE_CROSS_HALF,
+			y2: planet.y - BATTLE_CROSS_HALF,
+		};
+		const target: BattleMarkerTarget = {
+			kind: "battle",
+			battleId: battle.id,
+			planet: battle.planet,
+		};
+		primitives.push(lineA, lineB);
+		lookup.set(lineA.id, target);
+		lookup.set(lineB.id, target);
+	}
+
+	for (let i = 0; i < report.bombings.length; i++) {
+		const bombing = report.bombings[i];
+		const planet = planetByNumber.get(bombing.planetNumber);
+		if (planet === undefined) continue;
+		const color = bombing.wiped
+			? BOMBING_MARKER_COLOR_WIPED
+			: BOMBING_MARKER_COLOR_DAMAGED;
+		const style: Style = {
+			strokeColor: color,
+			strokeAlpha: 0.9,
+			strokeWidthPx: 1.5,
+		};
+		const id = BOMBING_MARKER_ID_PREFIX | i;
+		const ring: CirclePrim = {
+			kind: "circle",
+			id,
+			priority: BOMBING_MARKER_PRIORITY,
+			style,
+			hitSlopPx: 0,
+			x: planet.x,
+			y: planet.y,
+			radius: BOMBING_RING_RADIUS,
+		};
+		primitives.push(ring);
+		lookup.set(id, { kind: "bombing", planet: bombing.planetNumber });
+	}
+
+	return { primitives, lookup };
+}

ui/frontend/src/map/state-binding.ts

@@ -15,6 +15,7 @@
 
 import type { GameReport, ReportPlanet } from "../api/game-state";
 import type { ShipGroupRef } from "../lib/selection.svelte";
+import { buildBattleAndBombingMarkers } from "./battle-markers";
 import { shipGroupsToPrimitives } from "./ship-groups";
 import { World, type Primitive, type PrimitiveID, type Style } from "./world";
 
@@ -83,7 +84,9 @@ function priorityFor(kind: ReportPlanet["kind"]): number {
  */
 export type HitTarget =
 	| { kind: "planet"; number: number }
-	| { kind: "shipGroup"; ref: ShipGroupRef };
+	| { kind: "shipGroup"; ref: ShipGroupRef }
+	| { kind: "battle"; battleId: string; planet: number }
+	| { kind: "bombing"; planet: number };
 
 export interface ReportToWorldResult {
 	world: World;
@@ -127,6 +130,14 @@ export function reportToWorld(report: GameReport): ReportToWorldResult {
 		hitLookup.set(primId, { kind: "shipGroup", ref });
 	}
 
+	const markers = buildBattleAndBombingMarkers(report);
+	for (const prim of markers.primitives) {
+		primitives.push(prim);
+	}
+	for (const [primId, target] of markers.lookup) {
+		hitLookup.set(primId, target);
+	}
+
 	const width = report.mapWidth > 0 ? report.mapWidth : 1;
 	const height = report.mapHeight > 0 ? report.mapHeight : 1;
 	return { world: new World(width, height, primitives), hitLookup };

ui/frontend/src/proto/galaxy/fbs/lobby/application-submit-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ApplicationSummary, ApplicationSummaryT } from './application-summary.js';
+import { ApplicationSummary, ApplicationSummaryT } from '../lobby/application-summary.js';
 
 
 export class ApplicationSubmitResponse implements flatbuffers.IUnpackableObject<ApplicationSubmitResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/error-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ErrorBody, ErrorBodyT } from './error-body.js';
+import { ErrorBody, ErrorBodyT } from '../lobby/error-body.js';
 
 
 export class ErrorResponse implements flatbuffers.IUnpackableObject<ErrorResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/game-create-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { GameSummary, GameSummaryT } from './game-summary.js';
+import { GameSummary, GameSummaryT } from '../lobby/game-summary.js';
 
 
 export class GameCreateResponse implements flatbuffers.IUnpackableObject<GameCreateResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/invite-decline-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { InviteSummary, InviteSummaryT } from './invite-summary.js';
+import { InviteSummary, InviteSummaryT } from '../lobby/invite-summary.js';
 
 
 export class InviteDeclineResponse implements flatbuffers.IUnpackableObject<InviteDeclineResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/invite-redeem-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { InviteSummary, InviteSummaryT } from './invite-summary.js';
+import { InviteSummary, InviteSummaryT } from '../lobby/invite-summary.js';
 
 
 export class InviteRedeemResponse implements flatbuffers.IUnpackableObject<InviteRedeemResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/my-applications-list-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ApplicationSummary, ApplicationSummaryT } from './application-summary.js';
+import { ApplicationSummary, ApplicationSummaryT } from '../lobby/application-summary.js';
 
 
 export class MyApplicationsListResponse implements flatbuffers.IUnpackableObject<MyApplicationsListResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/my-games-list-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { GameSummary, GameSummaryT } from './game-summary.js';
+import { GameSummary, GameSummaryT } from '../lobby/game-summary.js';
 
 
 export class MyGamesListResponse implements flatbuffers.IUnpackableObject<MyGamesListResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/my-invites-list-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { InviteSummary, InviteSummaryT } from './invite-summary.js';
+import { InviteSummary, InviteSummaryT } from '../lobby/invite-summary.js';
 
 
 export class MyInvitesListResponse implements flatbuffers.IUnpackableObject<MyInvitesListResponseT> {

ui/frontend/src/proto/galaxy/fbs/lobby/public-games-list-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { GameSummary, GameSummaryT } from './game-summary.js';
+import { GameSummary, GameSummaryT } from '../lobby/game-summary.js';
 
 
 export class PublicGamesListResponse implements flatbuffers.IUnpackableObject<PublicGamesListResponseT> {

ui/frontend/src/proto/galaxy/fbs/order/command-item.ts

@@ -4,30 +4,30 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { CommandFleetMerge, CommandFleetMergeT } from './command-fleet-merge.js';
+import { CommandFleetMerge, CommandFleetMergeT } from '../order/command-fleet-merge.js';
-import { CommandFleetSend, CommandFleetSendT } from './command-fleet-send.js';
+import { CommandFleetSend, CommandFleetSendT } from '../order/command-fleet-send.js';
-import { CommandPayload, unionToCommandPayload, unionListToCommandPayload } from './command-payload.js';
+import { CommandPayload, unionToCommandPayload, unionListToCommandPayload } from '../order/command-payload.js';
-import { CommandPlanetProduce, CommandPlanetProduceT } from './command-planet-produce.js';
+import { CommandPlanetProduce, CommandPlanetProduceT } from '../order/command-planet-produce.js';
-import { CommandPlanetRename, CommandPlanetRenameT } from './command-planet-rename.js';
+import { CommandPlanetRename, CommandPlanetRenameT } from '../order/command-planet-rename.js';
-import { CommandPlanetRouteRemove, CommandPlanetRouteRemoveT } from './command-planet-route-remove.js';
+import { CommandPlanetRouteRemove, CommandPlanetRouteRemoveT } from '../order/command-planet-route-remove.js';
-import { CommandPlanetRouteSet, CommandPlanetRouteSetT } from './command-planet-route-set.js';
+import { CommandPlanetRouteSet, CommandPlanetRouteSetT } from '../order/command-planet-route-set.js';
-import { CommandRaceQuit, CommandRaceQuitT } from './command-race-quit.js';
+import { CommandRaceQuit, CommandRaceQuitT } from '../order/command-race-quit.js';
-import { CommandRaceRelation, CommandRaceRelationT } from './command-race-relation.js';
+import { CommandRaceRelation, CommandRaceRelationT } from '../order/command-race-relation.js';
-import { CommandRaceVote, CommandRaceVoteT } from './command-race-vote.js';
+import { CommandRaceVote, CommandRaceVoteT } from '../order/command-race-vote.js';
-import { CommandScienceCreate, CommandScienceCreateT } from './command-science-create.js';
+import { CommandScienceCreate, CommandScienceCreateT } from '../order/command-science-create.js';
-import { CommandScienceRemove, CommandScienceRemoveT } from './command-science-remove.js';
+import { CommandScienceRemove, CommandScienceRemoveT } from '../order/command-science-remove.js';
-import { CommandShipClassCreate, CommandShipClassCreateT } from './command-ship-class-create.js';
+import { CommandShipClassCreate, CommandShipClassCreateT } from '../order/command-ship-class-create.js';
-import { CommandShipClassMerge, CommandShipClassMergeT } from './command-ship-class-merge.js';
+import { CommandShipClassMerge, CommandShipClassMergeT } from '../order/command-ship-class-merge.js';
-import { CommandShipClassRemove, CommandShipClassRemoveT } from './command-ship-class-remove.js';
+import { CommandShipClassRemove, CommandShipClassRemoveT } from '../order/command-ship-class-remove.js';
-import { CommandShipGroupBreak, CommandShipGroupBreakT } from './command-ship-group-break.js';
+import { CommandShipGroupBreak, CommandShipGroupBreakT } from '../order/command-ship-group-break.js';
-import { CommandShipGroupDismantle, CommandShipGroupDismantleT } from './command-ship-group-dismantle.js';
+import { CommandShipGroupDismantle, CommandShipGroupDismantleT } from '../order/command-ship-group-dismantle.js';
-import { CommandShipGroupJoinFleet, CommandShipGroupJoinFleetT } from './command-ship-group-join-fleet.js';
+import { CommandShipGroupJoinFleet, CommandShipGroupJoinFleetT } from '../order/command-ship-group-join-fleet.js';
-import { CommandShipGroupLoad, CommandShipGroupLoadT } from './command-ship-group-load.js';
+import { CommandShipGroupLoad, CommandShipGroupLoadT } from '../order/command-ship-group-load.js';
-import { CommandShipGroupMerge, CommandShipGroupMergeT } from './command-ship-group-merge.js';
+import { CommandShipGroupMerge, CommandShipGroupMergeT } from '../order/command-ship-group-merge.js';
-import { CommandShipGroupSend, CommandShipGroupSendT } from './command-ship-group-send.js';
+import { CommandShipGroupSend, CommandShipGroupSendT } from '../order/command-ship-group-send.js';
-import { CommandShipGroupTransfer, CommandShipGroupTransferT } from './command-ship-group-transfer.js';
+import { CommandShipGroupTransfer, CommandShipGroupTransferT } from '../order/command-ship-group-transfer.js';
-import { CommandShipGroupUnload, CommandShipGroupUnloadT } from './command-ship-group-unload.js';
+import { CommandShipGroupUnload, CommandShipGroupUnloadT } from '../order/command-ship-group-unload.js';
-import { CommandShipGroupUpgrade, CommandShipGroupUpgradeT } from './command-ship-group-upgrade.js';
+import { CommandShipGroupUpgrade, CommandShipGroupUpgradeT } from '../order/command-ship-group-upgrade.js';
 
 
 export class CommandItem implements flatbuffers.IUnpackableObject<CommandItemT> {

ui/frontend/src/proto/galaxy/fbs/order/command-payload.ts

@@ -2,29 +2,29 @@
 
 /* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
 
-import { CommandFleetMerge, CommandFleetMergeT } from './command-fleet-merge.js';
+import { CommandFleetMerge, CommandFleetMergeT } from '../order/command-fleet-merge.js';
-import { CommandFleetSend, CommandFleetSendT } from './command-fleet-send.js';
+import { CommandFleetSend, CommandFleetSendT } from '../order/command-fleet-send.js';
-import { CommandPlanetProduce, CommandPlanetProduceT } from './command-planet-produce.js';
+import { CommandPlanetProduce, CommandPlanetProduceT } from '../order/command-planet-produce.js';
-import { CommandPlanetRename, CommandPlanetRenameT } from './command-planet-rename.js';
+import { CommandPlanetRename, CommandPlanetRenameT } from '../order/command-planet-rename.js';
-import { CommandPlanetRouteRemove, CommandPlanetRouteRemoveT } from './command-planet-route-remove.js';
+import { CommandPlanetRouteRemove, CommandPlanetRouteRemoveT } from '../order/command-planet-route-remove.js';
-import { CommandPlanetRouteSet, CommandPlanetRouteSetT } from './command-planet-route-set.js';
+import { CommandPlanetRouteSet, CommandPlanetRouteSetT } from '../order/command-planet-route-set.js';
-import { CommandRaceQuit, CommandRaceQuitT } from './command-race-quit.js';
+import { CommandRaceQuit, CommandRaceQuitT } from '../order/command-race-quit.js';
-import { CommandRaceRelation, CommandRaceRelationT } from './command-race-relation.js';
+import { CommandRaceRelation, CommandRaceRelationT } from '../order/command-race-relation.js';
-import { CommandRaceVote, CommandRaceVoteT } from './command-race-vote.js';
+import { CommandRaceVote, CommandRaceVoteT } from '../order/command-race-vote.js';
-import { CommandScienceCreate, CommandScienceCreateT } from './command-science-create.js';
+import { CommandScienceCreate, CommandScienceCreateT } from '../order/command-science-create.js';
-import { CommandScienceRemove, CommandScienceRemoveT } from './command-science-remove.js';
+import { CommandScienceRemove, CommandScienceRemoveT } from '../order/command-science-remove.js';
-import { CommandShipClassCreate, CommandShipClassCreateT } from './command-ship-class-create.js';
+import { CommandShipClassCreate, CommandShipClassCreateT } from '../order/command-ship-class-create.js';
-import { CommandShipClassMerge, CommandShipClassMergeT } from './command-ship-class-merge.js';
+import { CommandShipClassMerge, CommandShipClassMergeT } from '../order/command-ship-class-merge.js';
-import { CommandShipClassRemove, CommandShipClassRemoveT } from './command-ship-class-remove.js';
+import { CommandShipClassRemove, CommandShipClassRemoveT } from '../order/command-ship-class-remove.js';
-import { CommandShipGroupBreak, CommandShipGroupBreakT } from './command-ship-group-break.js';
+import { CommandShipGroupBreak, CommandShipGroupBreakT } from '../order/command-ship-group-break.js';
-import { CommandShipGroupDismantle, CommandShipGroupDismantleT } from './command-ship-group-dismantle.js';
+import { CommandShipGroupDismantle, CommandShipGroupDismantleT } from '../order/command-ship-group-dismantle.js';
-import { CommandShipGroupJoinFleet, CommandShipGroupJoinFleetT } from './command-ship-group-join-fleet.js';
+import { CommandShipGroupJoinFleet, CommandShipGroupJoinFleetT } from '../order/command-ship-group-join-fleet.js';
-import { CommandShipGroupLoad, CommandShipGroupLoadT } from './command-ship-group-load.js';
+import { CommandShipGroupLoad, CommandShipGroupLoadT } from '../order/command-ship-group-load.js';
-import { CommandShipGroupMerge, CommandShipGroupMergeT } from './command-ship-group-merge.js';
+import { CommandShipGroupMerge, CommandShipGroupMergeT } from '../order/command-ship-group-merge.js';
-import { CommandShipGroupSend, CommandShipGroupSendT } from './command-ship-group-send.js';
+import { CommandShipGroupSend, CommandShipGroupSendT } from '../order/command-ship-group-send.js';
-import { CommandShipGroupTransfer, CommandShipGroupTransferT } from './command-ship-group-transfer.js';
+import { CommandShipGroupTransfer, CommandShipGroupTransferT } from '../order/command-ship-group-transfer.js';
-import { CommandShipGroupUnload, CommandShipGroupUnloadT } from './command-ship-group-unload.js';
+import { CommandShipGroupUnload, CommandShipGroupUnloadT } from '../order/command-ship-group-unload.js';
-import { CommandShipGroupUpgrade, CommandShipGroupUpgradeT } from './command-ship-group-upgrade.js';
+import { CommandShipGroupUpgrade, CommandShipGroupUpgradeT } from '../order/command-ship-group-upgrade.js';
 
 
 export enum CommandPayload {

ui/frontend/src/proto/galaxy/fbs/order/command-planet-produce.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { PlanetProduction } from './planet-production.js';
+import { PlanetProduction } from '../order/planet-production.js';
 
 
 export class CommandPlanetProduce implements flatbuffers.IUnpackableObject<CommandPlanetProduceT> {

ui/frontend/src/proto/galaxy/fbs/order/command-planet-route-remove.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { PlanetRouteLoadType } from './planet-route-load-type.js';
+import { PlanetRouteLoadType } from '../order/planet-route-load-type.js';
 
 
 export class CommandPlanetRouteRemove implements flatbuffers.IUnpackableObject<CommandPlanetRouteRemoveT> {

ui/frontend/src/proto/galaxy/fbs/order/command-planet-route-set.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { PlanetRouteLoadType } from './planet-route-load-type.js';
+import { PlanetRouteLoadType } from '../order/planet-route-load-type.js';
 
 
 export class CommandPlanetRouteSet implements flatbuffers.IUnpackableObject<CommandPlanetRouteSetT> {

ui/frontend/src/proto/galaxy/fbs/order/command-race-relation.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { Relation } from './relation.js';
+import { Relation } from '../order/relation.js';
 
 
 export class CommandRaceRelation implements flatbuffers.IUnpackableObject<CommandRaceRelationT> {

ui/frontend/src/proto/galaxy/fbs/order/command-ship-group-load.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ShipGroupCargo } from './ship-group-cargo.js';
+import { ShipGroupCargo } from '../order/ship-group-cargo.js';
 
 
 export class CommandShipGroupLoad implements flatbuffers.IUnpackableObject<CommandShipGroupLoadT> {

ui/frontend/src/proto/galaxy/fbs/order/command-ship-group-upgrade.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ShipGroupUpgradeTech } from './ship-group-upgrade-tech.js';
+import { ShipGroupUpgradeTech } from '../order/ship-group-upgrade-tech.js';
 
 
 export class CommandShipGroupUpgrade implements flatbuffers.IUnpackableObject<CommandShipGroupUpgradeT> {

ui/frontend/src/proto/galaxy/fbs/order/user-games-command.ts

@@ -5,7 +5,7 @@
 import * as flatbuffers from 'flatbuffers';
 
 import { UUID, UUIDT } from '../common/uuid.js';
-import { CommandItem, CommandItemT } from './command-item.js';
+import { CommandItem, CommandItemT } from '../order/command-item.js';
 
 
 export class UserGamesCommand implements flatbuffers.IUnpackableObject<UserGamesCommandT> {

ui/frontend/src/proto/galaxy/fbs/order/user-games-order-get-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { UserGamesOrder, UserGamesOrderT } from './user-games-order.js';
+import { UserGamesOrder, UserGamesOrderT } from '../order/user-games-order.js';
 
 
 export class UserGamesOrderGetResponse implements flatbuffers.IUnpackableObject<UserGamesOrderGetResponseT> {

ui/frontend/src/proto/galaxy/fbs/order/user-games-order-response.ts

@@ -5,7 +5,7 @@
 import * as flatbuffers from 'flatbuffers';
 
 import { UUID, UUIDT } from '../common/uuid.js';
-import { CommandItem, CommandItemT } from './command-item.js';
+import { CommandItem, CommandItemT } from '../order/command-item.js';
 
 
 export class UserGamesOrderResponse implements flatbuffers.IUnpackableObject<UserGamesOrderResponseT> {

ui/frontend/src/proto/galaxy/fbs/order/user-games-order.ts

@@ -5,7 +5,7 @@
 import * as flatbuffers from 'flatbuffers';
 
 import { UUID, UUIDT } from '../common/uuid.js';
-import { CommandItem, CommandItemT } from './command-item.js';
+import { CommandItem, CommandItemT } from '../order/command-item.js';
 
 
 export class UserGamesOrder implements flatbuffers.IUnpackableObject<UserGamesOrderT> {

ui/frontend/src/proto/galaxy/fbs/report.ts

@@ -2,6 +2,7 @@
 
 /* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
 
+export { BattleSummary, BattleSummaryT } from './report/battle-summary.js';
 export { Bombing, BombingT } from './report/bombing.js';
 export { GameReportRequest, GameReportRequestT } from './report/game-report-request.js';
 export { IncomingGroup, IncomingGroupT } from './report/incoming-group.js';

ui/frontend/src/proto/galaxy/fbs/report/battle-summary.ts

@@ -0,0 +1,104 @@
+// automatically generated by the FlatBuffers compiler, do not modify
+
+/* eslint-disable @typescript-eslint/no-unused-vars, @typescript-eslint/no-explicit-any, @typescript-eslint/no-non-null-assertion */
+
+import * as flatbuffers from 'flatbuffers';
+
+import { UUID, UUIDT } from '../common/uuid.js';
+
+
+export class BattleSummary implements flatbuffers.IUnpackableObject<BattleSummaryT> {
+  bb: flatbuffers.ByteBuffer|null = null;
+  bb_pos = 0;
+  __init(i:number, bb:flatbuffers.ByteBuffer):BattleSummary {
+  this.bb_pos = i;
+  this.bb = bb;
+  return this;
+}
+
+static getRootAsBattleSummary(bb:flatbuffers.ByteBuffer, obj?:BattleSummary):BattleSummary {
+  return (obj || new BattleSummary()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+static getSizePrefixedRootAsBattleSummary(bb:flatbuffers.ByteBuffer, obj?:BattleSummary):BattleSummary {
+  bb.setPosition(bb.position() + flatbuffers.SIZE_PREFIX_LENGTH);
+  return (obj || new BattleSummary()).__init(bb.readInt32(bb.position()) + bb.position(), bb);
+}
+
+id(obj?:UUID):UUID|null {
+  const offset = this.bb!.__offset(this.bb_pos, 4);
+  return offset ? (obj || new UUID()).__init(this.bb_pos + offset, this.bb!) : null;
+}
+
+planet():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 6);
+  return offset ? this.bb!.readUint64(this.bb_pos + offset) : BigInt('0');
+}
+
+shots():bigint {
+  const offset = this.bb!.__offset(this.bb_pos, 8);
+  return offset ? this.bb!.readUint64(this.bb_pos + offset) : BigInt('0');
+}
+
+static startBattleSummary(builder:flatbuffers.Builder) {
+  builder.startObject(3);
+}
+
+static addId(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset) {
+  builder.addFieldStruct(0, idOffset, 0);
+}
+
+static addPlanet(builder:flatbuffers.Builder, planet:bigint) {
+  builder.addFieldInt64(1, planet, BigInt('0'));
+}
+
+static addShots(builder:flatbuffers.Builder, shots:bigint) {
+  builder.addFieldInt64(2, shots, BigInt('0'));
+}
+
+static endBattleSummary(builder:flatbuffers.Builder):flatbuffers.Offset {
+  const offset = builder.endObject();
+  builder.requiredField(offset, 4) // id
+  return offset;
+}
+
+static createBattleSummary(builder:flatbuffers.Builder, idOffset:flatbuffers.Offset, planet:bigint, shots:bigint):flatbuffers.Offset {
+  BattleSummary.startBattleSummary(builder);
+  BattleSummary.addId(builder, idOffset);
+  BattleSummary.addPlanet(builder, planet);
+  BattleSummary.addShots(builder, shots);
+  return BattleSummary.endBattleSummary(builder);
+}
+
+unpack(): BattleSummaryT {
+  return new BattleSummaryT(
+    (this.id() !== null ? this.id()!.unpack() : null),
+    this.planet(),
+    this.shots()
+  );
+}
+
+
+unpackTo(_o: BattleSummaryT): void {
+  _o.id = (this.id() !== null ? this.id()!.unpack() : null);
+  _o.planet = this.planet();
+  _o.shots = this.shots();
+}
+}
+
+export class BattleSummaryT implements flatbuffers.IGeneratedObject {
+constructor(
+  public id: UUIDT|null = null,
+  public planet: bigint = BigInt('0'),
+  public shots: bigint = BigInt('0')
+){}
+
+
+pack(builder:flatbuffers.Builder): flatbuffers.Offset {
+  return BattleSummary.createBattleSummary(builder,
+    (this.id !== null ? this.id!.pack(builder) : 0),
+    this.planet,
+    this.shots
+  );
+}
+}

ui/frontend/src/proto/galaxy/fbs/report/local-group.ts

@@ -5,7 +5,7 @@
 import * as flatbuffers from 'flatbuffers';
 
 import { UUID, UUIDT } from '../common/uuid.js';
-import { TechEntry, TechEntryT } from './tech-entry.js';
+import { TechEntry, TechEntryT } from '../report/tech-entry.js';
 
 
 export class LocalGroup implements flatbuffers.IUnpackableObject<LocalGroupT> {

ui/frontend/src/proto/galaxy/fbs/report/other-group.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { TechEntry, TechEntryT } from './tech-entry.js';
+import { TechEntry, TechEntryT } from '../report/tech-entry.js';
 
 
 export class OtherGroup implements flatbuffers.IUnpackableObject<OtherGroupT> {

ui/frontend/src/proto/galaxy/fbs/report/report.ts

@@ -4,24 +4,24 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { UUID, UUIDT } from '../common/uuid.js';
+import { BattleSummary, BattleSummaryT } from '../report/battle-summary.js';
-import { Bombing, BombingT } from './bombing.js';
+import { Bombing, BombingT } from '../report/bombing.js';
-import { IncomingGroup, IncomingGroupT } from './incoming-group.js';
+import { IncomingGroup, IncomingGroupT } from '../report/incoming-group.js';
-import { LocalFleet, LocalFleetT } from './local-fleet.js';
+import { LocalFleet, LocalFleetT } from '../report/local-fleet.js';
-import { LocalGroup, LocalGroupT } from './local-group.js';
+import { LocalGroup, LocalGroupT } from '../report/local-group.js';
-import { LocalPlanet, LocalPlanetT } from './local-planet.js';
+import { LocalPlanet, LocalPlanetT } from '../report/local-planet.js';
-import { OtherGroup, OtherGroupT } from './other-group.js';
+import { OtherGroup, OtherGroupT } from '../report/other-group.js';
-import { OtherPlanet, OtherPlanetT } from './other-planet.js';
+import { OtherPlanet, OtherPlanetT } from '../report/other-planet.js';
-import { OtherScience, OtherScienceT } from './other-science.js';
+import { OtherScience, OtherScienceT } from '../report/other-science.js';
-import { OthersShipClass, OthersShipClassT } from './others-ship-class.js';
+import { OthersShipClass, OthersShipClassT } from '../report/others-ship-class.js';
-import { Player, PlayerT } from './player.js';
+import { Player, PlayerT } from '../report/player.js';
-import { Route, RouteT } from './route.js';
+import { Route, RouteT } from '../report/route.js';
-import { Science, ScienceT } from './science.js';
+import { Science, ScienceT } from '../report/science.js';
-import { ShipClass, ShipClassT } from './ship-class.js';
+import { ShipClass, ShipClassT } from '../report/ship-class.js';
-import { ShipProduction, ShipProductionT } from './ship-production.js';
+import { ShipProduction, ShipProductionT } from '../report/ship-production.js';
-import { UnidentifiedGroup, UnidentifiedGroupT } from './unidentified-group.js';
+import { UnidentifiedGroup, UnidentifiedGroupT } from '../report/unidentified-group.js';
-import { UnidentifiedPlanet, UnidentifiedPlanetT } from './unidentified-planet.js';
+import { UnidentifiedPlanet, UnidentifiedPlanetT } from '../report/unidentified-planet.js';
-import { UninhabitedPlanet, UninhabitedPlanetT } from './uninhabited-planet.js';
+import { UninhabitedPlanet, UninhabitedPlanetT } from '../report/uninhabited-planet.js';
 
 
 export class Report implements flatbuffers.IUnpackableObject<ReportT> {
@@ -136,9 +136,9 @@ otherShipClassLength():number {
   return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
 }
 
-battle(index: number, obj?:UUID):UUID|null {
+battle(index: number, obj?:BattleSummary):BattleSummary|null {
   const offset = this.bb!.__offset(this.bb_pos, 30);
-  return offset ? (obj || new UUID()).__init(this.bb!.__vector(this.bb_pos + offset) + index * 16, this.bb!) : null;
+  return offset ? (obj || new BattleSummary()).__init(this.bb!.__indirect(this.bb!.__vector(this.bb_pos + offset) + index * 4), this.bb!) : null;
 }
 
 battleLength():number {
@@ -386,8 +386,16 @@ static addBattle(builder:flatbuffers.Builder, battleOffset:flatbuffers.Offset) {
   builder.addFieldOffset(13, battleOffset, 0);
 }
 
+static createBattleVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
 static startBattleVector(builder:flatbuffers.Builder, numElems:number) {
-  builder.startVector(16, numElems, 8);
+  builder.startVector(4, numElems, 4);
 }
 
 static addBombing(builder:flatbuffers.Builder, bombingOffset:flatbuffers.Offset) {
@@ -641,7 +649,7 @@ unpack(): ReportT {
     this.bb!.createObjList<OtherScience, OtherScienceT>(this.otherScience.bind(this), this.otherScienceLength()),
     this.bb!.createObjList<ShipClass, ShipClassT>(this.localShipClass.bind(this), this.localShipClassLength()),
     this.bb!.createObjList<OthersShipClass, OthersShipClassT>(this.otherShipClass.bind(this), this.otherShipClassLength()),
-    this.bb!.createObjList<UUID, UUIDT>(this.battle.bind(this), this.battleLength()),
+    this.bb!.createObjList<BattleSummary, BattleSummaryT>(this.battle.bind(this), this.battleLength()),
     this.bb!.createObjList<Bombing, BombingT>(this.bombing.bind(this), this.bombingLength()),
     this.bb!.createObjList<IncomingGroup, IncomingGroupT>(this.incomingGroup.bind(this), this.incomingGroupLength()),
     this.bb!.createObjList<LocalPlanet, LocalPlanetT>(this.localPlanet.bind(this), this.localPlanetLength()),
@@ -672,7 +680,7 @@ unpackTo(_o: ReportT): void {
   _o.otherScience = this.bb!.createObjList<OtherScience, OtherScienceT>(this.otherScience.bind(this), this.otherScienceLength());
   _o.localShipClass = this.bb!.createObjList<ShipClass, ShipClassT>(this.localShipClass.bind(this), this.localShipClassLength());
   _o.otherShipClass = this.bb!.createObjList<OthersShipClass, OthersShipClassT>(this.otherShipClass.bind(this), this.otherShipClassLength());
-  _o.battle = this.bb!.createObjList<UUID, UUIDT>(this.battle.bind(this), this.battleLength());
+  _o.battle = this.bb!.createObjList<BattleSummary, BattleSummaryT>(this.battle.bind(this), this.battleLength());
   _o.bombing = this.bb!.createObjList<Bombing, BombingT>(this.bombing.bind(this), this.bombingLength());
   _o.incomingGroup = this.bb!.createObjList<IncomingGroup, IncomingGroupT>(this.incomingGroup.bind(this), this.incomingGroupLength());
   _o.localPlanet = this.bb!.createObjList<LocalPlanet, LocalPlanetT>(this.localPlanet.bind(this), this.localPlanetLength());
@@ -703,7 +711,7 @@ constructor(
   public otherScience: (OtherScienceT)[] = [],
   public localShipClass: (ShipClassT)[] = [],
   public otherShipClass: (OthersShipClassT)[] = [],
-  public battle: (UUIDT)[] = [],
+  public battle: (BattleSummaryT)[] = [],
   public bombing: (BombingT)[] = [],
   public incomingGroup: (IncomingGroupT)[] = [],
   public localPlanet: (LocalPlanetT)[] = [],
@@ -727,7 +735,7 @@ pack(builder:flatbuffers.Builder): flatbuffers.Offset {
   const otherScience = Report.createOtherScienceVector(builder, builder.createObjectOffsetList(this.otherScience));
   const localShipClass = Report.createLocalShipClassVector(builder, builder.createObjectOffsetList(this.localShipClass));
   const otherShipClass = Report.createOtherShipClassVector(builder, builder.createObjectOffsetList(this.otherShipClass));
-  const battle = builder.createStructOffsetList(this.battle, Report.startBattleVector);
+  const battle = Report.createBattleVector(builder, builder.createObjectOffsetList(this.battle));
   const bombing = Report.createBombingVector(builder, builder.createObjectOffsetList(this.bombing));
   const incomingGroup = Report.createIncomingGroupVector(builder, builder.createObjectOffsetList(this.incomingGroup));
   const localPlanet = Report.createLocalPlanetVector(builder, builder.createObjectOffsetList(this.localPlanet));

ui/frontend/src/proto/galaxy/fbs/report/route.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { RouteEntry, RouteEntryT } from './route-entry.js';
+import { RouteEntry, RouteEntryT } from '../report/route-entry.js';
 
 
 export class Route implements flatbuffers.IUnpackableObject<RouteT> {

ui/frontend/src/proto/galaxy/fbs/user/account-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { AccountView, AccountViewT } from './account-view.js';
+import { AccountView, AccountViewT } from '../user/account-view.js';
 
 
 export class AccountResponse implements flatbuffers.IUnpackableObject<AccountResponseT> {

ui/frontend/src/proto/galaxy/fbs/user/account-view.ts

@@ -4,9 +4,9 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ActiveLimit, ActiveLimitT } from './active-limit.js';
+import { ActiveLimit, ActiveLimitT } from '../user/active-limit.js';
-import { ActiveSanction, ActiveSanctionT } from './active-sanction.js';
+import { ActiveSanction, ActiveSanctionT } from '../user/active-sanction.js';
-import { EntitlementSnapshot, EntitlementSnapshotT } from './entitlement-snapshot.js';
+import { EntitlementSnapshot, EntitlementSnapshotT } from '../user/entitlement-snapshot.js';
 
 
 export class AccountView implements flatbuffers.IUnpackableObject<AccountViewT> {

ui/frontend/src/proto/galaxy/fbs/user/active-limit.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ActorRef, ActorRefT } from './actor-ref.js';
+import { ActorRef, ActorRefT } from '../user/actor-ref.js';
 
 
 export class ActiveLimit implements flatbuffers.IUnpackableObject<ActiveLimitT> {

ui/frontend/src/proto/galaxy/fbs/user/active-sanction.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ActorRef, ActorRefT } from './actor-ref.js';
+import { ActorRef, ActorRefT } from '../user/actor-ref.js';
 
 
 export class ActiveSanction implements flatbuffers.IUnpackableObject<ActiveSanctionT> {

ui/frontend/src/proto/galaxy/fbs/user/entitlement-snapshot.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ActorRef, ActorRefT } from './actor-ref.js';
+import { ActorRef, ActorRefT } from '../user/actor-ref.js';
 
 
 export class EntitlementSnapshot implements flatbuffers.IUnpackableObject<EntitlementSnapshotT> {

ui/frontend/src/proto/galaxy/fbs/user/error-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { ErrorBody, ErrorBodyT } from './error-body.js';
+import { ErrorBody, ErrorBodyT } from '../user/error-body.js';
 
 
 export class ErrorResponse implements flatbuffers.IUnpackableObject<ErrorResponseT> {

ui/frontend/src/proto/galaxy/fbs/user/list-my-sessions-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { DeviceSessionView, DeviceSessionViewT } from './device-session-view.js';
+import { DeviceSessionView, DeviceSessionViewT } from '../user/device-session-view.js';
 
 
 export class ListMySessionsResponse implements flatbuffers.IUnpackableObject<ListMySessionsResponseT> {

ui/frontend/src/proto/galaxy/fbs/user/revoke-all-my-sessions-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { DeviceSessionRevocationSummaryView, DeviceSessionRevocationSummaryViewT } from './device-session-revocation-summary-view.js';
+import { DeviceSessionRevocationSummaryView, DeviceSessionRevocationSummaryViewT } from '../user/device-session-revocation-summary-view.js';
 
 
 export class RevokeAllMySessionsResponse implements flatbuffers.IUnpackableObject<RevokeAllMySessionsResponseT> {

ui/frontend/src/proto/galaxy/fbs/user/revoke-my-session-response.ts

@@ -4,7 +4,7 @@
 
 import * as flatbuffers from 'flatbuffers';
 
-import { DeviceSessionView, DeviceSessionViewT } from './device-session-view.js';
+import { DeviceSessionView, DeviceSessionViewT } from '../user/device-session-view.js';
 
 
 export class RevokeMySessionResponse implements flatbuffers.IUnpackableObject<RevokeMySessionResponseT> {

ui/frontend/src/routes/games/[id]/battle/[[battleId]]/+page.svelte

@@ -1,6 +1,16 @@
 <script lang="ts">
 	import { page } from "$app/state";
 	import BattleView from "$lib/active-view/battle.svelte";
+
+	const turn = $derived.by(() => {
+		const raw = page.url.searchParams.get("turn");
+		const n = raw === null ? NaN : Number(raw);
+		return Number.isFinite(n) && n >= 0 ? Math.trunc(n) : 0;
+	});
 </script>
 
-<BattleView battleId={page.params.battleId ?? ""} />
+<BattleView
+	gameId={page.params.id ?? ""}
+	{turn}
+	battleId={page.params.battleId ?? ""}
+/>

ui/frontend/tests/battle-markers.test.ts

@@ -0,0 +1,190 @@
+// Phase 27 unit tests for battle and bombing map markers.
+
+import { describe, expect, it } from "vitest";
+
+import type { GameReport } from "../src/api/game-state";
+import {
+	battleMarkerStrokeWidth,
+	BATTLE_MARKER_COLOR,
+	BOMBING_MARKER_COLOR_DAMAGED,
+	BOMBING_MARKER_COLOR_WIPED,
+	buildBattleAndBombingMarkers,
+} from "../src/map/battle-markers";
+import { EMPTY_SHIP_GROUPS } from "./helpers/empty-ship-groups";
+
+describe("battleMarkerStrokeWidth", () => {
+	it("clamps to 1 px at one shot", () => {
+		expect(battleMarkerStrokeWidth(1)).toBe(1);
+	});
+
+	it("clamps to 5 px at 100 shots", () => {
+		expect(battleMarkerStrokeWidth(100)).toBe(5);
+	});
+
+	it("caps above 100 shots at 5 px", () => {
+		expect(battleMarkerStrokeWidth(250)).toBe(5);
+	});
+
+	it("interpolates linearly between 1 and 100 shots", () => {
+		// ~halfway: 50 shots → 1 + 49 * 4 / 99 ≈ 2.98
+		expect(battleMarkerStrokeWidth(50)).toBeCloseTo(2.98, 2);
+	});
+});
+
+function makeReport(overrides: Partial<GameReport>): GameReport {
+	return {
+		turn: 1,
+		mapWidth: 200,
+		mapHeight: 200,
+		planetCount: 0,
+		race: "Earthlings",
+		planets: [],
+		localShipClass: [],
+		routes: [],
+		localPlayerDrive: 0,
+		localPlayerWeapons: 0,
+		localPlayerShields: 0,
+		localPlayerCargo: 0,
+		...EMPTY_SHIP_GROUPS,
+		...overrides,
+	};
+}
+
+describe("buildBattleAndBombingMarkers", () => {
+	it("returns no primitives when both battles and bombings are empty", () => {
+		const report = makeReport({});
+		const out = buildBattleAndBombingMarkers(report);
+		expect(out.primitives).toEqual([]);
+		expect(out.lookup.size).toBe(0);
+	});
+
+	it("emits two yellow lines through opposite corners of the planet square per battle", () => {
+		const report = makeReport({
+			planets: [
+				{
+					number: 4,
+					name: "Test",
+					kind: "local",
+					x: 10,
+					y: 20,
+					size: 50,
+					resources: 0,
+					industryStockpile: 0,
+					materialsStockpile: 0,
+					population: 0,
+					colonists: 0,
+					industry: 0,
+					freeIndustry: 0,
+					production: "MAT",
+					owner: null,
+				},
+			],
+			battles: [
+				{ id: "11111111-1111-1111-1111-111111111111", planet: 4, shots: 100 },
+			],
+		});
+
+		const out = buildBattleAndBombingMarkers(report);
+		const lines = out.primitives.filter((p) => p.kind === "line");
+		expect(lines).toHaveLength(2);
+		// Same yellow colour, 5 px wide for a 100-shot battle.
+		for (const l of lines) {
+			expect(l.style.strokeColor).toBe(BATTLE_MARKER_COLOR);
+			expect(l.style.strokeWidthPx).toBe(5);
+		}
+		// First line: top-left → bottom-right corner of the planet square.
+		const [a, b] = lines as Array<typeof lines[number] & { x1: number; y1: number; x2: number; y2: number }>;
+		expect(a.x1).toBeLessThan(a.x2);
+		expect(a.y1).toBeLessThan(a.y2);
+		// Second line: top-right → bottom-left.
+		expect(b.x1).toBeLessThan(b.x2);
+		expect(b.y1).toBeGreaterThan(b.y2);
+	});
+
+	it("skips battles whose planet is not in the planet list", () => {
+		const report = makeReport({
+			battles: [
+				{ id: "11111111-1111-1111-1111-111111111111", planet: 99, shots: 4 },
+			],
+		});
+		const out = buildBattleAndBombingMarkers(report);
+		expect(out.primitives).toHaveLength(0);
+	});
+
+	it("emits one yellow ring per damaged bombing and red per wiped", () => {
+		const report = makeReport({
+			planets: [
+				{
+					number: 1,
+					name: "A",
+					kind: "local",
+					x: 1,
+					y: 2,
+					size: 50,
+					resources: 0,
+					industryStockpile: 0,
+					materialsStockpile: 0,
+					population: 0,
+					colonists: 0,
+					industry: 0,
+					freeIndustry: 0,
+					production: "MAT",
+					owner: null,
+				},
+				{
+					number: 2,
+					name: "B",
+					kind: "local",
+					x: 5,
+					y: 6,
+					size: 50,
+					resources: 0,
+					industryStockpile: 0,
+					materialsStockpile: 0,
+					population: 0,
+					colonists: 0,
+					industry: 0,
+					freeIndustry: 0,
+					production: "MAT",
+					owner: null,
+				},
+			],
+			bombings: [
+				{
+					planetNumber: 1,
+					planet: "A",
+					owner: "X",
+					attacker: "Y",
+					production: "MAT",
+					industry: 0,
+					population: 0,
+					colonists: 0,
+					industryStockpile: 0,
+					materialsStockpile: 0,
+					attackPower: 1,
+					wiped: false,
+				},
+				{
+					planetNumber: 2,
+					planet: "B",
+					owner: "X",
+					attacker: "Y",
+					production: "MAT",
+					industry: 0,
+					population: 0,
+					colonists: 0,
+					industryStockpile: 0,
+					materialsStockpile: 0,
+					attackPower: 1,
+					wiped: true,
+				},
+			],
+		});
+
+		const out = buildBattleAndBombingMarkers(report);
+		const rings = out.primitives.filter((p) => p.kind === "circle");
+		expect(rings).toHaveLength(2);
+		expect(rings[0].style.strokeColor).toBe(BOMBING_MARKER_COLOR_DAMAGED);
+		expect(rings[1].style.strokeColor).toBe(BOMBING_MARKER_COLOR_WIPED);
+	});
+});

ui/frontend/tests/battle-player.test.ts

@@ -0,0 +1,146 @@
+// Unit tests for the BattleViewer's pure helpers: radial layout and
+// the timeline frame builder. Both are pure functions and don't
+// require DOM mounting, so they exercise the playback semantics in
+// isolation.
+
+import { describe, expect, it } from "vitest";
+
+import type { BattleReport } from "../src/api/battle-fetch";
+import { layoutRaces } from "../src/lib/battle-player/radial-layout";
+import {
+	buildFrames,
+	buildGroupRaceMap,
+	normaliseGroups,
+} from "../src/lib/battle-player/timeline";
+
+describe("layoutRaces", () => {
+	const center = { x: 100, y: 100 };
+	const radius = 50;
+
+	it("returns no anchors for an empty input", () => {
+		expect(layoutRaces([], { center, radius })).toEqual([]);
+	});
+
+	it("places one race at the 12 o'clock position", () => {
+		const result = layoutRaces([0], { center, radius });
+		expect(result).toHaveLength(1);
+		expect(result[0].raceId).toBe(0);
+		expect(result[0].x).toBeCloseTo(center.x, 5);
+		expect(result[0].y).toBeCloseTo(center.y - radius, 5);
+	});
+
+	it("places two races at opposite poles (180° apart)", () => {
+		const result = layoutRaces([0, 1], { center, radius });
+		expect(result).toHaveLength(2);
+		expect(result[0].x).toBeCloseTo(center.x, 5);
+		expect(result[0].y).toBeCloseTo(center.y - radius, 5);
+		expect(result[1].x).toBeCloseTo(center.x, 5);
+		expect(result[1].y).toBeCloseTo(center.y + radius, 5);
+	});
+
+	it("places three races at 120° intervals", () => {
+		const result = layoutRaces([0, 1, 2], { center, radius });
+		expect(result).toHaveLength(3);
+		expect(result[0].angle).toBeCloseTo(-Math.PI / 2, 5);
+		expect(result[1].angle - result[0].angle).toBeCloseTo((2 * Math.PI) / 3, 5);
+		expect(result[2].angle - result[1].angle).toBeCloseTo((2 * Math.PI) / 3, 5);
+	});
+
+	it("preserves the input race order", () => {
+		const result = layoutRaces([7, 2, 5], { center, radius });
+		expect(result.map((a) => a.raceId)).toEqual([7, 2, 5]);
+	});
+});
+
+const TWO_RACE_BATTLE: BattleReport = {
+	id: "battle-1",
+	planet: 4,
+	planetName: "Test",
+	races: { "0": "race-A-uuid", "1": "race-B-uuid" },
+	ships: {
+		"10": {
+			race: "Alpha",
+			className: "Drone",
+			tech: {},
+			num: 3,
+			numLeft: 1,
+			loadType: "EMP",
+			loadQuantity: 0,
+			inBattle: true,
+		},
+		"20": {
+			race: "Beta",
+			className: "Spy",
+			tech: {},
+			num: 2,
+			numLeft: 0,
+			loadType: "EMP",
+			loadQuantity: 0,
+			inBattle: true,
+		},
+		"99": {
+			race: "Gamma",
+			className: "Observer",
+			tech: {},
+			num: 4,
+			numLeft: 4,
+			loadType: "EMP",
+			loadQuantity: 0,
+			inBattle: false,
+		},
+	},
+	protocol: [
+		{ a: 0, sa: 10, d: 1, sd: 20, x: false },
+		{ a: 1, sa: 20, d: 0, sd: 10, x: true },
+		{ a: 0, sa: 10, d: 1, sd: 20, x: true },
+		{ a: 0, sa: 10, d: 1, sd: 20, x: true },
+	],
+};
+
+describe("buildGroupRaceMap", () => {
+	it("derives group → race from protocol entries", () => {
+		const map = buildGroupRaceMap(TWO_RACE_BATTLE.protocol);
+		expect(map.get(10)).toBe(0);
+		expect(map.get(20)).toBe(1);
+	});
+});
+
+describe("normaliseGroups", () => {
+	it("returns only in-battle groups with race index attached", () => {
+		const groups = normaliseGroups(TWO_RACE_BATTLE);
+		expect(groups.map((g) => g.key).sort((a, b) => a - b)).toEqual([10, 20]);
+		expect(groups.every((g) => g.group.inBattle)).toBe(true);
+	});
+});
+
+describe("buildFrames", () => {
+	it("produces protocol.length + 1 frames", () => {
+		const frames = buildFrames(TWO_RACE_BATTLE);
+		expect(frames).toHaveLength(TWO_RACE_BATTLE.protocol.length + 1);
+	});
+
+	it("frame 0 reports initial ship counts and all active races", () => {
+		const [first] = buildFrames(TWO_RACE_BATTLE);
+		expect(first.shotIndex).toBe(0);
+		expect(first.lastAction).toBeNull();
+		expect(first.remaining.get(10)).toBe(3);
+		expect(first.remaining.get(20)).toBe(2);
+		expect(first.activeRaceIds).toEqual([0, 1]);
+	});
+
+	it("decrements destroyed defenders only on x === true", () => {
+		const frames = buildFrames(TWO_RACE_BATTLE);
+		// Action 1: x=false → no decrement on defender 20.
+		expect(frames[1].remaining.get(20)).toBe(2);
+		// Action 2: x=true → attacker is race 1 group 20, defender
+		// is race 0 group 10 → group 10 drops 3→2.
+		expect(frames[2].remaining.get(10)).toBe(2);
+	});
+
+	it("drops a race from activeRaceIds once its last in-battle group reaches zero", () => {
+		const frames = buildFrames(TWO_RACE_BATTLE);
+		// After the 4-th action both Beta ships have been destroyed.
+		expect(frames[4].remaining.get(20)).toBe(0);
+		expect(frames[4].activeRaceIds).toEqual([0]);
+	});
+});

ui/frontend/tests/e2e/battle-viewer.spec.ts

@@ -0,0 +1,252 @@
+// Phase 27 — Playwright coverage for the Battle Viewer.
+//
+// Mocks both the Connect-RPC `user.games.report` (so the report
+// renders battles + bombings) and the REST forwarder
+// `/api/v1/user/games/{game_id}/battles/{turn}/{battle_id}` (so the
+// viewer page loads its `BattleReport` without an engine).
+// Drives three flows:
+//   1. Reports view → click battle UUID → viewer renders.
+//   2. Playback controls: play / step back.
+//   3. Reports view → click bombing marker proxy → row scrolls
+//      (here approximated by clicking the link in Reports — the
+//      map e2e flow is exercised separately by `map-roundtrip`).
+
+import { fromJson, type JsonValue } from "@bufbuild/protobuf";
+import { ByteBuffer } from "flatbuffers";
+import { expect, test, type Page } from "@playwright/test";
+
+import { ExecuteCommandRequestSchema } from "../../src/proto/galaxy/gateway/v1/edge_gateway_pb";
+import { UUID } from "../../src/proto/galaxy/fbs/common";
+import { GameReportRequest } from "../../src/proto/galaxy/fbs/report";
+
+import {
+	buildOrderResponsePayload,
+	buildOrderGetResponsePayload,
+} from "./fixtures/order-fbs";
+import { buildMyGamesListPayload, type GameFixture } from "./fixtures/lobby-fbs";
+import { buildReportPayload } from "./fixtures/report-fbs";
+import { forgeExecuteCommandResponseJson } from "./fixtures/sign-response";
+
+const GAME_ID = "00000000-0000-0000-0000-000000000010";
+const BATTLE_ID = "11111111-1111-1111-1111-111111111111";
+const SESSION_ID = "device-session-battle";
+const RACE_A = "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa";
+const RACE_B = "bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb";
+
+const SAMPLE_BATTLE = {
+	id: BATTLE_ID,
+	planet: 1,
+	planetName: "Earth",
+	races: { "0": RACE_A, "1": RACE_B },
+	ships: {
+		"10": {
+			race: "Earthlings",
+			className: "Cruiser",
+			tech: { WEAPONS: 1 },
+			num: 3,
+			numLeft: 2,
+			loadType: "EMP",
+			loadQuantity: 0,
+			inBattle: true,
+		},
+		"20": {
+			race: "Bajori",
+			className: "Hawk",
+			tech: { SHIELDS: 1 },
+			num: 2,
+			numLeft: 0,
+			loadType: "EMP",
+			loadQuantity: 0,
+			inBattle: true,
+		},
+	},
+	protocol: [
+		{ a: 0, sa: 10, d: 1, sd: 20, x: false },
+		{ a: 0, sa: 10, d: 1, sd: 20, x: true },
+		{ a: 1, sa: 20, d: 0, sd: 10, x: true },
+		{ a: 0, sa: 10, d: 1, sd: 20, x: true },
+	],
+};
+
+async function mockGatewayAndBattle(page: Page): Promise<void> {
+	const game: GameFixture = {
+		gameId: GAME_ID,
+		gameName: "Phase 27 Game",
+		gameType: "private",
+		status: "running",
+		ownerUserId: "user-1",
+		minPlayers: 2,
+		maxPlayers: 8,
+		enrollmentEndsAtMs: BigInt(Date.now() + 86_400_000),
+		createdAtMs: BigInt(Date.now() - 86_400_000),
+		updatedAtMs: BigInt(Date.now()),
+		currentTurn: 1,
+	};
+
+	await page.route(
+		"**/galaxy.gateway.v1.EdgeGateway/ExecuteCommand",
+		async (route) => {
+			const reqText = route.request().postData();
+			if (reqText === null) {
+				await route.fulfill({ status: 400 });
+				return;
+			}
+			const req = fromJson(
+				ExecuteCommandRequestSchema,
+				JSON.parse(reqText) as JsonValue,
+			);
+
+			let resultCode = "ok";
+			let payload: Uint8Array;
+			switch (req.messageType) {
+				case "lobby.my.games.list":
+					payload = buildMyGamesListPayload([game]);
+					break;
+				case "user.games.report": {
+					GameReportRequest.getRootAsGameReportRequest(
+						new ByteBuffer(req.payloadBytes),
+					).gameId(new UUID());
+					payload = buildReportPayload({
+						turn: 1,
+						mapWidth: 4000,
+						mapHeight: 4000,
+						race: "Earthlings",
+						localPlanets: [
+							{
+								number: 1,
+								name: "Earth",
+								x: 2000,
+								y: 2000,
+								size: 1000,
+								resources: 5,
+								population: 4000,
+								industry: 3000,
+								capital: 0,
+								material: 0,
+								colonists: 100,
+								freeIndustry: 800,
+								production: "Cruiser",
+							},
+						],
+						battles: [{ id: BATTLE_ID, planet: 1, shots: 4 }],
+					});
+					break;
+				}
+				case "user.games.order":
+					payload = buildOrderResponsePayload(GAME_ID, [], Date.now());
+					break;
+				case "user.games.order.get":
+					payload = buildOrderGetResponsePayload(GAME_ID, [], Date.now(), false);
+					break;
+				default:
+					resultCode = "internal_error";
+					payload = new Uint8Array();
+			}
+
+			const body = await forgeExecuteCommandResponseJson({
+				requestId: req.requestId,
+				timestampMs: BigInt(Date.now()),
+				resultCode,
+				payloadBytes: payload,
+			});
+			await route.fulfill({
+				status: 200,
+				headers: { "content-type": "application/json" },
+				body,
+			});
+		},
+	);
+
+	await page.route(
+		`**/api/v1/user/games/${GAME_ID}/battles/1/${BATTLE_ID}`,
+		async (route) => {
+			await route.fulfill({
+				status: 200,
+				contentType: "application/json",
+				body: JSON.stringify(SAMPLE_BATTLE),
+			});
+		},
+	);
+
+	await page.route(
+		`**/api/v1/user/games/${GAME_ID}/battles/1/missing-uuid`,
+		async (route) => {
+			await route.fulfill({ status: 404 });
+		},
+	);
+}
+
+async function bootSession(page: Page): Promise<void> {
+	await page.goto("/__debug/store");
+	await expect(page.getByTestId("debug-store-ready")).toBeVisible();
+	await page.waitForFunction(() => window.__galaxyDebug?.ready === true);
+	await page.evaluate(() => window.__galaxyDebug!.clearSession());
+	await page.evaluate(
+		(id) => window.__galaxyDebug!.setDeviceSessionId(id),
+		SESSION_ID,
+	);
+}
+
+test.describe("Phase 27 battle viewer", () => {
+	test("Reports UUID link opens the battle viewer", async ({ page }, testInfo) => {
+		test.skip(
+			testInfo.project.name.startsWith("chromium-mobile"),
+			"desktop variant covers the link flow",
+		);
+
+		await mockGatewayAndBattle(page);
+		await bootSession(page);
+		await page.goto(`/games/${GAME_ID}/report`);
+
+		await expect(page.getByTestId("active-view-report")).toBeVisible();
+		const row = page.getByTestId("report-battle-row").first();
+		await expect(row).toBeVisible();
+		await row.click();
+
+		await expect(page).toHaveURL(
+			new RegExp(`/games/${GAME_ID}/battle/${BATTLE_ID}\\?turn=1`),
+		);
+		await expect(page.getByTestId("battle-viewer")).toBeVisible();
+		await expect(page.getByTestId("battle-scene")).toBeVisible();
+		await expect(page.getByTestId("battle-frame-index")).toContainText("0 / 4");
+	});
+
+	test("playback play + step back updates the frame counter", async ({
+		page,
+	}, testInfo) => {
+		test.skip(
+			testInfo.project.name.startsWith("chromium-mobile"),
+			"desktop variant covers playback controls",
+		);
+
+		await mockGatewayAndBattle(page);
+		await bootSession(page);
+		await page.goto(`/games/${GAME_ID}/battle/${BATTLE_ID}?turn=1`);
+
+		await expect(page.getByTestId("battle-viewer")).toBeVisible();
+		await expect(page.getByTestId("battle-frame-index")).toContainText("0 / 4");
+
+		// Step forward once → 1 / 4.
+		await page.getByTestId("battle-control-step-forward").click();
+		await expect(page.getByTestId("battle-frame-index")).toContainText("1 / 4");
+
+		// Step back to 0 / 4.
+		await page.getByTestId("battle-control-step-back").click();
+		await expect(page.getByTestId("battle-frame-index")).toContainText("0 / 4");
+	});
+
+	test("missing battle id surfaces the not-found state", async ({
+		page,
+	}, testInfo) => {
+		test.skip(
+			testInfo.project.name.startsWith("chromium-mobile"),
+			"desktop variant covers the negative path",
+		);
+
+		await mockGatewayAndBattle(page);
+		await bootSession(page);
+		await page.goto(`/games/${GAME_ID}/battle/missing-uuid?turn=1`);
+
+		await expect(page.getByTestId("battle-not-found")).toBeVisible();
+	});
+});

ui/frontend/tests/e2e/fixtures/report-fbs.ts

@@ -19,6 +19,7 @@ import { Builder } from "flatbuffers";
 
 import { UUID } from "../../../src/proto/galaxy/fbs/common";
 import {
+	BattleSummary,
 	Bombing,
 	LocalPlanet,
 	OtherPlanet,
@@ -108,6 +109,12 @@ export interface OtherShipClassFixture extends ShipClassFixture {
 	mass?: number;
 }
 
+export interface BattleSummaryFixture {
+	id: string;
+	planet: number;
+	shots: number;
+}
+
 export interface BombingFixture {
 	planetNumber: number;
 	planet: string;
@@ -149,7 +156,7 @@ export interface ReportFixture {
 	myVoteFor?: string;
 	otherScience?: OtherScienceFixture[];
 	otherShipClass?: OtherShipClassFixture[];
-	battles?: string[];
+	battles?: BattleSummaryFixture[];
 	bombings?: BombingFixture[];
 	shipProductions?: ShipProductionFixture[];
 }
@@ -397,17 +404,22 @@ export function buildReportPayload(fixture: ReportFixture): Uint8Array {
 		shipProductionOffsets.length === 0
 			? null
 			: Report.createShipProductionVector(builder, shipProductionOffsets);
-	// `battle` is a struct vector (16 bytes per UUID, alignment 8), so
+	// Phase 27 — `battle` carries `BattleSummary` tables, each with
-	// it uses the start/inline-write/end pattern rather than a typical
+	// an inline `id:UUID` struct plus `planet` and `shots` slots.
-	// offset-list helper. Iterating in reverse matches the FlatBuffers
-	// convention that the vector is built end-to-start.
 	const battleVec = (() => {
-		const ids = fixture.battles ?? [];
+		const summaries = fixture.battles ?? [];
-		if (ids.length === 0) return null;
+		if (summaries.length === 0) return null;
-		Report.startBattleVector(builder, ids.length);
+		const offsets = summaries.map((s) => {
-		for (let i = ids.length - 1; i >= 0; i--) {
+			const [hi, lo] = uuidToHiLo(s.id);
-			const [hi, lo] = uuidToHiLo(ids[i]!);
+			BattleSummary.startBattleSummary(builder);
-			UUID.createUUID(builder, hi, lo);
+			BattleSummary.addId(builder, UUID.createUUID(builder, hi, lo));
+			BattleSummary.addPlanet(builder, BigInt(s.planet));
+			BattleSummary.addShots(builder, BigInt(s.shots));
+			return BattleSummary.endBattleSummary(builder);
+		});
+		Report.startBattleVector(builder, offsets.length);
+		for (let i = offsets.length - 1; i >= 0; i--) {
+			builder.addOffset(offsets[i]);
 		}
 		return builder.endVector();
 	})();

ui/frontend/tests/e2e/report-sections.spec.ts

@@ -151,7 +151,7 @@ async function mockGateway(page: Page): Promise<void> {
 							{ race: "Andori", name: "Spear", drive: 8, armament: 4, weapons: 6, shields: 3, cargo: 1, mass: 90 },
 							{ race: "Bajori", name: "Hawk", drive: 12, armament: 1, weapons: 4, shields: 2, cargo: 0, mass: 75 },
 						],
-						battles: [BATTLE_ID],
+						battles: [{ id: BATTLE_ID, planet: 1, shots: 12 }],
 						bombings: [
 							{ planetNumber: 1, planet: "Earth", owner: "Earthlings", attacker: "Bajori", production: "Cruiser", industry: 500, population: 200, colonists: 12, capital: 30, material: 5, attackPower: 250, wiped: false },
 							{ planetNumber: 99, planet: "DW-99", owner: "Earthlings", attacker: "Bajori", production: "Dron", industry: 0, population: 0, colonists: 0, capital: 0, material: 0, attackPower: 800, wiped: true },

ui/frontend/tests/game-shell-stubs.test.ts

@@ -76,18 +76,30 @@ describe("active-view stubs", () => {
 		);
 	});
 
-	test("battle stub stamps the battleId on the host element", () => {
+	test("battle view stamps the battleId and renders the back-to-map link", () => {
-		const ui = render(BattleView, { props: { battleId: "b-42" } });
+		// Phase 27 replaces the Phase 10 stub with the Battle Viewer
+		// wrapper. The wrapper mounts the loading copy until the
+		// fetcher resolves (component test runs in jsdom without a
+		// network); the back buttons and the data-battle-id stamp are
+		// rendered unconditionally so the orchestrator scaffold is the
+		// stable hook the active-view shell relies on.
+		const ui = render(BattleView, {
+			props: { gameId: "synthetic-test", turn: 0, battleId: "b-42" },
+		});
 		const node = ui.getByTestId("active-view-battle");
 		expect(node).toHaveAttribute("data-battle-id", "b-42");
-		expect(node).toHaveTextContent("battle log");
+		expect(ui.getByTestId("battle-back-to-map")).toBeInTheDocument();
+		expect(ui.getByTestId("battle-back-to-report")).toBeInTheDocument();
 	});
 
-	test("battle stub accepts an empty battleId for the list URL", () => {
+	test("battle view surfaces the not-found state for an empty battleId", () => {
-		const ui = render(BattleView, { props: { battleId: "" } });
+		const ui = render(BattleView, {
+			props: { gameId: "synthetic-test", turn: 0, battleId: "" },
+		});
 		expect(ui.getByTestId("active-view-battle")).toHaveAttribute(
 			"data-battle-id",
 			"",
 		);
+		expect(ui.getByTestId("battle-not-found")).toBeInTheDocument();
 	});
 });

ui/frontend/tests/helpers/empty-ship-groups.ts

@@ -8,6 +8,7 @@
 // every spec to enumerate the full GameReport surface.
 
 import type {
+	ReportBattle,
 	ReportBombing,
 	ReportIncomingShipGroup,
 	ReportLocalFleet,
@@ -36,6 +37,7 @@ export const EMPTY_SHIP_GROUPS: {
 	players: ReportPlayer[];
 	otherScience: ReportOtherScience[];
 	otherShipClass: ReportOtherShipClass[];
+	battles: ReportBattle[];
 	battleIds: string[];
 	bombings: ReportBombing[];
 	shipProductions: ReportShipProduction[];
@@ -53,6 +55,7 @@ export const EMPTY_SHIP_GROUPS: {
 	players: [],
 	otherScience: [],
 	otherShipClass: [],
+	battles: [],
 	battleIds: [],
 	bombings: [],
 	shipProductions: [],

ui/frontend/tests/pending-send-routes.test.ts

@@ -75,6 +75,7 @@ function makeReport(
 		players: [],
 		otherScience: [],
 		otherShipClass: [],
+		battles: [],
 		battleIds: [],
 		bombings: [],
 		shipProductions: [],