diff --git a/app/game-api/src/battleSim/environment.ts b/app/game-api/src/battleSim/environment.ts
index 3cea4877..6a6056b6 100644
--- a/app/game-api/src/battleSim/environment.ts
+++ b/app/game-api/src/battleSim/environment.ts
@@ -90,6 +90,9 @@ export interface BattleSimEnvironment {
     scenarioEffect: ScenarioEffectKey | null;
 }
 
+export const buildBattleSimSeedBase = (request: Pick<BattleSimRequestPayload, 'seed'>): string | null =>
+    request.seed ? null : randomUUID();
+
 export const buildBattleSimEnvironment = async (
     worldState: WorldStateRow,
     profileFallback: string
@@ -138,10 +141,11 @@ export const buildBattleSimJobPayload = async (
     profileFallback: string
 ): Promise<BattleSimJobPayload> => {
     const environment = await buildBattleSimEnvironment(worldState, profileFallback);
+    const seedBase = buildBattleSimSeedBase(request);
 
     return {
         ...request,
-        seeds: request.seed ? [] : Array.from({ length: request.repeatCnt }, () => randomUUID()),
+        ...(seedBase ? { seedBase } : {}),
         unitSet: environment.unitSet,
         config: environment.config,
         time: {
diff --git a/app/game-api/src/router/battle/index.ts b/app/game-api/src/router/battle/index.ts
index 56daf92f..45be9ebb 100644
--- a/app/game-api/src/router/battle/index.ts
+++ b/app/game-api/src/router/battle/index.ts
@@ -11,7 +11,11 @@ import {
     readOnlyAuthedProcedure,
     router,
 } from '../../trpc.js';
-import { buildBattleSimEnvironment, buildBattleSimJobPayload } from '../../battleSim/environment.js';
+import {
+    buildBattleSimEnvironment,
+    buildBattleSimJobPayload,
+    buildBattleSimSeedBase,
+} from '../../battleSim/environment.js';
 import { zBattleSimJobId, zBattleSimRequest } from '../../battleSim/schema.js';
 import {
     BATTLE_SIM_CITY_LEVELS,
@@ -62,17 +66,9 @@ const resolveDexValue = (meta: Record<string, unknown>, key: string): number =>
 };
 
 export const battleRouter = router({
-    prepareSimulation: accessReadOnlyAuthedInputProcedure(zBattleSimRequest).mutation(async ({ ctx, input }) => {
-        const worldState = await ctx.db.worldState.findFirst();
-        if (!worldState) {
-            throw new TRPCError({
-                code: 'PRECONDITION_FAILED',
-                message: 'World state is not initialized.',
-            });
-        }
-
-        return buildBattleSimJobPayload(worldState, input, ctx.profile.id);
-    }),
+    prepareSimulation: accessReadOnlyAuthedInputProcedure(zBattleSimRequest).mutation(({ input }) => ({
+        seedBase: buildBattleSimSeedBase(input),
+    })),
     simulate: accessReadOnlyAuthedInputProcedure(zBattleSimRequest).mutation(async ({ ctx, input }) => {
         const worldState = await ctx.db.worldState.findFirst();
         if (!worldState) {
@@ -104,30 +100,15 @@ export const battleRouter = router({
         const environment = await buildBattleSimEnvironment(worldState, ctx.profile.id);
         const [traits, items] = await Promise.all([loadBattleSimTraitOptions(), loadBattleSimItemOptions()]);
 
-        const crewTypes = (environment.unitSet.crewTypes ?? [])
-            .filter((crewType) => crewType.armType !== environment.config.armTypes.castle)
-            .map((crewType) => ({
-                id: crewType.id,
-                name: crewType.name,
-                armType: crewType.armType,
-            }));
-
         return {
             world: {
                 startYear: environment.startYear,
                 currentYear: worldState.currentYear,
                 currentMonth: worldState.currentMonth,
             },
-            config: {
-                maxTrainByWar: environment.config.maxTrainByWar,
-                maxAtmosByWar: environment.config.maxAtmosByWar,
-                maxTrainByCommand: environment.config.maxTrainByCommand,
-                maxAtmosByCommand: environment.config.maxAtmosByCommand,
-            },
-            unitSet: {
-                defaultCrewTypeId: environment.unitSet.defaultCrewTypeId ?? crewTypes[0]?.id ?? 0,
-                crewTypes,
-            },
+            config: environment.config,
+            unitSet: environment.unitSet,
+            scenarioEffect: environment.scenarioEffect,
             nationTypes: traits.nationTypes,
             eventDomesticTraits: traits.eventDomesticTraits,
             warTraits: traits.warTraits,
diff --git a/app/game-api/test/battleSimProcessor.test.ts b/app/game-api/test/battleSimProcessor.test.ts
index d569422a..8bead300 100644
--- a/app/game-api/test/battleSimProcessor.test.ts
+++ b/app/game-api/test/battleSimProcessor.test.ts
@@ -266,6 +266,7 @@ describe('battle sim processor', () => {
         const firstPayload = buildPayload('battle');
         delete firstPayload.seed;
         firstPayload.repeatCnt = 2;
+        firstPayload.seedBase = 'ignored-while-legacy-seeds-exist';
         firstPayload.seeds = ['server-repeat-0', 'server-repeat-1'];
         const secondPayload = structuredClone(firstPayload);
         const observedSeeds: string[] = [];
@@ -283,6 +284,30 @@ describe('battle sim processor', () => {
         expect(observedSeeds).toEqual(['server-repeat-0', 'server-repeat-1']);
     });
 
+    it('expands one seed base deterministically without a repeated seed array', () => {
+        const firstPayload = buildPayload('battle');
+        delete firstPayload.seed;
+        firstPayload.repeatCnt = 2;
+        firstPayload.seedBase = 'server-root';
+        const secondPayload = structuredClone(firstPayload);
+        const observedSeeds: string[] = [];
+
+        const first = processBattleSimJob(firstPayload, {
+            rngFactory: (seed) => {
+                observedSeeds.push(seed);
+                return new RandUtil(LiteHashDRBG.build(seed));
+            },
+        });
+        const second = processBattleSimJob(secondPayload);
+
+        expect(first).toEqual(second);
+        expect(first.repeatCnt).toBe(2);
+        expect(observedSeeds).toEqual([
+            'str(11,server-root)|str(16,battle-simulator)|int(0)',
+            'str(11,server-root)|str(16,battle-simulator)|int(1)',
+        ]);
+    });
+
     it('returns the fixed defender ID order for reorder action', () => {
         const payload = buildPayload('reorder');
         const result = processBattleSimJob(payload);
diff --git a/app/game-api/test/battleSimRouter.test.ts b/app/game-api/test/battleSimRouter.test.ts
index 7d60b37c..a30b9b4d 100644
--- a/app/game-api/test/battleSimRouter.test.ts
+++ b/app/game-api/test/battleSimRouter.test.ts
@@ -257,7 +257,7 @@ const buildContext = (options: {
 };
 
 describe('battle router orchestration', () => {
-    it('prepares the authoritative browser-worker payload without queuing server work', async () => {
+    it('returns one repeat seed base without reading world state or echoing the browser-worker payload', async () => {
         const battleSim = new QueuedBattleSimTransport();
         const state: WorldStateRow = {
             id: 1,
@@ -269,26 +269,29 @@ describe('battle router orchestration', () => {
             meta: { scenarioMeta: { startYear: 180 } },
             updatedAt: new Date('2026-01-01T00:00:00Z'),
         };
-        const caller = appRouter.createCaller(buildContext({ state, battleSim }));
+        let worldStateReads = 0;
+        const db = {
+            worldState: {
+                findFirst: async () => {
+                    worldStateReads += 1;
+                    return state;
+                },
+            },
+        } as unknown as DatabaseClient;
+        const caller = appRouter.createCaller(buildContext({ state, battleSim, db }));
         const request = { ...buildBattleRequest(), repeatCnt: 1000 };
         delete (request as Partial<typeof request>).seed;
 
         const prepared = await caller.battle.prepareSimulation(request);
 
-        expect(prepared).toMatchObject({
-            action: 'battle',
-            repeatCnt: 1000,
-            scenarioEffect: 'event_MoreEffect',
-            time: { year: 200, month: 1, startYear: 180 },
-            config: { armPerPhase: 500, maxTrainByWar: 110, maxAtmosByWar: 150 },
-        });
-        expect(prepared.unitSet.crewTypes?.length).toBeGreaterThan(0);
-        expect(prepared.seeds).toHaveLength(1000);
-        expect(new Set(prepared.seeds).size).toBe(1000);
+        expect(prepared.seedBase).toMatch(/^[0-9a-f-]{36}$/u);
+        expect(Object.keys(prepared)).toEqual(['seedBase']);
+        expect(Buffer.byteLength(JSON.stringify(prepared))).toBeLessThan(128);
+        expect(worldStateReads).toBe(0);
         expect(battleSim.simulateCalls).toBe(0);
     });
 
-    it('does not allocate repeat seeds when the client supplies a fixed seed', async () => {
+    it('does not allocate a repeat seed base when the client supplies a fixed seed', async () => {
         const battleSim = new QueuedBattleSimTransport();
         const state: WorldStateRow = {
             id: 1,
@@ -304,11 +307,48 @@ describe('battle router orchestration', () => {
 
         const prepared = await caller.battle.prepareSimulation(buildBattleRequest());
 
-        expect(prepared.seed).toBe('test-seed');
-        expect(prepared.seeds).toEqual([]);
+        expect(prepared).toEqual({ seedBase: null });
         expect(battleSim.simulateCalls).toBe(0);
     });
 
+    it('loads the full authoritative execution context once with the simulator form options', async () => {
+        const battleSim = new QueuedBattleSimTransport();
+        const state: WorldStateRow = {
+            id: 1,
+            scenarioCode: 'default',
+            currentYear: 200,
+            currentMonth: 1,
+            tickSeconds: 600,
+            config: { environment: { scenarioEffect: 'event_MoreEffect' } },
+            meta: { scenarioMeta: { startYear: 180 } },
+            updatedAt: new Date('2026-01-01T00:00:00Z'),
+        };
+        let worldStateReads = 0;
+        const db = {
+            worldState: {
+                findFirst: async () => {
+                    worldStateReads += 1;
+                    return state;
+                },
+            },
+        } as unknown as DatabaseClient;
+        const caller = appRouter.createCaller(buildContext({ state, battleSim, db }));
+
+        const context = await caller.battle.getSimulatorContext();
+
+        expect(context).toMatchObject({
+            world: { startYear: 180, currentYear: 200, currentMonth: 1 },
+            scenarioEffect: 'event_MoreEffect',
+            config: { armPerPhase: 500, maxTrainByWar: 110, maxAtmosByWar: 150 },
+        });
+        expect(context.unitSet.crewTypes?.[0]).toMatchObject({
+            id: expect.any(Number),
+            attack: expect.any(Number),
+            defence: expect.any(Number),
+        });
+        expect(worldStateReads).toBe(1);
+    });
+
     it('rejects the neutral storage nation type before preparing or queuing a simulation', async () => {
         const battleSim = new QueuedBattleSimTransport();
         const state: WorldStateRow = {
@@ -360,6 +400,40 @@ describe('battle router orchestration', () => {
         expect(completed.payload?.result).toBe(true);
     });
 
+    it('queues one seed base instead of 1000 repeated UUID strings for the server fallback', async () => {
+        const battleSim = new QueuedBattleSimTransport();
+        const state: WorldStateRow = {
+            id: 1,
+            scenarioCode: 'default',
+            currentYear: 200,
+            currentMonth: 1,
+            tickSeconds: 600,
+            config: {},
+            meta: {},
+            updatedAt: new Date('2026-01-01T00:00:00Z'),
+        };
+        const caller = appRouter.createCaller(buildContext({ state, battleSim }));
+        const request = { ...buildBattleRequest(), repeatCnt: 1000 };
+        delete (request as Partial<typeof request>).seed;
+
+        await caller.battle.simulate(request);
+
+        const payload = battleSim.lastPayload;
+        if (!payload) {
+            throw new Error('Expected the fallback transport payload.');
+        }
+        expect(payload?.seedBase).toMatch(/^[0-9a-f-]{36}$/u);
+        expect(payload?.seeds).toBeUndefined();
+        const legacyPayload = {
+            ...payload,
+            seedBase: undefined,
+            seeds: Array.from({ length: 1000 }, (_, index) => String(index).padStart(36, '0')),
+        };
+        expect(Buffer.byteLength(JSON.stringify(payload))).toBeLessThan(
+            Buffer.byteLength(JSON.stringify(legacyPayload)) * 0.45
+        );
+    });
+
     it('uses the stored scenario effect even when a client sends a same-named field', async () => {
         const battleSim = new QueuedBattleSimTransport();
         const state: WorldStateRow = {
@@ -435,8 +509,7 @@ describe('battle router orchestration', () => {
             buildContext({ state, battleSim, userId: 'user-without-general', db })
         );
         await expect(noGeneralUser.battle.prepareSimulation(buildBattleRequest())).resolves.toMatchObject({
-            action: 'battle',
-            seed: 'test-seed',
+            seedBase: null,
         });
         await expect(noGeneralUser.battle.simulate(buildBattleRequest())).resolves.toMatchObject({
             status: 'queued',
diff --git a/app/game-frontend/e2e/battleSimulator.spec.ts b/app/game-frontend/e2e/battleSimulator.spec.ts
index 64207b26..4e1833b2 100644
--- a/app/game-frontend/e2e/battleSimulator.spec.ts
+++ b/app/game-frontend/e2e/battleSimulator.spec.ts
@@ -43,7 +43,7 @@ const readImage = async (relative: string): Promise<Buffer> => {
     throw new Error(`Reference image not found: ${relative}`);
 };
 
-const simulatorOptions = {
+const simulatorFormOptions = {
     world: { startYear: 190, currentYear: 205, currentMonth: 8 },
     config: {
         maxTrainByWar: 120,
@@ -138,6 +138,16 @@ const engineConfig: BattleSimJobPayload['config'] = {
     },
 };
 
+const simulatorOptions = {
+    ...simulatorFormOptions,
+    config: {
+        ...engineConfig,
+        ...simulatorFormOptions.config,
+    },
+    unitSet: engineUnitSet,
+    scenarioEffect: null,
+};
+
 const generalMe = {
     general: {
         id: 7,
@@ -206,6 +216,7 @@ type Fixture = {
     requests: string[];
     preparedPayloads: BattleSimJobPayload[];
     serverResults: BattleSimResultPayload[];
+    prepareResponseBytes?: number[];
 };
 
 const readOperationInput = (
@@ -294,26 +305,29 @@ const installApi = async (page: Page, fixture: Fixture) => {
                     operations.length,
                     operationIndex
                 ) as BattleSimRequestPayload;
+                const seedBase = request.seed ? null : 'playwright-repeat-seed';
                 const prepared: BattleSimJobPayload = {
                     ...request,
-                    seeds: request.seed
-                        ? []
-                        : Array.from({ length: request.repeatCnt }, (_, index) => `playwright-repeat-${index}`),
+                    ...(seedBase ? { seedBase } : {}),
                     unitSet: engineUnitSet,
-                    config: engineConfig,
+                    config: simulatorOptions.config,
                     time: { year: request.year, month: request.month, startYear: 190 },
                     scenarioEffect: null,
                 };
                 fixture.preparedPayloads.push(prepared);
                 fixture.serverResults.push(processBattleSimJob(structuredClone(prepared)));
-                return response(prepared);
+                return response({ seedBase });
             }
             return errorResponse(operation, `Unhandled battle simulator fixture operation: ${operation}`);
         });
+        const body = JSON.stringify(results);
+        if (operations.includes('battle.prepareSimulation')) {
+            fixture.prepareResponseBytes?.push(Buffer.byteLength(body));
+        }
         await route.fulfill({
             status: 200,
             contentType: 'application/json',
-            body: JSON.stringify(results),
+            body,
         });
     });
 };
@@ -351,6 +365,7 @@ test('operates independent/game presets, imports my general, and renders battle
         requests: [],
         preparedPayloads: [],
         serverResults: [],
+        prepareResponseBytes: [],
     };
     await installApi(page, fixture);
     await page.setViewportSize({ width: 1280, height: 900 });
@@ -398,6 +413,8 @@ test('operates independent/game presets, imports my general, and renders battle
     }
     expect(fixture.requests).not.toContain('battle.simulate');
     expect(fixture.requests).not.toContain('battle.getSimulation');
+    expect(fixture.prepareResponseBytes).toEqual([expect.any(Number)]);
+    expect(fixture.prepareResponseBytes?.every((bytes) => bytes < 128)).toBe(true);
     expect(fixture.preparedPayloads[0]).toMatchObject({
         attackerGeneral: { special: 'che_event_신산' },
     });
@@ -439,6 +456,7 @@ test('keeps simulation available without a game general and preserves input afte
         requests: [],
         preparedPayloads: [],
         serverResults: [],
+        prepareResponseBytes: [],
     };
     await installApi(page, fixture);
     await page.setViewportSize({ width: 500, height: 900 });
@@ -453,6 +471,7 @@ test('keeps simulation available without a game general and preserves input afte
     await page.getByRole('button', { name: '전투', exact: true }).click();
     await expect(page.getByText('시뮬레이터 입력 오류')).toBeVisible();
     await expect(page.getByLabel('시드')).toHaveValue('keep-this-seed');
+    await expect(page.getByTestId('game-toast').filter({ hasText: '전투를 진행 중입니다.' })).toHaveCount(0);
 
     fixture.prepareDelayMs = 1_500;
     await page.getByRole('button', { name: '전투', exact: true }).click();
@@ -493,6 +512,7 @@ test('runs 1000 battles in the Chromium worker and matches the Node processor ex
         requests: [],
         preparedPayloads: [],
         serverResults: [],
+        prepareResponseBytes: [],
     };
     await installApi(page, fixture);
     await page.setViewportSize({ width: 1280, height: 900 });
@@ -520,8 +540,8 @@ test('runs 1000 battles in the Chromium worker and matches the Node processor ex
     await expect(progressToast).toHaveCount(0, { timeout: 30_000 });
 
     expect(fixture.preparedPayloads).toHaveLength(1);
-    expect(fixture.preparedPayloads[0]?.seeds).toHaveLength(1000);
-    expect(new Set(fixture.preparedPayloads[0]?.seeds).size).toBe(1000);
+    expect(fixture.preparedPayloads[0]?.seedBase).toBe('playwright-repeat-seed');
+    expect(fixture.preparedPayloads[0]?.seeds).toBeUndefined();
     expect(await readBrowserWorkerResult(page, 0)).toEqual(fixture.serverResults[0]);
     const battleSummary = page.locator('[data-parity-id="battle-summary"]');
     await expect(battleSummary.locator('tr').filter({ hasText: '전투 횟수' }).locator('td')).toHaveText('1,000');
@@ -531,6 +551,8 @@ test('runs 1000 battles in the Chromium worker and matches the Node processor ex
     expect(fixture.preparedPayloads[0]?.attackerGeneral.turntime).toMatch(/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/u);
     expect(fixture.requests).not.toContain('battle.simulate');
     expect(fixture.requests).not.toContain('battle.getSimulation');
+    expect(fixture.prepareResponseBytes).toEqual([expect.any(Number)]);
+    expect(fixture.prepareResponseBytes?.[0]).toBeLessThan(128);
     const workerUrls = await page.evaluate(() => {
         const testWindow = window as unknown as { __battleWorkerUrls?: string[] };
         return testWindow.__battleWorkerUrls ?? [];
diff --git a/app/game-frontend/src/components/battle/BattleGeneralCard.vue b/app/game-frontend/src/components/battle/BattleGeneralCard.vue
index 379f7c19..1f35164b 100644
--- a/app/game-frontend/src/components/battle/BattleGeneralCard.vue
+++ b/app/game-frontend/src/components/battle/BattleGeneralCard.vue
@@ -4,6 +4,7 @@ import type { BattleSimOptions, GeneralDraft } from '../../utils/battleSimulator
 
 interface Props {
     options: BattleSimOptions;
+    crewTypes: Array<{ id: number; name: string; armType: number }>;
     mode: 'attacker' | 'defender';
     title: string;
     canImportServer: boolean;
@@ -175,7 +176,7 @@ const officerLevelOptions = [
                 <label class="field">
                     <span>병종</span>
                     <select v-model.number="general.crewtype">
-                        <option v-for="crew in options.unitSet.crewTypes" :key="crew.id" :value="crew.id">
+                        <option v-for="crew in crewTypes" :key="crew.id" :value="crew.id">
                             {{ crew.name }}
                         </option>
                     </select>
diff --git a/app/game-frontend/src/utils/battleSimulatorTypes.ts b/app/game-frontend/src/utils/battleSimulatorTypes.ts
index e16ff60e..19de43a1 100644
--- a/app/game-frontend/src/utils/battleSimulatorTypes.ts
+++ b/app/game-frontend/src/utils/battleSimulatorTypes.ts
@@ -1,3 +1,5 @@
+import type { UnitSetDefinition, WarEngineConfig } from '@sammo-ts/logic';
+
 export type InheritBuff = {
     warAvoidRatio: number;
     warCriticalRatio: number;
@@ -47,16 +49,9 @@ export type BattleSimOptions = {
         currentYear: number;
         currentMonth: number;
     };
-    config: {
-        maxTrainByWar: number;
-        maxAtmosByWar: number;
-        maxTrainByCommand: number;
-        maxAtmosByCommand: number;
-    };
-    unitSet: {
-        defaultCrewTypeId: number;
-        crewTypes: Array<{ id: number; name: string; armType: number }>;
-    };
+    config: WarEngineConfig;
+    unitSet: UnitSetDefinition;
+    scenarioEffect: string | null;
     nationTypes: Array<{ key: string; name: string; info: string }>;
     eventDomesticTraits: Array<{ key: string; name: string; info: string }>;
     warTraits: Array<{ key: string; name: string; info: string }>;
diff --git a/app/game-frontend/src/views/BattleSimulatorView.vue b/app/game-frontend/src/views/BattleSimulatorView.vue
index 28b287e6..fe436612 100644
--- a/app/game-frontend/src/views/BattleSimulatorView.vue
+++ b/app/game-frontend/src/views/BattleSimulatorView.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { computed, onBeforeUnmount, onMounted, reactive, ref } from 'vue';
+import { computed, onBeforeUnmount, onMounted, reactive, ref, shallowRef } from 'vue';
 import type { BattleSimRequestPayload, BattleSimResultPayload } from '@sammo-ts/game-api';
 import PanelCard from '../components/ui/PanelCard.vue';
 import SkeletonLines from '../components/ui/SkeletonLines.vue';
@@ -33,7 +33,8 @@ type GeneralMeResponse = Awaited<ReturnType<typeof trpc.general.me.query>>;
 
 const loading = ref(true);
 const error = ref<string | null>(null);
-const options = ref<BattleSimOptions | null>(null);
+// Worker execution data must stay outside Vue's deep reactive proxy graph so it remains structured-cloneable.
+const options = shallowRef<BattleSimOptions | null>(null);
 const battleResult = ref<BattleSimResultPayload | null>(null);
 
 const attackerNation = reactive({
@@ -83,6 +84,16 @@ const generalListLoading = ref(false);
 const selectedGeneralId = ref<number | null>(null);
 const gameDefaults = ref<GeneralMeResponse>(null);
 
+const availableCrewTypes = computed(() => {
+    const context = options.value;
+    if (!context) {
+        return [];
+    }
+    return (context.unitSet.crewTypes ?? [])
+        .filter((crewType) => crewType.armType !== context.config.armTypes.castle)
+        .map((crewType) => ({ id: crewType.id, name: crewType.name, armType: crewType.armType }));
+});
+
 let generalIdSeed = 0;
 
 const createInheritBuff = (): InheritBuff => ({
@@ -125,7 +136,7 @@ const resolveGeneralNo = (preferred: number | null, excludeId?: string): number
 };
 
 const createGeneralDraft = (overrides?: Partial<GeneralDraft>): GeneralDraft => {
-    const baseCrew = options.value?.unitSet.defaultCrewTypeId ?? options.value?.unitSet.crewTypes[0]?.id ?? 1;
+    const baseCrew = options.value?.unitSet.defaultCrewTypeId ?? availableCrewTypes.value[0]?.id ?? 1;
     const draft: GeneralDraft = {
         id: nextGeneralId(),
         no: 0,
@@ -219,7 +230,7 @@ const applyGeneralExport = (target: GeneralDraft, data: GeneralExport) => {
     target.killcrew = data.killcrew;
     target.inheritBuff = data.inheritBuff ? { ...data.inheritBuff } : createInheritBuff();
     if (target.crewtype <= 0) {
-        target.crewtype = options.value?.unitSet.defaultCrewTypeId ?? options.value?.unitSet.crewTypes[0]?.id ?? 1;
+        target.crewtype = options.value?.unitSet.defaultCrewTypeId ?? availableCrewTypes.value[0]?.id ?? 1;
     }
 };
 
@@ -590,8 +601,19 @@ const runSimulation = async (action: BattleSimRequestPayload['action']) => {
 
     try {
         const payload = buildBattlePayload(action);
-        const preparedPayload = await trpc.battle.prepareSimulation.mutate(payload);
-        const result = await simulationWorker.run(preparedPayload);
+        const preparation = await trpc.battle.prepareSimulation.mutate(payload);
+        const result = await simulationWorker.run({
+            ...payload,
+            ...(preparation.seedBase ? { seedBase: preparation.seedBase } : {}),
+            unitSet: options.value.unitSet,
+            config: options.value.config,
+            time: {
+                year: payload.year,
+                month: payload.month,
+                startYear: options.value.world.startYear,
+            },
+            scenarioEffect: options.value.scenarioEffect,
+        });
 
         if (!result.result) {
             error.value = result.reason || 'battle_failed';
@@ -1106,6 +1128,7 @@ const shouldShowUI = computed(() => !loading.value && !!options.value);
                     v-model:general="attackerGeneral"
                     data-parity-id="attacker-general"
                     :options="options!"
+                    :crew-types="availableCrewTypes"
                     mode="attacker"
                     title="출병자 설정"
                     :can-import-server="hasGameGeneral"
@@ -1192,6 +1215,7 @@ const shouldShowUI = computed(() => !loading.value && !!options.value);
                         v-model:general="defenders[index]"
                         :data-parity-id="index === 0 ? 'defender-general' : `defender-general-${index + 1}`"
                         :options="options!"
+                        :crew-types="availableCrewTypes"
                         mode="defender"
                         title="수비자 설정"
                         :can-import-server="hasGameGeneral"
diff --git a/docs/architecture/action-module-protocol.md b/docs/architecture/action-module-protocol.md
index 9d6557fc..13f1697e 100644
--- a/docs/architecture/action-module-protocol.md
+++ b/docs/architecture/action-module-protocol.md
@@ -61,11 +61,13 @@ scenario parser, resource schema, PostgreSQL world loader와 battle simulator
 않습니다.
 
 전투 시뮬레이터의 효과는 공개 request가 아니라 저장된 world config에서
-서버가 파생합니다. `battle.prepareSimulation`은 해당 효과와 전체 병종 정의,
-전투 상수, 시나리오 시작 연도, 반복별 seed를 권위 payload로 만들고 브라우저
-Web Worker가 `@sammo-ts/logic`의 공용 프로세서를 실행합니다. 기존
-`battle.simulate`와 Redis worker도 같은 processor와 payload를 사용하므로
-검증·호환 fallback 경로에서 결과를 대조할 수 있습니다.
+서버가 파생합니다. `battle.getSimulatorContext`는 화면을 열 때 해당 효과와 전체
+병종 정의, 전투 상수, 시나리오 시작 연도를 한 번 전달합니다.
+`battle.prepareSimulation`은 실행할 때 입력을 검증하고 반복 실행용 단일
+`seedBase`만 발급하며, 브라우저 Web Worker가 두 자료를 합쳐
+`@sammo-ts/logic`의 공용 프로세서를 실행합니다. 기존 `battle.simulate`와 Redis
+worker도 같은 processor와 payload를 사용하므로 검증·호환 fallback 경로에서
+결과를 대조할 수 있습니다.
 
 ## 닫힌 의미 이벤트
 
diff --git a/docs/architecture/battle-simulator-browser-worker.md b/docs/architecture/battle-simulator-browser-worker.md
index 0b2895ae..7054bf14 100644
--- a/docs/architecture/battle-simulator-browser-worker.md
+++ b/docs/architecture/battle-simulator-browser-worker.md
@@ -2,19 +2,26 @@
 
 ## 요청과 권위 데이터
 
-`BattleSimulatorView.vue`는 사용자가 편집한 장수·국가·도시 입력을
-`battle.prepareSimulation`에 보냅니다. 이 API는 로그인만 요구하며 게임 장수
-보유 여부나 input-event transaction에는 의존하지 않습니다. 서버는 현재
-`WorldState`에서 다음 값을 읽어 실행 payload에 추가합니다.
+`BattleSimulatorView.vue`는 화면을 열 때 `battle.getSimulatorContext`에서 form
+option과 브라우저 Worker의 실행 context를 한 번 함께 받습니다. 이 API는 현재
+`WorldState`를 한 번 읽어 다음 서버 권위 값을 제공합니다.
 
 - 전체 `UnitSetDefinition`
 - 전투 상수와 성벽 병종/병과 ID
 - 시나리오 시작 연도와 저장된 `scenarioEffect`
-- 고정 seed가 없는 경우 각 반복에 사용할 UUID seed
 
-클라이언트가 같은 이름의 `scenarioEffect`를 보내도 입력 schema가 제거하며,
-저장된 효과가 유일한 기준입니다. 1000회 실행 seed를 서버에서 한 번 확정하므로
-브라우저와 Node가 동일 payload를 재실행해 전체 결과를 정확히 비교할 수 있습니다.
+사용자가 전투 또는 정렬을 시작하면 `battle.prepareSimulation`은 인증과 Zod 입력
+검증을 유지하되 `WorldState`를 다시 조회하거나 입력·병종 정의를 response에
+반복하지 않습니다. 고정 seed가 없을 때 단일 UUID `seedBase`만 반환합니다. 따라서
+전투 시작당 payload 준비를 위한 `WorldState` 추가 조회는 1회에서 0회로 줄고 응답
+크기는 반복 횟수와 무관합니다. weight 0 접속·최근 활동 기록 같은 공통 request
+lifecycle DB 작업은 기존 호환 계약대로 유지합니다. 브라우저는 로드 시 받은 권위
+context와 현재 입력을 합쳐 Worker payload를 만듭니다.
+
+`seedBase`는 반복 번호와 함께 명시적인 직렬화 문자열로 바뀐 뒤 SHA-512 기반
+`LiteHashDRBG`의 seed가 됩니다. 1000개 seed 문자열을 전송하지 않으면서도 동일한
+payload를 Node와 브라우저에서 재실행하면 전체 결과가 정확히 같습니다. 배포 전에
+queue에 들어간 `seeds[]` payload는 각 항목을 먼저 소비해 기존 결과를 보존합니다.
 
 ## 실행 경로
 
@@ -32,15 +39,15 @@ game-api의 processor/type 파일은 기존 import와 Redis worker 호환을 위
 ## RNG와 부작용
 
 - 고정 seed가 있으면 기존 계약대로 한 번만 실행합니다.
-- 고정 seed가 없으면 `payload.seeds[index]`를 반복 순서대로 소비합니다.
-- 구형 Redis payload처럼 seed 배열이 없을 때만 실행 runtime의
-  `crypto.randomUUID()`를 fallback으로 사용합니다.
+- 고정 seed가 없으면 구형 `payload.seeds[index]`, 새
+  `payload.seedBase + 반복 번호`, runtime `crypto.randomUUID()` 순서로 seed를
+  결정합니다.
 - 계산은 전달받은 plain object에서 새 도메인 객체를 만들며 DB, Redis, 턴 상태를
   변경하지 않습니다.
 
 ## 검증
 
 `battleSimulator.spec.ts`는 production bundle의 실제 Chromium module Worker를
-실행합니다. 고정 seed와 서버 발급 seed 1000개 케이스에서 Node processor 결과와
-브라우저 Worker의 전체 결과 객체를 비교하고, 기본 UI 경로가
-`battle.simulate`/`battle.getSimulation`을 호출하지 않는지 확인합니다.
+실행합니다. 고정 seed와 단일 seed base 1000회 케이스에서 Node processor 결과와
+브라우저 Worker의 전체 결과 객체를 비교하고, 준비 응답이 128 byte 미만이며 기본
+UI 경로가 `battle.simulate`/`battle.getSimulation`을 호출하지 않는지 확인합니다.
diff --git a/packages/logic/src/battleSimulator/processor.ts b/packages/logic/src/battleSimulator/processor.ts
index cdfa22e4..4a826e6f 100644
--- a/packages/logic/src/battleSimulator/processor.ts
+++ b/packages/logic/src/battleSimulator/processor.ts
@@ -26,6 +26,7 @@ import {
     createCrewTypeWarTriggerRegistry,
     resolveDefenderOrder,
     resolveWarBattle,
+    simpleSerialize,
     type WarBattleOutcome,
     type WarActionModule,
     type WarUnitReport,
@@ -264,6 +265,17 @@ const resolveRandomSeed = (): string => {
     return globalThis.crypto.randomUUID();
 };
 
+const resolveRepeatSeed = (payload: BattleSimJobPayload, index: number): string => {
+    const legacySeed = payload.seeds?.[index];
+    if (legacySeed) {
+        return legacySeed;
+    }
+    if (payload.seedBase) {
+        return simpleSerialize(payload.seedBase, 'battle-simulator', index);
+    }
+    return resolveRandomSeed();
+};
+
 const resolveCityTrainAtmos = (year: number, startYear: number): number =>
     Math.min(110, Math.max(60, year - startYear + 59));
 
@@ -369,7 +381,7 @@ export const processBattleSimJob = (
     const weight = 1 / Math.max(1, repeatCnt);
 
     for (let idx = 0; idx < repeatCnt; idx += 1) {
-        const seed = baseSeed || payload.seeds?.[idx] || resolveRandomSeed();
+        const seed = baseSeed || resolveRepeatSeed(payload, idx);
         const attackerNation = mapNationPayload(payload.attackerNation);
         const defenderNation = mapNationPayload(payload.defenderNation);
         const attackerCity = mapCityPayload(payload.attackerCity);
diff --git a/packages/logic/src/battleSimulator/types.ts b/packages/logic/src/battleSimulator/types.ts
index 3d45bc3e..00bb5973 100644
--- a/packages/logic/src/battleSimulator/types.ts
+++ b/packages/logic/src/battleSimulator/types.ts
@@ -103,7 +103,9 @@ export interface BattleSimJobPayload extends BattleSimRequestPayload {
     config: WarEngineConfig;
     time: WarTimeContext;
     scenarioEffect?: string | null;
-    /** Server-issued seeds make a repeated run exactly reproducible in Node and browser runtimes. */
+    /** One secure random value expands deterministically into every repeated battle seed. */
+    seedBase?: string;
+    /** Legacy queue payload compatibility. New jobs use seedBase instead of an O(repeatCnt) array. */
     seeds?: string[];
 }