diff --git a/app/game-api/src/router/general/index.ts b/app/game-api/src/router/general/index.ts
index d9e2c1c3..6b0984a9 100644
--- a/app/game-api/src/router/general/index.ts
+++ b/app/game-api/src/router/general/index.ts
@@ -76,12 +76,11 @@ const isFrontStatusPollActive = (poll: FrontStatusPoll, gameTime: CurrentGameTim
     return started && !ended;
 };
 
-const zGeneralSettings = z.object({
+const zGeneralSettings = z.strictObject({
     tnmt: z.number().int().optional(),
     defence_train: z.number().int().optional(),
     use_treatment: z.number().int().optional(),
     use_auto_nation_turn: z.number().int().optional(),
-    use_auto_nation_diplomacy: z.number().int().min(0).max(1).optional(),
     use_auto_nation_war: z.number().int().min(0).max(1).optional(),
     use_auto_nation_promotion: z.number().int().min(0).max(1).optional(),
     use_auto_nation_finance: z.number().int().min(0).max(1).optional(),
@@ -244,7 +243,6 @@ const resolveUserSettings = (meta: Record<string, unknown>) => {
         use_auto_nation_turn: readNumber(readSetting('use_auto_nation_turn'), 1),
         // Ref가 NPC 군주에게만 수행하던 국가 운영은 사용자 군주에게 opt-in이다.
         // 누락된 값은 신규 게임과 기존 장수 모두 안전한 기본값(사용 안함)으로 해석한다.
-        use_auto_nation_diplomacy: readNumber(readSetting('use_auto_nation_diplomacy'), 0),
         use_auto_nation_war: readNumber(readSetting('use_auto_nation_war'), 0),
         use_auto_nation_promotion: readNumber(readSetting('use_auto_nation_promotion'), 0),
         use_auto_nation_finance: readNumber(readSetting('use_auto_nation_finance'), 0),
diff --git a/app/game-api/test/inGameMenuPermissions.test.ts b/app/game-api/test/inGameMenuPermissions.test.ts
index d4320144..d51d9a05 100644
--- a/app/game-api/test/inGameMenuPermissions.test.ts
+++ b/app/game-api/test/inGameMenuPermissions.test.ts
@@ -584,7 +584,6 @@ describe('in-game my information ownership', () => {
             defence_train: 80,
             use_treatment: 21,
             use_auto_nation_turn: 1,
-            use_auto_nation_diplomacy: 0,
             use_auto_nation_war: 0,
             use_auto_nation_promotion: 0,
             use_auto_nation_finance: 0,
@@ -612,6 +611,18 @@ describe('in-game my information ownership', () => {
         expect(requestCommand).not.toHaveBeenCalled();
     });
 
+    it('rejects the removed automatic diplomacy setting before dispatching it to ENGINE', async () => {
+        const requestCommand = vi.fn(async () => ({ type: 'setMySetting', ok: true, generalId: 7 }));
+        const fixture = createContext({ requestCommand });
+
+        await expect(
+            appRouter.createCaller(fixture.context).general.setMySetting({
+                use_auto_nation_diplomacy: 1,
+            } as never)
+        ).rejects.toMatchObject({ code: 'BAD_REQUEST' });
+        expect(requestCommand).not.toHaveBeenCalled();
+    });
+
     it('sends settings directly to ENGINE without creating an API input event', async () => {
         const transaction = vi.fn(async () => {
             throw new Error('API transaction must not run');
diff --git a/app/game-engine/src/turn/ai/policies.ts b/app/game-engine/src/turn/ai/policies.ts
index b87c8af3..206b9f7c 100644
--- a/app/game-engine/src/turn/ai/policies.ts
+++ b/app/game-engine/src/turn/ai/policies.ts
@@ -61,10 +61,9 @@ export const AVAILABLE_INSTANT_TURN: Record<string, boolean> = {
     NPC전방발령: true,
 };
 
-export type UserRulerAutomationFeature = 'diplomacy' | 'war' | 'promotion' | 'finance' | 'capital';
+export type UserRulerAutomationFeature = 'war' | 'promotion' | 'finance' | 'capital';
 
 const USER_RULER_AUTOMATION_META_KEY = {
-    diplomacy: 'use_auto_nation_diplomacy',
     war: 'use_auto_nation_war',
     promotion: 'use_auto_nation_promotion',
     finance: 'use_auto_nation_finance',
@@ -72,7 +71,6 @@ const USER_RULER_AUTOMATION_META_KEY = {
 } as const satisfies Record<UserRulerAutomationFeature, string>;
 
 const USER_RULER_ACTION_FEATURE: Readonly<Record<string, UserRulerAutomationFeature>> = {
-    불가침제의: 'diplomacy',
     선전포고: 'war',
     천도: 'capital',
 };
diff --git a/app/game-engine/src/turn/commandRegistry.ts b/app/game-engine/src/turn/commandRegistry.ts
index d9b00d3e..2b70fc96 100644
--- a/app/game-engine/src/turn/commandRegistry.ts
+++ b/app/game-engine/src/turn/commandRegistry.ts
@@ -142,12 +142,11 @@ const zSetMySetting = z.object({
     type: z.literal('setMySetting'),
     userId: z.string().min(1),
     generalId: zFiniteNumber,
-    settings: z.object({
+    settings: z.strictObject({
         tnmt: z.number().int().optional(),
         defence_train: z.number().int().optional(),
         use_treatment: z.number().int().optional(),
         use_auto_nation_turn: z.number().int().optional(),
-        use_auto_nation_diplomacy: z.number().int().optional(),
         use_auto_nation_war: z.number().int().optional(),
         use_auto_nation_promotion: z.number().int().optional(),
         use_auto_nation_finance: z.number().int().optional(),
diff --git a/app/game-engine/src/turn/worldCommandHandler.ts b/app/game-engine/src/turn/worldCommandHandler.ts
index 6112f4f5..16ce9125 100644
--- a/app/game-engine/src/turn/worldCommandHandler.ts
+++ b/app/game-engine/src/turn/worldCommandHandler.ts
@@ -1896,7 +1896,6 @@ async function handleSetMySetting(
         nextMeta.use_auto_nation_turn = settings.use_auto_nation_turn === 0 ? 0 : 1;
     }
     for (const key of [
-        'use_auto_nation_diplomacy',
         'use_auto_nation_war',
         'use_auto_nation_promotion',
         'use_auto_nation_finance',
diff --git a/app/game-engine/test/authenticatedActorCommand.test.ts b/app/game-engine/test/authenticatedActorCommand.test.ts
index 160fef8d..d7a82780 100644
--- a/app/game-engine/test/authenticatedActorCommand.test.ts
+++ b/app/game-engine/test/authenticatedActorCommand.test.ts
@@ -98,6 +98,23 @@ describe('authenticated actor-bound command registry and execution', () => {
         ).toBeNull();
     });
 
+    it('rejects the removed automatic diplomacy setting at the daemon boundary', () => {
+        expect(
+            normalizeTurnDaemonCommand({
+                requestId: 'set-my-setting:removed-diplomacy',
+                sentAt: '2026-08-28T00:00:00.000Z',
+                command: {
+                    type: 'setMySetting',
+                    userId: 'user-7',
+                    generalId: 7,
+                    settings: {
+                        use_auto_nation_diplomacy: 1,
+                    },
+                } as unknown as TurnDaemonCommand,
+            })
+        ).toBeNull();
+    });
+
     it('rejects every actor-bound queue payload that omits userId', () => {
         for (const command of buildActorBoundCommands()) {
             const {
diff --git a/app/game-engine/test/generalAiLegacyDecisionParity.test.ts b/app/game-engine/test/generalAiLegacyDecisionParity.test.ts
index f9e3ccf3..ef2fa0a4 100644
--- a/app/game-engine/test/generalAiLegacyDecisionParity.test.ts
+++ b/app/game-engine/test/generalAiLegacyDecisionParity.test.ts
@@ -826,7 +826,7 @@ describe('legacy NPC user-chief promotion parity', () => {
         expect(run(3, 0, 1)).toEqual([{ generalId: 2, officerLevel: 11, officerCity: 0, permission: 'ambassador' }]);
     });
 
-    it('keeps user-ruler duties individually disabled until each setting is enabled', () => {
+    it('keeps non-aggression proposals NPC-only while user-ruler duties remain opt-in', () => {
         const ruler = makePromotionGeneral({ id: 1, officerLevel: 12, npcState: 0, meta: { killturn: 0 } });
         expect(canUseAutomatedNationAction(ruler, '선전포고')).toBe(false);
         expect(canUseAutomatedNationAction(ruler, '불가침제의')).toBe(false);
@@ -839,18 +839,21 @@ describe('legacy NPC user-chief promotion parity', () => {
             use_auto_nation_capital: 1,
             use_auto_nation_finance: 1,
         };
-        expect(canUseAutomatedNationAction(ruler, '불가침제의')).toBe(true);
+        // 기존 DB에 제거된 플래그가 남아 있어도 사용자 군주에게는 다시 활성화되지 않는다.
+        expect(canUseAutomatedNationAction(ruler, '불가침제의')).toBe(false);
         expect(canUseAutomatedNationAction(ruler, '선전포고')).toBe(false);
         expect(canUseAutomatedNationAction(ruler, '천도')).toBe(true);
         expect(canUseRulerAutomation(ruler, 'finance')).toBe(true);
 
         ruler.meta = {
             ...ruler.meta,
-            use_auto_nation_diplomacy: 0,
             use_auto_nation_war: 1,
         };
         expect(canUseAutomatedNationAction(ruler, '불가침제의')).toBe(false);
         expect(canUseAutomatedNationAction(ruler, '선전포고')).toBe(true);
+
+        const npcRuler = makePromotionGeneral({ id: 2, officerLevel: 12, npcState: 2, meta: { killturn: 0 } });
+        expect(canUseAutomatedNationAction(npcRuler, '불가침제의')).toBe(true);
     });
 
     it('honors the existing automatic nation-turn master switch for user chiefs only', () => {
diff --git a/app/game-engine/test/myInformationCommands.test.ts b/app/game-engine/test/myInformationCommands.test.ts
index f01f2754..b8d888c8 100644
--- a/app/game-engine/test/myInformationCommands.test.ts
+++ b/app/game-engine/test/myInformationCommands.test.ts
@@ -237,7 +237,6 @@ describe('my information world commands', () => {
                     defence_train: 94,
                     use_treatment: 200,
                     use_auto_nation_turn: 0,
-                    use_auto_nation_diplomacy: 1,
                     use_auto_nation_war: 1,
                     use_auto_nation_promotion: 1,
                     use_auto_nation_finance: 1,
@@ -254,7 +253,6 @@ describe('my information world commands', () => {
                 defence_train: 999,
                 use_treatment: 100,
                 use_auto_nation_turn: 0,
-                use_auto_nation_diplomacy: 1,
                 use_auto_nation_war: 1,
                 use_auto_nation_promotion: 1,
                 use_auto_nation_finance: 1,
diff --git a/app/game-frontend/e2e/inGameMenus.spec.ts b/app/game-frontend/e2e/inGameMenus.spec.ts
index 0fb1d9d7..73a765bd 100644
--- a/app/game-frontend/e2e/inGameMenus.spec.ts
+++ b/app/game-frontend/e2e/inGameMenus.spec.ts
@@ -276,7 +276,6 @@ const myGeneral = (state: FixtureState) => ({
         defence_train: 80,
         use_treatment: 21,
         use_auto_nation_turn: 1,
-        use_auto_nation_diplomacy: 0,
         use_auto_nation_war: 0,
         use_auto_nation_promotion: 0,
         use_auto_nation_finance: 0,
@@ -1347,13 +1346,12 @@ test('내 정보&설정 keeps desktop density and becomes a 390px horizontal-ide
     ]);
     const rulerAutomation = page.locator('.ruler-automation-settings');
     await expect(rulerAutomation).toBeVisible();
-    const diplomacyAutomation = page.getByRole('checkbox', { name: '자동 외교 (불가침 제의)' });
+    await expect(page.getByRole('checkbox', { name: '자동 외교 (불가침 제의)' })).toHaveCount(0);
     const warAutomation = page.getByRole('checkbox', { name: '자동 선전포고' });
     const promotionAutomation = page.getByRole('checkbox', { name: '자동 수뇌 임명' });
     const financeAutomation = page.getByRole('checkbox', { name: '자동 세율·지급률 조정' });
     const capitalAutomation = page.getByRole('checkbox', { name: '자동 천도' });
     for (const checkbox of [
-        diplomacyAutomation,
         warAutomation,
         promotionAutomation,
         financeAutomation,
@@ -1421,7 +1419,6 @@ test('내 정보&설정 keeps desktop density and becomes a 390px horizontal-ide
     await expect.poll(() => state.settingMutations.length).toBe(1);
     expect(state.settingMutations[0]).not.toHaveProperty('generalId');
     expect(state.settingMutations[0]).toMatchObject({
-        use_auto_nation_diplomacy: 1,
         use_auto_nation_war: 1,
         use_auto_nation_promotion: 1,
         use_auto_nation_finance: 1,
diff --git a/app/game-frontend/src/views/MyPageView.vue b/app/game-frontend/src/views/MyPageView.vue
index dfd8f35f..d56bda4c 100644
--- a/app/game-frontend/src/views/MyPageView.vue
+++ b/app/game-frontend/src/views/MyPageView.vue
@@ -32,7 +32,6 @@ type SettingForm = {
     defence_train: number;
     use_treatment: number;
     use_auto_nation_turn: number;
-    use_auto_nation_diplomacy: number;
     use_auto_nation_war: number;
     use_auto_nation_promotion: number;
     use_auto_nation_finance: number;
@@ -69,7 +68,6 @@ const form = reactive<SettingForm>({
     defence_train: 80,
     use_treatment: 10,
     use_auto_nation_turn: 1,
-    use_auto_nation_diplomacy: 0,
     use_auto_nation_war: 0,
     use_auto_nation_promotion: 0,
     use_auto_nation_finance: 0,
@@ -430,15 +428,6 @@ onMounted(() => {
                     :disabled="form.use_auto_nation_turn === 0"
                 >
                     <legend>사용자 군주 자동 업무</legend>
-                    <label>
-                        <input
-                            v-model="form.use_auto_nation_diplomacy"
-                            type="checkbox"
-                            :true-value="1"
-                            :false-value="0"
-                        />
-                        자동 외교 (불가침 제의)
-                    </label>
                     <label>
                         <input
                             v-model="form.use_auto_nation_war"
diff --git a/packages/common/src/turnDaemon/types.ts b/packages/common/src/turnDaemon/types.ts
index ac8335ad..a8fb7ae5 100644
--- a/packages/common/src/turnDaemon/types.ts
+++ b/packages/common/src/turnDaemon/types.ts
@@ -172,7 +172,6 @@ export type TurnDaemonCommand =
               defence_train?: number;
               use_treatment?: number;
               use_auto_nation_turn?: number;
-              use_auto_nation_diplomacy?: number;
               use_auto_nation_war?: number;
               use_auto_nation_promotion?: number;
               use_auto_nation_finance?: number;