diff --git a/AGENTS.md b/AGENTS.md
index e225b38..adb39cc 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -36,7 +36,7 @@ Admin panel for the chocomae service (mouse-typing), extracted into a standalone
 | `lib/logger.ts` | Structured logger — `debug/info/warn/error`, level controlled by `LOG_LEVEL` / `APP_ENV` |
 | `lib/errors.ts` | `ApiError` — unified error class with HTTP status code |
 | `lib/api-handler.ts` | `withApiHandler` — wraps route handlers with auth, timing, and error logging |
-| `lib/constants.ts` | Status code constants (`ACTIVATE_STATUS`, `ACCOUNT_TYPE`, `REQUEST_STATUS`) |
+| `lib/constants.ts` | Status code constants (`ACTIVATE_STATUS`, `ACCOUNT_TYPE`, `REQUEST_STATUS`); `PAID_ACCOUNT_TYPE_VALUES` (유료 계정 유형 배열 — 중복 정의 방지용 공용 상수) |
 | `lib/maestros.ts` | Maestro DB queries |
 | `lib/extension-requests.ts` | Extension request queries and approval logic |
 | `lib/upgrade-requests.ts` | Upgrade request queries and approval logic |
@@ -67,11 +67,17 @@ Always record a log entry after a successful DB change. Use these `Type` values:
 
 - Phase 0–8: login, maestro list/detail, extension requests, upgrade requests, Docker setup, transaction safety, auth guards.
 - Phase 9 (substantially complete): structured logging (`lib/logger.ts`), `withApiHandler` wrapper (`lib/api-handler.ts`), `ApiError` class (`lib/errors.ts`), Prisma SQL pretty-logging and result table logging (`lib/db.ts`). Remaining: correlation IDs, stage/production log verification.
+- Phase 10: Maestro info edit form (`PATCH /api/maestros/[id]`) + student list with server-side pagination (`GET /api/maestros/[id]/students`).
+- Phase 11: Email auto-send via Nodemailer after extension/upgrade approval (`lib/mail.ts`). Upgrade email edge-case verification (trial→paid, paid→paid) still pending.
+- Phase 12: Admin-initiated extension/upgrade request registration from maestro detail page.
+  - `POST /api/maestros/[id]/extension-requests` — inserts into `maestro_extension` using maestro's current `AccountType` read server-side; rejects trial account types.
+  - `POST /api/maestros/[id]/upgrade-requests` — inserts into `maestro_upgrade` inside a transaction; validates `requestedAccountType > maestro.AccountType`.
+  - `ExtensionRequestsSection.tsx`, `UpgradeRequestsSection.tsx` — client components with inline action UI; call `router.refresh()` on success.
+  - `PAID_ACCOUNT_TYPE_VALUES` consolidated in `lib/constants.ts` — shared by `lib/maestros.ts`, `lib/extension-requests.ts`, `lib/upgrade-requests.ts`, and both new API routes.
 
 ## Planned phases (not yet implemented)
 
-- **Phase 10** — Maestro info edit form + student list with pagination (`PATCH /api/maestros/[id]`, `GET /api/maestros/[id]/students`)
-- **Phase 11** — Email auto-send via Nodemailer after extension/upgrade approval (`lib/mail.ts`)
+이후 작업 후보는 `docs/plan/project-plan.md` Section 10 "MVP 이후 확장 후보" 참조.
 
 ## Packages to know
 
diff --git a/app/(admin)/maestros/[maestroId]/ExtensionRequestsSection.tsx b/app/(admin)/maestros/[maestroId]/ExtensionRequestsSection.tsx
index 4dc27d9..1ca4695 100644
--- a/app/(admin)/maestros/[maestroId]/ExtensionRequestsSection.tsx
+++ b/app/(admin)/maestros/[maestroId]/ExtensionRequestsSection.tsx
@@ -5,6 +5,7 @@ import { useRouter } from "next/navigation";
 import { Plus } from "lucide-react";
 
 import { Button } from "@/components/ui/button";
+import { PAID_ACCOUNT_TYPE_VALUES } from "@/lib/constants";
 import { formatDateTime, getAccountTypeLabel, getRequestStatusLabel } from "@/lib/utils";
 import type { MaestroDetail } from "@/lib/maestros";
 
@@ -26,6 +27,7 @@ export function ExtensionRequestsSection({
   const [isCreating, setIsCreating] = useState(false);
   const [errorMessage, setErrorMessage] = useState("");
 
+  const isPaidAccount = (PAID_ACCOUNT_TYPE_VALUES as readonly number[]).includes(accountType);
   const isDisabled = isCreating || isPending;
 
   async function handleCreate() {
@@ -37,11 +39,7 @@ export function ExtensionRequestsSection({
     try {
       const response = await fetch(
         `/api/maestros/${maestroID}/extension-requests`,
-        {
-          method: "POST",
-          headers: { "Content-Type": "application/json" },
-          body: JSON.stringify({ accountType }),
-        }
+        { method: "POST" }
       );
 
       const body = (await response.json().catch(() => null)) as {
@@ -75,7 +73,7 @@ export function ExtensionRequestsSection({
         </div>
         <div className="flex flex-col items-end gap-1">
           <Button
-            disabled={isDisabled}
+            disabled={isDisabled || !isPaidAccount}
             onClick={() => void handleCreate()}
             size="sm"
             type="button"
diff --git a/app/api/maestros/[id]/extension-requests/route.ts b/app/api/maestros/[id]/extension-requests/route.ts
index 04d3431..d93ad94 100644
--- a/app/api/maestros/[id]/extension-requests/route.ts
+++ b/app/api/maestros/[id]/extension-requests/route.ts
@@ -1,32 +1,15 @@
-import { z } from "zod";
 import { NextResponse } from "next/server";
 
 import { createExtensionRequest } from "@/lib/extension-requests";
 import { ApiError } from "@/lib/errors";
 import { withApiHandler } from "@/lib/api-handler";
 import { logger } from "@/lib/logger";
-import { ACCOUNT_TYPES } from "@/lib/constants";
 
 const CTX = "maestros/[id]/extension-requests";
 
-const paidAccountTypeValues = [
-  ACCOUNT_TYPES.BASIC_20,
-  ACCOUNT_TYPES.STANDARD_50,
-  ACCOUNT_TYPES.PRO_100,
-  ACCOUNT_TYPES.SCHOOL_500,
-  ACCOUNT_TYPES.SCHOOL_1000,
-] as const;
-
-const postBodySchema = z.object({
-  accountType: z.coerce
-    .number()
-    .int()
-    .refine((v) => (paidAccountTypeValues as readonly number[]).includes(v)),
-});
-
 export const POST = withApiHandler<{ id: string }>(
   CTX,
-  async (request, { params, t0 }) => {
+  async (_request, { params, t0 }) => {
     const { id } = await params;
     const maestroID = Number(id);
 
@@ -34,14 +17,7 @@ export const POST = withApiHandler<{ id: string }>(
       throw new ApiError("Invalid maestro id", 400);
     }
 
-    const body = postBodySchema.safeParse(
-      await request.json().catch(() => ({}))
-    );
-    if (!body.success) {
-      throw new ApiError("Invalid request body", 400);
-    }
-
-    const result = await createExtensionRequest(maestroID, body.data.accountType);
+    const result = await createExtensionRequest(maestroID);
 
     logger.info(CTX, "created", {
       maestroID,
diff --git a/app/api/maestros/[id]/upgrade-requests/route.ts b/app/api/maestros/[id]/upgrade-requests/route.ts
index a2199b7..8926034 100644
--- a/app/api/maestros/[id]/upgrade-requests/route.ts
+++ b/app/api/maestros/[id]/upgrade-requests/route.ts
@@ -5,23 +5,15 @@ import { createUpgradeRequest } from "@/lib/upgrade-requests";
 import { ApiError } from "@/lib/errors";
 import { withApiHandler } from "@/lib/api-handler";
 import { logger } from "@/lib/logger";
-import { ACCOUNT_TYPES } from "@/lib/constants";
+import { PAID_ACCOUNT_TYPE_VALUES } from "@/lib/constants";
 
 const CTX = "maestros/[id]/upgrade-requests";
 
-const paidAccountTypeValues = [
-  ACCOUNT_TYPES.BASIC_20,
-  ACCOUNT_TYPES.STANDARD_50,
-  ACCOUNT_TYPES.PRO_100,
-  ACCOUNT_TYPES.SCHOOL_500,
-  ACCOUNT_TYPES.SCHOOL_1000,
-] as const;
-
 const postBodySchema = z.object({
   requestedAccountType: z.coerce
     .number()
     .int()
-    .refine((v) => (paidAccountTypeValues as readonly number[]).includes(v)),
+    .refine((v) => (PAID_ACCOUNT_TYPE_VALUES as readonly number[]).includes(v)),
 });
 
 export const POST = withApiHandler<{ id: string }>(
diff --git a/docs/plan/project-plan.md b/docs/plan/project-plan.md
index 13a7775..8ee161e 100644
--- a/docs/plan/project-plan.md
+++ b/docs/plan/project-plan.md
@@ -162,7 +162,11 @@ chocoadmin/
 │   │   ├── maestros/
 │   │   │   ├── page.tsx          # 마에스트로 전체 목록
 │   │   │   └── [maestroId]/
-│   │   │       └── page.tsx      # 마에스트로 상세 정보
+│   │   │       ├── page.tsx                      # 마에스트로 상세 정보 (server)
+│   │   │       ├── MaestroEditForm.tsx            # 기본 정보 수정 폼 (client)
+│   │   │       ├── StudentsSection.tsx            # 학생 목록 + 검색/페이지네이션 (client)
+│   │   │       ├── ExtensionRequestsSection.tsx   # 연장 신청 이력 + [연장] 버튼 (client)
+│   │   │       └── UpgradeRequestsSection.tsx     # 업그레이드 신청 이력 + 신청 UI (client)
 │   │   ├── extension-requests/
 │   │   │   └── page.tsx          # 연장 신청 목록 + 승인/취소
 │   │   └── upgrade-requests/
@@ -172,8 +176,10 @@ chocoadmin/
 │       ├── maestros/
 │       │   ├── route.ts          # GET: 목록
 │       │   └── [id]/
-│       │       ├── route.ts      # GET: 상세, PATCH: 정보 수정
-│       │       └── students/route.ts # GET: 학생 목록
+│       │       ├── route.ts                      # GET: 상세, PATCH: 정보 수정
+│       │       ├── students/route.ts             # GET: 학생 목록
+│       │       ├── extension-requests/route.ts   # POST: 연장 신청 등록 (관리자 직접)
+│       │       └── upgrade-requests/route.ts     # POST: 업그레이드 신청 등록 (관리자 직접)
 │       ├── extension-requests/
 │       │   └── [id]/route.ts     # PATCH: 승인/취소
 │       └── upgrade-requests/
@@ -237,8 +243,15 @@ chocoadmin/
 - 플레이어(학생) 전체 목록
   - 서버 사이드 페이지네이션
   - 이름 검색
-- 연장 신청 이력
-- 업그레이드 신청 이력
+- 연장 신청 이력 + [연장] 버튼
+  - 유료 요금제 계정에서만 버튼 활성화 (체험 계정 비활성)
+  - 클릭 시 현재 `AccountType`으로 `maestro_extension` INSERT (서버에서 DB 조회)
+  - 등록 후 이력 목록 즉시 갱신 (`router.refresh()`)
+- 업그레이드 신청 이력 + 요금제 콤보박스 + [업그레이드] 버튼
+  - 콤보박스: 현재 요금제 이하 항목 비활성화, 상위 요금제만 선택 가능
+  - 클릭 시 선택한 `requestedAccountType`으로 `maestro_upgrade` INSERT (트랜잭션 내 서버 조회)
+  - 서버에서 `requestedAccountType > maestro.AccountType` 검증 (다운그레이드 차단)
+  - 등록 후 이력 목록 즉시 갱신 (`router.refresh()`)
 - 관리자 처리 로그 (`maestro_log`)
 
 ### 7-4. 연장 신청 목록 (`/extension-requests`)
@@ -498,6 +511,30 @@ chocoadmin/
   - [ ] 업그레이드 승인 후 유료→유료 케이스: `{prev_price}원` 본문 확인
   - [x] SMTP 오류 시 승인 API 200 응답 + `error: send failed` 로그 확인
 
+### Phase 12. 관리자 직접 연장/업그레이드 신청 등록
+
+> 마에스트로 상세 화면에서 관리자가 직접 연장·업그레이드 신청을 DB에 등록할 수 있도록 한다. 메일 발송은 하지 않는다.
+
+- [x] 연장 신청 등록 API 구현 (`POST /api/maestros/[id]/extension-requests`)
+  - [x] 서버에서 `maestro.AccountType` 직접 조회 — 클라이언트 값 신뢰 안 함
+  - [x] 유료 요금제 계정이 아닌 경우 400 반환 (체험 계정 차단)
+  - [x] `maestro_extension` INSERT (`AccountType`, `RequestedDateTime`, `Status=1`)
+- [x] 업그레이드 신청 등록 API 구현 (`POST /api/maestros/[id]/upgrade-requests`)
+  - [x] 트랜잭션 내에서 `maestro` SELECT → `maestro_upgrade` INSERT (원자성 보장)
+  - [x] `requestedAccountType > maestro.AccountType` 검증 (다운그레이드 차단, 400 반환)
+  - [x] `RegisteredActivateStatus`, `RegisteredAccountType` 서버 DB 조회값으로 저장
+- [x] 연장 신청 이력 클라이언트 컴포넌트 (`ExtensionRequestsSection.tsx`)
+  - [x] 섹션 우상단 [연장] 버튼
+  - [x] 체험 계정 (`AccountType` ∉ `PAID_ACCOUNT_TYPE_VALUES`) 시 버튼 비활성화
+  - [x] 등록 성공 후 `router.refresh()`로 이력 테이블 즉시 갱신
+- [x] 업그레이드 신청 이력 클라이언트 컴포넌트 (`UpgradeRequestsSection.tsx`)
+  - [x] 섹션 우상단 요금제 콤보박스 + [업그레이드] 버튼
+  - [x] 현재 요금제 이하 옵션 `disabled`, 상위 요금제만 선택 가능
+  - [x] 선택 후 등록 성공 시 콤보박스 초기화 + `router.refresh()`
+- [x] `PAID_ACCOUNT_TYPE_VALUES` 공용 상수로 추출 (`lib/constants.ts`)
+  - [x] 기존 `lib/maestros.ts`의 로컬 정의 제거 및 import로 교체
+  - [x] 두 신규 API route의 로컬 정의 제거 및 import로 교체
+
 ---
 
 ## 10. MVP 범위
diff --git a/lib/constants.ts b/lib/constants.ts
index c981fe8..a422fe8 100644
--- a/lib/constants.ts
+++ b/lib/constants.ts
@@ -68,6 +68,14 @@ export const REQUEST_STATUS_LABELS = {
   [REQUEST_STATUSES.APPLIED]: "적용 완료",
 } as const;
 
+export const PAID_ACCOUNT_TYPE_VALUES = [
+  ACCOUNT_TYPES.BASIC_20,
+  ACCOUNT_TYPES.STANDARD_50,
+  ACCOUNT_TYPES.PRO_100,
+  ACCOUNT_TYPES.SCHOOL_500,
+  ACCOUNT_TYPES.SCHOOL_1000,
+] as const;
+
 export type AccountType = (typeof ACCOUNT_TYPES)[keyof typeof ACCOUNT_TYPES];
 export type PaidAccountType =
   | typeof ACCOUNT_TYPES.BASIC_20
diff --git a/lib/extension-requests.ts b/lib/extension-requests.ts
index 5d6fcd9..34c8e3e 100644
--- a/lib/extension-requests.ts
+++ b/lib/extension-requests.ts
@@ -3,7 +3,7 @@ import { z } from "zod";
 import { db } from "@/lib/db";
 import { logger } from "@/lib/logger";
 import { ApiError } from "@/lib/errors";
-import { REQUEST_STATUSES } from "@/lib/constants";
+import { PAID_ACCOUNT_TYPE_VALUES, REQUEST_STATUSES } from "@/lib/constants";
 import type { Prisma } from "@/lib/generated/prisma/client";
 import {
   calculateExtendedAvailableDate,
@@ -158,22 +158,25 @@ export async function approveExtensionRequest(
 }
 
 export async function createExtensionRequest(
-  maestroID: number,
-  accountType: number
+  maestroID: number
 ): Promise<{ maestroExtensionID: number; requestedDateTime: string; status: number }> {
   const maestro = await db.maestro.findUnique({
     where: { MaestroID: maestroID },
-    select: { MaestroID: true },
+    select: { AccountType: true },
   });
 
   if (!maestro) {
     throw new ApiError("마에스트로를 찾을 수 없습니다.", 404);
   }
 
+  if (!(PAID_ACCOUNT_TYPE_VALUES as readonly number[]).includes(maestro.AccountType)) {
+    throw new ApiError("유료 요금제 계정만 연장 신청이 가능합니다.", 400);
+  }
+
   const request = await db.maestro_extension.create({
     data: {
       MaestroID: maestroID,
-      AccountType: accountType,
+      AccountType: maestro.AccountType,
       RequestedDateTime: new Date(),
       Status: REQUEST_STATUSES.REQUESTED,
     },
diff --git a/lib/maestros.ts b/lib/maestros.ts
index 097d171..304f5c3 100644
--- a/lib/maestros.ts
+++ b/lib/maestros.ts
@@ -3,7 +3,7 @@ import { z } from "zod";
 import { db } from "@/lib/db";
 import { logger } from "@/lib/logger";
 import { ApiError } from "@/lib/errors";
-import { ACTIVATE_STATUSES, ACCOUNT_TYPES } from "@/lib/constants";
+import { ACTIVATE_STATUSES, PAID_ACCOUNT_TYPE_VALUES } from "@/lib/constants";
 import type { Prisma } from "@/lib/generated/prisma/client";
 
 const pageSizeOptions = [10, 20, 50, 100] as const;
@@ -104,14 +104,6 @@ export type MaestroDetail = {
   }>;
 };
 
-const paidAccountTypeValues = [
-  ACCOUNT_TYPES.BASIC_20,
-  ACCOUNT_TYPES.STANDARD_50,
-  ACCOUNT_TYPES.PRO_100,
-  ACCOUNT_TYPES.SCHOOL_500,
-  ACCOUNT_TYPES.SCHOOL_1000,
-] as const;
-
 const activateStatusValues = [
   ACTIVATE_STATUSES.PENDING,
   ACTIVATE_STATUSES.TRIAL,
@@ -130,7 +122,7 @@ export const updateMaestroSchema = z.object({
   accountType: z.coerce
     .number()
     .int()
-    .refine((v) => (paidAccountTypeValues as readonly number[]).includes(v))
+    .refine((v) => (PAID_ACCOUNT_TYPE_VALUES as readonly number[]).includes(v))
     .optional(),
   availableActivateDateTime: z.string().min(1).optional(),
   allowEditEnterCode: z.coerce.number().int().min(0).max(1).optional(),
diff --git a/lib/upgrade-requests.ts b/lib/upgrade-requests.ts
index 2dccd0c..791b032 100644
--- a/lib/upgrade-requests.ts
+++ b/lib/upgrade-requests.ts
@@ -3,7 +3,7 @@ import { z } from "zod";
 import { db } from "@/lib/db";
 import { logger } from "@/lib/logger";
 import { ApiError } from "@/lib/errors";
-import { ACTIVATE_STATUSES, REQUEST_STATUSES } from "@/lib/constants";
+import { ACTIVATE_STATUSES, PAID_ACCOUNT_TYPE_VALUES, REQUEST_STATUSES } from "@/lib/constants";
 import type { Prisma } from "@/lib/generated/prisma/client";
 import {
   calculateUpgradePrice,
@@ -171,38 +171,44 @@ export async function createUpgradeRequest(
   maestroID: number,
   requestedAccountType: number
 ): Promise<{ maestroUpgradeID: number; registeredAccountType: number; requestedDateTime: string; status: number }> {
-  const maestro = await db.maestro.findUnique({
-    where: { MaestroID: maestroID },
-    select: { ActivateStatus: true, AccountType: true },
+  return db.$transaction(async (tx) => {
+    const maestro = await tx.maestro.findUnique({
+      where: { MaestroID: maestroID },
+      select: { ActivateStatus: true, AccountType: true },
+    });
+
+    if (!maestro) {
+      throw new ApiError("마에스트로를 찾을 수 없습니다.", 404);
+    }
+
+    if (requestedAccountType <= maestro.AccountType) {
+      throw new ApiError("현재 요금제보다 높은 요금제로만 업그레이드 신청이 가능합니다.", 400);
+    }
+
+    const request = await tx.maestro_upgrade.create({
+      data: {
+        MaestroID: maestroID,
+        RegisteredActivateStatus: maestro.ActivateStatus,
+        RegisteredAccountType: maestro.AccountType,
+        RequestedAccountType: requestedAccountType,
+        RequestedDateTime: new Date(),
+        Status: REQUEST_STATUSES.REQUESTED,
+      },
+      select: {
+        MaestroUpgradeID: true,
+        RegisteredAccountType: true,
+        RequestedDateTime: true,
+        Status: true,
+      },
+    });
+
+    return {
+      maestroUpgradeID: request.MaestroUpgradeID,
+      registeredAccountType: request.RegisteredAccountType,
+      requestedDateTime: request.RequestedDateTime.toISOString(),
+      status: request.Status,
+    };
   });
-
-  if (!maestro) {
-    throw new ApiError("마에스트로를 찾을 수 없습니다.", 404);
-  }
-
-  const request = await db.maestro_upgrade.create({
-    data: {
-      MaestroID: maestroID,
-      RegisteredActivateStatus: maestro.ActivateStatus,
-      RegisteredAccountType: maestro.AccountType,
-      RequestedAccountType: requestedAccountType,
-      RequestedDateTime: new Date(),
-      Status: REQUEST_STATUSES.REQUESTED,
-    },
-    select: {
-      MaestroUpgradeID: true,
-      RegisteredAccountType: true,
-      RequestedDateTime: true,
-      Status: true,
-    },
-  });
-
-  return {
-    maestroUpgradeID: request.MaestroUpgradeID,
-    registeredAccountType: request.RegisteredAccountType,
-    requestedDateTime: request.RequestedDateTime.toISOString(),
-    status: request.Status,
-  };
 }
 
 export async function rejectUpgradeRequest(