diff --git a/pyproject.toml b/pyproject.toml
index 1eb00b8..99eb7b6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,8 +18,10 @@ dependencies = [
 engine = ["faster-whisper>=1.0.3", "av>=11"]
 # GPU CUDA 런타임 (faster-whisper GPU 추론 시)
 gpu = ["nvidia-cublas-cu12", "nvidia-cudnn-cu12"]
-# P2 API + Queue
-api = ["fastapi>=0.110", "uvicorn[standard]>=0.29", "redis>=5.0", "rq>=1.16"]
+# 테스트 API (동기) — serve
+api = ["fastapi>=0.110", "uvicorn[standard]>=0.29", "python-multipart>=0.0.9"]
+# P2 비동기 큐 (보류)
+queue = ["redis>=5.0", "rq>=1.16"]
 # P5 옵션
 diarize = ["pyannote.audio>=3.1"]
 llm = ["openai>=1.30"]
@@ -35,4 +37,4 @@ build-backend = "hatchling.build"
 packages = ["src/luke_scribe"]
 
 [dependency-groups]
-dev = ["pytest>=8.2", "ruff>=0.5"]
+dev = ["pytest>=8.2", "ruff>=0.5", "httpx>=0.27"]
diff --git a/scripts/llm_correct.py b/scripts/llm_correct.py
new file mode 100644
index 0000000..c08264c
--- /dev/null
+++ b/scripts/llm_correct.py
@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+"""STT 후처리 PoC — 음차된 영문 기술용어를 사내 LLM(OpenAI 호환)으로 복원.
+
+게이트가 닿는 환경에서 실행:
+    export SCRIBE_LLM_BASE_URL=http://localhost:8080/v1
+    export SCRIBE_LLM_API_KEY=<사내 키>
+    export SCRIBE_LLM_MODEL=copilot-gpt-4o
+    python3 scripts/llm_correct.py              # 내장 샘플로 데모
+    python3 scripts/llm_correct.py < my.txt     # 임의 전사 교정
+
+외부 의존성 없음(urllib). 향후 postprocess/llm.py(confidence-gated, 청크/러닝글로서리)로 발전.
+"""
+from __future__ import annotations
+
+import json
+import os
+import sys
+import time
+import urllib.error
+import urllib.request
+
+SYSTEM = (
+    "너는 한국어 STT 전사 후처리기다. 한국어 음성에 섞여 나온 영어 기술용어·고유명사가 "
+    "발음대로 한글로 음차되어 잘못 적힌 부분을 문맥과 지식으로 원래 영어 표기로 복원하라. "
+    "일반 한국어는 그대로 두고, 확실하지 않으면 바꾸지 마라. 설명 없이 교정된 전사문만 출력하라."
+)
+
+# turbo가 망친 실제 전사(EmbeddingGemma 강연) — 내장 데모용
+SAMPLE = (
+    "그래서 오늘 준비한 내용은 기본적으로 인베딩 점마에 대해서 설명을 드릴 텐데요. "
+    "여러분들이 알고 계시는 랭기징 모델이 정말 사람이 생각하는 것처럼 하는데 "
+    "그 다음에 구글에 런칭한 오픈모델입니다. 인베딩 점마 라는 것을 소개를 해드릴 예정입니다. "
+    "그리고 어 재미나이 하고 이제 점마하고 두 가지가 있는데요. "
+    "구글 포 디벨로퍼스 사이트에 가시면 제가 올린 포스트도 보실 수 있는데."
+)
+
+
+def correct(text: str) -> str:
+    base = os.environ.get("SCRIBE_LLM_BASE_URL", "http://localhost:8080/v1").rstrip("/")
+    key = os.environ.get("SCRIBE_LLM_API_KEY", "")
+    model = os.environ.get("SCRIBE_LLM_MODEL", "copilot-gpt-4o")
+    payload = {
+        "model": model,
+        "temperature": 0,
+        "messages": [
+            {"role": "system", "content": SYSTEM},
+            {"role": "user", "content": text},
+        ],
+    }
+    req = urllib.request.Request(
+        base + "/chat/completions",
+        data=json.dumps(payload).encode(),
+        headers={"Content-Type": "application/json", "Authorization": "Bearer " + key},
+    )
+    retries = 4
+    for attempt in range(1, retries + 1):
+        try:
+            with urllib.request.urlopen(req, timeout=90) as resp:
+                return json.loads(resp.read())["choices"][0]["message"]["content"]
+        except urllib.error.HTTPError:
+            raise  # 실제 HTTP 응답(401/400 등) — 재시도 무의미
+        except (urllib.error.URLError, OSError) as exc:  # 연결 reset/timeout 등 transient
+            if attempt == retries:
+                raise
+            print(f"  [retry {attempt}/{retries - 1}] {type(exc).__name__} → 재시도", file=sys.stderr)
+            time.sleep(1.5 * attempt)
+    raise RuntimeError("unreachable")
+
+
+def main() -> None:
+    src = (sys.stdin.read().strip() if not sys.stdin.isatty() else "") or SAMPLE
+    print("=== 원본 ===\n" + src + "\n\n=== 교정 ===")
+    try:
+        print(correct(src))
+    except urllib.error.HTTPError as exc:
+        sys.exit(f"HTTP {exc.code}: {exc.read().decode()[:300]}")
+    except Exception as exc:  # noqa: BLE001
+        sys.exit(f"{type(exc).__name__}: {exc}")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/src/luke_scribe/api/__init__.py b/src/luke_scribe/api/__init__.py
new file mode 100644
index 0000000..ef7fad9
--- /dev/null
+++ b/src/luke_scribe/api/__init__.py
@@ -0,0 +1 @@
+"""HTTP API (FastAPI) — 동기 테스트 API. 비동기 큐/실시간은 P2/P3."""
diff --git a/src/luke_scribe/api/app.py b/src/luke_scribe/api/app.py
new file mode 100644
index 0000000..49ea76e
--- /dev/null
+++ b/src/luke_scribe/api/app.py
@@ -0,0 +1,24 @@
+"""FastAPI 앱 팩토리."""
+from __future__ import annotations
+
+import contextlib
+import logging
+from collections.abc import AsyncIterator
+
+from fastapi import FastAPI
+
+from .deps import ensure_keys
+from .routes.transcribe import router
+
+logger = logging.getLogger("luke_scribe.api")
+
+
+def create_app() -> FastAPI:
+    @contextlib.asynccontextmanager
+    async def lifespan(_app: FastAPI) -> AsyncIterator[None]:
+        logger.info("luke_scribe API ready · X-API-Key=%s", ensure_keys()[0])
+        yield
+
+    app = FastAPI(title="luke_scribe", version="0.1.0", lifespan=lifespan)
+    app.include_router(router)
+    return app
diff --git a/src/luke_scribe/api/deps.py b/src/luke_scribe/api/deps.py
new file mode 100644
index 0000000..3203f49
--- /dev/null
+++ b/src/luke_scribe/api/deps.py
@@ -0,0 +1,26 @@
+"""인증 — X-API-Key (스펙 §3.8). 키 미설정 시 기동 때 임시 키 1개 생성·강제."""
+from __future__ import annotations
+
+import secrets
+
+from fastapi import Header, HTTPException, status
+
+from ..config import settings
+
+_ephemeral_key: str | None = None
+
+
+def ensure_keys() -> list[str]:
+    """유효 키 목록. 설정이 없으면 임시 키를 1회 생성해 반환(앱이 출력)."""
+    global _ephemeral_key
+    if settings.api_keys:
+        return settings.api_keys
+    if _ephemeral_key is None:
+        _ephemeral_key = "sk-luke-" + secrets.token_urlsafe(24)
+    return [_ephemeral_key]
+
+
+def require_api_key(x_api_key: str | None = Header(default=None)) -> str:
+    if x_api_key not in ensure_keys():
+        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "invalid or missing X-API-Key")
+    return x_api_key
diff --git a/src/luke_scribe/api/engine_pool.py b/src/luke_scribe/api/engine_pool.py
new file mode 100644
index 0000000..122f47d
--- /dev/null
+++ b/src/luke_scribe/api/engine_pool.py
@@ -0,0 +1,27 @@
+"""프로세스 레벨 엔진 캐시 — 모델 load-once 재사용 (스펙 §3.5).
+
+전사는 `transcribe_lock`으로 직렬화(단일 GPU/CPU, 테스트 등급). uvicorn 단일 워커 전제.
+"""
+from __future__ import annotations
+
+import threading
+
+from ..engine.faster_whisper_engine import FasterWhisperEngine
+
+_engines: dict[tuple[str, str, str], FasterWhisperEngine] = {}
+_cache_lock = threading.Lock()
+transcribe_lock = threading.Lock()
+
+
+def get_engine(
+    model: str, device: str, compute_type: str, cache_dir: str | None = None
+) -> FasterWhisperEngine:
+    key = (model, device, compute_type)
+    eng = _engines.get(key)
+    if eng is None:
+        with _cache_lock:
+            eng = _engines.get(key)
+            if eng is None:
+                eng = FasterWhisperEngine(model, device, compute_type, cache_dir)
+                _engines[key] = eng
+    return eng
diff --git a/src/luke_scribe/api/routes/__init__.py b/src/luke_scribe/api/routes/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/src/luke_scribe/api/routes/transcribe.py b/src/luke_scribe/api/routes/transcribe.py
new file mode 100644
index 0000000..d9e8f7b
--- /dev/null
+++ b/src/luke_scribe/api/routes/transcribe.py
@@ -0,0 +1,123 @@
+"""라우트 — /health, /v1/system, /v1/models, POST /v1/transcribe (동기)."""
+from __future__ import annotations
+
+import contextlib
+import os
+import tempfile
+
+from fastapi import APIRouter, Depends, File, Form, HTTPException, UploadFile, status
+from fastapi.responses import PlainTextResponse
+
+from ...audio.ingest import probe_media
+from ...config import settings
+from ...devices import DeviceManager
+from ...postprocess import llm as llm_correct
+from ...postprocess import rules
+from ...results import formats
+from ..deps import require_api_key
+from ..engine_pool import get_engine, transcribe_lock
+
+router = APIRouter()
+
+
+@router.get("/health")
+def health() -> dict[str, str]:
+    return {"status": "ok"}
+
+
+@router.get("/v1/system")
+def system():  # noqa: ANN201 — DeviceProfile(pydantic) 직렬화
+    return DeviceManager.detect()
+
+
+@router.get("/v1/models")
+def models() -> dict:
+    profile = DeviceManager.detect()
+    return {
+        "tier": profile.tier.value,
+        "served": profile.served_models,
+        "realtime": settings.model_realtime,
+        "batch": settings.model_batch,
+    }
+
+
+@router.post("/v1/transcribe")
+def transcribe_ep(  # noqa: PLR0913 — 요청 옵션 다수(스펙 options 스키마)
+    file: UploadFile = File(...),
+    language: str | None = Form(None),
+    model: str | None = Form(None),
+    device: str = Form("auto"),
+    vad: bool = Form(True),
+    word_timestamps: bool = Form(False),
+    correct: bool = Form(False),
+    response_format: str = Form("json"),
+    _api_key: str = Depends(require_api_key),
+):
+    suffix = os.path.splitext(file.filename or "")[1] or ".bin"
+    fd, tmp = tempfile.mkstemp(prefix="luke_up_", suffix=suffix)
+    try:
+        with os.fdopen(fd, "wb") as out:
+            while chunk := file.file.read(1 << 20):
+                out.write(chunk)
+
+        info = probe_media(tmp)
+        if info.duration_s > settings.max_duration_s or info.size_bytes > settings.max_size_bytes:
+            raise HTTPException(
+                status.HTTP_413_CONTENT_TOO_LARGE,
+                f"{info.duration_s:.0f}s/{info.size_bytes}B "
+                f"exceeds {settings.max_duration_s}s/{settings.max_size_bytes}B",
+            )
+
+        profile = DeviceManager.detect(force_device=(None if device == "auto" else device))
+        dev = "cpu" if profile.kind == "cpu" else "cuda"
+        model_name = model or settings.model_realtime
+        lang = language or settings.language
+
+        engine = get_engine(model_name, dev, profile.compute_type, settings.model_cache_dir)
+        with transcribe_lock:
+            segments, tinfo = engine.transcribe(
+                tmp, language=lang, word_timestamps=word_timestamps, vad=vad
+            )
+            seg_list = [
+                {"start": float(s.start), "end": float(s.end), "text": s.text.strip()}
+                for s in segments
+            ]
+
+        text = " ".join(s["text"] for s in seg_list).strip()
+        corrected = False
+        if correct:
+            try:
+                text = rules.normalize(
+                    llm_correct.correct(
+                        text,
+                        base_url=settings.llm_base_url,
+                        api_key=settings.llm_api_key,
+                        model=settings.llm_model,
+                    )
+                )
+                corrected = True
+            except llm_correct.LLMNotConfigured as exc:
+                raise HTTPException(status.HTTP_400_BAD_REQUEST, f"correct=true but {exc}") from exc
+            except Exception as exc:  # noqa: BLE001
+                raise HTTPException(
+                    status.HTTP_502_BAD_GATEWAY, f"LLM correction failed: {exc}"
+                ) from exc
+
+        if response_format == "txt":
+            return PlainTextResponse(text)
+        if response_format == "srt":
+            return PlainTextResponse(formats.to_srt(seg_list))
+        if response_format == "vtt":
+            return PlainTextResponse(formats.to_vtt(seg_list))
+        return {
+            "text": text,
+            "segments": seg_list,
+            "language": getattr(tinfo, "language", None),
+            "model_used": model_name,
+            "corrected": corrected,
+            "duration_s": info.duration_s,
+        }
+    finally:
+        with contextlib.suppress(OSError):
+            os.remove(tmp)  # 프라이버시: 모든 종료경로에서 임시파일 삭제
+        file.file.close()
diff --git a/src/luke_scribe/api/schemas.py b/src/luke_scribe/api/schemas.py
new file mode 100644
index 0000000..7dd3595
--- /dev/null
+++ b/src/luke_scribe/api/schemas.py
@@ -0,0 +1,19 @@
+"""API 응답 스키마."""
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+
+class Segment(BaseModel):
+    start: float
+    end: float
+    text: str
+
+
+class TranscribeResult(BaseModel):
+    text: str
+    segments: list[Segment]
+    language: str | None = None
+    model_used: str
+    corrected: bool = False
+    duration_s: float = 0.0
diff --git a/src/luke_scribe/cli.py b/src/luke_scribe/cli.py
index 09c30ca..9fb8ee8 100644
--- a/src/luke_scribe/cli.py
+++ b/src/luke_scribe/cli.py
@@ -110,9 +110,49 @@ def bench(samples: str = typer.Option(None, help="라벨된 KO+EN 샘플 디렉
 
 
 @app.command()
-def serve() -> None:
-    """API 서버 (P2)."""
-    _todo("serve", "→ P2 (FastAPI + Redis/RQ)")
+def serve(
+    host: str = typer.Option(None, help="bind host (기본 설정값)"),
+    port: int = typer.Option(None, help="bind port (기본 설정값)"),
+    tunnel: str = typer.Option("none", help="none|cloudflare (Colab 외부 노출)"),
+) -> None:
+    """테스트 API 서버 (동기 transcribe + opt-in 보정). AC-1/11/12 일부."""
+    from .config import settings
+
+    try:
+        import uvicorn
+
+        from .api.app import create_app
+        from .api.deps import ensure_keys
+    except ImportError as exc:
+        console.print(f"[red]API 의존성 미설치:[/] {exc}\n→ `uv sync --extra api --extra engine`")
+        raise typer.Exit(code=1) from exc
+
+    bind_host = host or settings.host
+    bind_port = port or settings.port
+    key = ensure_keys()[0]
+    console.print(
+        f"[green]luke_scribe API[/] → http://{bind_host}:{bind_port}   "
+        f"(X-API-Key: [bold]{key}[/])"
+    )
+
+    proc = None
+    if tunnel == "cloudflare":
+        try:
+            from .connectivity.tunnel import start_cloudflared
+
+            proc, public = start_cloudflared(bind_port)
+            console.print(
+                f"[green]public:[/] {public}" if public
+                else "[yellow]cloudflared URL 미수신(계속 진행).[/]"
+            )
+        except Exception as exc:  # noqa: BLE001
+            console.print(f"[yellow]터널 실패(무시): {exc}[/]")
+
+    try:
+        uvicorn.run(create_app(), host=bind_host, port=bind_port, workers=1, log_level="info")
+    finally:
+        if proc is not None:
+            proc.terminate()
 
 
 def main() -> None:
diff --git a/src/luke_scribe/config.py b/src/luke_scribe/config.py
index 795cc29..f9761c3 100644
--- a/src/luke_scribe/config.py
+++ b/src/luke_scribe/config.py
@@ -34,5 +34,15 @@ class Settings(BaseSettings):
     # 모델 캐시 디렉터리 (None=HF 기본)
     model_cache_dir: str | None = None
 
+    # API 서버 (테스트 동기 API)
+    host: str = "127.0.0.1"
+    port: int = 8000
+
+    # LLM 보정 (opt-in, 사내/로컬 OpenAI 호환 백엔드)
+    llm_enabled: bool = False
+    llm_base_url: str | None = None      # 예: http://192.168.0.123:8080/v1 (allowlist=이 endpoint만)
+    llm_api_key: str | None = None       # env SCRIBE_LLM_API_KEY 로만 주입
+    llm_model: str = "copilot-gpt-4o"
+
 
 settings = Settings()
diff --git a/src/luke_scribe/connectivity/__init__.py b/src/luke_scribe/connectivity/__init__.py
new file mode 100644
index 0000000..5151d98
--- /dev/null
+++ b/src/luke_scribe/connectivity/__init__.py
@@ -0,0 +1 @@
+"""외부 노출 — Colab 등 공인 IP 부재 환경 (스펙 §8). MVP: cloudflared quick tunnel."""
diff --git a/src/luke_scribe/connectivity/tunnel.py b/src/luke_scribe/connectivity/tunnel.py
new file mode 100644
index 0000000..cb9e10a
--- /dev/null
+++ b/src/luke_scribe/connectivity/tunnel.py
@@ -0,0 +1,63 @@
+"""cloudflared quick tunnel (스펙 §8). 바이너리 없으면 캐시에 다운로드. best-effort.
+
+`serve --tunnel cloudflare` 가 호출 → 공개 https://<rand>.trycloudflare.com 발급(계정 불필요).
+"""
+from __future__ import annotations
+
+import os
+import platform
+import re
+import shutil
+import stat
+import subprocess
+import time
+import urllib.request
+
+_RELEASE = "https://github.com/cloudflare/cloudflared/releases/latest/download"
+_ASSETS = {
+    ("Linux", "x86_64"): "cloudflared-linux-amd64",
+    ("Linux", "aarch64"): "cloudflared-linux-arm64",
+}
+_URL_RE = re.compile(r"https://[-a-z0-9]+\.trycloudflare\.com")
+
+
+def ensure_cloudflared() -> str:
+    found = shutil.which("cloudflared")
+    if found:
+        return found
+    cache = os.path.expanduser("~/.cache/luke_scribe")
+    os.makedirs(cache, exist_ok=True)
+    path = os.path.join(cache, "cloudflared")
+    if os.path.exists(path):
+        return path
+    asset = _ASSETS.get((platform.system(), platform.machine()))
+    if not asset:
+        raise RuntimeError(
+            f"cloudflared 자동설치 미지원: {platform.system()}/{platform.machine()} "
+            "— 수동 설치 후 PATH에 두세요."
+        )
+    urllib.request.urlretrieve(f"{_RELEASE}/{asset}", path)  # noqa: S310
+    os.chmod(path, os.stat(path).st_mode | stat.S_IEXEC)
+    return path
+
+
+def start_cloudflared(port: int, timeout: float = 30.0) -> tuple[subprocess.Popen, str | None]:
+    """터널 프로세스 시작 → (proc, public_url). URL 못 받으면 url=None(프로세스는 유지)."""
+    binp = ensure_cloudflared()
+    proc = subprocess.Popen(  # noqa: S603
+        [binp, "tunnel", "--no-autoupdate", "--url", f"http://localhost:{port}"],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+        text=True,
+    )
+    deadline = time.time() + timeout
+    while time.time() < deadline:
+        line = proc.stdout.readline() if proc.stdout else ""
+        if not line:
+            if proc.poll() is not None:
+                break
+            continue
+        m = _URL_RE.search(line)
+        if m:
+            return proc, m.group(0)
+    return proc, None
diff --git a/src/luke_scribe/postprocess/__init__.py b/src/luke_scribe/postprocess/__init__.py
new file mode 100644
index 0000000..f5c44ab
--- /dev/null
+++ b/src/luke_scribe/postprocess/__init__.py
@@ -0,0 +1 @@
+"""후처리 — glossary/rules + (opt-in) LLM 보정 + confidence (스펙 §7)."""
diff --git a/src/luke_scribe/postprocess/llm.py b/src/luke_scribe/postprocess/llm.py
new file mode 100644
index 0000000..0d191c4
--- /dev/null
+++ b/src/luke_scribe/postprocess/llm.py
@@ -0,0 +1,66 @@
+"""LLM 보정 (스펙 §7 stage 3 / §3.8) — 음차된 영문 용어를 문맥+지식으로 복원.
+
+OpenAI 호환 백엔드(사내/로컬). **opt-in**(요청 correct=true에서만 호출), **allowlist**(설정된
+base_url만), **감사로그**(호출 1줄). transient(연결 reset/timeout) 재시도.
+긴 입력 청크/러닝글로서리는 TODO — MVP는 단일 호출(짧은 클립엔 충분).
+"""
+from __future__ import annotations
+
+import json
+import logging
+import time
+import urllib.error
+import urllib.request
+
+logger = logging.getLogger("luke_scribe.postprocess.llm")
+
+SYSTEM = (
+    "너는 한국어 STT 전사 후처리기다. 한국어 음성에 섞여 나온 영어 기술용어·고유명사가 "
+    "발음대로 한글로 음차되어 잘못 적힌 부분을 문맥과 지식으로 원래 영어 표기로 복원하라. "
+    "일반 한국어는 그대로 두고, 확실하지 않으면 바꾸지 마라. 설명 없이 교정된 전사문만 출력하라."
+)
+
+
+class LLMNotConfigured(RuntimeError):
+    """llm_base_url / llm_api_key 미설정."""
+
+
+def correct(
+    text: str,
+    *,
+    base_url: str | None,
+    api_key: str | None,
+    model: str = "copilot-gpt-4o",
+    retries: int = 4,
+    timeout: float = 90.0,
+) -> str:
+    if not base_url or not api_key:
+        raise LLMNotConfigured("llm_base_url/llm_api_key 미설정 — correct를 쓰려면 SCRIBE_LLM_* 설정 필요")
+    url = base_url.rstrip("/") + "/chat/completions"
+    payload = {
+        "model": model,
+        "temperature": 0,
+        "messages": [
+            {"role": "system", "content": SYSTEM},
+            {"role": "user", "content": text},
+        ],
+    }
+    req = urllib.request.Request(
+        url,
+        data=json.dumps(payload).encode(),
+        headers={"Content-Type": "application/json", "Authorization": "Bearer " + api_key},
+    )
+    # 감사로그 (allowlist=설정 endpoint, 호출 1줄)
+    logger.info("llm-correct egress endpoint=%s model=%s chars=%d", url, model, len(text))
+    for attempt in range(1, retries + 1):
+        try:
+            with urllib.request.urlopen(req, timeout=timeout) as resp:
+                data = json.loads(resp.read())
+            return data["choices"][0]["message"]["content"]
+        except urllib.error.HTTPError:
+            raise  # 실제 HTTP 응답(401/4xx) — 재시도 무의미
+        except (urllib.error.URLError, OSError):  # 연결 reset/timeout 등 transient
+            if attempt == retries:
+                raise
+            time.sleep(1.0 * attempt)
+    raise RuntimeError("unreachable")
diff --git a/src/luke_scribe/postprocess/rules.py b/src/luke_scribe/postprocess/rules.py
new file mode 100644
index 0000000..4c42866
--- /dev/null
+++ b/src/luke_scribe/postprocess/rules.py
@@ -0,0 +1,18 @@
+"""결정적 정규화 (스펙 §7 stage 2). LLM 복원 뒤 정확한 표기로 보정.
+
+발견 노트: LLM이 'Embedding Gemma'로 복원 → rules가 공식 표기 'EmbeddingGemma'로 정규화.
+"""
+from __future__ import annotations
+
+# 기본 내장 맵 (config/glossary로 확장 가능)
+DEFAULT_RULES: dict[str, str] = {
+    "Embedding Gemma": "EmbeddingGemma",
+    "embedding gemma": "EmbeddingGemma",
+    "Google for developers": "Google for Developers",
+}
+
+
+def normalize(text: str, extra: dict[str, str] | None = None) -> str:
+    for src, dst in {**DEFAULT_RULES, **(extra or {})}.items():
+        text = text.replace(src, dst)
+    return text
diff --git a/src/luke_scribe/results/__init__.py b/src/luke_scribe/results/__init__.py
new file mode 100644
index 0000000..2b9ae64
--- /dev/null
+++ b/src/luke_scribe/results/__init__.py
@@ -0,0 +1 @@
+"""결과 포맷·보관 (스펙 §4). MVP: 출력 포맷(txt/srt/vtt)."""
diff --git a/src/luke_scribe/results/formats.py b/src/luke_scribe/results/formats.py
new file mode 100644
index 0000000..41c85d5
--- /dev/null
+++ b/src/luke_scribe/results/formats.py
@@ -0,0 +1,45 @@
+"""세그먼트 → txt/srt/vtt 변환 (스펙 §4, AC-9). 세그먼트=dict{start,end,text}."""
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+Segment = dict  # {"start": float, "end": float, "text": str}
+
+
+def _hms(t: float) -> tuple[int, int, int, int]:
+    t = max(0.0, t)
+    h = int(t // 3600)
+    m = int((t % 3600) // 60)
+    s = int(t % 60)
+    ms = int(round((t - int(t)) * 1000))
+    if ms == 1000:  # 반올림 보정
+        ms, s = 0, s + 1
+    return h, m, s, ms
+
+
+def _ts_srt(t: float) -> str:
+    h, m, s, ms = _hms(t)
+    return f"{h:02d}:{m:02d}:{s:02d},{ms:03d}"
+
+
+def _ts_vtt(t: float) -> str:
+    h, m, s, ms = _hms(t)
+    return f"{h:02d}:{m:02d}:{s:02d}.{ms:03d}"
+
+
+def to_txt(segments: Sequence[Segment]) -> str:
+    return "\n".join(s["text"].strip() for s in segments)
+
+
+def to_srt(segments: Sequence[Segment]) -> str:
+    out: list[str] = []
+    for i, s in enumerate(segments, 1):
+        out += [str(i), f"{_ts_srt(s['start'])} --> {_ts_srt(s['end'])}", s["text"].strip(), ""]
+    return "\n".join(out).strip() + "\n"
+
+
+def to_vtt(segments: Sequence[Segment]) -> str:
+    out: list[str] = ["WEBVTT", ""]
+    for s in segments:
+        out += [f"{_ts_vtt(s['start'])} --> {_ts_vtt(s['end'])}", s["text"].strip(), ""]
+    return "\n".join(out).strip() + "\n"
diff --git a/tests/test_api.py b/tests/test_api.py
new file mode 100644
index 0000000..17b361c
--- /dev/null
+++ b/tests/test_api.py
@@ -0,0 +1,86 @@
+"""API — FastAPI TestClient. 엔진은 monkeypatch(가짜)로 모델 로드 회피."""
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+from fastapi.testclient import TestClient
+
+import luke_scribe.api.routes.transcribe as route
+from luke_scribe.api.app import create_app
+from luke_scribe.config import settings
+
+
+class _FakeSeg:
+    def __init__(self, start: float, end: float, text: str) -> None:
+        self.start = start
+        self.end = end
+        self.text = text
+
+
+class _FakeEngine:
+    def transcribe(self, _audio, **_kw):
+        return [_FakeSeg(0.0, 1.0, "안녕 vLLM"), _FakeSeg(1.0, 2.0, "두번째")], SimpleNamespace(
+            language="ko"
+        )
+
+
+@pytest.fixture
+def client(monkeypatch):
+    monkeypatch.setattr(route, "get_engine", lambda *a, **k: _FakeEngine())
+    monkeypatch.setattr(
+        route, "probe_media", lambda p: SimpleNamespace(path=p, duration_s=2.0, size_bytes=1234)
+    )
+    monkeypatch.setattr(settings, "api_keys", ["testkey"])
+    return TestClient(create_app())
+
+
+def _files():
+    return {"file": ("a.wav", b"RIFF0000WAVE", "audio/wav")}
+
+
+def test_health(client):
+    assert client.get("/health").json() == {"status": "ok"}
+
+
+def test_requires_key(client):
+    assert client.post("/v1/transcribe", files=_files()).status_code == 401
+
+
+def test_transcribe_ok(client):
+    r = client.post(
+        "/v1/transcribe", files=_files(), headers={"X-API-Key": "testkey"}, data={"language": "ko"}
+    )
+    assert r.status_code == 200
+    body = r.json()
+    assert body["segments"][0]["text"] == "안녕 vLLM"
+    assert body["model_used"]
+    assert body["corrected"] is False
+
+
+def test_413(client, monkeypatch):
+    monkeypatch.setattr(
+        route, "probe_media", lambda p: SimpleNamespace(path=p, duration_s=999999, size_bytes=1)
+    )
+    r = client.post("/v1/transcribe", files=_files(), headers={"X-API-Key": "testkey"})
+    assert r.status_code == 413
+
+
+def test_srt_format(client):
+    r = client.post(
+        "/v1/transcribe",
+        files=_files(),
+        headers={"X-API-Key": "testkey"},
+        data={"response_format": "srt"},
+    )
+    assert r.status_code == 200
+    assert "00:00:00,000 --> 00:00:01,000" in r.text
+
+
+def test_correct_path(client, monkeypatch):
+    monkeypatch.setattr(route.llm_correct, "correct", lambda text, **k: text + " [보정]")
+    r = client.post(
+        "/v1/transcribe", files=_files(), headers={"X-API-Key": "testkey"}, data={"correct": "true"}
+    )
+    assert r.status_code == 200
+    assert r.json()["corrected"] is True
diff --git a/tests/test_formats.py b/tests/test_formats.py
new file mode 100644
index 0000000..6d945b5
--- /dev/null
+++ b/tests/test_formats.py
@@ -0,0 +1,25 @@
+"""results.formats — txt/srt/vtt."""
+from __future__ import annotations
+
+from luke_scribe.results import formats
+
+SEGS = [
+    {"start": 0.0, "end": 1.5, "text": "안녕 world"},
+    {"start": 1.5, "end": 3.0, "text": "두번째"},
+]
+
+
+def test_txt():
+    assert formats.to_txt(SEGS) == "안녕 world\n두번째"
+
+
+def test_srt():
+    out = formats.to_srt(SEGS)
+    assert "1\n00:00:00,000 --> 00:00:01,500\n안녕 world" in out
+    assert "2\n00:00:01,500 --> 00:00:03,000\n두번째" in out
+
+
+def test_vtt():
+    out = formats.to_vtt(SEGS)
+    assert out.startswith("WEBVTT")
+    assert "00:00:00.000 --> 00:00:01.500" in out
diff --git a/tests/test_postprocess.py b/tests/test_postprocess.py
new file mode 100644
index 0000000..225ee19
--- /dev/null
+++ b/tests/test_postprocess.py
@@ -0,0 +1,41 @@
+"""postprocess.rules / postprocess.llm (urllib monkeypatch)."""
+from __future__ import annotations
+
+import json
+
+import pytest
+
+from luke_scribe.postprocess import llm, rules
+
+
+def test_rules_normalize():
+    assert rules.normalize("구글 Embedding Gemma 소개") == "구글 EmbeddingGemma 소개"
+    assert rules.normalize("그대로") == "그대로"
+
+
+def test_llm_not_configured():
+    with pytest.raises(llm.LLMNotConfigured):
+        llm.correct("x", base_url=None, api_key=None)
+
+
+class _FakeResp:
+    def __init__(self, payload: dict) -> None:
+        self._p = payload
+
+    def read(self) -> bytes:
+        return json.dumps(self._p).encode()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_a):
+        return False
+
+
+def test_llm_correct_monkeypatched(monkeypatch):
+    def fake_urlopen(_req, timeout=90):  # noqa: ARG001
+        return _FakeResp({"choices": [{"message": {"content": "EmbeddingGemma 복원됨"}}]})
+
+    monkeypatch.setattr(llm.urllib.request, "urlopen", fake_urlopen)
+    out = llm.correct("인베딩 점마", base_url="http://x/v1", api_key="k", model="m")
+    assert out == "EmbeddingGemma 복원됨"
diff --git a/uv.lock b/uv.lock
index 9a8122e..62ad319 100644
--- a/uv.lock
+++ b/uv.lock
@@ -521,7 +521,7 @@ name = "cuda-bindings"
 version = "13.3.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "cuda-pathfinder" },
+    { name = "cuda-pathfinder", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/51/6b/457ca12dad3ee9bfcc9a545cfd6b64b359ba49de40f776f6e028e678f262/cuda_bindings-13.3.1-cp311-cp311-manylinux_2_24_aarch64.manylinux_2_28_aarch64.whl", hash = "sha256:c5879712accf6e14bb01aa5e67440eb84998b8d104b509cc7a6dc0b8f656a474", size = 6053539, upload-time = "2026-05-29T23:11:43.19Z" },
@@ -554,34 +554,34 @@ wheels = [
 
 [package.optional-dependencies]
 cudart = [
-    { name = "nvidia-cuda-runtime", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cuda-runtime", marker = "sys_platform == 'linux'" },
 ]
 cufft = [
-    { name = "nvidia-cufft", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cufft", marker = "sys_platform == 'linux'" },
 ]
 cufile = [
     { name = "nvidia-cufile", marker = "sys_platform == 'linux'" },
 ]
 cupti = [
-    { name = "nvidia-cuda-cupti", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cuda-cupti", marker = "sys_platform == 'linux'" },
 ]
 curand = [
-    { name = "nvidia-curand", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-curand", marker = "sys_platform == 'linux'" },
 ]
 cusolver = [
-    { name = "nvidia-cusolver", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cusolver", marker = "sys_platform == 'linux'" },
 ]
 cusparse = [
-    { name = "nvidia-cusparse", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cusparse", marker = "sys_platform == 'linux'" },
 ]
 nvjitlink = [
-    { name = "nvidia-nvjitlink", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-nvjitlink", marker = "sys_platform == 'linux'" },
 ]
 nvrtc = [
-    { name = "nvidia-cuda-nvrtc", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-cuda-nvrtc", marker = "sys_platform == 'linux'" },
 ]
 nvtx = [
-    { name = "nvidia-nvtx", marker = "sys_platform == 'linux' or sys_platform == 'win32'" },
+    { name = "nvidia-nvtx", marker = "sys_platform == 'linux'" },
 ]
 
 [[package]]
@@ -1384,8 +1384,7 @@ dependencies = [
 [package.optional-dependencies]
 api = [
     { name = "fastapi" },
-    { name = "redis" },
-    { name = "rq" },
+    { name = "python-multipart" },
     { name = "uvicorn", extra = ["standard"] },
 ]
 diarize = [
@@ -1402,9 +1401,14 @@ gpu = [
 llm = [
     { name = "openai" },
 ]
+queue = [
+    { name = "redis" },
+    { name = "rq" },
+]
 
 [package.dev-dependencies]
 dev = [
+    { name = "httpx" },
     { name = "pytest" },
     { name = "ruff" },
 ]
@@ -1423,16 +1427,18 @@ requires-dist = [
     { name = "pyannote-audio", marker = "extra == 'diarize'", specifier = ">=3.1" },
     { name = "pydantic", specifier = ">=2.7" },
     { name = "pydantic-settings", specifier = ">=2.3" },
-    { name = "redis", marker = "extra == 'api'", specifier = ">=5.0" },
+    { name = "python-multipart", marker = "extra == 'api'", specifier = ">=0.0.9" },
+    { name = "redis", marker = "extra == 'queue'", specifier = ">=5.0" },
     { name = "rich", specifier = ">=13.7" },
-    { name = "rq", marker = "extra == 'api'", specifier = ">=1.16" },
+    { name = "rq", marker = "extra == 'queue'", specifier = ">=1.16" },
     { name = "typer", specifier = ">=0.12" },
     { name = "uvicorn", extras = ["standard"], marker = "extra == 'api'", specifier = ">=0.29" },
 ]
-provides-extras = ["engine", "gpu", "api", "diarize", "llm"]
+provides-extras = ["engine", "gpu", "api", "queue", "diarize", "llm"]
 
 [package.metadata.requires-dev]
 dev = [
+    { name = "httpx", specifier = ">=0.27" },
     { name = "pytest", specifier = ">=8.2" },
     { name = "ruff", specifier = ">=0.5" },
 ]
@@ -1836,7 +1842,7 @@ name = "nvidia-cublas"
 version = "13.1.1.3"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "nvidia-cuda-nvrtc" },
+    { name = "nvidia-cuda-nvrtc", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/a7/a1/0bd24ee8c8d03adac032fd2909426a00c88f8c57961b1277ded97f91119f/nvidia_cublas-13.1.1.3-py3-none-manylinux_2_27_aarch64.whl", hash = "sha256:b7a210458267ac818974c53038fbec2e969d5c99f305ab15c72522fa9f001dd5", size = 542848918, upload-time = "2026-04-08T18:46:22.985Z" },
@@ -1911,7 +1917,7 @@ name = "nvidia-cudnn-cu13"
 version = "9.20.0.48"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "nvidia-cublas" },
+    { name = "nvidia-cublas", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/56/c5/83384d846b2fd17c44bd499b36c75a45ed4f095fbbb2252294e89cea5c5c/nvidia_cudnn_cu13-9.20.0.48-py3-none-manylinux_2_27_aarch64.whl", hash = "sha256:e31454ae00094b0c55319d9d15b6fa2fc50a9e1c0f5c8c80fb75258234e731e1", size = 444574296, upload-time = "2026-03-09T19:28:27.751Z" },
@@ -1923,7 +1929,7 @@ name = "nvidia-cufft"
 version = "12.0.0.61"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "nvidia-nvjitlink" },
+    { name = "nvidia-nvjitlink", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/8b/ae/f417a75c0259e85c1d2f83ca4e960289a5f814ed0cea74d18c353d3e989d/nvidia_cufft-12.0.0.61-py3-none-manylinux2014_aarch64.manylinux_2_17_aarch64.whl", hash = "sha256:2708c852ef8cd89d1d2068bdbece0aa188813a0c934db3779b9b1faa8442e5f5", size = 214053554, upload-time = "2025-09-04T08:31:38.196Z" },
@@ -1953,9 +1959,9 @@ name = "nvidia-cusolver"
 version = "12.0.4.66"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "nvidia-cublas" },
-    { name = "nvidia-cusparse" },
-    { name = "nvidia-nvjitlink" },
+    { name = "nvidia-cublas", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
+    { name = "nvidia-cusparse", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
+    { name = "nvidia-nvjitlink", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/c8/c3/b30c9e935fc01e3da443ec0116ed1b2a009bb867f5324d3f2d7e533e776b/nvidia_cusolver-12.0.4.66-py3-none-manylinux_2_27_aarch64.whl", hash = "sha256:02c2457eaa9e39de20f880f4bd8820e6a1cfb9f9a34f820eb12a155aa5bc92d2", size = 223467760, upload-time = "2025-09-04T08:33:04.222Z" },
@@ -1967,7 +1973,7 @@ name = "nvidia-cusparse"
 version = "12.6.3.3"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "nvidia-nvjitlink" },
+    { name = "nvidia-nvjitlink", marker = "sys_platform != 'emscripten' and sys_platform != 'win32'" },
 ]
 wheels = [
     { url = "https://files.pythonhosted.org/packages/f8/94/5c26f33738ae35276672f12615a64bd008ed5be6d1ebcb23579285d960a9/nvidia_cusparse-12.6.3.3-py3-none-manylinux2014_aarch64.manylinux_2_17_aarch64.whl", hash = "sha256:80bcc4662f23f1054ee334a15c72b8940402975e0eab63178fc7e670aa59472c", size = 162155568, upload-time = "2025-09-04T08:33:42.864Z" },
@@ -2834,6 +2840,15 @@ wheels = [
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 ]
 
+[[package]]
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+sdist = { url = "https://files.pythonhosted.org/packages/5b/42/55c32bb9b12693c092ad250a0e82edb5b31ddeda6eb772de5f308b3804ad/python_multipart-0.0.32.tar.gz", hash = "sha256:be54b7f3fa167bb83e4fcd936b887b708f4e57fe75911c02aebf53efaf8d938e", size = 46881, upload-time = "2026-06-04T16:18:58.647Z" }
+wheels = [
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+]
+
 [[package]]
 name = "pytorch-lightning"
 version = "2.6.5"