diff --git a/README.md b/README.md
index a92102f..edef7a1 100644
--- a/README.md
+++ b/README.md
@@ -11,16 +11,16 @@
 
 ## 빠른 시작 (개발)
 ```bash
-uv sync                       # 코어 의존성
-uv run luke-scribe detect     # 하드웨어 감지 → 능력등급/정밀도/워커수
-# 엔진(transcribe/bench)은 다음 증분:
-# uv sync --extra engine
+uv sync                                            # 코어 의존성
+uv run luke-scribe detect                          # 하드웨어 감지 → 능력등급/정밀도/워커수
+uv sync --extra engine                             # 엔진(faster-whisper)
+uv run luke-scribe transcribe FILE --model tiny    # 단발 전사
 ```
 
 ## CLI
 | 명령 | 설명 | 상태 |
 |------|------|------|
 | `detect` | 하드웨어 감지·능력등급(T0~T3)·정밀도·워커수 | ✅ P1 |
-| `transcribe <file>` | 단발 파일 전사 | ⏳ P1 |
+| `transcribe <file>` | 단발 파일 전사 (faster-whisper, CPU/GPU) | ✅ P1 |
 | `bench` | turbo vs large-v3 도메인 벤치(게이트) | ⏳ P1 (샘플셋 필요) |
 | `serve` | API 서버 | ⏳ P2 |
diff --git a/src/luke_scribe/audio/__init__.py b/src/luke_scribe/audio/__init__.py
new file mode 100644
index 0000000..33d380a
--- /dev/null
+++ b/src/luke_scribe/audio/__init__.py
@@ -0,0 +1,4 @@
+"""오디오/영상 입력 — ingest(probe·상한), VAD (스펙 §4-4)."""
+from .ingest import MediaInfo, probe_media
+
+__all__ = ["MediaInfo", "probe_media"]
diff --git a/src/luke_scribe/audio/ingest.py b/src/luke_scribe/audio/ingest.py
new file mode 100644
index 0000000..f2ce1d8
--- /dev/null
+++ b/src/luke_scribe/audio/ingest.py
@@ -0,0 +1,41 @@
+"""미디어 입력 — duration/size probe + 상한 점검 (스펙 §4-4, AC-7).
+
+상한 초과는 호출측이 413으로 매핑(P2). 실제 디코딩은 엔진(faster-whisper/PyAV)이 수행.
+"""
+from __future__ import annotations
+
+import json
+import os
+import shutil
+import subprocess
+from dataclasses import dataclass
+
+
+@dataclass
+class MediaInfo:
+    path: str
+    duration_s: float
+    size_bytes: int
+
+
+def probe_media(path: str) -> MediaInfo:
+    if not os.path.exists(path):
+        raise FileNotFoundError(path)
+    return MediaInfo(path=path, duration_s=_ffprobe_duration(path), size_bytes=os.path.getsize(path))
+
+
+def _ffprobe_duration(path: str) -> float:
+    ffprobe = shutil.which("ffprobe")
+    if not ffprobe:
+        return 0.0
+    try:
+        out = subprocess.run(
+            [ffprobe, "-v", "error", "-show_entries", "format=duration", "-of", "json", path],
+            capture_output=True,
+            text=True,
+            timeout=30,
+            check=True,
+        ).stdout
+        return float(json.loads(out).get("format", {}).get("duration") or 0.0)
+    except Exception:
+        return 0.0
diff --git a/src/luke_scribe/cli.py b/src/luke_scribe/cli.py
index f7d26e6..09c30ca 100644
--- a/src/luke_scribe/cli.py
+++ b/src/luke_scribe/cli.py
@@ -48,9 +48,59 @@ def _todo(name: str, hint: str = "") -> None:
 
 
 @app.command()
-def transcribe(file: str = typer.Argument(..., help="오디오/영상 파일")) -> None:
-    """단발 파일 전사 (다음 증분: engine + ffmpeg ingest)."""
-    _todo("transcribe", "→ `uv sync --extra engine` 후 구현 예정")
+def transcribe(
+    file: str = typer.Argument(..., help="오디오/영상 파일"),
+    model: str = typer.Option(None, help="모델 오버라이드(기본=실시간 모델). tiny|base|large-v3|large-v3-turbo"),
+    language: str = typer.Option(None, help="언어(기본 설정값). 'auto' 가능"),
+    device: str = typer.Option("auto", help="auto|cpu|cuda"),
+    word_timestamps: bool = typer.Option(False, "--word-timestamps"),
+    vad: bool = typer.Option(True, "--vad/--no-vad", help="무음 제거"),
+    timestamps: bool = typer.Option(False, "--timestamps", help="세그먼트 [start–end] 표시"),
+) -> None:
+    """단발 파일 전사 (faster-whisper, CPU/GPU 자동, AC-4 일부)."""
+    from .config import settings
+
+    try:
+        from .audio.ingest import probe_media
+        from .engine.faster_whisper_engine import FasterWhisperEngine
+    except ImportError as exc:
+        console.print(f"[red]엔진 미설치:[/] {exc}\n→ `uv sync --extra engine` 후 다시 시도하세요.")
+        raise typer.Exit(code=1) from exc
+
+    try:
+        info = probe_media(file)
+    except FileNotFoundError:
+        console.print(f"[red]파일 없음:[/] {file}")
+        raise typer.Exit(code=1) from None
+
+    if info.duration_s > settings.max_duration_s or info.size_bytes > settings.max_size_bytes:
+        console.print(
+            f"[red]입력 상한 초과(413):[/] {info.duration_s:.0f}s / {info.size_bytes}B "
+            f"(상한 {settings.max_duration_s}s / {settings.max_size_bytes}B)"
+        )
+        raise typer.Exit(code=1)
+
+    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
+    console.print(
+        f"[dim]model={model_name} device={dev} compute={profile.compute_type} "
+        f"lang={lang} dur={info.duration_s:.1f}s[/]"
+    )
+
+    engine = FasterWhisperEngine(model_name, dev, profile.compute_type, cache_dir=settings.model_cache_dir)
+    segments, tinfo = engine.transcribe(file, language=lang, word_timestamps=word_timestamps, vad=vad)
+
+    count = 0
+    for seg in segments:
+        count += 1
+        if timestamps:
+            console.print(f"[cyan][{seg.start:6.2f}–{seg.end:6.2f}][/] {seg.text.strip()}")
+        else:
+            console.print(seg.text.strip())
+    detected = getattr(tinfo, "language", None)
+    console.print(f"[green]✓ {count} segments · detected_lang={detected} · model_used={model_name}[/]")
 
 
 @app.command()
diff --git a/src/luke_scribe/engine/__init__.py b/src/luke_scribe/engine/__init__.py
new file mode 100644
index 0000000..de79378
--- /dev/null
+++ b/src/luke_scribe/engine/__init__.py
@@ -0,0 +1,5 @@
+"""추론 엔진 — faster-whisper(CTranslate2) 단일 엔진 + 얇은 추상화 (계획 §3 D3)."""
+from .faster_whisper_engine import FasterWhisperEngine
+from .model_registry import resolve_model
+
+__all__ = ["FasterWhisperEngine", "resolve_model"]
diff --git a/src/luke_scribe/engine/faster_whisper_engine.py b/src/luke_scribe/engine/faster_whisper_engine.py
new file mode 100644
index 0000000..48e9d70
--- /dev/null
+++ b/src/luke_scribe/engine/faster_whisper_engine.py
@@ -0,0 +1,55 @@
+"""faster-whisper(CTranslate2) 엔진 래퍼 (스펙 §2 / 계획 §4-3).
+
+faster-whisper가 내부적으로 PyAV로 디코딩하므로 파일 경로(오디오/영상)를 그대로 받는다.
+segments는 제너레이터 — 호출측이 소비하며 progress/취소 점검(P2)에 활용.
+"""
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+from .model_registry import resolve_model
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+
+class FasterWhisperEngine:
+    def __init__(
+        self,
+        model_name: str,
+        device: str,
+        compute_type: str,
+        cache_dir: str | None = None,
+    ) -> None:
+        from faster_whisper import WhisperModel
+
+        self.model_name = model_name
+        self.device = device
+        self.compute_type = compute_type
+        self.model = WhisperModel(
+            resolve_model(model_name),
+            device=device,
+            compute_type=compute_type,
+            download_root=cache_dir,
+        )
+
+    def transcribe(
+        self,
+        audio: str,
+        *,
+        language: str | None = "ko",
+        word_timestamps: bool = False,
+        vad: bool = True,
+        hotwords: list[str] | None = None,
+        initial_prompt: str | None = None,
+        beam_size: int = 5,
+    ) -> tuple[Iterable[Any], Any]:
+        return self.model.transcribe(
+            audio,
+            language=(None if language in (None, "auto") else language),
+            word_timestamps=word_timestamps,
+            vad_filter=vad,
+            hotwords=(" ".join(hotwords) if hotwords else None),
+            initial_prompt=initial_prompt,
+            beam_size=beam_size,
+        )
diff --git a/src/luke_scribe/engine/model_registry.py b/src/luke_scribe/engine/model_registry.py
new file mode 100644
index 0000000..f5a880a
--- /dev/null
+++ b/src/luke_scribe/engine/model_registry.py
@@ -0,0 +1,16 @@
+"""논리 모델명 → faster-whisper(CT2) 식별자 (계획 §4-3).
+
+표준 사이즈(tiny/base/small/medium/large-v3)는 그대로 통과.
+turbo류는 검증된 CT2 변환 레포로 매핑.
+"""
+from __future__ import annotations
+
+_MODEL_IDS: dict[str, str] = {
+    "large-v3-turbo": "deepdml/faster-whisper-large-v3-turbo-ct2",
+    "turbo": "deepdml/faster-whisper-large-v3-turbo-ct2",
+    "large-v3": "large-v3",
+}
+
+
+def resolve_model(name: str) -> str:
+    return _MODEL_IDS.get(name, name)
diff --git a/tests/test_engine_audio.py b/tests/test_engine_audio.py
new file mode 100644
index 0000000..c44e74f
--- /dev/null
+++ b/tests/test_engine_audio.py
@@ -0,0 +1,23 @@
+"""engine.model_registry / audio.ingest 경량 단위 테스트 (모델 로드 불요)."""
+from __future__ import annotations
+
+import pytest
+
+from luke_scribe.audio.ingest import probe_media
+from luke_scribe.engine.model_registry import resolve_model
+
+
+def test_resolve_model_turbo_maps_to_ct2_repo():
+    expected = "deepdml/faster-whisper-large-v3-turbo-ct2"
+    assert resolve_model("large-v3-turbo") == expected
+    assert resolve_model("turbo") == expected
+
+
+def test_resolve_model_standard_passthrough():
+    assert resolve_model("tiny") == "tiny"
+    assert resolve_model("large-v3") == "large-v3"
+
+
+def test_probe_media_missing_raises():
+    with pytest.raises(FileNotFoundError):
+        probe_media("/no/such/file.wav")