diff --git a/PLAN.md b/PLAN.md
index ae451b9..a3a2623 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -68,7 +68,7 @@
 
 ---
 
-## [ ] 단계 2 — 동기화 실행 + 진행률 폴링 (화면 2)
+## [x] 단계 2 — 동기화 실행 + 진행률 폴링 (화면 2)
 
 **목표:** [동기화] 클릭 → sync task 시작 → 3초 폴링으로 진행률 갱신 → 완료/실패 표시.
 
@@ -148,6 +148,7 @@ distribution PATCH → task 폴링 → 배지 갱신 → 감사 로그 기록.
    wheel/오프라인 인덱스로 설치 가능하게(litellm 반입 방식 참고, 스펙 §9).
 3. 실행 문서화: `README` 또는 CLAUDE.md "Conventions"에 기동 명령/환경변수 정리.
 4. (선택, §5-3) 읽기전용 / 배포권한 계정 분리 여지를 남긴 인증 훅 위치 표시.
+5. 디자인 가이드는 ref 하위의 markdown 파일들을 참고.
 
 **검증:** 네트워크 차단 상태에서 컨테이너/venv만으로 앱이 뜨고 모든 정적 자산이 로드된다.
 
diff --git a/app/demo.py b/app/demo.py
index 47334ce..a180f90 100644
--- a/app/demo.py
+++ b/app/demo.py
@@ -67,3 +67,17 @@ class DemoPulpClient:
 
     def get_version(self, version_href: str) -> dict[str, Any]:
         return _VERSIONS.get(version_href, {})
+
+    def get_repo(self, uuid: str) -> dict[str, Any]:
+        return {"remote": "/pulp/api/v3/remotes/rpm/rpm/demo/"}
+
+    def sync_repo(self, uuid: str, remote_href: str) -> str:
+        return f"/pulp/api/v3/tasks/demo-{uuid}/"
+
+    def get_task(self, task_href: str) -> dict[str, Any]:
+        # 데모: 첫 폴링에서 바로 완료 처리
+        return {
+            "state": "completed",
+            "progress_reports": [{"done": 120, "total": 120}],
+            "created_resources": ["/pulp/api/v3/repositories/rpm/rpm/demo/versions/9/"],
+        }
diff --git a/app/main.py b/app/main.py
index d5f4fe7..566d690 100644
--- a/app/main.py
+++ b/app/main.py
@@ -15,13 +15,14 @@ from fastapi.staticfiles import StaticFiles
 # 테스트 호환을 위해 re-export (tests 가 app.main.get_pulp_client 를 override 함)
 from .deps import get_pulp_client, templates
 from .pulp_client import PulpClient
-from .routes import dashboard
+from .routes import dashboard, sync
 
 BASE_DIR = Path(__file__).resolve().parent
 
 app = FastAPI(title="Pulp 패치 관리 콘솔")
 app.mount("/static", StaticFiles(directory=str(BASE_DIR / "static")), name="static")
 app.include_router(dashboard.router)
+app.include_router(sync.router)
 
 __all__ = ["app", "get_pulp_client"]
 
diff --git a/app/pulp_client.py b/app/pulp_client.py
index 4580c9c..8ad0fd7 100644
--- a/app/pulp_client.py
+++ b/app/pulp_client.py
@@ -48,7 +48,9 @@ class PulpClient:
         resp.raise_for_status()
         return resp.json()
 
-    def patch(self, href: str, json: Any | None = None, **kwargs: Any) -> dict[str, Any]:
+    def patch(
+        self, href: str, json: Any | None = None, **kwargs: Any
+    ) -> dict[str, Any]:
         resp = self._client.patch(href, json=json, **kwargs)
         resp.raise_for_status()
         return resp.json()
@@ -66,3 +68,23 @@ class PulpClient:
     def get_version(self, version_href: str) -> dict[str, Any]:
         """RepositoryVersion 단건 조회 (href 기준). content_summary 등 포함."""
         return self.get(version_href)
+
+    def get_repo(self, uuid: str) -> dict[str, Any]:
+        """저장소 단건 조회 (remote href 등 확인용)."""
+        return self.get(f"{API_PREFIX}/repositories/rpm/rpm/{uuid}/")
+
+    def sync_repo(self, uuid: str, remote_href: str) -> str:
+        """동기화 시작 → 비동기 task. 반환 task_href 를 폴링으로 추적한다(스펙 §4).
+
+        POST .../repositories/rpm/rpm/{uuid}/sync/  body {"remote": <remote_href>}
+        응답 {"task": "/pulp/api/v3/tasks/<uuid>/"} 에서 task href 추출.
+        """
+        data = self.post(
+            f"{API_PREFIX}/repositories/rpm/rpm/{uuid}/sync/",
+            json={"remote": remote_href},
+        )
+        return data["task"]
+
+    def get_task(self, task_href: str) -> dict[str, Any]:
+        """task 단건 조회 (state, progress_reports, created_resources, error)."""
+        return self.get(task_href)
diff --git a/app/routes/dashboard.py b/app/routes/dashboard.py
index 7c444e9..53e9e76 100644
--- a/app/routes/dashboard.py
+++ b/app/routes/dashboard.py
@@ -12,7 +12,7 @@ import httpx
 from fastapi import APIRouter, Depends, Request
 from fastapi.responses import HTMLResponse
 
-from .. import views
+from .. import task_store, views
 from ..deps import get_pulp_client, templates
 from ..pulp_client import PulpClient
 
@@ -21,10 +21,11 @@ router = APIRouter()
 
 def _load_repos(pulp: PulpClient) -> dict[str, Any]:
     """저장소 목록을 읽어 표시 모델 + 요약 + (실패 시) 에러 메시지를 만든다."""
+    syncing = task_store.active_count()
     try:
         repos = pulp.list_repos()
     except httpx.HTTPError as exc:
-        return {"repos": [], "summary": views.summarize([]), "error": str(exc)}
+        return {"repos": [], "summary": views.summarize([], syncing), "error": str(exc)}
 
     repo_views: list[dict[str, Any]] = []
     for repo in repos:
@@ -37,7 +38,11 @@ def _load_repos(pulp: PulpClient) -> dict[str, Any]:
                 version = None  # 버전 상세 실패는 치명적이지 않음 — 행은 표시
         repo_views.append(views.build_repo_view(repo, version))
 
-    return {"repos": repo_views, "summary": views.summarize(repo_views), "error": None}
+    return {
+        "repos": repo_views,
+        "summary": views.summarize(repo_views, syncing),
+        "error": None,
+    }
 
 
 @router.get("/", response_class=HTMLResponse)
diff --git a/app/routes/sync.py b/app/routes/sync.py
new file mode 100644
index 0000000..cfb4039
--- /dev/null
+++ b/app/routes/sync.py
@@ -0,0 +1,114 @@
+"""동기화 실행 + 진행률 폴링 (화면 2).
+
+POST /repos/{uuid}/sync     → 동기화 시작, 진행률 바 조각 반환 (이후 3초 폴링)
+GET  /repos/{uuid}/progress → 진행률 바 조각 (폴링 대상)
+
+동기화는 외부 미러에서 새 스냅샷을 만들 뿐 운영망 배포가 아니므로 비교적 안전 →
+확인 모달 없이 바로 실행한다(스펙 §5-1). 폴링은 화면(HTMX)이 담당한다(스펙 §7).
+"""
+
+from __future__ import annotations
+
+import httpx
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+
+from .. import task_store, views
+from ..deps import get_pulp_client, templates
+from ..pulp_client import PulpClient
+
+router = APIRouter()
+
+
+def _render(request: Request, uuid: str, progress: dict, status_code: int = 200):
+    return templates.TemplateResponse(
+        request,
+        "partials/progress.html",
+        {"uuid": uuid, "progress": progress},
+        status_code=status_code,
+    )
+
+
+@router.post("/repos/{uuid}/sync", response_class=HTMLResponse)
+def start_sync(
+    request: Request, uuid: str, pulp: PulpClient = Depends(get_pulp_client)
+) -> HTMLResponse:
+    try:
+        repo = pulp.get_repo(uuid)
+        remote = repo.get("remote")
+        if not remote:
+            return _render(
+                request,
+                uuid,
+                {
+                    "running": False,
+                    "completed": False,
+                    "failed": True,
+                    "error": "이 저장소에 remote(미러 소스)가 설정되어 있지 않습니다.",
+                },
+                status_code=400,
+            )
+        task_href = pulp.sync_repo(uuid, remote)
+    except httpx.HTTPError as exc:
+        return _render(
+            request,
+            uuid,
+            {
+                "running": False,
+                "completed": False,
+                "failed": True,
+                "error": f"동기화 시작 실패: {exc}",
+            },
+            status_code=502,
+        )
+
+    task_store.set_task(uuid, task_href)
+    # 첫 조각: 폴링 시작 (아직 progress_reports 없음 → 준비 중)
+    return _render(
+        request,
+        uuid,
+        {
+            "running": True,
+            "completed": False,
+            "failed": False,
+            "state": "waiting",
+            "done": 0,
+            "total": 0,
+            "percent": 0,
+        },
+    )
+
+
+@router.get("/repos/{uuid}/progress", response_class=HTMLResponse)
+def progress(
+    request: Request, uuid: str, pulp: PulpClient = Depends(get_pulp_client)
+) -> HTMLResponse:
+    task_href = task_store.get_task(uuid)
+    if not task_href:
+        # 추적 중인 sync 없음 → 폴링 중단(빈 조각)
+        return _render(
+            request,
+            uuid,
+            {"running": False, "completed": False, "failed": False, "idle": True},
+        )
+
+    try:
+        task = pulp.get_task(task_href)
+    except httpx.HTTPError as exc:
+        task_store.clear_task(uuid)
+        return _render(
+            request,
+            uuid,
+            {
+                "running": False,
+                "completed": False,
+                "failed": True,
+                "error": f"작업 상태 조회 실패: {exc}",
+            },
+            status_code=502,
+        )
+
+    prog = views.task_progress(task)
+    if prog["completed"] or prog["failed"]:
+        task_store.clear_task(uuid)  # 폴링 종료 + 동기화중 카운트에서 제외
+    return _render(request, uuid, prog)
diff --git a/app/static/app.css b/app/static/app.css
index a773caa..94eeae2 100644
--- a/app/static/app.css
+++ b/app/static/app.css
@@ -220,6 +220,21 @@ button:disabled,
   opacity: 0.45;
 }
 
+/* 동기화 진행률 바 */
+.sync-progress {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  min-width: 160px;
+}
+.sync-progress progress {
+  margin: 0;
+  height: 6px;
+}
+.sync-progress small {
+  color: var(--text-muted);
+}
+
 /* 연결 상태 표시 (dot + 텍스트) */
 .status-line {
   display: inline-flex;
diff --git a/app/task_store.py b/app/task_store.py
new file mode 100644
index 0000000..1808d0d
--- /dev/null
+++ b/app/task_store.py
@@ -0,0 +1,26 @@
+"""진행 중 동기화 task 의 메모리 저장소 (uuid → task_href).
+
+폐쇄망 단일 인스턴스 가정. 다중 워커/프로세스로 띄우면 워커 간 공유되지 않으므로,
+규모가 커지면 Redis 등 외부 저장소로 교체해야 한다. 폴링 자체는 화면(HTMX)이 한다(스펙 §7).
+"""
+
+from __future__ import annotations
+
+_active: dict[str, str] = {}
+
+
+def set_task(uuid: str, task_href: str) -> None:
+    _active[uuid] = task_href
+
+
+def get_task(uuid: str) -> str | None:
+    return _active.get(uuid)
+
+
+def clear_task(uuid: str) -> None:
+    _active.pop(uuid, None)
+
+
+def active_count() -> int:
+    """대시보드 '동기화 중' 카드용 — 아직 완료/실패로 정리되지 않은 sync 수."""
+    return len(_active)
diff --git a/app/templates/partials/progress.html b/app/templates/partials/progress.html
new file mode 100644
index 0000000..981fc7d
--- /dev/null
+++ b/app/templates/partials/progress.html
@@ -0,0 +1,21 @@
+{# 진행률 바 조각. running 일 때만 hx-trigger 를 달아 3초 폴링; 완료/실패 시 폴링 중단. #}
+<div id="prog-{{ uuid }}"
+     {% if progress.running %}hx-get="/repos/{{ uuid }}/progress" hx-trigger="every 3s" hx-swap="outerHTML"{% endif %}>
+  {% if progress.failed %}
+    <span class="status-line status-bad">동기화 실패: {{ progress.error }}</span>
+  {% elif progress.completed %}
+    <span class="badge badge-pass">동기화 완료{% if progress.new_version %} · v{{ progress.new_version }} 생성됨{% endif %}</span>
+  {% elif progress.idle %}
+    {# 추적 중인 작업 없음 — 빈 조각 #}
+  {% else %}
+    <div class="sync-progress">
+      {% if progress.total %}
+        <progress value="{{ progress.done }}" max="{{ progress.total }}"></progress>
+        <small class="num">{{ progress.done }}/{{ progress.total }} 패키지 · {{ progress.percent }}%</small>
+      {% else %}
+        <progress></progress>
+        <small>동기화 준비 중…</small>
+      {% endif %}
+    </div>
+  {% endif %}
+</div>
diff --git a/app/templates/partials/repo_list.html b/app/templates/partials/repo_list.html
index 2866902..3b5d22a 100644
--- a/app/templates/partials/repo_list.html
+++ b/app/templates/partials/repo_list.html
@@ -31,8 +31,13 @@
             <td class="num">{% if repo.package_count is not none %}{{ repo.package_count }}{% else %}—{% endif %}</td>
             <td>{{ repo.last_sync or "—" }}</td>
             <td>
-              <!-- 동기화 버튼은 단계2에서 동작 연결 -->
-              <button disabled class="secondary">동기화</button>
+              <div id="sync-{{ repo.uuid }}">
+                <button class="secondary"
+                        hx-post="/repos/{{ repo.uuid }}/sync"
+                        hx-target="#sync-{{ repo.uuid }}"
+                        hx-swap="innerHTML"
+                        hx-disabled-elt="this">동기화</button>
+              </div>
             </td>
           </tr>
           {% endfor %}
diff --git a/app/views.py b/app/views.py
index 4c9d98b..5aa4bcc 100644
--- a/app/views.py
+++ b/app/views.py
@@ -69,12 +69,47 @@ def build_repo_view(
     }
 
 
-def summarize(repo_views: list[dict[str, Any]]) -> dict[str, int]:
-    """상단 요약 카드 수치."""
+def summarize(repo_views: list[dict[str, Any]], syncing: int = 0) -> dict[str, int]:
+    """상단 요약 카드 수치. syncing 은 task_store.active_count() 에서 주입."""
     return {
         "total": len(repo_views),
-        # TODO(단계2): 진행 중 sync task 수를 메모리 task 맵에서 집계
-        "syncing": 0,
+        "syncing": syncing,
         "gpg_pass": sum(1 for r in repo_views if r["gpg"]["level"] == "pass"),
         "total_packages": sum(r["package_count"] or 0 for r in repo_views),
     }
+
+
+def task_progress(task: dict[str, Any]) -> dict[str, Any]:
+    """Pulp task → 진행률 표시 모델.
+
+    progress_reports[] 의 done/total 을 합산해 퍼센트를 낸다. 완료 시
+    created_resources 에서 새 RepositoryVersion 번호(vN)를 추출한다.
+    """
+    state = task.get("state", "waiting")
+    reports = task.get("progress_reports") or []
+    done = sum((r or {}).get("done") or 0 for r in reports)
+    total = sum((r or {}).get("total") or 0 for r in reports)
+    percent = int(done / total * 100) if total else 0
+
+    new_version = None
+    for href in task.get("created_resources") or []:
+        if "/versions/" in href:
+            new_version = version_number(href)
+            break
+
+    error = None
+    if state == "failed":
+        err = task.get("error") or {}
+        error = err.get("description") or "동기화 작업이 실패했습니다."
+
+    return {
+        "state": state,
+        "done": done,
+        "total": total,
+        "percent": percent,
+        "new_version": new_version,
+        "error": error,
+        "completed": state == "completed",
+        "failed": state == "failed",
+        "running": state in ("waiting", "running"),
+    }
diff --git a/tests/test_pulp_client.py b/tests/test_pulp_client.py
index 64fbd74..b04650e 100644
--- a/tests/test_pulp_client.py
+++ b/tests/test_pulp_client.py
@@ -37,3 +37,27 @@ def test_get_raises_on_http_error():
     )
     with PulpClient() as pulp, pytest.raises(httpx.HTTPStatusError):
         pulp.status()
+
+
+@respx.mock
+def test_sync_repo_posts_remote_and_returns_task():
+    import json
+
+    route = respx.post(
+        f"{PULP_TEST_URL}/pulp/api/v3/repositories/rpm/rpm/abc/sync/"
+    ).mock(return_value=httpx.Response(202, json={"task": "/pulp/api/v3/tasks/t1/"}))
+    with PulpClient() as pulp:
+        href = pulp.sync_repo("abc", "/pulp/api/v3/remotes/rpm/rpm/r1/")
+    assert href == "/pulp/api/v3/tasks/t1/"
+    body = json.loads(route.calls.last.request.content)
+    assert body == {"remote": "/pulp/api/v3/remotes/rpm/rpm/r1/"}
+
+
+@respx.mock
+def test_get_task_returns_state():
+    respx.get(f"{PULP_TEST_URL}/pulp/api/v3/tasks/t1/").mock(
+        return_value=httpx.Response(200, json={"state": "running"})
+    )
+    with PulpClient() as pulp:
+        task = pulp.get_task("/pulp/api/v3/tasks/t1/")
+    assert task["state"] == "running"
diff --git a/tests/test_sync.py b/tests/test_sync.py
new file mode 100644
index 0000000..aeeb512
--- /dev/null
+++ b/tests/test_sync.py
@@ -0,0 +1,115 @@
+import httpx
+from fastapi.testclient import TestClient
+
+from app import task_store
+from app.main import app, get_pulp_client
+
+client = TestClient(app)
+
+
+class _FakePulp:
+    def __init__(self, repo=None, task=None, sync_raises=False):
+        self._repo = (
+            {"remote": "/pulp/api/v3/remotes/rpm/rpm/r1/"} if repo is None else repo
+        )
+        self._task = task
+        self._sync_raises = sync_raises
+        self.synced = None
+
+    def get_repo(self, uuid):
+        return self._repo
+
+    def sync_repo(self, uuid, remote_href):
+        if self._sync_raises:
+            raise httpx.ConnectError("connection refused")
+        self.synced = (uuid, remote_href)
+        return f"/pulp/api/v3/tasks/t-{uuid}/"
+
+    def get_task(self, task_href):
+        return self._task
+
+
+def _use(fake):
+    app.dependency_overrides[get_pulp_client] = lambda: fake
+
+
+def teardown_function():
+    app.dependency_overrides.clear()
+    task_store._active.clear()
+
+
+def test_start_sync_begins_polling_and_records_task():
+    fake = _FakePulp()
+    _use(fake)
+    resp = client.post("/repos/abc/sync")
+    assert resp.status_code == 200
+    assert 'hx-get="/repos/abc/progress"' in resp.text
+    assert 'hx-trigger="every 3s"' in resp.text
+    assert task_store.get_task("abc") == "/pulp/api/v3/tasks/t-abc/"
+    assert fake.synced == ("abc", "/pulp/api/v3/remotes/rpm/rpm/r1/")
+
+
+def test_start_sync_without_remote_is_rejected():
+    _use(_FakePulp(repo={}))  # remote 미설정
+    resp = client.post("/repos/abc/sync")
+    assert resp.status_code == 400
+    assert "remote" in resp.text
+    assert task_store.get_task("abc") is None
+
+
+def test_start_sync_handles_pulp_error():
+    _use(_FakePulp(sync_raises=True))
+    resp = client.post("/repos/abc/sync")
+    assert resp.status_code == 502
+    assert "동기화 시작 실패" in resp.text
+    assert task_store.get_task("abc") is None
+
+
+def test_progress_running_renders_bar_and_keeps_polling():
+    task_store.set_task("abc", "/pulp/api/v3/tasks/t1/")
+    _use(
+        _FakePulp(
+            task={"state": "running", "progress_reports": [{"done": 4, "total": 8}]}
+        )
+    )
+    resp = client.get("/repos/abc/progress")
+    assert resp.status_code == 200
+    assert "50%" in resp.text
+    assert 'hx-trigger="every 3s"' in resp.text
+    assert task_store.get_task("abc") is not None  # 아직 추적 중
+
+
+def test_progress_completed_stops_polling_and_clears():
+    task_store.set_task("abc", "/pulp/api/v3/tasks/t1/")
+    _use(
+        _FakePulp(
+            task={
+                "state": "completed",
+                "created_resources": [
+                    "/pulp/api/v3/repositories/rpm/rpm/abc/versions/7/"
+                ],
+            }
+        )
+    )
+    resp = client.get("/repos/abc/progress")
+    assert "동기화 완료" in resp.text
+    assert "v7" in resp.text
+    assert "hx-trigger" not in resp.text  # 폴링 중단
+    assert task_store.get_task("abc") is None  # 정리됨
+
+
+def test_progress_failed_shows_error_and_clears():
+    task_store.set_task("abc", "/pulp/api/v3/tasks/t1/")
+    _use(_FakePulp(task={"state": "failed", "error": {"description": "GPG 검증 실패"}}))
+    resp = client.get("/repos/abc/progress")
+    assert "동기화 실패" in resp.text
+    assert "GPG 검증 실패" in resp.text
+    assert "hx-trigger" not in resp.text
+    assert task_store.get_task("abc") is None
+
+
+def test_progress_idle_when_no_active_task():
+    _use(_FakePulp())
+    resp = client.get("/repos/zzz/progress")
+    assert resp.status_code == 200
+    assert "hx-trigger" not in resp.text  # 폴링하지 않음
diff --git a/tests/test_views.py b/tests/test_views.py
index 3a573d4..797047c 100644
--- a/tests/test_views.py
+++ b/tests/test_views.py
@@ -70,3 +70,34 @@ def test_summarize_counts():
         "gpg_pass": 2,
         "total_packages": 150,
     }
+
+
+def test_summarize_includes_syncing_count():
+    assert views.summarize([], syncing=2)["syncing"] == 2
+
+
+def test_task_progress_running_sums_reports():
+    task = {
+        "state": "running",
+        "progress_reports": [{"done": 5, "total": 10}, {"done": 3, "total": 10}],
+    }
+    p = views.task_progress(task)
+    assert p["running"] is True
+    assert p["completed"] is False
+    assert (p["done"], p["total"], p["percent"]) == (8, 20, 40)
+
+
+def test_task_progress_completed_extracts_version():
+    task = {
+        "state": "completed",
+        "created_resources": ["/pulp/api/v3/repositories/rpm/rpm/x/versions/4/"],
+    }
+    p = views.task_progress(task)
+    assert p["completed"] is True
+    assert p["new_version"] == 4
+
+
+def test_task_progress_failed_surfaces_error():
+    p = views.task_progress({"state": "failed", "error": {"description": "boom"}})
+    assert p["failed"] is True
+    assert p["error"] == "boom"