diff --git a/yunke-server/app/api/main.py b/yunke-server/app/api/main.py
index 3fee548..815ae8a 100644
--- a/yunke-server/app/api/main.py
+++ b/yunke-server/app/api/main.py
@@ -20,8 +20,10 @@ Includes:
 * ``GET /api/search`` (see :mod:`app.api.routers.search`).
 * ``GET /api/export/chat-html`` (see :mod:`app.api.routers.export`).
 
-CORS is configured permissively (wildcard origin, no credentials) so the local
-frontend can call the API during development.
+CORS is configured to read explicit allowed origins from ``Settings.cors_origins``
+(comma-separated ``CORS_ORIGINS`` env var). Empty (default) falls back to the dev
+origin ``http://localhost:5173``; set ``CORS_ORIGINS=https://app.example.com`` in
+prod. Never wildcard — see the comment near ``add_middleware`` below.
 
 Auth (Task 2.9): a single shared-token dependency (:func:`app.api.auth.require_auth`)
 is applied globally on the app. Trust model: when ``Settings.api_token`` is
@@ -52,14 +54,27 @@ from app.api.routers import (
     sync,
     voice_clips,
 )
+from app.config import get_settings
 
 app = FastAPI(title="yunke data mirror", dependencies=[Depends(require_auth)])
 
+# CORS: read explicit allowed origins from Settings (``CORS_ORIGINS`` env var,
+# comma-separated). Empty -> dev fallback (``http://localhost:5173``). Never
+# ``*`` — wildcard CORS on an authenticated API is an open door even without
+# credentials, since the middleware would reflect any attacker-controlled
+# origin back in ``Access-Control-Allow-Origin``.
+_settings = get_settings()
+_cors = _settings.cors_origins.strip()
+if _cors:
+    _origins = [o.strip() for o in _cors.split(",") if o.strip()]
+else:
+    _origins = []  # empty = deny all cross-origin (safest default)
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=["*"],
-    allow_methods=["*"],
+    allow_origins=_origins or ["http://localhost:5173"],  # dev fallback
+    allow_methods=["GET", "PATCH", "POST"],
     allow_headers=["*"],
+    allow_credentials=False,
 )
 
 app.include_router(customer.router)
diff --git a/yunke-server/app/api/routers/organization.py b/yunke-server/app/api/routers/organization.py
index e283144..dec8b56 100644
--- a/yunke-server/app/api/routers/organization.py
+++ b/yunke-server/app/api/routers/organization.py
@@ -10,9 +10,10 @@ Read-only queries over the mirrored ``department``, ``staff``,
 * ``GET /api/accounts`` -> ``Page[AccountOut]`` projecting both staff-messaging
   account tables onto a unified shape (see :class:`AccountOut`). The optional
   ``channel`` filter restricts to one of ``wechat`` / ``whatsapp``; when
-  omitted, both tables are unioned in memory. Staff-account volumes are modest
-  (tens to low hundreds of rows), so the in-memory merge is cheap and keeps
-  the API contract simple.
+  omitted, both tables are UNIONed at the SQL level and paginated in-database
+  (no full-table Python materialization). Staff-account volumes are modest in
+  practice today, but the SQL-level pagination keeps the endpoint safe if a
+  tenant ever scales past thousands of rows.
 """
 
 from __future__ import annotations
@@ -91,49 +92,80 @@ async def list_accounts(
     """List staff messaging accounts (WeChat / WhatsApp) in a unified shape.
 
     ``channel`` optional; one of ``wechat`` / ``whatsapp``. When omitted, both
-    tables are merged in memory. Pagination is applied after the merge using a
-    stable ``(channel, account_id)`` ordering.
+    tables are UNIONed at the SQL level. Pagination and total count are pushed
+    down to the database (single ``COUNT(*)`` over the UNION subquery + a
+    paginated ``SELECT`` with ``OFFSET``/``LIMIT``) so we never materialize the
+    full cross-table row set in Python. Stable ordering is ``(channel,
+    account_id)``.
+
+    ``AccountOut`` field mapping (identical shape from both source tables):
+
+    * WeChat: account_id=wx_id, nickname=nick_name, user_id, user_name, phone,
+      contacts_num, group_num, is_on_job, raw_json (verbatim upstream record).
+    * WhatsApp: account_id=uid (+ same projection).
     """
-    selected_channels = [channel] if channel else ["wechat", "whatsapp"]
+    wechat_q = sa.select(
+        WechatAccount.wx_id.label("account_id"),
+        sa.literal("wechat").label("channel"),
+        WechatAccount.nick_name.label("nickname"),
+        WechatAccount.user_id.label("user_id"),
+        WechatAccount.user_name.label("user_name"),
+        WechatAccount.phone.label("phone"),
+        WechatAccount.contacts_num.label("contacts_num"),
+        WechatAccount.group_num.label("group_num"),
+        WechatAccount.is_on_job.label("is_on_job"),
+        WechatAccount.raw_json.label("raw_json"),
+    )
+    whatsapp_q = sa.select(
+        WhatsappAccount.uid.label("account_id"),
+        sa.literal("whatsapp").label("channel"),
+        WhatsappAccount.nick_name.label("nickname"),
+        WhatsappAccount.user_id.label("user_id"),
+        WhatsappAccount.user_name.label("user_name"),
+        WhatsappAccount.phone.label("phone"),
+        WhatsappAccount.contacts_num.label("contacts_num"),
+        WhatsappAccount.group_num.label("group_num"),
+        WhatsappAccount.is_on_job.label("is_on_job"),
+        WhatsappAccount.raw_json.label("raw_json"),
+    )
 
-    rows: list[AccountOut] = []
-    if "wechat" in selected_channels:
-        result = (await session.execute(sa.select(WechatAccount))).scalars().all()
-        for r in result:
-            rows.append(
-                AccountOut(
-                    channel="wechat",
-                    account_id=r.wx_id,
-                    nickname=r.nick_name,
-                    user_id=r.user_id,
-                    user_name=r.user_name,
-                    phone=r.phone,
-                    contacts_num=r.contacts_num,
-                    group_num=r.group_num,
-                    is_on_job=r.is_on_job,
-                    raw_json=r.raw_json,
-                )
-            )
-    if "whatsapp" in selected_channels:
-        result = (await session.execute(sa.select(WhatsappAccount))).scalars().all()
-        for r in result:
-            rows.append(
-                AccountOut(
-                    channel="whatsapp",
-                    account_id=r.uid,
-                    nickname=r.nick_name,
-                    user_id=r.user_id,
-                    user_name=r.user_name,
-                    phone=r.phone,
-                    contacts_num=r.contacts_num,
-                    group_num=r.group_num,
-                    is_on_job=r.is_on_job,
-                    raw_json=r.raw_json,
-                )
-            )
+    if channel == "wechat":
+        parts: list[sa.Select] = [wechat_q]
+    elif channel == "whatsapp":
+        parts = [whatsapp_q]
+    else:
+        parts = [wechat_q, whatsapp_q]
 
-    rows.sort(key=lambda a: (a.channel, a.account_id))
-    total = len(rows)
-    start = (page - 1) * page_size
-    items = rows[start : start + page_size]
+    base_q: sa.Select = parts[0] if len(parts) == 1 else sa.union_all(*parts)
+
+    # Wrap in a subquery so COUNT and paginated SELECT both have a stable
+    # column set (the labelled columns become ``sub.c.<label>``).
+    sub = base_q.subquery()
+
+    total = (
+        await session.execute(sa.select(sa.func.count()).select_from(sub))
+    ).scalar_one()
+
+    page_q = (
+        sa.select(sub)
+        .order_by(sub.c.channel.asc(), sub.c.account_id.asc())
+        .offset((page - 1) * page_size)
+        .limit(page_size)
+    )
+    rows = (await session.execute(page_q)).all()
+    items = [
+        AccountOut(
+            channel=row.channel,
+            account_id=row.account_id,
+            nickname=row.nickname,
+            user_id=row.user_id,
+            user_name=row.user_name,
+            phone=row.phone,
+            contacts_num=row.contacts_num,
+            group_num=row.group_num,
+            is_on_job=row.is_on_job,
+            raw_json=row.raw_json,
+        )
+        for row in rows
+    ]
     return Page(items=items, total=total, page=page, page_size=page_size)
diff --git a/yunke-server/app/api/routers/voice_clips.py b/yunke-server/app/api/routers/voice_clips.py
index 7645b15..34bbf6b 100644
--- a/yunke-server/app/api/routers/voice_clips.py
+++ b/yunke-server/app/api/routers/voice_clips.py
@@ -30,7 +30,7 @@ from __future__ import annotations
 from typing import Annotated, Any
 
 import sqlalchemy as sa
-from fastapi import APIRouter, Depends, HTTPException, Query
+from fastapi import APIRouter, Depends, Header, HTTPException, Query
 from pydantic import BaseModel
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -153,20 +153,46 @@ async def match_voice_clip(
     session: SessionDep,
     voice_clip_id: int,
     body: MatchBody,
+    if_match: Annotated[str | None, Header()] = None,
 ) -> dict[str, Any]:
     """Associate (or clear) the customer match on a voice_clip.
 
     LOCAL write only — ``matched_friend_id`` is stored in the mirror's
     ``voice_clip`` row and never pushed to 云客. ``friend_id=None`` clears an
     existing match.
+
+    Optimistic lock (optional, backward-compatible): the client may send
+    ``If-Match: <updated_at ISO>`` with the ``updated_at`` it last read. When
+    present, the server compares it against the row's current ``updated_at``
+    and rejects with ``409`` if the row was modified by another request in
+    between. Without the header, behavior is unchanged.
+
+    The response echoes the post-update ``updated_at`` so the client can fold
+    it into its next read.
     """
     clip = await session.get(VoiceClip, voice_clip_id)
     if not clip:
         raise HTTPException(status_code=404, detail="voice_clip not found")
+    # Optimistic lock: if the client sent If-Match, verify the row has not been
+    # modified since the value it read. The header carries the ISO 8601
+    # ``updated_at`` the client last saw; a mismatch means another writer
+    # committed first.
+    if if_match is not None and clip.updated_at is not None:
+        expected = clip.updated_at.isoformat()
+        if if_match != expected:
+            raise HTTPException(
+                status_code=409,
+                detail="voice_clip was modified by another request",
+            )
     clip.matched_friend_id = body.friend_id  # None clears the match
     await session.commit()
+    # Refresh to pick up the server-generated ``updated_at`` from the UPDATE
+    # (``onupdate=func.now()``); with ``expire_on_commit=False`` the attribute
+    # otherwise stays at the pre-update value.
+    await session.refresh(clip)
 
     return {
         "voice_clip_id": voice_clip_id,
         "matched_friend_id": body.friend_id,
+        "updated_at": clip.updated_at.isoformat() if clip.updated_at else None,
     }
diff --git a/yunke-server/app/config.py b/yunke-server/app/config.py
index f0c2771..1842ab4 100644
--- a/yunke-server/app/config.py
+++ b/yunke-server/app/config.py
@@ -34,6 +34,15 @@ class Settings(BaseSettings):
     # <token>`` or ``?token=<token>``. See app/api/auth.py.
     api_token: str = ""
 
+    # Comma-separated list of allowed CORS origins for the viewing API. Empty
+    # (default) -> only the dev fallback (``http://localhost:5173``) is allowed;
+    # set ``CORS_ORIGINS=https://app.example.com`` in prod to lock cross-origin
+    # access down to explicit origins. Never ``*`` (wildcard + credentialed APIs
+    # are an open door; we accept no credentials but still restrict origins to
+    # avoid reflecting arbitrary attacker-controlled origins in ``Acces-Control-
+    # Allow-Origin``).
+    cors_origins: str = ""
+
     # --- Anti-risk-control / stealth tuning ---------------------------------
     # Tuned 2026-08-11 after triggering 风控 during a heavy session (~500+
     # consecutive requests across groups/WA/voice-clips/SMS in ~1 hour).
diff --git a/yunke-server/app/scraper/media.py b/yunke-server/app/scraper/media.py
index 2b76b63..3c80f92 100644
--- a/yunke-server/app/scraper/media.py
+++ b/yunke-server/app/scraper/media.py
@@ -145,9 +145,17 @@ async def download_url(client: YunkeClient, url: str) -> bytes:
     for the public OSS media URLs, useful for any same-origin authenticated
     URLs) and is the transport ``respx`` mocks in the test suite, so media
     downloads go through the same mocked transport as every other scraper
-    request. Redirects are followed (OSS / avatar URLs commonly redirect).
+    request.
+
+    Redirects are NOT followed (SSRF protection): the URL is the trusted OSS /
+    recording endpoint resolved at scrape time, and following a 3xx would allow
+    a malicious or compromised host to redirect us to internal addresses such
+    as ``http://169.254.169.254/`` (cloud metadata) or other RFC1918 hosts.
+    OSS media URLs return the blob directly with 200; a 3xx here is treated as
+    a download failure and surfaces through the caller's existing
+    ``except (httpx.HTTPError, OSError)`` clause.
     """
-    resp = await client.client.get(url, follow_redirects=True)
+    resp = await client.client.get(url, follow_redirects=False)
     resp.raise_for_status()
     return resp.content
 
diff --git a/yunke-server/tests/test_api_voice_clips.py b/yunke-server/tests/test_api_voice_clips.py
index 96e0f6e..f5d9151 100644
--- a/yunke-server/tests/test_api_voice_clips.py
+++ b/yunke-server/tests/test_api_voice_clips.py
@@ -268,7 +268,12 @@ async def test_match_returns_payload_and_persists(make_client):
     r = await client.patch("/api/voice-clips/1/match", json={"friend_id": "fid_remark"})
     assert r.status_code == 200
     body = r.json()
-    assert body == {"voice_clip_id": 1, "matched_friend_id": "fid_remark"}
+    # Response now carries the post-update ``updated_at`` for the optimistic-
+    # lock flow (client folds it into the next request's ``If-Match`` header).
+    assert body["voice_clip_id"] == 1
+    assert body["matched_friend_id"] == "fid_remark"
+    assert "updated_at" in body
+    updated_at_v1 = body["updated_at"]
 
     # The GET list now reflects the match (cross-request persistence —
     # requires the PATCH to commit, not just flush).
@@ -280,6 +285,7 @@ async def test_match_returns_payload_and_persists(make_client):
     # The other wechat clip for u1 is still unmatched.
     assert by_id[3]["matched_friend_id"] is None
     assert by_id[3]["matched_friend_name"] is None
+    return updated_at_v1  # for reuse by optimistic-lock tests below if needed
 
 
 async def test_match_name_falls_back_through_nickname_real_name(make_client):
@@ -332,7 +338,10 @@ async def test_unmatch_clears_friend_id(make_client):
     # Now clear it.
     r = await client.patch("/api/voice-clips/1/match", json={"friend_id": None})
     assert r.status_code == 200
-    assert r.json() == {"voice_clip_id": 1, "matched_friend_id": None}
+    body = r.json()
+    assert body["voice_clip_id"] == 1
+    assert body["matched_friend_id"] is None
+    assert "updated_at" in body
 
     r2 = await client.get("/api/voice-clips", params={"user_id": "u1"})
     by_id = {it["voice_clip_id"]: it for it in r2.json()["items"]}
@@ -356,4 +365,88 @@ async def test_match_default_null_body_is_treated_as_unmatch(make_client):
     # Empty body -> body.friend_id defaults to None -> unmatch.
     r = await client.patch("/api/voice-clips/1/match", json={})
     assert r.status_code == 200
-    assert r.json()["matched_friend_id"] is None
+    body = r.json()
+    assert body["matched_friend_id"] is None
+    assert "updated_at" in body
+
+
+# ---------------------------------------------------------------------------
+# Optimistic lock — If-Match header on PATCH /api/voice-clips/{id}/match
+# ---------------------------------------------------------------------------
+
+
+async def test_match_with_if_match_accepts_current_updated_at(make_client):
+    """If-Match equal to the row's current ``updated_at`` is accepted (200).
+
+    The flow: GET to read the current ``updated_at`` (via a successful PATCH
+    echo), send that value as ``If-Match`` on the next PATCH — the server
+    accepts the request because the row has not changed in between.
+    """
+    client = await make_client(_seed_with_customer)
+    # First PATCH establishes the match and returns the post-update timestamp.
+    r1 = await client.patch(
+        "/api/voice-clips/1/match", json={"friend_id": "fid_remark"}
+    )
+    assert r1.status_code == 200
+    current = r1.json()["updated_at"]
+    assert current is not None
+
+    # Second PATCH with If-Match=current: accepted (200), match cleared.
+    r2 = await client.patch(
+        "/api/voice-clips/1/match",
+        json={"friend_id": None},
+        headers={"If-Match": current},
+    )
+    assert r2.status_code == 200
+    assert r2.json()["matched_friend_id"] is None
+
+
+async def test_match_with_stale_if_match_returns_409(make_client):
+    """An If-Match that doesn't match the row's current ``updated_at`` -> 409.
+
+    Simulates the lost-update race: client A reads the clip, client B modifies
+    it (bumping ``updated_at``), then client A's PATCH carrying A's now-stale
+    timestamp is rejected. We force a clearly stale value rather than relying
+    on wall-clock drift because SQLite's ``CURRENT_TIMESTAMP`` (the dialect
+    compilation of ``func.now()``) has 1-second resolution and two PATCHes
+    inside the same second produce identical timestamps.
+    """
+    client = await make_client(_seed_with_customer)
+    # First PATCH: succeeds, returns the post-update timestamp.
+    r1 = await client.patch(
+        "/api/voice-clips/1/match", json={"friend_id": "fid_remark"}
+    )
+    assert r1.status_code == 200
+    current = r1.json()["updated_at"]
+    assert current is not None
+
+    # Any string that differs from the row's current updated_at is "stale" —
+    # 409. We use an obviously-older timestamp so the test is deterministic.
+    stale = "2000-01-01T00:00:00"
+    assert stale != current
+
+    r2 = await client.patch(
+        "/api/voice-clips/1/match",
+        json={"friend_id": None},
+        headers={"If-Match": stale},
+    )
+    assert r2.status_code == 409
+    assert "modified" in r2.json()["detail"].lower()
+
+
+async def test_match_without_if_match_is_backward_compatible(make_client):
+    """No If-Match header -> no optimistic-lock check; behavior unchanged."""
+    client = await make_client(_seed_with_customer)
+    # First PATCH establishes a value.
+    r1 = await client.patch(
+        "/api/voice-clips/1/match", json={"friend_id": "fid_remark"}
+    )
+    assert r1.status_code == 200
+
+    # Second PATCH WITHOUT If-Match — accepted regardless of staleness
+    # (backward compatible: clients that don't send the header keep working).
+    r2 = await client.patch(
+        "/api/voice-clips/1/match", json={"friend_id": "fid_nick"}
+    )
+    assert r2.status_code == 200
+    assert r2.json()["matched_friend_id"] == "fid_nick"