diff --git a/yunke-server/app/scraper/wechat.py b/yunke-server/app/scraper/wechat.py
index 0b4e6df..5a33cfe 100644
--- a/yunke-server/app/scraper/wechat.py
+++ b/yunke-server/app/scraper/wechat.py
@@ -346,11 +346,21 @@ def _normalize_message(record: dict[str, Any]) -> dict[str, Any]:
     if timestamp is None:
         timestamp = record.get("createTime")
 
+    # talker_id = the message's sender/peer FULL id (the timeline join key).
+    # 1:1 (empty roomid): upstream `talker` is masked, the full peer is
+    # `oriTalker`. group (roomid set): `talker` is the sending member, while
+    # `oriTalker` is the chatroom id — so the member is in `talker`.
+    roomid = record.get("roomid") or ""
+    if roomid:
+        talker_id = record.get("talker")
+    else:
+        talker_id = record.get("oriTalker") or record.get("talker")
+
     return {
         "msg_id": record.get("msgSvrId"),
         "channel": "wechat",
         "owner_account_id": record.get("wechatId"),
-        "talker_id": record.get("talker"),
+        "talker_id": talker_id,
         "ori_talker": record.get("oriTalker"),
         "room_id": record.get("roomid"),
         "is_send": is_send,
diff --git a/yunke-server/app/session/yunke_client.py b/yunke-server/app/session/yunke_client.py
index 6476002..b393de2 100644
--- a/yunke-server/app/session/yunke_client.py
+++ b/yunke-server/app/session/yunke_client.py
@@ -42,10 +42,13 @@ from app.session.login import (
     pc_login,
 )
 
-# The 4 constant auth headers. ``userid`` + ``company`` come from the
-# LoginResult and are merged in separately.
+# Constant auth headers. ``userid`` + ``company`` come from the LoginResult
+# and are merged in separately. NOTE: ``source`` is intentionally NOT sent —
+# the real CRM session cookie authenticates data APIs (confirmed in Phase 0),
+# and several endpoints (e.g. ``msg/chats``) bind a ``source`` parameter as
+# Integer, so a ``source: "yunkepc"`` header makes them 500. Cookie-only auth
+# works for all data endpoints.
 _STATIC_AUTH_HEADERS: dict[str, str] = {
-    "source": "yunkepc",
     "channel": "4",
     "content-type": "application/json",
 }
diff --git a/yunke-server/tests/test_yunke_client.py b/yunke-server/tests/test_yunke_client.py
index 53ba5b2..19d8fe4 100644
--- a/yunke-server/tests/test_yunke_client.py
+++ b/yunke-server/tests/test_yunke_client.py
@@ -127,7 +127,10 @@ async def test_post_injects_auth_headers(client: YunkeClient):
     # The 5 known auth headers must be on every outgoing request.
     assert sent.headers["userid"] == USERID
     assert sent.headers["company"] == COMPANY
-    assert sent.headers["source"] == "yunkepc"
+    # NOTE: ``source`` is intentionally NOT sent — several endpoints (msg/chats)
+    # bind a ``source`` param as Integer, so ``source: "yunkepc"`` 500s. Cookie
+    # auth suffices for all data endpoints (Phase 0).
+    assert "source" not in sent.headers
     assert sent.headers["channel"] == "4"
     assert sent.headers["content-type"] == "application/json"
     # And the session cookie travels along too.
diff --git a/yunke-server/tests/test_yunke_client_stealth.py b/yunke-server/tests/test_yunke_client_stealth.py
index e742ff3..f5e3434 100644
--- a/yunke-server/tests/test_yunke_client_stealth.py
+++ b/yunke-server/tests/test_yunke_client_stealth.py
@@ -113,7 +113,7 @@ async def test_browser_headers_present_on_every_request(client: YunkeClient):
     assert sent["sec-ch-ua-platform"] == '"Windows"'
     assert sent["referer"] == "https://crm2.yunkecn.com/"
     # The existing auth headers still ride along unchanged.
-    assert sent["source"] == "yunkepc"
+    assert "source" not in sent  # omitted: breaks msg/chats Integer binding
     assert sent["channel"] == "4"
     assert sent["userid"] == USERID
     assert sent["company"] == COMPANY