From c162a9b92f271cab13b29db76551813e9ae11062 Mon Sep 17 00:00:00 2001
From: Belugary <53219544+Belugary@users.noreply.github.com>
Date: Tue, 12 May 2026 16:18:43 +0800
Subject: [PATCH] fix(mcp): trim raw XML payload from namecard (type=42) chat
 output (#83)
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When a chat history contains a name-card message (msg_type=42), the
dispatcher in `_format_message_text` had no case for `base_type == 42`,
so it fell through to the generic non-text branch:

    elif base_type != 1:
        type_label = format_msg_type(local_type)
        text = f"[{type_label}] {text}" if text else f"[{type_label}]"

`text` for type=42 is the full raw `<msg ...>` element, so chat history
exports emitted `[名片] <msg username="..." antispamticket="v2_..."
brandIconUrl="https://wx.qlogo.cn/..." bigheadimgurl="..." ... />`.

That payload has two problems:
1. It leaks anti-spam tokens (`antispamticket`) and head-image CDN URLs
   into chat logs that are routinely piped to LLMs and other downstream
   tools.
2. The raw XML drowns out the actual signal — a human or an LLM reading
   the chat just wants to know "X shared Y's contact".

This PR adds `_format_namecard_text(content)` that pulls only the three
useful attributes:

- `nickname` — display name
- `username` — wxid (annotated as "公众号" when prefixed `gh_`)
- `certinfo` — user-authored bio

and wires it into the dispatch chain via a new `elif base_type == 42:`
branch, sitting alongside the existing `49` (app message) handler. It
reuses `_parse_xml_root` and `_collapse_text` — no new helpers
introduced.

Tests: 7 cases in `tests/test_namecard_format.py` covering the realistic
shape (with antispamticket / brand URLs that must NOT appear in output),
official accounts (`gh_*`), missing certinfo, missing nickname, missing
both identifiers, and broken-XML fallthrough.

All 158 tests pass locally (151 baseline + 7 new).
---
 mcp_server.py                 | 27 +++++++++++++
 tests/test_namecard_format.py | 73 +++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 tests/test_namecard_format.py

diff --git a/mcp_server.py b/mcp_server.py
index 619af79..d604271 100644
--- a/mcp_server.py
+++ b/mcp_server.py
@@ -666,6 +666,31 @@ def _parse_app_message_outer(content):
     return root
 
 
+def _format_namecard_text(content):
+    """Parse type=42 (名片) XML into a compact human-readable line.
+
+    Source XML carries dozens of fields (antispamticket, biznamecardinfo,
+    brand URLs, image MD5s) but the useful signal is just three attrs:
+    ``nickname`` (display name), ``username`` (wxid; ``gh_*`` for 公众号),
+    and ``certinfo`` (the user-authored bio). Everything else is either
+    auth tokens that should not be piped to downstream systems, or
+    rendering metadata that bloats the chat log without helping a human
+    or an LLM understand the conversation.
+    """
+    root = _parse_xml_root(content)
+    if root is None:
+        return None
+    nickname = (root.get("nickname") or "").strip()
+    username = (root.get("username") or "").strip()
+    certinfo = _collapse_text(root.get("certinfo") or "")
+    if not nickname and not username:
+        return None
+    head = nickname or username
+    if username.startswith("gh_"):
+        head = f"{head} (公众号 {username})"
+    return f"[名片] {head}: {certinfo}" if certinfo else f"[名片] {head}"
+
+
 def _format_app_message_text(content, local_type, is_group, chat_username, chat_display_name, names):
     if not content or '<appmsg' not in content:
         return None
@@ -865,6 +890,8 @@ def _format_message_text(local_id, local_type, content, is_group, chat_username,
         text = "[表情]"
     elif base_type == 50:
         text = _format_voip_message_text(text) or "[通话]"
+    elif base_type == 42:
+        text = _format_namecard_text(text) or "[名片]"
     elif base_type == 49:
         formatted = _format_app_message_text(
             text, local_type, is_group, chat_username, chat_display_name, names
diff --git a/tests/test_namecard_format.py b/tests/test_namecard_format.py
new file mode 100644
index 0000000..e61184d
--- /dev/null
+++ b/tests/test_namecard_format.py
@@ -0,0 +1,73 @@
+"""Tests for `_format_namecard_text` (msg_type=42 鉴定).
+
+Before this helper, type=42 messages fell through the generic non-text branch
+and emitted `[名片] <raw XML>`, dumping the full `<msg .../>` element including
+antispamticket, biznamecardinfo and head-image URLs. Those tokens are PII that
+should not be piped to downstream LLM / log systems.
+
+These tests pin the new behaviour: a compact `[名片] <head>: <bio>` line,
+without any source-only XML fields.
+"""
+import unittest
+
+import mcp_server
+
+
+# Realistic-shape sample with the noisy / sensitive attrs that used to leak.
+_REAL_NAMECARD = (
+    '<msg username="wxid_friend_demo" nickname="李雷" '
+    'antispamticket="v2_abc123def456_should_not_leak" '
+    'fullpy="lilei" shortpy="LL" alias="" '
+    'imagestatus="3" scene="17" province="北京" city="海淀" sign="" '
+    'sex="1" certflag="0" certinfo="搬砖工人 / 业余摄影" '
+    'brandIconUrl="https://wx.qlogo.cn/should_not_leak" '
+    'bigheadimgurl="https://wx.qlogo.cn/should_not_leak_big" '
+    'smallheadimgurl="https://wx.qlogo.cn/should_not_leak_small" />'
+)
+
+
+class FormatNamecardTextTests(unittest.TestCase):
+    def test_compact_line_for_real_namecard(self):
+        out = mcp_server._format_namecard_text(_REAL_NAMECARD)
+        self.assertEqual(out, "[名片] 李雷: 搬砖工人 / 业余摄影")
+
+    def test_no_pii_or_url_in_output(self):
+        out = mcp_server._format_namecard_text(_REAL_NAMECARD)
+        self.assertNotIn("antispamticket", out)
+        self.assertNotIn("v2_abc123def456", out)
+        self.assertNotIn("qlogo.cn", out)
+        self.assertNotIn("brandIconUrl", out)
+        self.assertNotIn("headimgurl", out)
+
+    def test_official_account_marked(self):
+        xml = (
+            '<msg username="gh_some_official" nickname="Some Official Account" '
+            'certinfo="一个公众号" />'
+        )
+        out = mcp_server._format_namecard_text(xml)
+        self.assertEqual(
+            out, "[名片] Some Official Account (公众号 gh_some_official): 一个公众号"
+        )
+
+    def test_no_certinfo_falls_back_to_head_only(self):
+        xml = '<msg username="wxid_demo" nickname="韩梅梅" />'
+        out = mcp_server._format_namecard_text(xml)
+        self.assertEqual(out, "[名片] 韩梅梅")
+
+    def test_only_username_when_nickname_missing(self):
+        xml = '<msg username="wxid_demo" nickname="" />'
+        out = mcp_server._format_namecard_text(xml)
+        self.assertEqual(out, "[名片] wxid_demo")
+
+    def test_missing_both_identifiers_returns_none(self):
+        xml = '<msg nickname="" username="" />'
+        self.assertIsNone(mcp_server._format_namecard_text(xml))
+
+    def test_broken_xml_returns_none(self):
+        self.assertIsNone(mcp_server._format_namecard_text(""))
+        self.assertIsNone(mcp_server._format_namecard_text("<msg "))
+        self.assertIsNone(mcp_server._format_namecard_text("not xml at all"))
+
+
+if __name__ == "__main__":
+    unittest.main()