diff --git a/tests/integration/test_api_mail.py b/tests/integration/test_api_mail.py
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+++ b/tests/integration/test_api_mail.py
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+"""Mail API 集成测试 — 覆盖全部端点 + 防御逻辑 A1-A10"""
+
+import json
+import os
+from pathlib import Path
+
+import pytest
+from fastapi.testclient import TestClient
+
+from src.main import app
+
+pytestmark = pytest.mark.integration
+
+# 有效 Agent（与 mail_routes fallback 一致）
+VALID_AGENTS = [
+    "zhangfei-dev", "guanyu-dev", "zhaoyun-data",
+    "jiangwei-infra", "pangtong-fujunshi", "simayi-challenger",
+]
+FROM_AGENT = "zhangfei-dev"
+TO_AGENT = "simayi-challenger"
+OTHER_AGENT = "pangtong-fujunshi"
+
+
+@pytest.fixture
+def mail_env(tmp_path):
+    """创建临时 Mail 环境，确保 BLACKBOARD_ROOT 隔离"""
+    mail_root = tmp_path / "mail_root"
+    mail_root.mkdir()
+    os.environ["BLACKBOARD_ROOT"] = str(mail_root)
+    yield mail_root
+    del os.environ["BLACKBOARD_ROOT"]
+
+
+@pytest.fixture
+def client():
+    return TestClient(app)
+
+
+def _send(client, from_a: str = FROM_AGENT, to_a: str = TO_AGENT,
+          title: str = "Test Mail", text: str = "Hello",
+          **kwargs) -> dict:
+    """发送邮件的便捷方法"""
+    body = {"from": from_a, "to": to_a, "title": title, "text": text}
+    body.update(kwargs)
+    resp = client.post("/api/mail", json=body)
+    return resp
+
+
+# ===================================================================
+# TestMailList
+# ===================================================================
+
+class TestMailList:
+    def test_list_returns_all(self, client, mail_env):
+        _send(client, title="Mail A")
+        _send(client, from_a=TO_AGENT, to_a=FROM_AGENT, title="Mail B")
+        resp = client.get("/api/mail")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["total"] == 2
+
+    def test_filter_by_from_agent(self, client, mail_env):
+        _send(client, title="From ZF")
+        _send(client, from_a=OTHER_AGENT, to_a=TO_AGENT, title="From PT")
+        resp = client.get("/api/mail", params={"from_agent": FROM_AGENT})
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["total"] == 1
+        assert data["mails"][0]["from"] == FROM_AGENT
+
+    def test_filter_by_to_agent(self, client, mail_env):
+        _send(client, title="To SMY")
+        _send(client, from_a=TO_AGENT, to_a=OTHER_AGENT, title="To PT")
+        resp = client.get("/api/mail", params={"to_agent": TO_AGENT})
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["total"] == 1
+        assert data["mails"][0]["to"] == TO_AGENT
+
+    def test_filter_unread(self, client, mail_env):
+        r = _send(client, title="Unread")
+        mail_id = r.json()["mail_id"]
+        # 标记已读
+        client.patch(f"/api/mail/{mail_id}", json={"is_read": True})
+        # 再发一封未读
+        _send(client, from_a=OTHER_AGENT, to_a=FROM_AGENT, title="Still unread")
+        resp = client.get("/api/mail", params={"unread": True})
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["total"] == 1
+
+    def test_limit_parameter(self, client, mail_env):
+        for i in range(5):
+            _send(client, title=f"Mail {i}")
+        resp = client.get("/api/mail", params={"limit": 2})
+        assert resp.status_code == 200
+        assert resp.json()["total"] == 2
+
+
+# ===================================================================
+# TestMailAgents
+# ===================================================================
+
+class TestMailAgents:
+    def test_agents_list(self, client, mail_env):
+        _send(client, title="A")
+        _send(client, from_a=OTHER_AGENT, to_a=TO_AGENT, title="B")
+        resp = client.get("/api/mail/agents/list")
+        assert resp.status_code == 200
+        agents = resp.json()["agents"]
+        assert FROM_AGENT in agents
+        assert TO_AGENT in agents
+        assert OTHER_AGENT in agents
+
+
+# ===================================================================
+# TestMailSummary
+# ===================================================================
+
+class TestMailSummary:
+    def test_summary_fields(self, client, mail_env):
+        _send(client, title="Info", type="inform")
+        _send(client, title="Req", type="request")
+        resp = client.get("/api/mail/summary")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["total"] == 2
+        assert data["unread"] == 2
+        assert data["by_type"]["inform"] == 1
+        assert data["by_type"]["request"] == 1
+
+
+# ===================================================================
+# TestMailDetail
+# ===================================================================
+
+class TestMailDetail:
+    def test_get_detail(self, client, mail_env):
+        r = _send(client, title="Detail Test", text="Body content")
+        mail_id = r.json()["mail_id"]
+        resp = client.get(f"/api/mail/{mail_id}")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["title"] == "Detail Test"
+        assert data["description"] == "Body content"
+        assert data["from"] == FROM_AGENT
+        assert data["to"] == TO_AGENT
+        assert "comments" in data
+
+    def test_detail_404(self, client, mail_env):
+        resp = client.get("/api/mail/nonexistent-mail-id")
+        assert resp.status_code == 404
+
+
+# ===================================================================
+# TestSendMail — A1-A10 防御逻辑
+# ===================================================================
+
+class TestSendMail:
+    # --- 防御逻辑 ---
+
+    def test_A1_from_missing(self, client, mail_env):
+        """A1: from 必填 → 400"""
+        resp = client.post("/api/mail", json={
+            "to": TO_AGENT, "title": "T", "text": "Hi",
+        })
+        assert resp.status_code == 400
+        assert "from" in resp.json()["detail"]
+
+    def test_A9_from_invalid(self, client, mail_env):
+        """A9: from 不是有效 Agent → 400"""
+        resp = client.post("/api/mail", json={
+            "from": "unknown-agent", "to": TO_AGENT, "title": "T", "text": "Hi",
+        })
+        assert resp.status_code == 400
+        assert "不是有效的 Agent" in resp.json()["detail"]
+
+    def test_A2_to_missing_non_reply(self, client, mail_env):
+        """A2: 非回复时 to 缺失 → 400"""
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "title": "T", "text": "Hi",
+        })
+        assert resp.status_code == 400
+        assert "to" in resp.json()["detail"]
+
+    def test_A3_from_equals_to(self, client, mail_env):
+        """A3: from == to 防自环 → 400"""
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "to": FROM_AGENT, "title": "T", "text": "Self",
+        })
+        assert resp.status_code == 400
+        assert "不能给自己发邮件" in resp.json()["detail"]
+
+    def test_A4_to_invalid(self, client, mail_env):
+        """A4: to 不是有效 Agent → 400"""
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "to": "nobody", "title": "T", "text": "Hi",
+        })
+        assert resp.status_code == 400
+        assert "不是有效的 Agent" in resp.json()["detail"]
+
+    def test_A10_text_empty(self, client, mail_env):
+        """A10: 正文为空 → 400"""
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "to": TO_AGENT, "title": "T", "text": "   ",
+        })
+        assert resp.status_code == 400
+        assert "正文" in resp.json()["detail"]
+
+    def test_A10_description_empty(self, client, mail_env):
+        """A10: description 字段为空也触发 → 400"""
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "to": TO_AGENT, "title": "T",
+        })
+        assert resp.status_code == 400
+
+    # --- 正常发送 ---
+
+    def test_send_inform(self, client, mail_env):
+        """正常发送 inform → 200"""
+        resp = _send(client, type="inform")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["ok"]
+        assert data["mail_id"]
+        # 验证列表可见
+        mails = client.get("/api/mail").json()["mails"]
+        assert len(mails) == 1
+        assert mails[0]["type"] == "inform"
+
+    def test_send_request(self, client, mail_env):
+        """正常发送 request → 200"""
+        resp = _send(client, type="request")
+        assert resp.status_code == 200
+        mails = client.get("/api/mail").json()["mails"]
+        assert mails[0]["type"] == "request"
+
+    # --- 回复逻辑 ---
+
+    def test_A5_reply_to_nonexistent(self, client, mail_env):
+        """A5: in_reply_to 不存在 → 400"""
+        resp = _send(client, in_reply_to="mail-99999")
+        assert resp.status_code == 400
+        assert "不存在" in resp.json()["detail"]
+
+    def test_A6_A7_auto_correct_to(self, client, mail_env):
+        """A6/A7: 回复时 to 被自动纠正为原发件者 → 200 + auto_corrected"""
+        # simayi → zhangfei
+        r = _send(client, from_a=TO_AGENT, to_a=FROM_AGENT,
+                  title="Original", text="Original body")
+        orig_id = r.json()["mail_id"]
+
+        # zhangfei 回复 simayi，但故意传错 to
+        resp = _send(client, from_a=FROM_AGENT, to_a=OTHER_AGENT,
+                     title="Reply", text="Reply body",
+                     in_reply_to=orig_id)
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["ok"]
+        assert "auto_corrected" in data
+        assert data["auto_corrected"]["field"] == "to"
+        assert data["auto_corrected"]["original"] == OTHER_AGENT
+        assert data["auto_corrected"]["corrected"] == TO_AGENT
+
+    def test_A8_non_party_reply_rejected(self, client, mail_env):
+        """A8: 非邮件双方回复 → 400"""
+        # zhangfei → simayi
+        r = _send(client, title="Private", text="Secret")
+        orig_id = r.json()["mail_id"]
+
+        # pangtong（第三方）尝试回复
+        resp = _send(client, from_a=OTHER_AGENT, to_a=FROM_AGENT,
+                     title="Intrude", text="I shouldn't be here",
+                     in_reply_to=orig_id)
+        assert resp.status_code == 400
+        assert "发送者或接收者" in resp.json()["detail"]
+
+    def test_reply_inherits_conversation_id(self, client, mail_env):
+        """回复时 conversation_id 继承"""
+        r = _send(client, from_a=TO_AGENT, to_a=FROM_AGENT,
+                  title="Conv Start", text="Start",
+                  conversation_id="conv-test-123")
+        orig_id = r.json()["mail_id"]
+
+        resp = _send(client, from_a=FROM_AGENT, to_a=TO_AGENT,
+                     title="Conv Reply", text="Reply",
+                     in_reply_to=orig_id)
+        assert resp.status_code == 200
+        reply_id = resp.json()["mail_id"]
+
+        # 验证回复邮件继承了 conversation_id
+        detail = client.get(f"/api/mail/{reply_id}").json()
+        assert detail["conversation_id"] == "conv-test-123"
+
+    def test_reply_type_defaults_inform(self, client, mail_env):
+        """回复时 type 默认 inform"""
+        r = _send(client, from_a=TO_AGENT, to_a=FROM_AGENT,
+                  title="Orig", text="Hi", type="request")
+        orig_id = r.json()["mail_id"]
+
+        # 不传 type，应默认 inform
+        resp = client.post("/api/mail", json={
+            "from": FROM_AGENT, "to": TO_AGENT,
+            "title": "Re: Orig", "text": "Reply",
+            "in_reply_to": orig_id,
+        })
+        assert resp.status_code == 200
+        reply_id = resp.json()["mail_id"]
+        detail = client.get(f"/api/mail/{reply_id}").json()
+        assert detail["type"] == "inform"
+
+
+# ===================================================================
+# TestDeleteMail
+# ===================================================================
+
+class TestDeleteMail:
+    def test_delete_by_prefix(self, client, mail_env):
+        _send(client, title="[BULK] Alert 1")
+        _send(client, title="[BULK] Alert 2")
+        _send(client, title="Keep this")
+        resp = client.delete("/api/mail", params={"prefix": "[BULK]"})
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["ok"]
+        assert data["deleted_count"] == 2
+        # 只有 1 封保留
+        mails = client.get("/api/mail").json()["mails"]
+        assert len(mails) == 1
+        assert mails[0]["title"] == "Keep this"
+
+    def test_delete_prefix_missing(self, client, mail_env):
+        resp = client.delete("/api/mail")
+        assert resp.status_code == 400
+
+    def test_delete_no_match(self, client, mail_env):
+        _send(client, title="Keep")
+        resp = client.delete("/api/mail", params={"prefix": "NONEXISTENT"})
+        assert resp.status_code == 200
+        assert resp.json()["deleted_count"] == 0
+
+
+# ===================================================================
+# TestUpdateMail
+# ===================================================================
+
+class TestUpdateMail:
+    def test_mark_read(self, client, mail_env):
+        r = _send(client, title="Read me")
+        mail_id = r.json()["mail_id"]
+
+        resp = client.patch(f"/api/mail/{mail_id}", json={"is_read": True})
+        assert resp.status_code == 200
+        assert resp.json()["ok"]
+
+        # 验证已读
+        detail = client.get(f"/api/mail/{mail_id}").json()
+        assert detail["is_read"] is True
+
+    def test_mark_executed(self, client, mail_env):
+        r = _send(client, title="Do me")
+        mail_id = r.json()["mail_id"]
+
+        resp = client.patch(f"/api/mail/{mail_id}", json={"mark_executed": True})
+        assert resp.status_code == 200
+        assert resp.json()["ok"]
+
+        # 验证已读 + status=done
+        detail = client.get(f"/api/mail/{mail_id}").json()
+        assert detail["is_read"] is True
+        assert detail["status"] == "done"
+
+    def test_update_404(self, client, mail_env):
+        resp = client.patch("/api/mail/no-such-mail", json={"is_read": True})
+        assert resp.status_code == 404