feat(fam-edge): DSM 运动侦测预过滤 - 空转时段跳过云端视频分析

群晖 Surveillance Station 用 SYNO.SurveillanceStation.EventCenter.Event（未公开
文档的内部接口，参数是下划线风格 camera_ids/start_time/end_time，公开文档里的
cameraIds/fromTime/toTime 是旧版 Event API 的参数名，两者不通用）记录了摄像头
真实的运动侦测事件（event_type=10=运动，start_time+duration 精确到秒），比自己
本地跑 ffmpeg 帧差分更准、不需要额外算力，之前一直在这台 NAS 上验证可行性。

新增 DsmMotionClient：process_video() 分析每段视频前，先用视频的
[event_start, event_start+duration] 时间窗查一次这个接口，窗口内一条运动事件都
没有就跳过云端分析（标记 done，compute_provider=skipped_no_motion），省掉长期
无人时段白白消耗的 Gemini/NVIDIA 配额。

安全设计：查询本身失败/未配置/账号密码没填一律 fail-open（当作"有运动"，照常
分析），不会因为这层可选优化漏检真实事件——这是一个纯粹的省配额优化，不能反过来
影响监控系统的可靠性。

新增 12 个单测覆盖：禁用/缺凭证时的 fail-open、登录失败、网络异常、无事件、有
事件、按 camera_id 过滤（响应是按 ds_id 分组不是按 camera_id，容易搞混）、
最短运动时长阈值、session 过期重登录重试、env 变量解析。

账号密码走 .env 的 DSM_ACCOUNT/DSM_PASSWORD，不明文入库。

fam-edge/tests/test_dsm_motion_client.py

@@ -0,0 +1,157 @@
+from datetime import datetime
+
+from fam_edge.dsm_motion_client import DsmMotionClient
+
+
+def _cfg(**overrides):
+    base = {
+        "enabled": True,
+        "host": "192.168.50.64",
+        "port": 5000,
+        "account": "ericwyuan",
+        "password": "secret",
+        "camera_id": 2,
+        "min_motion_seconds": 0,
+        "timeout_sec": 5,
+    }
+    base.update(overrides)
+    return base
+
+
+class _FakeResp:
+    def __init__(self, payload):
+        self._payload = payload
+
+    def json(self):
+        return self._payload
+
+
+def _events_payload(events, ds_id="0"):
+    return {"success": True, "data": {ds_id: events}}
+
+
+def test_disabled_config_always_returns_none():
+    c = DsmMotionClient(_cfg(enabled=False))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is None
+
+
+def test_missing_credentials_returns_none():
+    c = DsmMotionClient(_cfg(account="", password=""))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is None
+
+
+def test_login_failure_returns_none(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        return _FakeResp({"success": False, "error": {"code": 400}})
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg())
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is None
+
+
+def test_login_network_exception_returns_none(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        raise ConnectionError("boom")
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg())
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is None
+
+
+def test_no_motion_events_returns_false(monkeypatch):
+    calls = {"n": 0}
+
+    def fake_get(url, params=None, timeout=None):
+        calls["n"] += 1
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload([]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg())
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is False
+
+
+def test_motion_event_present_returns_true(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 2, "event_type": 10, "start_time": 1000, "duration": 12}]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg())
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is True
+
+
+def test_events_grouped_by_ds_id_not_camera_id(monkeypatch):
+    """核心场景: 响应按 ds_id 分组（单机固定 "0"），不是按 camera_id 分组——
+    错把 camera_id 当 dict key 去取会永远拿到空列表。"""
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 2, "event_type": 10, "start_time": 1000, "duration": 5}], ds_id="0"))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg(camera_id=2))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is True
+
+
+def test_events_for_other_camera_ignored(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 99, "event_type": 10, "start_time": 1000, "duration": 999}]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg(camera_id=2))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is False
+
+
+def test_total_motion_below_threshold_is_treated_as_no_motion(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 2, "event_type": 10, "start_time": 1000, "duration": 1}]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg(min_motion_seconds=3))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is False
+
+
+def test_total_motion_meeting_threshold_counts_as_motion(monkeypatch):
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            return _FakeResp({"success": True, "data": {"sid": "abc"}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 2, "event_type": 10, "start_time": 1000, "duration": 2},
+             {"camera_id": 2, "event_type": 10, "start_time": 1100, "duration": 2}]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg(min_motion_seconds=3))
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is True
+
+
+def test_expired_session_relogins_and_retries_once(monkeypatch):
+    """session 过期(错误码 106)时应该重新登录一次再查，而不是直接放弃。"""
+    state = {"logins": 0, "queries": 0}
+
+    def fake_get(url, params=None, timeout=None):
+        if params.get("api") == "SYNO.API.Auth":
+            state["logins"] += 1
+            return _FakeResp({"success": True, "data": {"sid": f"sid{state['logins']}"}})
+        state["queries"] += 1
+        if state["queries"] == 1:
+            return _FakeResp({"success": False, "error": {"code": 106}})
+        return _FakeResp(_events_payload(
+            [{"camera_id": 2, "event_type": 10, "start_time": 1000, "duration": 5}]))
+    monkeypatch.setattr("fam_edge.dsm_motion_client.requests.get", fake_get)
+    c = DsmMotionClient(_cfg())
+    assert c.has_motion_in_range(datetime(2026, 8, 22), 1800) is True
+    assert state["logins"] == 2
+    assert state["queries"] == 2
+
+
+def test_env_var_credentials_resolved():
+    import os
+    os.environ["TEST_DSM_ACCOUNT_XYZ"] = "realaccount"
+    try:
+        c = DsmMotionClient(_cfg(account="${TEST_DSM_ACCOUNT_XYZ}"))
+        assert c.account == "realaccount"
+    finally:
+        del os.environ["TEST_DSM_ACCOUNT_XYZ"]