feat(server): 归因v2——paid_social渠道与fb+付费medium优先规则

Co-Authored-By: Claude Code <noreply@anthropic.com>

server/tracker/services/attribution.py

@@ -29,6 +29,9 @@ _AD_FAMILIES = {
     "bing": "bing", "bingads": "bing", "microsoftads": "bing",
     "yandex": "yandex", "yandexads": "yandex", "директ": "yandex",
 }
+_FB_FAMILY = "meta"   # fb 家族名（_AD_FAMILIES 归一结果）：fb+付费 medium → paid_social
+# 点击参数 → 付费渠道（v2）：fbclid 属社交广告（Meta），其余（gclid/msclkid/yclid）搜索广告
+_PAID_PARAM_CHANNELS = {"fbclid": "paid_social"}
 # UTM 标签 ↔ 平台名别名（家族表之外的零散别名）；baidu 恒等仅为可读
 _UTM_ALIASES = {"tt": "tiktok",
                 "wa": "whatsapp", "g": "google", "baidu": "baidu", "百度": "baidu"}
@@ -157,7 +160,8 @@ def classify(*, referrer_url: str = "", utm: dict | None = None,
 
     paid = _paid_param(landing_path, referrer_url)
     if paid:
-        out.update(channel="paid_search", platform=paid[1],
+        out.update(channel=_PAID_PARAM_CHANNELS.get(paid[0], "paid_search"),
+                   platform=paid[1],
                    evidence_kind="observed_referrer", resolution="resolved",
                    detail={"click_param": paid[0]})
     elif host:
@@ -199,8 +203,16 @@ def classify(*, referrer_url: str = "", utm: dict | None = None,
                                  "utm_evidence": {
                                      "channel": _utm_channel(utm_source), "platform": utm_source,
                                      "evidence_kind": "utm_label"}}
-        else:   # 无 referrer 观察 → 仅标签：按 utm_source 归类显示，状态诚实标注
-            out.update(channel=_utm_channel(utm_source), platform=utm_source,
+        else:   # 无 referrer 观察 → 仅标签：按 utm_source/utm_medium 归类显示，状态诚实标注
+            medium = str(utm.get("utm_medium") or "").strip().lower()
+            channel = _utm_channel(utm_source)
+            if medium in C.PAID_MEDIUMS:
+                if _canon(utm_source) == _FB_FAMILY:
+                    channel = "paid_social"   # fb 家族 + 付费 medium（实测主导 paid+fb）
+                elif medium not in C.SOCIAL_MEDIUMS:
+                    channel = "paid_search"   # 非 fb + 搜索系付费 medium（cpc/ppc/paid…）
+                # 非 fb + 纯社交 medium 不判付费——防误伤自然社交，保持 _utm_channel 走向
+            out.update(channel=channel, platform=utm_source,
                        evidence_kind="utm_label", resolution="label_only")
 
     # 应用内浏览器 UA：有来源 → 作为 surface 叠加；无任何来源 → 本身就是来源