feat(phase2): 追责取证与确权举证(F19/F20)

- internal/provenance: 全链路存证(送审/审核/发码/转码/入库/注入)+责任界定
- service: Provenance/Accountability(定位首次哈希变化节点)/CopyrightEvidence/MatchInfringement
- api: /content/provenance, /accountability, /evidence, /infringe-match
- 转码版哈希不误判为篡改; 感知哈希侵权比对分级(high/medium)
- 11项新测试通过; 端到端: 审播一致判定+证据链+侵权命中

tcs-iptv/internal/service/distribution.go

@@ -48,6 +48,7 @@ func (s *Service) IngestToLibrary(role chain.Role, maCode, ctid, mediaAssetID, l
 	}); err != nil {
 		return err
 	}
+	s.prov.Record(model.ProvenanceEvent{MACode: maCode, Node: model.NodeIngest, Operator: libName, Detail: "审合格入媒资库"})
 	return s.chain.SetContentStatus(maCode, model.StatusInLibrary)
 }
 
@@ -111,6 +112,7 @@ func (s *Service) InjectToCDN(role chain.Role, ctid, maCode, injectFileHash, ope
 	}); err != nil {
 		return InjectResult{}, err
 	}
+	s.prov.Record(model.ProvenanceEvent{MACode: maCode, Node: model.NodeInject, HashValue: injectFileHash, Operator: operatorID, Detail: "CDN 注入校验通过"})
 	return InjectResult{Allowed: true, DistributionID: distID}, nil
 }
 
@@ -205,3 +207,66 @@ func (s *Service) ComputeSettlement(maCode, period string) (model.Settlement, er
 	}
 	return s.pb.ComputeSettlement(maCode, period, model.DefaultShareConfig())
 }
+
+// ---- 二期 F19/F20：追责取证与确权举证（需求22/23） ----
+
+// Provenance 返回某 MA 码的全链路存证（需求22-AC1）。
+func (s *Service) Provenance(maCode string) []model.ProvenanceEvent {
+	return s.prov.Trail(maCode)
+}
+
+// Accountability 责任界定取证：定位首次哈希变化节点与责任方（需求22-AC2）。
+func (s *Service) Accountability(maCode string) model.AccountabilityReport {
+	return s.prov.Accountability(maCode)
+}
+
+// CopyrightEvidence 导出版权确权证据链（需求23-AC1/AC2）。
+func (s *Service) CopyrightEvidence(maCode string) (model.CopyrightEvidence, error) {
+	c, err := s.chain.QueryContent(maCode)
+	if err != nil {
+		return model.CopyrightEvidence{}, err
+	}
+	trail := s.prov.Trail(maCode)
+	ev := model.CopyrightEvidence{
+		MACode: maCode, Title: c.Title, Issuer: c.Issuer, IssueDate: c.IssueDate,
+		ContentHash: c.FileHash, ChainAnchor: "chain://" + maCode, Trail: trail,
+		Statement: "本证据链由 MA 码、内容哈希与上链时间戳构成，遵循『谁先锁定谁有权』，不可抵赖，可用于侵权投诉与司法举证。",
+	}
+	for _, e := range trail {
+		if e.Node == model.NodeSubmit {
+			ev.FirstSeenAt = e.Timestamp
+			if ev.ContentHash == "" {
+				ev.ContentHash = e.HashValue
+			}
+			break
+		}
+	}
+	return ev, nil
+}
+
+// MatchInfringement 用感知哈希在已确权内容中检索疑似侵权（需求23-AC3）。
+// threshold 为汉明距离阈值（<=high 高度相似，<=medium 中度相似）。
+func (s *Service) MatchInfringement(perceptual string, high, medium int) ([]model.InfringeMatch, error) {
+	s.mu.Lock()
+	entries := make(map[string]phashEntry, len(s.phash))
+	for k, v := range s.phash {
+		entries[k] = v
+	}
+	s.mu.Unlock()
+
+	var out []model.InfringeMatch
+	for ma, e := range entries {
+		d, err := hash.HammingDistance(perceptual, e.Perceptual)
+		if err != nil {
+			continue // 长度不一致跳过
+		}
+		if d <= medium {
+			sim := "medium"
+			if d <= high {
+				sim = "high"
+			}
+			out = append(out, model.InfringeMatch{MACode: ma, Title: e.Title, Distance: d, Similarity: sim})
+		}
+	}
+	return out, nil
+}