diff --git a/internal/bizdev/service.go b/internal/bizdev/service.go
index 78869523..894eb744 100644
--- a/internal/bizdev/service.go
+++ b/internal/bizdev/service.go
@@ -51,6 +51,22 @@ type Service struct {
 	stageTaskHook func(context.Context, TaskRunRequest) (*TaskRunResult, error)
 	// createDocumentHook 仅测试注入：覆盖账本创建失败路径。
 	createDocumentHook func(ctx context.Context, docID string, projectID int64, taskKey, title, stage, workDir string, authorID int64, authorName string, reviewerID int64, reviewerName string, approverID int64, approverName string) (*docgov.DocumentRecord, error)
+	// instanceDuty 可选：活跃工作流实例对 taskKey 的治理职责（由 app 装配，避免导入 projectinstance）。
+	instanceDuty InstanceDutySource
+}
+
+// InstanceDutySource 返回项目当前活跃实例对 taskKey 的治理结论。
+// governed=false 表示未受实例治理，调用方应回退项目默认职责逻辑。
+type InstanceDutySource interface {
+	ResolveGovernedDuty(ctx context.Context, projectID int64, taskKey string) (author, reviewer, approver int64, dutyPolicy string, governed bool, err error)
+}
+
+// SetInstanceDutySource 注入实例职责解析源（组合根可选装配）。
+func (s *Service) SetInstanceDutySource(src InstanceDutySource) {
+	if s == nil {
+		return
+	}
+	s.instanceDuty = src
 }
 
 // NewService 构造业务服务；生产/test 环境数据库不可用且未显式 ALLOW_IN_MEMORY 时返回 error。
@@ -456,7 +472,7 @@ func (s *Service) ExecuteTask(ctx context.Context, req TaskRunRequest) (*TaskRun
 		}
 	}
 
-	duties := resolveTaskDocumentDuties(ctx, s.pool, req)
+	duties, dutyPolicy, governed := resolveTaskDocumentDuties(ctx, s.pool, req, s.instanceDuty)
 	authorID, authorName := duties.Author.UserID, duties.Author.Name
 	reviewerID, reviewerName := duties.Reviewer.UserID, duties.Reviewer.Name
 	approverID, approverName := duties.Approver.UserID, duties.Approver.Name
@@ -500,6 +516,21 @@ func (s *Service) ExecuteTask(ctx context.Context, req TaskRunRequest) (*TaskRun
 				DocRecord:     docRec,
 			}, createErr
 		}
+		if governed && docRec != nil {
+			if lockErr := s.docGov.LockDocumentDuty(ctx, docRec.DocID, dutyPolicy); lockErr != nil {
+				log.Printf("[docgov] lock document duty %s failed: %v", docRec.DocID, lockErr)
+				return &TaskRunResult{
+					TaskKey:       req.TaskKey,
+					ArtifactTitle: artifactTitle,
+					WorkDir:       req.WorkDir,
+					Success:       false,
+					ErrorReason:   "lock document duty failed: " + lockErr.Error(),
+					DocRecord:     docRec,
+				}, lockErr
+			}
+			docRec.DutyLocked = true
+			docRec.DutyPolicy = dutyPolicy
+		}
 		if s.pool != nil && req.ProjectID > 0 {
 			assigned, _, healErr := docduty.HealProjectDocuments(ctx, s.pool, req.ProjectID)
 			if healErr != nil {
@@ -513,7 +544,8 @@ func (s *Service) ExecuteTask(ctx context.Context, req TaskRunRequest) (*TaskRun
 					DocRecord:     docRec,
 				}, healErr
 			}
-			if docRec != nil {
+			// 受实例治理的文档不得用项目默认职责覆盖内存态返回值。
+			if !governed && docRec != nil {
 				members, creator, loadErr := docduty.LoadProjectMembers(ctx, s.pool, req.ProjectID)
 				if loadErr != nil {
 					log.Printf("[docduty] load members project %d after generate failed: %v", req.ProjectID, loadErr)
@@ -1339,7 +1371,35 @@ func (s *Service) ResumeOrModifyWorkspace(ctx context.Context, req squad.ModifyW
 	return s.squad.ResumeOrModifyWorkspace(ctx, req)
 }
 
-func resolveTaskDocumentDuties(ctx context.Context, pool *pgxpool.Pool, req TaskRunRequest) docduty.Binding {
+func resolveTaskDocumentDuties(ctx context.Context, pool *pgxpool.Pool, req TaskRunRequest, instanceDuty InstanceDutySource) (docduty.Binding, string, bool) {
+	if instanceDuty != nil && req.ProjectID > 0 && strings.TrimSpace(req.TaskKey) != "" {
+		authorID, reviewerID, approverID, dutyPolicy, governed, err := instanceDuty.ResolveGovernedDuty(ctx, req.ProjectID, req.TaskKey)
+		if err == nil && governed {
+			bound := docduty.Binding{
+				Author:   docduty.Holder{UserID: authorID},
+				Reviewer: docduty.Holder{UserID: reviewerID},
+				Approver: docduty.Holder{UserID: approverID},
+			}
+			if pool != nil {
+				if members, creator, loadErr := docduty.LoadProjectMembers(ctx, pool, req.ProjectID); loadErr == nil {
+					bound.Author.Name = holderName(members, creator, authorID, req.AuthorName)
+					bound.Reviewer.Name = holderName(members, creator, reviewerID, req.ReviewerName)
+					bound.Approver.Name = holderName(members, creator, approverID, req.ApproverName)
+				}
+			}
+			if bound.Author.Name == "" {
+				bound.Author.Name = strings.TrimSpace(req.AuthorName)
+			}
+			if bound.Reviewer.Name == "" {
+				bound.Reviewer.Name = strings.TrimSpace(req.ReviewerName)
+			}
+			if bound.Approver.Name == "" {
+				bound.Approver.Name = strings.TrimSpace(req.ApproverName)
+			}
+			return bound, dutyPolicy, true
+		}
+	}
+
 	reqDuties := docduty.RequestDuties{
 		AuthorID: req.AuthorID, AuthorName: req.AuthorName,
 		ReviewerID: req.ReviewerID, ReviewerName: req.ReviewerName,
@@ -1353,11 +1413,26 @@ func resolveTaskDocumentDuties(ctx context.Context, pool *pgxpool.Pool, req Task
 			if bound.Author.UserID == 0 && req.UserID > 0 {
 				bound.Author = docduty.Holder{UserID: req.UserID, Name: strings.TrimSpace(req.AuthorName)}
 			}
-			return bound
+			return bound, "", false
 		}
 	}
 	creator := docduty.Holder{UserID: req.UserID, Name: strings.TrimSpace(req.AuthorName)}
-	return docduty.Resolve(nil, creator, reqDuties)
+	return docduty.Resolve(nil, creator, reqDuties), "", false
+}
+
+func holderName(members []docduty.Member, creator docduty.Holder, userID int64, fallback string) string {
+	if userID <= 0 {
+		return strings.TrimSpace(fallback)
+	}
+	if creator.UserID == userID && strings.TrimSpace(creator.Name) != "" {
+		return strings.TrimSpace(creator.Name)
+	}
+	for _, m := range members {
+		if m.UserID == userID && strings.TrimSpace(m.Name) != "" {
+			return strings.TrimSpace(m.Name)
+		}
+	}
+	return strings.TrimSpace(fallback)
 }
 
 func bindingFromDoc(doc *docgov.DocumentRecord) docduty.Binding {