feat: add --parent flag to bd update for reparenting issues (bd-cj2e)

Allows reparenting issues to a different epic/parent:
  bd update bd-xyz --parent=bd-epic

Implementation:
- Add Parent field to UpdateArgs in protocol.go
- Handle reparenting in RPC handler (server_issues_epics.go)
- Add --parent flag to updateCmd with both daemon and direct mode support
- Remove old parent-child dependency before adding new one
- Pass empty string to remove parent entirely

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/rpc/protocol.go

@@ -124,6 +124,8 @@ type UpdateArgs struct {
 	SupersededBy *string `json:"superseded_by,omitempty"` // Replacement issue ID if obsolete
 	// Pinned field (bd-iea)
 	Pinned *bool `json:"pinned,omitempty"` // If true, issue is a persistent context marker
+	// Reparenting field (bd-cj2e)
+	Parent *string `json:"parent,omitempty"` // New parent issue ID (reparents the issue)
 }
 
 // CloseArgs represents arguments for the close operation

internal/rpc/server_issues_epics.go

@@ -466,8 +466,65 @@ func (s *Server) handleUpdate(req *Request) Response {
 		}
 	}
 
-	// Emit mutation event for event-driven daemon (only if any updates or label operations were performed)
-	if len(updates) > 0 || len(updateArgs.SetLabels) > 0 || len(updateArgs.AddLabels) > 0 || len(updateArgs.RemoveLabels) > 0 {
+	// Handle reparenting (bd-cj2e)
+	if updateArgs.Parent != nil {
+		newParentID := *updateArgs.Parent
+
+		// Validate new parent exists (unless empty string to remove parent)
+		if newParentID != "" {
+			newParent, err := store.GetIssue(ctx, newParentID)
+			if err != nil {
+				return Response{
+					Success: false,
+					Error:   fmt.Sprintf("failed to get new parent: %v", err),
+				}
+			}
+			if newParent == nil {
+				return Response{
+					Success: false,
+					Error:   fmt.Sprintf("parent issue %s not found", newParentID),
+				}
+			}
+		}
+
+		// Find and remove existing parent-child dependency
+		deps, err := store.GetDependencyRecords(ctx, updateArgs.ID)
+		if err != nil {
+			return Response{
+				Success: false,
+				Error:   fmt.Sprintf("failed to get dependencies: %v", err),
+			}
+		}
+		for _, dep := range deps {
+			if dep.Type == types.DepParentChild {
+				if err := store.RemoveDependency(ctx, updateArgs.ID, dep.DependsOnID, actor); err != nil {
+					return Response{
+						Success: false,
+						Error:   fmt.Sprintf("failed to remove old parent dependency: %v", err),
+					}
+				}
+				break // Only one parent-child dependency expected
+			}
+		}
+
+		// Add new parent-child dependency (if not removing parent)
+		if newParentID != "" {
+			newDep := &types.Dependency{
+				IssueID:     updateArgs.ID,
+				DependsOnID: newParentID,
+				Type:        types.DepParentChild,
+			}
+			if err := store.AddDependency(ctx, newDep, actor); err != nil {
+				return Response{
+					Success: false,
+					Error:   fmt.Sprintf("failed to add parent dependency: %v", err),
+				}
+			}
+		}
+	}
+
+	// Emit mutation event for event-driven daemon (only if any updates or label/parent operations were performed)
+	if len(updates) > 0 || len(updateArgs.SetLabels) > 0 || len(updateArgs.AddLabels) > 0 || len(updateArgs.RemoveLabels) > 0 || updateArgs.Parent != nil {
 		// Check if this was a status change - emit rich MutationStatus event
 		if updateArgs.Status != nil && *updateArgs.Status != string(issue.Status) {
 			s.emitRichMutation(MutationEvent{