diff --git a/compiler/kernel/filter.go b/compiler/kernel/filter.go
index 51b50a630c..4c1885d148 100644
--- a/compiler/kernel/filter.go
+++ b/compiler/kernel/filter.go
@@ -24,7 +24,7 @@ func (f *Filter) AsBufferFilter() (*expr.BufferFilter, error) {
 	if f == nil {
 		return nil, nil
 	}
-	return CompileBufferFilter(f.builder.rctx.Zctx, f.pushdown)
+	return CompileBufferFilter(f.builder.zctx(), f.pushdown)
 }
 
 type DeleteFilter struct {
diff --git a/compiler/kernel/op.go b/compiler/kernel/op.go
index 197381fa44..c47d65259a 100644
--- a/compiler/kernel/op.go
+++ b/compiler/kernel/op.go
@@ -155,7 +155,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 			return nil, err
 		}
 		lhs, rhs := splitAssignments(assignments)
-		cutter := expr.NewCutter(b.rctx.Zctx, lhs, rhs)
+		cutter := expr.NewCutter(b.zctx(), lhs, rhs)
 		return op.NewApplier(b.rctx, parent, cutter, b.resetters), nil
 	case *dag.Drop:
 		if len(v.Args) == 0 {
@@ -169,7 +169,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 			}
 			fields = append(fields, field.Path)
 		}
-		dropper := expr.NewDropper(b.rctx.Zctx, fields)
+		dropper := expr.NewDropper(b.zctx(), fields)
 		return op.NewApplier(b.rctx, parent, dropper, expr.Resetters{}), nil
 	case *dag.Sort:
 		b.resetResetters()
@@ -208,21 +208,21 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 		if err != nil {
 			return nil, fmt.Errorf("compiling filter: %w", err)
 		}
-		return op.NewApplier(b.rctx, parent, expr.NewFilterApplier(b.rctx.Zctx, f), b.resetters), nil
+		return op.NewApplier(b.rctx, parent, expr.NewFilterApplier(b.zctx(), f), b.resetters), nil
 	case *dag.Top:
 		b.resetResetters()
 		fields, err := b.compileExprs(v.Args)
 		if err != nil {
 			return nil, fmt.Errorf("compiling top: %w", err)
 		}
-		return top.New(b.rctx.Zctx, parent, v.Limit, fields, v.Flush, b.resetters), nil
+		return top.New(b.zctx(), parent, v.Limit, fields, v.Flush, b.resetters), nil
 	case *dag.Put:
 		b.resetResetters()
 		clauses, err := b.compileAssignments(v.Args)
 		if err != nil {
 			return nil, err
 		}
-		putter := expr.NewPutter(b.rctx.Zctx, clauses)
+		putter := expr.NewPutter(b.zctx(), clauses)
 		return op.NewApplier(b.rctx, parent, putter, b.resetters), nil
 	case *dag.Rename:
 		b.resetResetters()
@@ -230,7 +230,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 		if err != nil {
 			return nil, err
 		}
-		renamer := expr.NewRenamer(b.rctx.Zctx, srcs, dsts)
+		renamer := expr.NewRenamer(b.zctx(), srcs, dsts)
 		return op.NewApplier(b.rctx, parent, renamer, b.resetters), nil
 	case *dag.Fuse:
 		return fuse.New(b.rctx, parent)
@@ -241,7 +241,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 	case *dag.Merge:
 		return nil, errors.New("merge: multiple upstream paths required")
 	case *dag.Explode:
-		typ, err := zson.ParseType(b.rctx.Zctx, v.Type)
+		typ, err := zson.ParseType(b.zctx(), v.Type)
 		if err != nil {
 			return nil, err
 		}
@@ -250,7 +250,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 		if err != nil {
 			return nil, err
 		}
-		return explode.New(b.rctx.Zctx, parent, args, typ, v.As, b.resetters)
+		return explode.New(b.zctx(), parent, args, typ, v.As, b.resetters)
 	case *dag.Over:
 		return b.compileOver(parent, v)
 	case *dag.Yield:
@@ -267,7 +267,7 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 		}
 		return b.compilePoolScan(v)
 	case *dag.PoolMetaScan:
-		return meta.NewPoolMetaScanner(b.rctx.Context, b.rctx.Zctx, b.source.Lake(), v.ID, v.Meta)
+		return meta.NewPoolMetaScanner(b.rctx.Context, b.zctx(), b.source.Lake(), v.ID, v.Meta)
 	case *dag.CommitMetaScan:
 		var pruner expr.Evaluator
 		if v.Tap && v.KeyPruner != nil {
@@ -277,14 +277,14 @@ func (b *Builder) compileLeaf(o dag.Op, parent zbuf.Puller) (zbuf.Puller, error)
 				return nil, err
 			}
 		}
-		return meta.NewCommitMetaScanner(b.rctx.Context, b.rctx.Zctx, b.source.Lake(), v.Pool, v.Commit, v.Meta, pruner)
+		return meta.NewCommitMetaScanner(b.rctx.Context, b.zctx(), b.source.Lake(), v.Pool, v.Commit, v.Meta, pruner)
 	case *dag.LakeMetaScan:
-		return meta.NewLakeMetaScanner(b.rctx.Context, b.rctx.Zctx, b.source.Lake(), v.Meta)
+		return meta.NewLakeMetaScanner(b.rctx.Context, b.zctx(), b.source.Lake(), v.Meta)
 	case *dag.HTTPScan:
 		body := strings.NewReader(v.Body)
-		return b.source.OpenHTTP(b.rctx.Context, b.rctx.Zctx, v.URL, v.Format, v.Method, v.Headers, body, demand.All())
+		return b.source.OpenHTTP(b.rctx.Context, b.zctx(), v.URL, v.Format, v.Method, v.Headers, body, demand.All())
 	case *dag.FileScan:
-		return b.source.Open(b.rctx.Context, b.rctx.Zctx, v.Path, v.Format, b.PushdownOf(v.Filter), demand.All())
+		return b.source.Open(b.rctx.Context, b.zctx(), v.Path, v.Format, b.PushdownOf(v.Filter), demand.All())
 	case *dag.DefaultScan:
 		pushdown := b.PushdownOf(v.Filter)
 		if len(b.readers) == 1 {
diff --git a/compiler/kernel/vop.go b/compiler/kernel/vop.go
index e815e68f8e..d32980cade 100644
--- a/compiler/kernel/vop.go
+++ b/compiler/kernel/vop.go
@@ -78,14 +78,14 @@ func (b *Builder) compileVamLeaf(o dag.Op, parent vector.Puller) (vector.Puller,
 		if err != nil {
 			return nil, err
 		}
-		return vamop.NewFilter(b.rctx.Zctx, parent, e), nil
+		return vamop.NewFilter(b.zctx(), parent, e), nil
 	case *dag.Head:
 		return vamop.NewHead(parent, o.Count), nil
 	case *dag.Summarize:
 		if name, ok := optimizer.IsCountByString(o); ok {
-			return vamop.NewCountByString(b.rctx.Zctx, parent, name), nil
+			return vamop.NewCountByString(b.zctx(), parent, name), nil
 		} else if name, ok := optimizer.IsSum(o); ok {
-			return vamop.NewSum(b.rctx.Zctx, parent, name), nil
+			return vamop.NewSum(b.zctx(), parent, name), nil
 		} else {
 			return nil, fmt.Errorf("internal error: unhandled dag.Summarize: %#v", o)
 		}
@@ -112,7 +112,7 @@ func (b *Builder) compileVamLeaf(o dag.Op, parent vector.Puller) (vector.Puller,
 		if err != nil {
 			return nil, err
 		}
-		return vamop.NewYield(b.rctx.Zctx, parent, exprs), nil
+		return vamop.NewYield(b.zctx(), parent, exprs), nil
 	case *dag.Output:
 		// XXX Ignore Output op for vectors for now.
 		return parent, nil