diff --git a/cmd/cue/cmd/common.go b/cmd/cue/cmd/common.go
index 9a4e14d4e78..9e0d16c0381 100644
--- a/cmd/cue/cmd/common.go
+++ b/cmd/cue/cmd/common.go
@@ -20,6 +20,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/spf13/pflag"
@@ -33,6 +34,7 @@ import (
 	"cuelang.org/go/cue/load"
 	"cuelang.org/go/cue/parser"
 	"cuelang.org/go/cue/token"
+	"cuelang.org/go/internal/core/adt"
 	"cuelang.org/go/internal/encoding"
 	"cuelang.org/go/internal/filetypes"
 	"cuelang.org/go/internal/value"
@@ -539,6 +541,8 @@ func parseArgs(cmd *Command, args []string, cfg *config) (p *buildPlan, err erro
 		return nil, err
 	}
 
+	adt.DebugSort, _ = strconv.Atoi(os.Getenv("CUE_DEBUG_SORT_ARCS"))
+
 	builds := loadFromArgs(cmd, args, cfg.loadCfg)
 	if builds == nil {
 		return nil, errors.Newf(token.NoPos, "invalid args")
diff --git a/cue/types.go b/cue/types.go
index 0499065535d..12664f1f094 100644
--- a/cue/types.go
+++ b/cue/types.go
@@ -1354,7 +1354,7 @@ func (v Value) structValOpts(ctx *adt.OpContext, o options) (s structValue, err
 		}
 	}
 
-	features := export.VertexFeatures(obj)
+	features := export.VertexFeatures(ctx, obj)
 
 	k := 0
 	for _, f := range features {
diff --git a/internal/core/adt/context.go b/internal/core/adt/context.go
index bbcc7b9c10f..f974a40b4c6 100644
--- a/internal/core/adt/context.go
+++ b/internal/core/adt/context.go
@@ -20,6 +20,7 @@ import (
 	"os"
 	"reflect"
 	"regexp"
+	"sort"
 	"strings"
 
 	"github.com/cockroachdb/apd/v2"
@@ -40,6 +41,44 @@ var Debug bool = os.Getenv("CUE_DEBUG") != "0"
 //   1: logging
 var Verbosity int
 
+// DebugSort specifies that arcs be sorted consistently between implementations.
+// 0: default
+// 1: sort by Feature: this should be consistent between implementations where
+//    there is no change in the compiler and indexing code.
+// 2: alphabetical
+var DebugSort int
+
+func DebugSortArcs(c *OpContext, n *Vertex) {
+	if n.IsList() {
+		return
+	}
+	switch a := n.Arcs; DebugSort {
+	case 1:
+		sort.SliceStable(a, func(i, j int) bool {
+			return a[i].Label < a[j].Label
+		})
+	case 2:
+		sort.SliceStable(a, func(i, j int) bool {
+			return a[i].Label.SelectorString(c.Runtime) <
+				a[j].Label.SelectorString(c.Runtime)
+		})
+	}
+}
+
+func DebugSortFields(c *OpContext, a []Feature) {
+	switch DebugSort {
+	case 1:
+		sort.SliceStable(a, func(i, j int) bool {
+			return a[i] < a[j]
+		})
+	case 2:
+		sort.SliceStable(a, func(i, j int) bool {
+			return a[i].SelectorString(c.Runtime) <
+				a[j].SelectorString(c.Runtime)
+		})
+	}
+}
+
 // Assert panics if the condition is false. Assert can be used to check for
 // conditions that are considers to break an internal variant or unexpected
 // condition, but that nonetheless probably will be handled correctly down the
diff --git a/internal/core/adt/eval.go b/internal/core/adt/eval.go
index d217e11adfc..9f8bb31e393 100644
--- a/internal/core/adt/eval.go
+++ b/internal/core/adt/eval.go
@@ -639,6 +639,9 @@ func (n *nodeContext) checkClosed(state VertexStatus) bool {
 }
 
 func (n *nodeContext) completeArcs(state VertexStatus) {
+	if DebugSort > 0 {
+		DebugSortArcs(n.ctx, n.node)
+	}
 
 	if state <= AllArcs {
 		n.node.UpdateStatus(AllArcs)
diff --git a/internal/core/export/expr.go b/internal/core/export/expr.go
index ae868c2bc76..c8d7a1290d5 100644
--- a/internal/core/export/expr.go
+++ b/internal/core/export/expr.go
@@ -163,13 +163,17 @@ func (x *exporter) mergeValues(label adt.Feature, src *adt.Vertex, a []conjunct,
 		return fields[i] > fields[j]
 	})
 
-	m := sortArcs(extractFeatures(e.structs))
-	sort.SliceStable(fields, func(i, j int) bool {
-		if m[fields[j]] == 0 {
-			return m[fields[i]] != 0
-		}
-		return m[fields[i]] > m[fields[j]]
-	})
+	if adt.DebugSort == 0 {
+		m := sortArcs(extractFeatures(e.structs))
+		sort.SliceStable(fields, func(i, j int) bool {
+			if m[fields[j]] == 0 {
+				return m[fields[i]] != 0
+			}
+			return m[fields[i]] > m[fields[j]]
+		})
+	} else {
+		adt.DebugSortFields(e.ctx, fields)
+	}
 
 	if len(e.fields) == 0 && !e.hasEllipsis {
 		switch len(e.embed) + len(e.conjuncts) {
diff --git a/internal/core/export/toposort.go b/internal/core/export/toposort.go
index 4d7935a1889..7f68df97210 100644
--- a/internal/core/export/toposort.go
+++ b/internal/core/export/toposort.go
@@ -26,7 +26,7 @@ import (
 // VertexFeatures returns the feature list of v. The list may include more
 // features than for which there are arcs and also includes features for
 // optional fields. It assumes the Structs fields is properly initialized.
-func VertexFeatures(v *adt.Vertex) []adt.Feature {
+func VertexFeatures(c *adt.OpContext, v *adt.Vertex) []adt.Feature {
 	sets := extractFeatures(v.Structs)
 	m := sortArcs(sets) // TODO: use for convenience.
 
@@ -44,7 +44,11 @@ func VertexFeatures(v *adt.Vertex) []adt.Feature {
 		sets = append(sets, a)
 	}
 
-	return sortedArcs(sets)
+	a = sortedArcs(sets)
+	if adt.DebugSort > 0 {
+		adt.DebugSortFields(c, a)
+	}
+	return a
 }
 
 // func structFeatures(a []*adt.StructLit) []adt.Feature {
@@ -53,6 +57,10 @@ func VertexFeatures(v *adt.Vertex) []adt.Feature {
 // }
 
 func (e *exporter) sortedArcs(v *adt.Vertex) (sorted []*adt.Vertex) {
+	if adt.DebugSort > 0 {
+		return v.Arcs
+	}
+
 	a := extractFeatures(v.Structs)
 	if len(a) == 0 {
 		return v.Arcs
diff --git a/internal/core/export/value.go b/internal/core/export/value.go
index 358da1575ee..53065e9e826 100644
--- a/internal/core/export/value.go
+++ b/internal/core/export/value.go
@@ -415,7 +415,7 @@ func (e *exporter) structComposite(v *adt.Vertex, attrs []*ast.Attribute) ast.Ex
 	}
 
 	p := e.cfg
-	for _, label := range VertexFeatures(v) {
+	for _, label := range VertexFeatures(e.ctx, v) {
 		show := false
 		switch label.Typ() {
 		case adt.StringLabel:
diff --git a/internal/core/subsume/vertex.go b/internal/core/subsume/vertex.go
index 362ec292b80..55f83dcff92 100644
--- a/internal/core/subsume/vertex.go
+++ b/internal/core/subsume/vertex.go
@@ -99,7 +99,7 @@ func (s *subsumer) vertices(x, y *adt.Vertex) bool {
 	}
 
 	// All arcs in x must exist in y and its values must subsume.
-	xFeatures := export.VertexFeatures(x)
+	xFeatures := export.VertexFeatures(s.ctx, x)
 	for _, f := range xFeatures {
 		if s.Final && !f.IsRegular() {
 			continue
@@ -165,7 +165,7 @@ func (s *subsumer) vertices(x, y *adt.Vertex) bool {
 		return false
 	}
 
-	yFeatures := export.VertexFeatures(y)
+	yFeatures := export.VertexFeatures(s.ctx, y)
 outer:
 	for _, f := range yFeatures {
 		if s.Final && !f.IsRegular() {