diff --git a/d2layouts/d2dagrelayout/layout.go b/d2layouts/d2dagrelayout/layout.go
index b88e5e6b9..66ae6c8f3 100644
--- a/d2layouts/d2dagrelayout/layout.go
+++ b/d2layouts/d2dagrelayout/layout.go
@@ -6,9 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"math"
-	"regexp"
 	"sort"
-	"strconv"
 	"strings"
 
 	"cdr.dev/slog"
@@ -412,59 +410,6 @@ func setGraphAttrs(attrs dagreOpts) string {
 	)
 }
 
-type objectMapper struct {
-	objToID map[*d2graph.Object]string
-	idToObj map[string]*d2graph.Object
-}
-
-func NewObjectMapper() *objectMapper {
-	return &objectMapper{
-		objToID: make(map[*d2graph.Object]string),
-		idToObj: make(map[string]*d2graph.Object),
-	}
-}
-
-func (c *objectMapper) Register(obj *d2graph.Object) {
-	id := strconv.Itoa(len(c.idToObj))
-	c.idToObj[id] = obj
-	c.objToID[obj] = id
-}
-
-func (c *objectMapper) ToID(obj *d2graph.Object) string {
-	return c.objToID[obj]
-}
-
-func (c *objectMapper) ToObj(id string) *d2graph.Object {
-	return c.idToObj[id]
-}
-
-func escapeID(id string) string {
-	// fixes \\
-	id = strings.ReplaceAll(id, "\\", `\\`)
-	// replaces \n with \\n whenever \n is not preceded by \ (does not replace \\n)
-	re := regexp.MustCompile(`[^\\]\n`)
-	id = re.ReplaceAllString(id, `\\n`)
-	// avoid an unescaped \r becoming a \n in the layout result
-	id = strings.ReplaceAll(id, "\r", `\r`)
-	return id
-}
-
-func (c objectMapper) generateAddNodeLine(obj *d2graph.Object, width, height int) string {
-	id := c.ToID(obj)
-	return fmt.Sprintf("g.setNode(`%s`, { id: `%s`, width: %d, height: %d });\n", id, id, width, height)
-}
-
-func (c objectMapper) generateAddParentLine(child, parent *d2graph.Object) string {
-	return fmt.Sprintf("g.setParent(`%s`, `%s`);\n", c.ToID(child), c.ToID(parent))
-}
-
-func (c objectMapper) generateAddEdgeLine(from, to *d2graph.Object, edgeID string, width, height int) string {
-	return fmt.Sprintf(
-		"g.setEdge({v:`%s`, w:`%s`, name:`%s`}, { width:%d, height:%d, labelpos: `c` });\n",
-		c.ToID(from), c.ToID(to), escapeID(edgeID), width, height,
-	)
-}
-
 // getLongestEdgeChainHead finds the longest chain in a container and gets its head
 // If there are multiple chains of the same length, get the head closest to the center
 func getLongestEdgeChainHead(g *d2graph.Graph, container *d2graph.Object) *d2graph.Object {
diff --git a/d2layouts/d2dagrelayout/object_mapper.go b/d2layouts/d2dagrelayout/object_mapper.go
new file mode 100644
index 000000000..6ac2b637e
--- /dev/null
+++ b/d2layouts/d2dagrelayout/object_mapper.go
@@ -0,0 +1,63 @@
+package d2dagrelayout
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"oss.terrastruct.com/d2/d2graph"
+)
+
+type objectMapper struct {
+	objToID map[*d2graph.Object]string
+	idToObj map[string]*d2graph.Object
+}
+
+func NewObjectMapper() *objectMapper {
+	return &objectMapper{
+		objToID: make(map[*d2graph.Object]string),
+		idToObj: make(map[string]*d2graph.Object),
+	}
+}
+
+func (c *objectMapper) Register(obj *d2graph.Object) {
+	id := strconv.Itoa(len(c.idToObj))
+	c.idToObj[id] = obj
+	c.objToID[obj] = id
+}
+
+func (c *objectMapper) ToID(obj *d2graph.Object) string {
+	return c.objToID[obj]
+}
+
+func (c *objectMapper) ToObj(id string) *d2graph.Object {
+	return c.idToObj[id]
+}
+
+func (c objectMapper) generateAddNodeLine(obj *d2graph.Object, width, height int) string {
+	id := c.ToID(obj)
+	return fmt.Sprintf("g.setNode(`%s`, { id: `%s`, width: %d, height: %d });\n", id, id, width, height)
+}
+
+func (c objectMapper) generateAddParentLine(child, parent *d2graph.Object) string {
+	return fmt.Sprintf("g.setParent(`%s`, `%s`);\n", c.ToID(child), c.ToID(parent))
+}
+
+func (c objectMapper) generateAddEdgeLine(from, to *d2graph.Object, edgeID string, width, height int) string {
+	return fmt.Sprintf(
+		"g.setEdge({v:`%s`, w:`%s`, name:`%s`}, { width:%d, height:%d, labelpos: `c` });\n",
+		c.ToID(from), c.ToID(to), escapeID(edgeID), width, height,
+	)
+}
+
+func escapeID(id string) string {
+	// fixes \\
+	id = strings.ReplaceAll(id, "\\", `\\`)
+	// replaces \n with \\n whenever \n is not preceded by \ (does not replace \\n)
+	re := regexp.MustCompile(`[^\\]\n`)
+	id = re.ReplaceAllString(id, `\\n`)
+	// avoid an unescaped \r becoming a \n in the layout result
+	id = strings.ReplaceAll(id, "\r", `\r`)
+	return id
+}