diff --git a/internal/edit/text.go b/internal/edit/text.go
index 61f5f324..235f23eb 100644
--- a/internal/edit/text.go
+++ b/internal/edit/text.go
@@ -5,6 +5,8 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+
+	"gopkg.in/yaml.v3"
 )
 
 // Top-level YAML keys are edited line by line. That keeps every comment and
@@ -44,7 +46,9 @@ func SetYAMLTop(path string, kvs ...KV) error {
 	lines := splitLines(string(raw))
 	for _, kv := range kvs {
 		v := toString(kv.Value)
-		if !yamlPlain.MatchString(v) {
+		var decoded any
+		_, isString := kv.Value.(string)
+		if !yamlPlain.MatchString(v) || (isString && (yaml.Unmarshal([]byte(v), &decoded) != nil || decoded != v)) {
 			v = strconv.Quote(v)
 		}
 		lines = setLine(lines, kv.Path, kv.Path+": "+v, nil, func(line string) (string, bool) {
@@ -139,8 +143,9 @@ func tomlValue(v string) string {
 }
 
 func yamlValue(v string) string {
-	if s, ok := unquote(v); ok {
-		return s
+	var n yaml.Node
+	if err := yaml.Unmarshal([]byte(v), &n); err == nil && len(n.Content) > 0 && n.Content[0].Kind == yaml.ScalarNode {
+		return n.Content[0].Value
 	}
 	if i := strings.Index(v, " #"); i >= 0 {
 		v = strings.TrimSpace(v[:i])
diff --git a/internal/edit/yaml_roundtrip_test.go b/internal/edit/yaml_roundtrip_test.go
new file mode 100644
index 00000000..3a633fbe
--- /dev/null
+++ b/internal/edit/yaml_roundtrip_test.go
@@ -0,0 +1,57 @@
+package edit
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"gopkg.in/yaml.v3"
+)
+
+func TestYAMLTopStringScalars(t *testing.T) {
+	for _, v := range []string{"null", "true", "123", "a\t\nb"} {
+		p := filepath.Join(t.TempDir(), "goose.yaml")
+		if e := SetYAMLTop(p, KV{"GOOSE_MODEL", v}); e != nil {
+			t.Fatal(e)
+		}
+		b, err := os.ReadFile(p)
+		if err != nil {
+			t.Fatal(err)
+		}
+		var m map[string]any
+		if e := yaml.Unmarshal(b, &m); e != nil {
+			t.Fatal(e)
+		}
+		if got, ok := m["GOOSE_MODEL"].(string); !ok || got != v {
+			t.Errorf("value %q serialized %q reads %T %v", v, b, m["GOOSE_MODEL"], m["GOOSE_MODEL"])
+		}
+	}
+}
+func TestYAMLTopSingleQuotedEscape(t *testing.T) {
+	p := tmpFile(t, "goose.yaml", "GOOSE_MODEL: 'owner''s/model'\n")
+	v, ok := GetYAMLTop(p, "GOOSE_MODEL")
+	if !ok {
+		t.Fatal("model not found")
+	}
+	if v != "owner's/model" {
+		t.Fatalf("got %q", v)
+	}
+}
+
+func TestYAMLTopTypedValues(t *testing.T) {
+	p := filepath.Join(t.TempDir(), "config.yaml")
+	if err := SetYAMLTop(p, KV{"enabled", true}, KV{"count", 123}); err != nil {
+		t.Fatal(err)
+	}
+	b, err := os.ReadFile(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m map[string]any
+	if err := yaml.Unmarshal(b, &m); err != nil {
+		t.Fatal(err)
+	}
+	if m["enabled"] != true || m["count"] != 123 {
+		t.Fatalf("types changed: %#v", m)
+	}
+}