fix vars fmt

d2format/format.go

@@ -127,7 +127,7 @@ func (p *printer) blockComment(bc *d2ast.BlockComment) {
 }
 
 func (p *printer) interpolationBoxes(boxes []d2ast.InterpolationBox, isDoubleString bool) {
-	for _, b := range boxes {
+	for i, b := range boxes {
 		if b.Substitution != nil {
 			p.substitution(b.Substitution)
 			continue
@@ -140,6 +140,11 @@ func (p *printer) interpolationBoxes(boxes []d2ast.InterpolationBox, isDoubleStr
 				s = escapeUnquotedValue(*b.String, p.inKey)
 			}
 			b.StringRaw = &s
+		} else if i > 0 && boxes[i-1].Substitution != nil {
+			// If this string follows a substitution, we need to make sure to use
+			// the actual string content, not the raw value which might be incorrect
+			s := *b.String
+			b.StringRaw = &s
 		}
 		if !isDoubleString {
 			if _, ok := d2ast.ReservedKeywords[strings.ToLower(*b.StringRaw)]; ok {

d2format/format_test.go

@@ -892,6 +892,19 @@ scenarios: {}
 steps: asdf
 `,
 			exp: `k
+`,
+		},
+		{
+			name: "vars",
+			in: `vars: {
+  a: "a"
+  b: "X${a})"
+}
+`,
+			exp: `vars: {
+  a: "a"
+  b: "X${a})"
+}
 `,
 		},
 	}