feat(util): add pure keycodes and safeJs template helper

1 files changed, 20 insertions, 0 deletions

diff --git a/src/util/js-template.ts b/src/util/js-template.ts
new file mode 100644
index 0000000..e536b3d
--- /dev/null
+++ b/src/util/js-template.ts
@@ -0,0 +1,20 @@
+/**
+ * Build a JavaScript source string with safely-interpolated values.
+ * Every interpolated value is JSON.stringify'd, so strings, numbers,
+ * objects, and special characters all become valid JS literals.
+ *
+ * This is the ONLY supported way to build evaluation source in the
+ * codebase — never use raw template literals for JS that crosses the
+ * CDP boundary.
+ */
+export const safeJs = (
+  strings: TemplateStringsArray,
+  ...values: ReadonlyArray<unknown>
+): string => {
+  let out = strings[0] ?? "";
+  for (let i = 0; i < values.length; i++) {
+    out += JSON.stringify(values[i]);
+    out += strings[i + 1] ?? "";
+  }
+  return out;
+};