diff --git a/src/api/writer-generator/typescript/profile.ts b/src/api/writer-generator/typescript/profile.ts
index 82d638727..d41ce336e 100644
--- a/src/api/writer-generator/typescript/profile.ts
+++ b/src/api/writer-generator/typescript/profile.ts
@@ -771,6 +771,9 @@ const detectConstrainedChoice = (
         const variantField = baseSchema.fields[variantName];
         if (!variantField || !isChoiceInstanceField(variantField)) continue;
 
+        // Skip flattening for primitive types — can't intersect object with boolean/string/etc.
+        if (isPrimitiveIdentifier(variantField.type)) continue;
+
         return {
             choiceBase: fieldName,
             variant: variantName,