Factor stripOpaqueJsonMarker into utils.ts

Move the inline `delete rewritten["x-opaque-json"]` out of the TS
codegen's rewrite loop and into a named helper next to isOpaqueJson, so
the paired `read the marker` / `ignore the marker` operations live
together and each language codegen calls the one it needs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

scripts/codegen/typescript.ts

@@ -37,6 +37,7 @@ import {
     isVoidSchema,
     isSchemaExperimental,
     getEnumValueDescriptions,
+    stripOpaqueJsonMarker,
     type ApiSchema,
     type DefinitionCollections,
     type RpcMethod,
@@ -280,13 +281,12 @@ export function normalizeSchemaForTypeScript(schema: JSONSchema7): JSONSchema7 {
             Object.entries(value as Record<string, unknown>).map(([key, child]) => [key, rewrite(child)])
         ) as Record<string, unknown>;
 
-        // Strip the `x-opaque-json` marker so json-schema-to-typescript sees
-        // the original (typeless) schema and emits the same shape it did
-        // before the marker was introduced. C# codegen reads the marker from
-        // the un-normalized schema and emits `JsonElement` instead.
-        if ("x-opaque-json" in rewritten) {
-            delete rewritten["x-opaque-json"];
-        }
+        // The TypeScript codegen doesn't distinguish opaque JSON from any
+        // other unconstrained value, so drop the marker before feeding the
+        // schema to json-schema-to-typescript. C# codegen reads the marker
+        // from its own (un-normalized) view of the schema and emits
+        // `JsonElement` instead.
+        stripOpaqueJsonMarker(rewritten);
 
         const enumValueDescriptions = getEnumValueDescriptions(rewritten as JSONSchema7);
         if (enumValueDescriptions && Array.isArray(rewritten.enum) && rewritten.enum.every((entry) => typeof entry === "string")) {

scripts/codegen/utils.ts

@@ -516,6 +516,17 @@ export function isOpaqueJson(schema: JSONSchema7 | null | undefined): boolean {
     return typeof schema === "object" && schema !== null && (schema as Record<string, unknown>)["x-opaque-json"] === true;
 }
 
+/**
+ * Removes the `x-opaque-json` marker from a schema node in place. Useful for
+ * codegens (e.g. TypeScript) that don't distinguish opaque JSON from any other
+ * unconstrained value and would otherwise have the marker confuse downstream
+ * tooling. Codegens that *do* care (e.g. C#, which maps opaque JSON to
+ * `JsonElement`) should call `isOpaqueJson` *before* this point.
+ */
+export function stripOpaqueJsonMarker(schema: Record<string, unknown>): void {
+    delete schema["x-opaque-json"];
+}
+
 /**
  * Append `@internal` and/or `@experimental` JSDoc-style tags to the `description`
  * of every property that carries `visibility: "internal"` or `stability: "experimental"`