Autoparser - complete refactoring of parser architecture (#18675)

* Autoparser - full single commit squish

* Final pre-merge changes: minor fixes, Kimi 2.5 model parser

tools/server/public_legacy/json-schema-to-grammar.mjs

@@ -729,6 +729,10 @@ export class SchemaConverter {
       return this._addRule(ruleName, out.join(''));
     } else if ((schemaType === 'object') || (Object.keys(schema).length === 0)) {
       return this._addRule(ruleName, this._addPrimitive('object', PRIMITIVE_RULES['object']));
+    } else if (schemaType === undefined && typeof schema === 'object' && !Array.isArray(schema) && schema !== null) {
+      // No type constraint and no recognized structural keywords (e.g. {"description": "..."}).
+      // Per JSON Schema semantics this is equivalent to {} and accepts any value.
+      return this._addRule(ruleName, this._addPrimitive('value', PRIMITIVE_RULES['value']));
     } else {
       if (!(schemaType in PRIMITIVE_RULES)) {
         throw new Error(`Unrecognized schema: ${JSON.stringify(schema)}`);