fix regress

src/bson.ts

@@ -132,3 +132,14 @@ export function resolveBSONOptions(
       options?.enableUtf8Validation ?? parentOptions?.enableUtf8Validation ?? true
   };
 }
+
+/** @internal */
+export function parseUtf8ValidationOption(options?: { enableUtf8Validation?: boolean }): {
+  utf8: { writeErrors: false } | false;
+} {
+  const enableUtf8Validation = options?.enableUtf8Validation;
+  if (enableUtf8Validation === false) {
+    return { utf8: false };
+  }
+  return { utf8: { writeErrors: false } };
+}

src/cmap/connection.ts

@@ -69,6 +69,7 @@ import {
   type MongoDBResponseConstructor
 } from './wire_protocol/responses';
 import { getReadPreference, isSharded } from './wire_protocol/shared';
+import { DeserializeOptions } from 'bson';
 
 /** @internal */
 export interface CommandOptions extends BSONSerializeOptions {
@@ -487,7 +488,7 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
 
     // If `documentsReturnedIn` not set or raw is not enabled, use input bson options
     // Otherwise, support raw flag. Raw only works for cursors that hardcode firstBatch/nextBatch fields
-    const bsonOptions =
+    const bsonOptions: DeserializeOptions  =
       options.documentsReturnedIn == null || !options.raw
         ? options
         : {

src/cmap/wire_protocol/on_demand/document.ts

@@ -1,15 +1,17 @@
+import { DeserializeOptions } from 'bson';
 import {
   Binary,
-  BSON,
   type BSONElement,
   BSONError,
   type BSONSerializeOptions,
   BSONType,
+  deserialize,
   getBigInt64LE,
   getFloat64LE,
   getInt32LE,
   ObjectId,
   parseToElementsToArray,
+  pluckBSONSerializeOptions,
   Timestamp,
   toUTF8
 } from '../../../bson';
@@ -329,8 +331,8 @@ export class OnDemandDocument {
    * Deserialize this object, DOES NOT cache result so avoid multiple invocations
    * @param options - BSON deserialization options
    */
-  public toObject(options?: BSONSerializeOptions): Record<string, any> {
-    return BSON.deserialize(this.bson, {
+  public toObject(options?: DeserializeOptions & { enableUtf8Validation?: never }): Record<string, any> {
+    return deserialize(this.bson, {
       ...options,
       index: this.offset,
       allowObjectSmallerThanBufferSize: true

src/cmap/wire_protocol/responses.ts

@@ -1,11 +1,11 @@
+import { DeserializeOptions } from 'bson';
 import {
   type BSONElement,
   type BSONSerializeOptions,
   BSONType,
   type Document,
   Long,
   parseToElementsToArray,
-  pluckBSONSerializeOptions,
   type Timestamp
 } from '../../bson';
 import { MongoUnexpectedServerResponseError } from '../../error';
@@ -166,24 +166,6 @@ export class MongoDBResponse extends OnDemandDocument {
     }
     return this.clusterTime ?? null;
   }
-
-  public override toObject(options?: BSONSerializeOptions): Record<string, any> {
-    const exactBSONOptions = {
-      ...pluckBSONSerializeOptions(options ?? {}),
-      validation: this.parseBsonSerializationOptions(options)
-    };
-    return super.toObject(exactBSONOptions);
-  }
-
-  private parseBsonSerializationOptions(options?: { enableUtf8Validation?: boolean }): {
-    utf8: { writeErrors: false } | false;
-  } {
-    const enableUtf8Validation = options?.enableUtf8Validation;
-    if (enableUtf8Validation === false) {
-      return { utf8: false };
-    }
-    return { utf8: { writeErrors: false } };
-  }
 }
 
 /** @internal */
@@ -272,7 +254,7 @@ export class CursorResponse extends MongoDBResponse {
     );
   }
 
-  public shift(options?: BSONSerializeOptions): any {
+  public shift(options?: DeserializeOptions & { __tag: 'shift options' }): any {
     if (this.iterated >= this.batchSize) {
       return null;
     }
@@ -324,7 +306,7 @@ export class ExplainedCursorResponse extends CursorResponse {
     return this._length;
   }
 
-  override shift(options?: BSONSerializeOptions | undefined) {
+  override shift(options?: DeserializeOptions) {
     if (this._length === 0) return null;
     this._length -= 1;
     return this.toObject(options);

src/cursor/abstract_cursor.ts

@@ -1,6 +1,6 @@
 import { Readable, Transform } from 'stream';
 
-import { type BSONSerializeOptions, type Document, Long, pluckBSONSerializeOptions } from '../bson';
+import { type BSONSerializeOptions, type Document, Long, parseUtf8ValidationOption, pluckBSONSerializeOptions } from '../bson';
 import { type CursorResponse } from '../cmap/wire_protocol/responses';
 import {
   MongoAPIError,
@@ -21,6 +21,7 @@ import { type AsyncDisposable, configureResourceManagement } from '../resource_m
 import type { Server } from '../sdam/server';
 import { ClientSession, maybeClearPinnedConnection } from '../sessions';
 import { type MongoDBNamespace, squashError } from '../utils';
+import { DeserializeOptions } from 'bson';
 
 /**
  * @internal
@@ -157,6 +158,8 @@ export abstract class AbstractCursor<
   /** @event */
   static readonly CLOSE = 'close' as const;
 
+  protected deserializationOptions: DeserializeOptions &  { __tag: 'shift options' };
+
   /** @internal */
   protected constructor(
     client: MongoClient,
@@ -211,6 +214,12 @@ export abstract class AbstractCursor<
     } else {
       this.cursorSession = this.cursorClient.startSession({ owner: this, explicit: false });
     }
+
+    this.deserializationOptions = {
+      ...this.cursorOptions,
+      validation: parseUtf8ValidationOption(this.cursorOptions),
+     __tag: 'shift options'
+    }
   }
 
   /**
@@ -304,7 +313,7 @@ export abstract class AbstractCursor<
     );
 
     for (let count = 0; count < documentsToRead; count++) {
-      const document = this.documents?.shift(this.cursorOptions);
+      const document = this.documents?.shift(this.deserializationOptions);
       if (document != null) {
         bufferedDocs.push(document);
       }
@@ -406,7 +415,7 @@ export abstract class AbstractCursor<
     }
 
     do {
-      const doc = this.documents?.shift(this.cursorOptions);
+      const doc = this.documents?.shift(this.deserializationOptions);
       if (doc != null) {
         if (this.transform != null) return await this.transformDocument(doc);
         return doc;
@@ -425,15 +434,15 @@ export abstract class AbstractCursor<
       throw new MongoCursorExhaustedError();
     }
 
-    let doc = this.documents?.shift(this.cursorOptions);
+    let doc = this.documents?.shift(this.deserializationOptions);
     if (doc != null) {
       if (this.transform != null) return await this.transformDocument(doc);
       return doc;
     }
 
     await this.fetchBatch();
 
-    doc = this.documents?.shift(this.cursorOptions);
+    doc = this.documents?.shift(this.deserializationOptions);
     if (doc != null) {
       if (this.transform != null) return await this.transformDocument(doc);
       return doc;

src/cursor/aggregation_cursor.ts

@@ -76,7 +76,7 @@ export class AggregationCursor<TSchema = any> extends AbstractCursor<TSchema> {
           explain: verbosity ?? true
         })
       )
-    ).shift(this.aggregateOptions);
+    ).shift(this.deserializationOptions);
   }
 
   /** Add a stage to the aggregation pipeline

src/cursor/find_cursor.ts

@@ -143,7 +143,7 @@ export class FindCursor<TSchema = any> extends AbstractCursor<TSchema> {
           explain: verbosity ?? true
         })
       )
-    ).shift(this.findOptions);
+    ).shift(this.deserializationOptions);
   }
 
   /** Set the cursor query */