Announcement: `feature/s3/manager` durability update on 10/27/25

[lucix-aws]

The 10/27/25 release of the feature/s3/manager module adds two additional durability checks:

• Upload() calls will verify that we send the expected number of parts, assuming that the input object's Reader is seekable such that we can determine its length.
• Download() calls will verify that individual range requests from S3 return the expected byte range.

Errors will look like the following:

uploaded part count mismatch: expected x, got y

invalid content range: expect x-y, got a-b

You can disable either or both of these new behaviors with a new DisableValidateParts flag in options for Uploader and Downloader. Amazon S3 does not advise doing this as it damages the durability posture of your application.

// same for NewDownloader
u := manager.NewUploader(svc, func (o *manager.Uploader) {
    o.DisableValidateParts = true
})

#3202