Merge branch 'master' into list-pagination

buds/02.md

@@ -15,7 +15,7 @@ A blob descriptor is a JSON object containing `url`, `sha256`, `size`, `type`, a
 - `url` A publicly accessible URL to the [BUD-01](./01.md#get-sha256---get-blob) `GET /<sha256>` endpoint with a file extension
 - `sha256` The sha256 hash of the blob
 - `size` The size of the blob in bytes
-- `type` (optional) The MIME type of the blob
+- `type` The MIME type of the blob (falling back to `application/octet-stream` if unknown)
 - `uploaded` The unix timestamp of when the blob was uploaded to the server
 
 Servers MUST include a file extension in the URL in the `url` field to allow clients to easily embed the URL in social posts or other content
@@ -44,6 +44,13 @@ The endpoint MUST return a [Blob Descriptor](#blob-descriptor) if the upload was
 
 Servers MAY reject an upload for any reason and SHOULD respond with the appropriate HTTP `4xx` status code and an error message explaining the reason for the rejection
 
+### File extension normalization (Optional)
+
+When storing blobs, servers MAY normalise the file extension to a standard format (e.g. `.pdf`, `.png`, etc.) based on
+the MIME type of the blob. This can be especially useful when the `GET /<sha256>` endpoint is redirected to an external
+URL (see the [proxying and redirection section from BUD-01](./01.md#proxying-and-redirection-optional)), as external
+servers may rely on the file extension to serve the blob correctly.
+
 ### Upload Authorization (Optional)
 
 Servers MAY accept an authorization event when uploading blobs and SHOULD perform additional checks