Proposal: Default to Resumable Download Endpoint

Hi,
I saw that over on the LocalSend GitHub repository some protocol version 3 stuff is being uploaded. I haven’t looked at it in detail yet, but here are some changes I propose:

Download Endpoint
I propose changing the default behavior from upload to download instead.

Endpoint

GET /api/localsend/v3/download/{session_id}/{file_id}/
Authorization: Bearer <token>

Problems with POST-based uploads:

• Large requests can trigger server or proxy timeouts.
• Some servers buffer the whole body in memory -> Out-Of-Memory risk
• Resuming uploads is hard without a resumable protocol.

Benefits:

• Native Range/Content-Range support -> easy resumable downloads.
• Client-driven retries/resume - simpler recovery after connection loss.
• Server can stream from disk - lower memory use.
• Works with many existing tools/libraries (curl, aria2, OkHttp, NSURLSession, requests).

The existing upload-to-receiver can remain as a fallback.

We could also consider supporting the TUS protocol (open-source protocol for resumable uploads using HTTP): https://tus.io/

Start by reviewing the LocalSend protocol v3 material and the existing upload-to-receiver behavior described in this issue. Define the download endpoint, resumable transfer behavior, authentication, and fallback semantics, then verify the protocol proposal against the listed client and server use cases.