Recipient to decide between downloading low vs. high quality attachment

I feel like there are several recent feature requests that are all aligning on something. Like this one too: Add hash of attachments to the pre-message to not download cached ones

Instead of always sending attachments through email:

  • Store attachments locally as blobs keyed by hash
  • Share them over iroh using the hash as the identifier
  • Include in the message:
    • hash
    • size
    • mime
    • optional iroh addressing info

So the message becomes a pointer, not the payload.

For images specifically:

  • Generate a small preview (compressed)
  • Keep the original uncompressed
  • Send both hashes in the message

Behavior:

  • chat renders instantly from preview
  • original is fetched on demand via iroh
  • if already cached → no fetch at all

Thoughts on that?