There are some infos in the repo index which the client might need:

• csize, the encrypted/compressed chunk size
• maybe flags

Scenarios:

• chunks index gets lost on the client side (has id -> refcount, size mapping) (we can neither reconstruct the refcount from the index nor the uncompressed plaintext size, since borg2 we do not have csize in the chunks index any more)
• chunks index missing size info for some chunks (same reason)
• we could get csize for some statistics