Remove dependency on bitswap?

[BigLep]

Done Criteria

Assuming Bitswap is not needed, Lotus no longer has a dependency on Bitswap (which currently resides in ipfs/boxo).
If Bitswap is needed, it's documented as to why.

Why Important

General reasons for reducing dependencies.
Maintainers have debt to payoff for dependency upgrades and need a mechanism to upgrade. These issues magnify with larger dependencies like ipfs/boxo.

User/Customer

Maintainers

Notes

In handling #13202, it was identified that Lotus may be able to remove its dependency on Bitswap. This would then allow Lotus to simplify its dependency tree. This issue was created to capture notes on the initial investigation in case this effort gets prioritized for the future.

[magik6k]

Unless something has changed I believe bitswap is still needed for fetching of messages in chain following mode (which doesn’t use the chain exchange protocol) - it propagates messages which weren’t delivered over gossipsub, which is a small but still critical feature.

I’d propose running a fleet of 5-10 lotus nodes with bitswap removed for a month and a smoke test before committing to actually removing bitswap from chain sync.

[BigLep]

Bitswap being required and why is documented in #13216

[BigLep]

Assigning this to @rvagg since he is effectively resolving this with #13216

[rvagg]

Some more info @ #13221 which has some investigation of actual level of reliance on bitswap.