Farcaster Devs

I would love a JS package that handles interpolating mentions into a cast

That + creating and managing signers are the most annoying parts of trying to interact directly with hubs IMO

likes building things • https://alexgrover.me/links

Which part of creating and managing signers is annoying out of curiosity? Are these accounts created onchain or using some other third party API?

I normally just use Neynar but essentially I'd like a package that simplifies the guide on this page so it's easy to do without a 3rd party:

I normally just use Neynar but essentially I'd like a package that simplifies the guide on this page so it's easy to do without a 3rd party: https://docs.farcaster.xyz/developers/guides/accounts/create-account-key

Please let me know if this covers your use case or if there is anything missing from your ideal flow: 
https://github.com/0x330a-public/jesse

You can register a new fid onchain, sign and claim an fname, add a new key to the account based on a private key or mnemonic currently in typescript (with sponsored txes and more native integration in the rust library)