Storage rent

Nodes keep an account’s messages only while the account has storage. Storage is rented in units, and each unit allows a number of messages of each kind. The Farcaster docs describe it under Messages.

What a unit holds

The limits per unit depend on the unit’s type. @farcaster/core 0.20.0 defines three:

Unit type	Casts	Reactions	Links	User data	Verifications
UNIT_TYPE_LEGACY	5000	2500	2500	50	25
UNIT_TYPE_2024	2000	1000	1000	50	25
UNIT_TYPE_2025	100	200	200	25	5

casty does not compute limits itself; it shows what your node reports for your fid.

When a store fills up

When an account goes over the limit for one kind, the oldest message of that kind is pruned to make room. Removes count too: a deleted cast leaves a CAST_REMOVE behind, and that takes a slot like a cast does.

When the storage expires, nodes keep the messages for a 30-day grace period, then drop them.

What casty shows

./bin/casty storage

prints your units and, for each store, how many messages it holds, its limit and how full it is. It warns at 90 percent:

warning: <store> is <percent>% full; when it fills, the oldest messages of that kind are pruned

casty whoami shows the same numbers on one line, and casty storage --fid <fid> shows any account’s. casty init refuses an fid with no units at all, because the network would not accept its messages.

casty does not rent storage.