Two places that both think they are the truth
A durable source of truth and an in-memory one give the same answers until a process dies. Deciding which is authoritative is a design act, not a default.
data
6 posts
A retry queue with nothing to run it is a graveyard
A failed-sync flag is not a retry mechanism. Three parts are needed: a connectivity signal, an enumeration of what failed, and backoff with a ceiling.
Last write wins is a decision, not a default
When two writes reach one record and no code decides between them, the policy is whichever ran last. Name the resolver so the choice becomes reviewable.
Your list flickers because the page swap is not atomic
Replacing a cached page is several row operations, and a reader arriving between them observes a state that never existed. Make the swap one transaction.
Five ways a cache and its writes drift apart
A cache and the writes against it drift apart in five distinct ways. Each ships separately, each looks reasonable, and all five look identical to a user.
A read path that cannot ask for fresh data
A cold open and a deliberate refresh want different things from a cache. One read method forces the repository to guess what only the call site knows.