Caching and fail-open

Personalization is the part of the system most likely to be slow, because it depends on the largest payload and often the oldest system. It is therefore built so that it can never hold up a reply.

Cached summaries

A shopper’s summary is cached after it is built, keyed to their identifier, so a returning shopper does not pay the cost of summarizing again.

Fail-open

If the cache is unavailable, or history cannot be fetched in time, the failure is swallowed and the session continues without personalization. A shopper gets a slightly less tailored cart rather than an error, and tight timeouts mean they do not wait to find out.

What this means for you

A history system that is slow or intermittently available is still worth connecting. It degrades rather than breaks.

Note on this page

Described from the current implementation rather than from a published contract. Field names and shapes are what Neomi normalizes to today; our engineering team confirms the public naming when the reference is finalized.