Useful on visit one
No history required, because the ranking reads the session rather than a profile. The cold-start case is the normal case here rather than the degraded one.
Recommendations
Most engines need history before they say anything useful, so a new visitor gets your bestsellers. This reads the visit that is happening and ranks against it, which means the first session is served as well as the hundredth.
Signals available before the first recommendation
Referrer, landing product, search terms, filters touched, products opened, time on each, and what was skipped. None of it needs a profile.
Where you are

Collaborative filtering needs a history to filter against. On a visitor with no history it has nothing, so it falls back to what sold well last week, which is the same strip every anonymous visitor sees. That is most of your traffic on most storefronts.
The usual fix is to shorten the cold-start window by collecting more: a login prompt, a cookie, a profile stitched across devices. Each of those adds a consent surface, a regulatory question and an engineering commitment, and none of them help the person who is on your site right now for the first and possibly only time.
The information you need is already in front of you. Somebody who has opened three products under a price point and filtered twice has told you a great deal, and none of it required knowing who they are.
A recommendation engine that needs to know who somebody is cannot help on the visit where it would matter most.
The cold start, stated plainly
Two approaches to the same first-time visitor, and only one of them has anything to work with.
Collaborative filtering learns from what people like you bought. On a first visit there is no you to be like, so the fallback is a bestseller strip, which is the same strip everybody sees.
Silent exactly when the visitor is deciding whether to stay.
What was searched, filtered, opened and skipped in the last ninety seconds narrows what this person is deciding between, whether or not they have ever been here before.
No identity required, and nothing to warm up.
What it looks like
Not a second model. The four factors that order a search result order a recommendation strip.
No history, no cookie, no login. Ranked from this visit alone.
What happens
The same ranker as search, pointed at a slot rather than a result set.
Views, searches, filters and cart actions in this session. Each one moves persona weight and attribute affinity. Nothing is stored against a person, because there is no person to store it against.
The slot asks for n products and gets them ranked on base relevance, persona fit, attribute affinity and price band, the same four factors search uses.
What was shown is recorded against the decision id, so the strip can be evaluated later rather than assumed to have worked.
What you get
No history required, because the ranking reads the session rather than a profile. The cold-start case is the normal case here rather than the degraded one.
Product detail, cart, category, home. A slot asks for products and gets them ordered; nothing about the placement is special-cased in the engine.
The strip and the search results are ordered by the same four factors. A merchandiser who understands one understands the other, and there is no second model to keep in sync.
If the engine is slow or unreachable the surface renders whatever you had. Degrading quietly is the default path, not an error state in front of a live store.
Before you commit
Questions
A strip can only order products your catalogue can tell apart. The audit answers that before anything is turned on.
Request a Decision AuditPriced after a pilot, against what the held-back arm actually shows.