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andheiberg
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Sep 26, 2025
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What sets this header? I can't see it being set ever.
Even on cache miss we do now the current theme I believe as basic shop is fetched. So I'm not sure we need a header at all?
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Apologies. I should've added https://github.com/shop/world/pull/199868 to the description
The goal here is to know the theme on a cache hit without having to query the DB |
gmalette
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Sep 26, 2025
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As outlined in https://shopify.slack.com/archives/C098UMNCU3A/p1758527247056459, I think we need a different mechanism than the
Speculation-Rulesheader to distinguish Horizon themes in cache hits.This PR adds a
Shopify-Themeheader to the cacheable headers. Once that happens, we can add such a header in SFR for cache misses that match the Horizon theme detection, and use it on cache hits to inject Horizon-specific speculation rules.There's a related PR on the SFR side: https://github.com/shop/world/pull/199868
It adds the use of this header as part of the speculation rules logic.