Core cache: lock FOUND to USABLE#552
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cceckman-at-fastly merged 3 commits intomainfrom Nov 10, 2025
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The Compute platform, at the moment, only returns FOUND if within the USABLE period (in HTTP semantics, "fresh" or "stale-while-revalidate"). Unfortunately, SDKs rely on this property, and check FOUND or USABLE variously; sometimes (e.g. in Rust), this results in a `FOUND`-but-not-`USABLE` result being returned. We can fix SDKs going forward, but not existing usage. Match Compute's behavior by locking `FOUND` to `USABLE`. If we want to return expired results, we'll need more / other bits.
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The Compute platform, at the moment, only returns FOUND if within the USABLE period (in HTTP semantics, "fresh" or "stale-while-revalidate"). Unfortunately, SDKs rely on this property, and check FOUND or USABLE variously; sometimes (e.g. in Rust), this results in a
FOUND-but-not-USABLEresult being returned.We can fix SDKs going forward, but not existing usage. Match Compute's behavior by locking
FOUNDtoUSABLE. If we want to return expired results, we'll need more / other bits.Also add tests that exercise this behavior. (Really they're testing the Rust SDK's handling of this behavior, but, better than not having it.)