docs(caching): the pingora cache engine is Enterprise-only in v2.3.0 too

[claudespice]

Summary

The version-2.3.x snapshot was published on 2026-09-10 at 11:24 UTC; #2188 merged at 15:07 the same day and edited website/docs/ only. So the newest release's caching page still presents engine: pingora as an ordinary open source backend, and describes its sharded-LRU behaviour as what a reader who sets it will get.

On a published open source spiced they will not get it. pingora is absent from bin/spiced's default feature list, the CacheEngine enum is not feature-gated (so the value parses and nothing fails), and the dispatch arm warns and builds a Moka backend instead. This is the edition-gating shape the hygiene reference calls out: a config enum declared in spicepod but implemented behind a cargo feature.

This applies #2188's text to the 2.3.x snapshot; the page is now byte-identical to trunk's vNext copy.

Scope: only version-2.3.x. features/caching/index.md in 2.0.x, 2.1.x and 2.2.x does not mention engine/pingora at all.

Source PRs

• docs(caching): the pingora cache engine is Enterprise-only and falls back silently #2188 — the vNext half of this correction

Test plan

• Docusaurus build gate — cd website && npm run build:

[SUCCESS] [docusaurus-plugin-llms-txt] Plugin completed successfully - processed 488 documents
[SUCCESS] Generated static files in "build".

• Versioned-docs propagation — diff -u website/versioned_docs/version-2.3.x/features/caching/index.md website/docs/features/caching/index.md now prints nothing: the snapshot matches vNext exactly.
• Cross-page sweep — grep -rln 'pingora' website/docs website/versioned_docs returns only the two caching pages plus the acknowledgements/index.md dependency lists; no other page carries the claim.
• Files updated: 1 — versioned_docs/version-2.3.x/features/caching/index.md, matching the diff.

Reproduction

Doc said (website/versioned_docs/version-2.3.x/features/caching/index.md:54 at docs c0f47f88):

engine … Cache backend: moka or pingora.

Code says — pingora is not in the default feature set at v2.3.0:

$ git show v2.3.0:bin/spiced/Cargo.toml | sed -n '/^default = \[/,/^\]/p' | grep -c pingora
0

and the non-pingora build arm falls back (crates/cache/src/lru_cache.rs at v2.3.0):

#[cfg(not(feature = "pingora"))]
{
    tracing::warn!(
        "{PINGORA_ENTERPRISE_ONLY_MESSAGE} Falling back to the Moka cache engine."
    );
    let cache = build_moka_cache(cache_max_size, ttl, hasher.clone(), caching_policy);
    CacheBackendEnum::MokaFallback(MokaBackend::from_cache(cache))
}

Every string the page quotes is grepped from v2.3.0 source, not paraphrased:

$ git grep -n 'PINGORA_ENTERPRISE_ONLY_MESSAGE\|TinyLFU caching policy' v2.3.0 -- crates/cache/src/lru_cache.rs
v2.3.0:crates/cache/src/lru_cache.rs:53:pub const PINGORA_ENTERPRISE_ONLY_MESSAGE: &str = "The Pingora cache engine is included in the Enterprise distribution of Spice.ai. Learn more at https://docs.spice.ai/docs/enterprise";
v2.3.0:crates/cache/src/lru_cache.rs:364:  "Pingora cache engine does not support TinyLFU caching policy. Falling back to LRU."

The startup line the page tells readers to check is the Display impl at lru_cache.rs:208 ("max size: {:.2}, item ttl: {:?}, engine: {}") interpolated into tracing::info!("Initialized sql results cache; {cache_provider}") at crates/runtime/src/init/caching.rs:54, and CacheBackendEnum::MokaFallback(_) => CacheEngine::Moka at lru_cache.rs:177 is why it reads Moka rather than the configured value.

Behavior claim: not run — reproducing the fallback warning needs a spiced built at the v2.3.0 tag with the default feature set. The correction rests on the feature-list grep and the #[cfg(not(feature = "pingora"))] arm quoted above, so it is labeled Unverified, code inspection only for the runtime behaviour and Reproduced for the edition-gating claim itself.

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