Transient Cache

transient_cache stores cache data that is only valid within a single compilation lifecycle.

Difference from artifact:

• artifact is designed to be reused across compilations, and participates in incremental recovery and persistent caching.
• transient_cache is designed to not be reused across compilations. It is re-initialized each compilation, and should only accelerate the current build. It must not be part of incremental recovery or persistent cache flows.

Use transient_cache when the cache must not affect or depend on future compilation state (avoid cross-compilation contamination or when strict isolation is required).