Use 1h prompt-cache TTL to lift hit rate on sparse usage - #5
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The cached system/tools prefix used the default 5-min ephemeral TTL, which expires between Aria's bursty, intermittent interactions — so each turn re-paid a cache write instead of getting cheap reads (low hit rate, wasted spend). Switch the stable block to a 1h TTL (env-overridable via ARIA_CACHE_TTL); reads stay ~0.1x and the cache spans the gaps between clustered turns. SDK (anthropic 0.84) supports ttl in cache_control. Assisted-by: Claude Code (Opus 4.8)
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The cached system/tools prefix used the default 5-min ephemeral TTL, which expires between Aria's bursty, intermittent interactions — so each turn re-paid a cache write instead of getting cheap reads (low hit rate, wasted spend). Switch the stable block to a 1h TTL (env-overridable via ARIA_CACHE_TTL); reads stay ~0.1x and the cache spans the gaps between clustered turns. SDK (anthropic 0.84) supports ttl in cache_control.
Assisted-by: Claude Code (Opus 4.8)