Prefix is below the provider minimum, so caching is silently skipped
PrefixAudit rule below-minimum · v0.1.0
Why it breaks your cache
Every provider has a minimum cacheable prefix length. Below it the cache_control marker is ignored with NO error and NO warning. You keep paying full input price while believing caching is on.
How to fix it
Either grow the static prefix above the minimum (bundle stable reference docs, examples and tool schemas into the cached block) or drop the breakpoint and stop paying the write premium for nothing.
How common is it?
Detected in 68 of 236 production system prompts (28.8%) across 16 vendors.
Estimated impact
Modelled as invalidating 0% of the cached prefix.
Is your prompt affected?
Paste it and find out. Static analysis, in-browser, nothing leaves the page.
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