Unverified50% confidenceFactExact time
The key constraint of prefix caching is that the prefix must match token by token; even inserting a single character earlier in the text invalidates everything from that position onward.
1
Sources
50%
Confidence
Long-term
Relevance
11/6/2026
First Seen
Sources
Related Entities
Related Claims
VerifiedWhether prompt caching hits depends on byte-for-byte consistency of the request prefix; if even one character at the beginning differs, the entire cache is invalidated.78% similarUnverifiedPrefix caching depends on strict conditions: the reused portion must be identical from the very first token of the sequence, otherwise the cache is invalidated and the entire segment is recomputed.73% similarUnverifiedToken Memory uses token count rather than message count as the budget cap, and trimming may cut a sentence off in the middle, leaving the semantics incomplete.72% similarUnverifiedPrompt Caching requires the prompt to meet a minimum cacheable length (typically 1024 tokens for Anthropic), and the prefix must be byte-for-byte identical for the cache to hit.71% similarUnverifiedPrompt caching divides prefixes by 'breakpoints', and the prefix must be byte-for-byte identical to hit the cache, so it is critical to put unstable content such as timestamps and random IDs in the suffix.71% similar
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