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Thresholds, Costs, ZDR

⚡ Prompt Caching Framework⏱ 15 min⭐ 400 BASE XP

Economic and Technical Limits

Caching involves a write premium (1.25x base input cost) during the initial serialization of the context. However, all subsequent 'reads' of that cache hit a massive 90% discount (0.1x base input cost). To justify the overhead, Anthropic enforces minimum token thresholds:

  • 1,024 tokens: Claude 3.7 Sonnet, Claude 3.5 Sonnet, Claude 3 Opus
  • 2,048 tokens: Claude 3.5 Haiku

If your context prefix is smaller than this minimum threshold, the cache header is ignored.

Lifecycle & Compliance

Caches are ephemeral and have a default TTL (Time To Live) of 5 minutes. Every time a cache is 'read', the TTL timer resets. For enterprises focused on security, this system is fully compatible with Zero Data Retention (ZDR)-the cached bits are held recursively in the inference boundary and vaporize immediately upon expiry, ensuring no persistent logs are generated natively.

SYNAPSE VERIFICATION
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If you send a 500-token prompt with a cache header to Claude 3.7 Sonnet, what happens?
It caches successfully
The system ignores the header because the context is below the 1,024-token minimum
It costs double tokens
It throws a 400 error