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Vikram Ray
Vikram Ray

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Prompt Caching Is Quietly Becoming the Operating System of AI Agents

The most unintuitive AI agent lesson I read recently:

Switching to a CHEAPER model mid-conversation can actually increase your costs.

Why?

Because prompt caches are model-specific.

You lose the entire cached context and recompute everything from scratch.

Another wild one:

Adding a single tool mid-session can invalidate 100k+ cached tokens because tools are part of the prompt prefix.

AI agents are slowly becoming a distributed systems problem disguised as prompting.

Excellent engineering write-up from Anthropic:
https://claude.com/blog/lessons-from-building-claude-code-prompt-caching-is-everything

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