Anthropic - Enable automatic cache

[krisjan-oldekamp]

Anthropic recently enabled auto caching: https://platform.claude.com/docs/en/build-with-claude/prompt-caching#automatic-caching

• Instead of explicit cache breakpoints (at message level), you can now enable auto caching
• For this, we need to add a cache_control parameter "cache_control": {"type": "ephemeral"}, at the top_level of the request to the Anthropic API:

curl https://api.anthropic.com/v1/messages \
  -H "content-type: application/json" \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-opus-4-6",
    "max_tokens": 1024,
    "cache_control": {"type": "ephemeral"},
    "system": "You are an AI assistant tasked with analyzing literary works. Your goal is to provide insightful commentary on themes, characters, and writing style.",
    "messages": [
      {
        "role": "user",
        "content": "Analyze the major themes in Pride and Prejudice."
      }
    ]
  }'

I tried the following, but it doesn't seem to work:

return new ToolLoopAgent({
    model,
    instructions,
    tools,
    stopWhen: stepCountIs(maxSteps),
    providerOptions: {
      openrouter: {
        cacheControl: { type: 'ephemeral' },
      },
    },
});

Is this something already supported, but should we configure this differently? Or is this something that needs to be implemented? In many usecases, this can save you significant costs

[seannetlife]

would this work?

import { createOpenRouter } from "@openrouter/ai-sdk-provider";

const openrouter = createOpenRouter({
  apiKey: "...",
  compatibility: "strict",
});

const opus = openrouter.chat("anthropic/claude-opus-4.6", {
  extraBody: { cache_control: { type: "ephemeral" } },
});

[seannetlife]

hmmm, this just looks like it would result in the same config as what you have provided. probs not working then.

[krisjan-oldekamp]

would this work?

import { createOpenRouter } from "@openrouter/ai-sdk-provider";

const openrouter = createOpenRouter({
apiKey: "...",
compatibility: "strict",
});

const opus = openrouter.chat("anthropic/claude-opus-4.6", {
extraBody: { cache_control: { type: "ephemeral" } },
});

Also tried this, but indeed didn't work

[seannetlife]

paging @robert-j-y - this could be huuuuge for us on cost savings as we often have long running agent conversations. ran some potential numbers. pretty keen on realising this dream. 💜