prompt_caching.py — langchain Source File

Source Code

"""Anthropic prompt caching middleware.

Requires:
    - `langchain`: For agent middleware framework
    - `langchain-anthropic`: For `ChatAnthropic` model (already a dependency)
"""

from collections.abc import Awaitable, Callable
from typing import Literal
from warnings import warn

from langchain_anthropic.chat_models import ChatAnthropic

try:
    from langchain.agents.middleware.types import (
        AgentMiddleware,
        ModelCallResult,
        ModelRequest,
        ModelResponse,
    )
except ImportError as e:
    msg = (
        "AnthropicPromptCachingMiddleware requires 'langchain' to be installed. "
        "This middleware is designed for use with LangChain agents. "
        "Install it with: pip install langchain"
    )
    raise ImportError(msg) from e


class AnthropicPromptCachingMiddleware(AgentMiddleware):
    """Prompt Caching Middleware.

    Optimizes API usage by caching conversation prefixes for Anthropic models.

    Requires both `langchain` and `langchain-anthropic` packages to be installed.

    Learn more about Anthropic prompt caching
    [here](https://platform.claude.com/docs/en/build-with-claude/prompt-caching).
    """

    def __init__(
        self,
        type: Literal["ephemeral"] = "ephemeral",  # noqa: A002
        ttl: Literal["5m", "1h"] = "5m",
        min_messages_to_cache: int = 0,
        unsupported_model_behavior: Literal["ignore", "warn", "raise"] = "warn",
    ) -> None:
        """Initialize the middleware with cache control settings.

        Args:
            type: The type of cache to use, only `'ephemeral'` is supported.
            ttl: The time to live for the cache, only `'5m'` and `'1h'` are
                supported.
            min_messages_to_cache: The minimum number of messages until the
                cache is used.
            unsupported_model_behavior: The behavior to take when an
                unsupported model is used.

                `'ignore'` will ignore the unsupported model and continue without
                caching.
// ... (88 more lines)