AWS Bedrock Converse API Prompt Caching not supported

[isaac-j-miller]

Checked other resources

• I added a very descriptive title to this issue.
• I searched the LangChain.js documentation with the integrated search.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain.js rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

Example Code

the following code:

import { BedrockRuntimeClient } from '@aws-sdk/client-bedrock-runtime';
import { ChatBedrockConverse } from '@langchain/aws';
import {
    SystemMessage,
    HumanMessage
} from '@langchain/core/messages';

const bedrock = new BedrockRuntimeClient({region:"us-east-1"});
const chatBedrockConverse = new ChatBedrockConverse({
    model: "us.amazon.nova-lite-v1:0",
    client: bedrock
});

const messages = [
  new SystemMessage({content:[
    {
        type: "text",
        text: "my system prompt"
    },
    {
        cachePoint: {
        type: "default"
        }
    }
  ]
}),
new HumanMessage("foo bar")
]

await chatBedrockConverse.invoke(messages);
// throws "System message content must be either a string, or a content array containing a single text object."
// from https://github.com/langchain-ai/langchainjs/blob/main/libs/langchain-aws/src/common.ts:355

Error Message and Stack Trace (if applicable)

"System message content must be either a string, or a content array containing a single text object."
from https://github.com/langchain-ai/langchainjs/blob/main/libs/langchain-aws/src/common.ts:355

Description

I'm trying to use prompt caching, per https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html, with the Converse API. It works with langchain in python.

System Info

[email protected] | MIT | deps: 12 | versions: 319
Typescript bindings for langchain
https://github.com/langchain-ai/langchainjs/tree/main/langchain/

keywords: llm, ai, gpt3, chain, prompt, prompt engineering, chatgpt, machine learning, ml, openai, embeddings, vectorstores

dist
.tarball: https://registry.npmjs.org/langchain/-/langchain-0.3.24.tgz
.shasum: 24c5e16f7a43be8ce54d32079ea8dc8087c56777
.integrity: sha512-BTjiYkUCpWFAmufK8J5zMqc5aUs4eEnAXPWtPe2+R4ZPP+U7bXJSBHAcrB40rQ3VeTdRgMvgDjekOOgCMWut6Q==
.unpackedSize: 4.8 MB

dependencies:
@langchain/openai: >=0.1.0 <0.6.0 js-yaml: ^4.1.0 openapi-types: ^12.1.3 yaml: ^2.2.1
@langchain/textsplitters: >=0.0.0 <0.2.0 jsonpointer: ^5.0.1 p-retry: 4 zod-to-json-schema: ^3.22.3
js-tiktoken: ^1.0.12 langsmith: ^0.3.16 uuid: ^10.0.0 zod: ^3.22.4

maintainers:

• nfcampos [email protected]
• jacoblee93 [email protected]
• andrewnguonly [email protected]
• benjamincburns [email protected]
• davidduong [email protected]
• hwchase17 [email protected]
• basproul [email protected]

dist-tags:
latest: 0.3.24 next: 0.3.2-rc.0 tag-for-publishing-older-releases: 0.2.20

published 2 weeks ago by basproul [email protected]

Using Node.js v22, on Fedora

[kishan0725]

Any update on this? @benjamincburns