first message must use the "user" role error with Bedrock but not with Anthropic

[dandv]

In addition to the minor difference in behavior between the 1P Anthropic and 3P Bedrock Messages endpoint in #565, there is also a difference in how they handle: Assistant as the first role (succeeds on Anthropic but fails on Bedrock):

import Anthropic from '@anthropic-ai/sdk';
import AnthropicBedrock from '@anthropic-ai/bedrock-sdk';

const clientAnthropic = new Anthropic();
const clientBedrock = new AnthropicBedrock();

const haiku = {
  anthropic: 'claude-3-haiku-20240307',
  bedrock: 'anthropic.claude-3-haiku-20240307-v1:0',
};

async function assistantFirstRole(client: Anthropic | AnthropicBedrock, model = haiku.anthropic) {
  const response = await client.messages.create({
    max_tokens: 1,
    stream: false,
    messages: [
      { role: 'assistant', content: 'How can I help?' },
      { role: 'user', content: 'What is the color of the sky? Answer with only one word.' },
    ],
    model,
  });
  console.log('Response content: ', response.content);
}

await assistantFirstRole(clientAnthropic, haiku.anthropic);  // [ { type: 'text', text: 'Blue' } ]
await assistantFirstRole(clientBedrock, haiku.bedrock);  // Error: 400 messages: first message must use the "user" role

[aaron-lerner]

I believe this may have been due to timing differences between 1P and 3P releases. The expected behavior here is for it to no longer throw an error. Are you still running into errors on Bedrock?

[aaron-lerner]

Just tested and not seeing errors on Bedrock. Please reopen if you're still running into issues.

[dandv]

I'm still seeing this error with Bedrock reliably if I run this test script.

[aaron-lerner]

I'm unfortunately not in that repo and can't see the test script. I'm testing with the below:

import json
import boto3

client = boto3.client("bedrock-runtime", region_name="us-west-2")
model_id = "anthropic.claude-3-5-sonnet-20241022-v2:0"
try:
    response = client.invoke_model(
        modelId=model_id,
        contentType="application/json",
        body=json.dumps({
            "anthropic_version": "bedrock-2023-05-31",
            "max_tokens": 1024,
            "messages": [
                {
                    "role": "assistant",
                    "content": [
                        {"type": "text", "text": "Hello"},
                    ],
                },
            ],
        }),
    )
    [print(r) for r in response.get("body")]
except BaseException as e:
    print(f"ERROR: Can't invoke '{model_id}'. Reason: {e}")
    exit(1)

Which model are you seeing this behavior with?