Bedrock: roles must alternate between "user" and "assistant", but found multiple "user" roles in a row error after the silent change to combine consecutive turns

[dandv]

The Messages API docs now state,

Consecutive user or assistant turns in your request will be combined into a single turn.

This change does not seem to be active for Bedrock yet. The code below returns a ValidationException:http://internal.amazon.com/coral/com.amazon.bedrock/:

await client.messages.create({
  max_tokens: 1,
  stream: false,
  messages: [
    { role: 'user', content: 'What is the color of' },
    { role: 'user', content: 'the sky?' },
  ],
  model: 'anthropic.claude-3-sonnet-20240229-v1:0',
});

Using @anthropic-ai/bedrock-sdk 0.10.4 and @anthropic-ai/sdk 0.29.2, but the error seems to come from Bedrock rather than the SDK.

[rabsef-bicrym]

I get this error with sdk 0.32.1, not with bedrock.

  51 |   for (let i = 1; i < result.length; i++) {
  52 |     if (result[i].role === result[i-1].role) {
> 53 |       throw new Error('Invalid message sequence - messages must alternate between user and assistant');
     |            ^
  54 |     }
  55 |   }
  56 |

[dandv]

Can still reproduce with
"@anthropic-ai/bedrock-sdk": "^0.11.2",
"@anthropic-ai/sdk": "^0.32.1",

 error: {
    message: 'messages: roles must alternate between "user" and "assistant", but found multiple "user" roles in a row'
  }

[dandv]

To clarify, I'm seeing different behaviors from Anthropic and Bedrock on the same prompt with identical consecutive roles.

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

await consecutiveRoles(clientAnthropic, haiku.anthropic);  // [ { type: 'text', text: 'Blue' } ]
await consecutiveRoles(clientBedrock, haiku.bedrock);  // Error: 400 messages: roles must alternate between "user" and "assistant", but found multiple "user" roles in a row

Per the Messages API docs that "Consecutive user or assistant turns in your request will be combined into a single turn.", it seems that Bedrock might not be running the same version of the API handlers.