Amazon Bedrock Mantle

FluffBuzz includes a bundled Amazon Bedrock Mantle provider that connects to the Mantle OpenAI-compatible endpoint. Mantle hosts open-source and third-party models (GPT-OSS, Qwen, Kimi, GLM, and similar) through a standard /v1/chat/completions surface backed by Bedrock infrastructure.

Property	Value
Provider ID	`amazon-bedrock-mantle`
API	`openai-completions` (OpenAI-compatible) or `anthropic-messages` (Anthropic Messages route)
Auth	Explicit `AWS_BEARER_TOKEN_BEDROCK` or IAM credential-chain bearer-token generation
Default region	`us-east-1` (override with `AWS_REGION` or `AWS_DEFAULT_REGION`)

Getting started

Choose your preferred auth method and follow the setup steps.

Explicit bearer token
IAM credentials

Best for: environments where you already have a Mantle bearer token.

Set the bearer token on the gateway host

export AWS_BEARER_TOKEN_BEDROCK="..."

Optionally set a region (defaults to us-east-1):

export AWS_REGION="us-west-2"

Verify models are discovered

fluffbuzz models list

Discovered models appear under the amazon-bedrock-mantle provider. No additional config is required unless you want to override defaults.

Best for: using AWS SDK-compatible credentials (shared config, SSO, web identity, instance or task roles).

Configure AWS credentials on the gateway host

Any AWS SDK-compatible auth source works:

export AWS_PROFILE="default"
export AWS_REGION="us-west-2"

Verify models are discovered

fluffbuzz models list

FluffBuzz generates a Mantle bearer token from the credential chain automatically.

When AWS_BEARER_TOKEN_BEDROCK is not set, FluffBuzz mints the bearer token for you from the AWS default credential chain, including shared credentials/config profiles, SSO, web identity, and instance or task roles.

Automatic model discovery

When AWS_BEARER_TOKEN_BEDROCK is set, FluffBuzz uses it directly. Otherwise, FluffBuzz attempts to generate a Mantle bearer token from the AWS default credential chain. It then discovers available Mantle models by querying the region’s /v1/models endpoint.

Behavior	Detail
Discovery cache	Results cached for 1 hour
IAM token refresh	Hourly

The bearer token is the same AWS_BEARER_TOKEN_BEDROCK used by the standard Amazon Bedrock provider.

Supported regions

us-east-1, us-east-2, us-west-2, ap-northeast-1, ap-south-1, ap-southeast-3, eu-central-1, eu-west-1, eu-west-2, eu-south-1, eu-north-1, sa-east-1.

Manual configuration

If you prefer explicit config instead of auto-discovery:

{
  models: {
    providers: {
      "amazon-bedrock-mantle": {
        baseUrl: "https://bedrock-mantle.us-east-1.api.aws/v1",
        api: "openai-completions",
        auth: "api-key",
        apiKey: "env:AWS_BEARER_TOKEN_BEDROCK",
        models: [
          {
            id: "gpt-oss-120b",
            name: "GPT-OSS 120B",
            reasoning: true,
            input: ["text"],
            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
            contextWindow: 32000,
            maxTokens: 4096,
          },
        ],
      },
    },
  },
}

Advanced configuration

Reasoning support

Reasoning support is inferred from model IDs containing patterns like thinking, reasoner, or gpt-oss-120b. FluffBuzz sets reasoning: true automatically for matching models during discovery.

Endpoint unavailability

If the Mantle endpoint is unavailable or returns no models, the provider is silently skipped. FluffBuzz does not error; other configured providers continue to work normally.

Claude Opus 4.7 via the Anthropic Messages route

Mantle also exposes an Anthropic Messages route that carries Claude models through the same bearer-authenticated streaming path. Claude Opus 4.7 (amazon-bedrock-mantle/claude-opus-4.7) is callable through this route with provider-owned streaming, so AWS bearer tokens are not treated like Anthropic API keys.When you pin an Anthropic Messages model on the Mantle provider, FluffBuzz uses the anthropic-messages API surface instead of openai-completions for that model. Auth still comes from AWS_BEARER_TOKEN_BEDROCK (or the minted IAM bearer token).

{
  models: {
    providers: {
      "amazon-bedrock-mantle": {
        models: [
          {
            id: "claude-opus-4.7",
            name: "Claude Opus 4.7",
            api: "anthropic-messages",
            reasoning: true,
            input: ["text", "image"],
            contextWindow: 1000000,
            maxTokens: 32000,
          },
        ],
      },
    },
  },
}

Relationship to Amazon Bedrock provider

Bedrock Mantle is a separate provider from the standard Amazon Bedrock provider. Mantle uses an OpenAI-compatible /v1 surface, while the standard Bedrock provider uses the native Bedrock API.Both providers share the same AWS_BEARER_TOKEN_BEDROCK credential when present.

Amazon Bedrock

Native Bedrock provider for Anthropic Claude, Titan, and other models.

Model selection

Choosing providers, model refs, and failover behavior.

OAuth and auth

Auth details and credential reuse rules.

Troubleshooting

Common issues and how to resolve them.

Overview

Concepts and configuration

Providers

Amazon Bedrock Mantle

Getting started

Automatic model discovery

Supported regions

Manual configuration

Advanced configuration

Amazon Bedrock

Model selection

OAuth and auth

Troubleshooting

​Getting started

​Automatic model discovery

​Supported regions

​Manual configuration

​Advanced configuration

​Related

Amazon Bedrock

Model selection

OAuth and auth

Troubleshooting

Getting started

Automatic model discovery

Supported regions

Manual configuration

Advanced configuration

Related