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docs(bedrock): clarify Mantle model-family API roots #885

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docs(bedrock): clarify Mantle model-family routes
fscfede-beep Sep 4, 2026
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docs(bedrock): reconcile root route guidance
fscfede-beep Sep 4, 2026
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7 changes: 4 additions & 3 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1361,9 +1361,10 @@ The region is resolved from `AWSRegion`, `AWS_REGION`, `AWS_DEFAULT_REGION`,
or the standard AWS config chain. The base URL is resolved from `BaseURL`,
`AWS_BEDROCK_BASE_URL`, or
`https://bedrock-mantle.{region}.api.aws/openai/v1`.
The `/openai/v1` prefix is intentional; Bedrock's generic `/v1` route is a
different API surface and is not interchangeable with the OpenAI-compatible
route.
The default Mantle base URL remains `/openai/v1`, which AWS documents for OpenAI
model families. Some other Mantle model families use `/v1` instead; see
[Mantle API roots](bedrock/README.md#mantle-api-roots) and the AWS model card for
your deployment before overriding `BaseURL`.

To select a named profile:

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16 changes: 16 additions & 0 deletions bedrock/README.md
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Expand Up @@ -9,6 +9,22 @@ Use the `bedrock` package to configure the normal OpenAI client for Amazon Bedro

Runtime hostnames use the correct suffix for the selected AWS partition. Canonical Runtime, FIPS, and dual-stack `BaseURL` overrides automatically select the endpoint family when `Endpoint` is omitted. Canonical AWS hosts must use HTTPS and match the configured region and endpoint. Custom or proxy hosts default to the Mantle signer; set `EndpointRuntime` explicitly when a custom host requires Runtime signing.

### Mantle API roots

Amazon Bedrock exposes more than one OpenAI-compatible API root on `bedrock-mantle`, and the route depends on the model family. OpenAI model pages such as [GPT-5.5](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-openai-gpt-55.html) document `/openai/v1`, while other model pages such as [Kimi K2.5](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-moonshot-ai-kimi-k2-5.html) document `/v1`. `EndpointMantle` keeps `/openai/v1` as its default for backwards compatibility; choosing `EndpointMantle` does not automatically select a route from the model name.
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When the AWS model card for a deployment documents `/v1`, set the Mantle `BaseURL` explicitly:

```go
bedrock.Config{
Endpoint: bedrock.EndpointMantle,
AWSRegion: "us-east-1",
BaseURL: "https://bedrock-mantle.us-east-1.api.aws/v1",
}
```

See the AWS model card for the model you are using before choosing the route. For example, AWS documents `https://bedrock-mantle.<region>.api.aws/openai/v1` for GPT-5.5 and `https://bedrock-mantle.<region>.api.aws/v1` for Kimi K2.5.

## Runtime Chat Completions

```go
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