# bedrock: Add native support for Bedrock Mantle models \(\#60480\) · gitcafe/zed

[View on GitCafe](https://git.cafe/gitcafe/zed/commit/d12b980ee0721dc7fb72aeea511b1ab7b62af98c)

Repository: [gitcafe/zed](https://git.cafe/gitcafe/zed)

Visibility: public

Requested revision: d12b980ee0721dc7fb72aeea511b1ab7b62af98c

Requested commit: d12b980ee0721dc7fb72aeea511b1ab7b62af98c

Commit: d12b980ee0721dc7fb72aeea511b1ab7b62af98c

Tree: 6ff1395dd80d634d185f8d17e2470f1e331e27e3

Author: Anant Goel

Committer: GitHub

## Message

```
bedrock: Add native support for Bedrock Mantle models (#60480)

Adds native support for AWS Bedrock's Mantle endpoint
(`bedrock-mantle`), which serves models with no `Converse`/`Invoke`
support on `bedrock-runtime`, such as GPT-5.5, GPT-5.4, and Grok 4.3 but
more importantly **open-weight** models

Closes #60471 

## What's changed

- Renamed the existing `Model` enum in the `bedrock` crate to
`ConverseModel`, and added a new `MantleModel` enum for Mantle-only
models. Mantle models reuse the existing OpenAI-compatible Chat
Completions/Responses request and response plumbing
(`into_open_ai`/`into_open_ai_response`,
`OpenAiEventMapper`/`OpenAiResponseEventMapper`) already used by the
native OpenAI and OpenAI-compatible providers, rather than introducing
new marshalling code.
- Added a `BedrockMantleModel` language model that routes requests to
the `bedrock-mantle` endpoint, dispatching to Chat Completions or the
Responses API depending on the model. Mantle models appear in the model
picker alongside Converse models under the same Bedrock provider.
- Added region gating: `bedrock-mantle` is only available in a subset of
AWS Regions, so using a Mantle model outside of them surfaces a clear
error naming the current Region and the supported ones, instead of an
opaque HTTP failure.
- Implemented Bedrock bearer token authentication for Mantle requests: a
configured Bedrock API key is used as-is, and every other auth method
(IAM credentials, named profile, SSO, automatic) derives a short-term
token by locally SigV4-presigning a `CallWithBearerToken` request. This
requires no extra network round trip and no token caching, since
re-signing locally is cheap.
- Added a specific error for the 403 you get when your credentials have
`bedrock:CallWithBearerToken` but not the separate
`bedrock-mantle:CallWithBearerToken` permission Mantle models require,
since this is the most common misconfiguration.
- Added a `mantle_available_models` setting so custom models served
through `bedrock-mantle` can be configured, the same way other providers
support custom models via `available_models`.
- Documented Mantle models and the new setting in the Amazon Bedrock
section of [Use a
Gateway](https://zed.dev/docs/ai/use-a-gateway#amazon-bedrock).

## Testing

- Added unit tests covering: the local SigV4 bearer-token signing
(including a byte-for-byte cross-check against a reference
implementation), Mantle endpoint URL construction, the
Mantle-supported-regions list, thinking-effort normalization, and the
settings-to-model protocol mapping.
- `cargo test -p bedrock -p language_models -p settings_content -p
settings` passes.
- `./script/clippy` passes with no new warnings.

Release Notes:

- Added native support for AWS Bedrock's Mantle endpoint, enabling
GPT-5.5, GPT-5.4, and Grok 4.3 through the Amazon Bedrock provider.
```

## Parents

- [5d7d1d3f09f1d0934a472f654a6448a366497edf](https://git.cafe/gitcafe/zed/commit/5d7d1d3f09f1d0934a472f654a6448a366497edf?format=markdown)

[Source at this commit](https://git.cafe/gitcafe/zed/tree/d12b980ee0721dc7fb72aeea511b1ab7b62af98c?format=markdown)