## Summary
Codex's Amazon Bedrock provider signs Mantle requests with SigV4 using
credentials resolved by the AWS SDK. That worked for standard AWS
profiles and environment credentials, but AWS CLI console-login profiles
created by `aws login` require the SDK's `credentials-login` feature to
resolve `login_session` credentials.
This change enables that credential provider so Bedrock can use AWS
console-login credentials through the existing provider-owned AWS auth
path.
While testing the console-login path, we also hit a Mantle-specific
SigV4 regression from the new split between `session_id` and
`thread_id`. Mantle does not preserve legacy OpenAI compatibility
headers that use `snake_case` before SigV4 verification, so signing
those headers can make the server reconstruct a different canonical
request. The Bedrock auth path now removes that header class before
signing, keeping preserved hyphenated Codex/AWS headers such as
`x-codex-turn-metadata` signed normally.
## Changes
- Enable `aws-config`'s `credentials-login` feature in
`codex-rs/aws-auth`.
- Add a compile-time regression test for
`aws_config::login::LoginCredentialsProvider`.
- Strip `snake_case` compatibility headers from Bedrock Mantle SigV4
requests before signing.
- Expand the Bedrock auth regression test to cover `session_id`,
`thread_id`, and future headers of the same shape.
- Refresh Cargo and Bazel lockfiles for the added `aws-sdk-signin`
dependency.
## Tests
- tested with `aws login` locally and verified that it works as
intended.
## Summary
Add first-class Amazon Bedrock Mantle provider support so Codex can keep
using its existing Responses API transport with OpenAI-compatible
AWS-hosted endpoints such as AOA/Mantle.
This is needed for the AWS launch path, where provider traffic should
authenticate with AWS credentials instead of OpenAI bearer credentials.
Requests are authenticated immediately before transport send, so SigV4
signs the final method, URL, headers, and body bytes that `reqwest` will
send.
## What Changed
- Added a new `codex-aws-auth` crate for loading AWS SDK config,
resolving credentials, and signing finalized HTTP requests with AWS
SigV4.
- Added a built-in `amazon-bedrock` provider that targets Bedrock Mantle
Responses endpoints, defaults to `us-east-1`, supports region/profile
overrides, disables WebSockets, and does not require OpenAI auth.
- Added Amazon Bedrock auth resolution in `codex-model-provider`: prefer
`AWS_BEARER_TOKEN_BEDROCK` when set, otherwise use AWS SDK credentials
and SigV4 signing.
- Added `AuthProvider::apply_auth` and `Request::prepare_body_for_send`
so request-signing providers can sign the exact outbound request after
JSON serialization/compression.
- Determine the region by taking the `aws.region` config first (required
for bearer token codepath), and fallback to SDK default region.
## Testing
Amazon Bedrock Mantle Responses paths:
- Built the local Codex binary with `cargo build`.
- Verified the custom proxy-backed `aws` provider using `env_key =
"AWS_BEARER_TOKEN_BEDROCK"` streamed raw `responses` output with
`response.output_text.delta`, `response.completed`, and `mantle-env-ok`.
- Verified a full `codex exec --profile aws` turn returned
`mantle-env-ok`.
- Confirmed the custom provider used the bearer env var, not AWS profile
auth: bogus `AWS_PROFILE` still passed, empty env var failed locally,
and malformed env var reached Mantle and failed with `401
invalid_api_key`.
- Verified built-in `amazon-bedrock` with `AWS_BEARER_TOKEN_BEDROCK` set
passed despite bogus AWS profiles, returning `amazon-bedrock-env-ok`.
- Verified built-in `amazon-bedrock` SDK/SigV4 auth passed with
`AWS_BEARER_TOKEN_BEDROCK` unset and temporary AWS session env
credentials, returning `amazon-bedrock-sdk-env-ok`.
