## Why
`codex-models-manager` had grown to own provider-specific concerns:
constructing OpenAI-compatible `/models` requests, resolving provider
auth, emitting request telemetry, and deciding how provider catalogs
should be sourced. That made the manager harder to reuse for providers
whose model catalog is not fetched from the OpenAI `/models` endpoint,
such as Amazon Bedrock.
This change moves provider-specific model discovery behind
provider-owned implementations, so the models manager can focus on
refresh policy, cache behavior, picker ordering, and model metadata
merging.
## What Changed
- Introduced a `ModelsManager` trait with separate `OpenAiModelsManager`
and `StaticModelsManager` implementations.
- Added `ModelsEndpointClient` so OpenAI-compatible HTTP fetching lives
outside `codex-models-manager`.
- Moved `/models` request construction, provider auth resolution,
timeout handling, and request telemetry into `codex-model-provider` via
`OpenAiModelsEndpoint`.
- Added provider-owned `models_manager(...)` construction so configured
OpenAI-compatible providers use `OpenAiModelsManager`, while
static/catalog-backed providers can return `StaticModelsManager`.
- Added an Amazon Bedrock static model catalog for the GPT OSS Bedrock
model IDs.
- Updated core/session/thread manager code and tests to depend on
`Arc<dyn ModelsManager>`.
- Moved offline model test helpers into
`codex_models_manager::test_support`.
## Metadata References
The Bedrock catalog metadata is based on the official Amazon Bedrock
OpenAI model documentation:
- [Amazon Bedrock OpenAI
models](https://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-openai.html)
lists the Bedrock model IDs, text input/output modalities, and `128,000`
token context window for `gpt-oss-20b` and `gpt-oss-120b`.
- [Amazon Bedrock `gpt-oss-120b` model
card](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-openai-gpt-oss-120b.html)
lists the `bedrock-runtime` model ID `openai.gpt-oss-120b-1:0`, the
`bedrock-mantle` model ID `openai.gpt-oss-120b`, text-only modalities,
and `128K` context window.
- [OpenAI `gpt-oss-120b` model
docs](https://developers.openai.com/api/docs/models/gpt-oss-120b)
document configurable reasoning effort with `low`, `medium`, and `high`,
plus text input/output modality.
The display names, default reasoning effort, and priority ordering are
Codex-local catalog choices.
## Test Plan
- Manually verified app-server model listing with an AWS profile:
```shell
CODEX_HOME="$(mktemp -d)" cargo run -p codex-app-server-test-client -- \
--codex-bin ./target/debug/codex \
-c 'model_provider="amazon-bedrock"' \
-c 'model_providers.amazon-bedrock.aws.profile="codex-bedrock"' \
-c 'model_providers.amazon-bedrock.aws.region="us-west-2"' \
model-list
```
The response returned the Bedrock catalog with `openai.gpt-oss-120b-1:0`
as the default model and `openai.gpt-oss-20b-1:0` as the second listed
model, both text-only and supporting low/medium/high reasoning effort.
## Summary
The Bedrock Mantle SigV4 auth provider currently looks like it can
lazily load `AwsAuthContext`, but the provider is only constructed after
`resolve_auth_method` has already loaded that context. Because
`with_context` always pre-populates the `OnceCell`, the
`get_or_try_init` fallback is unused in normal operation and makes the
provider lifecycle harder to reason about.
This change removes that dead lazy-loading path and makes the actual
behavior explicit:
- `BedrockAuthMethod::AwsSdkAuth` carries only the resolved
`AwsAuthContext`.
- `BedrockMantleSigV4AuthProvider` stores the resolved context directly.
- request signing uses the stored context without going through
`OnceCell`.
The existing eager AWS auth resolution behavior is unchanged; this is a
simplification of the provider state, not a behavior change.
## Testing
- `cargo shear`
- `cargo test -p codex-model-provider`
- `just bazel-lock-check`
## 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`.
## Summary
- Add `codex-model-provider` as the runtime home for model-provider
behavior that does not belong in `codex-core`, `codex-login`, or
`codex-api`.
- The new crate wraps configured `ModelProviderInfo` in a
`ModelProvider` trait object that can resolve the API provider config,
provider-scoped auth manager, and request auth provider for each call.
- This centralizes provider auth behavior in one place today, and gives
us an extension point for future provider-specific auth, model listing,
request setup, and related runtime behavior.
## Tests
Ran tests manually to make sure that provider auth under different
configs still work as expected.
---------
Co-authored-by: pakrym-oai <pakrym@openai.com>
