## Why
`codex-core` was re-exporting APIs owned by sibling `codex-*` crates,
which made downstream crates depend on `codex-core` as a proxy module
instead of the actual owner crate.
Removing those forwards makes crate boundaries explicit and lets leaf
crates drop unnecessary `codex-core` dependencies. In this PR, this
reduces the dependency on `codex-core` to `codex-login` in the following
files:
```
codex-rs/backend-client/Cargo.toml
codex-rs/mcp-server/tests/common/Cargo.toml
```
## What
- Remove `codex-rs/core/src/lib.rs` re-exports for symbols owned by
`codex-login`, `codex-mcp`, `codex-rollout`, `codex-analytics`,
`codex-protocol`, `codex-shell-command`, `codex-sandboxing`,
`codex-tools`, and `codex-utils-path`.
- Delete the `default_client` forwarding shim in `codex-rs/core`.
- Update in-crate and downstream callsites to import directly from the
owning `codex-*` crate.
- Add direct Cargo dependencies where callsites now target the owner
crate, and remove `codex-core` from `codex-rs/backend-client`.
## Summary
Fixes#15189.
Custom model providers that set `requires_openai_auth = false` could
only use static credentials via `env_key` or
`experimental_bearer_token`. That is not enough for providers that mint
short-lived bearer tokens, because Codex had no way to run a command to
obtain a bearer token, cache it briefly in memory, and retry with a
refreshed token after a `401`.
This PR adds that provider config and wires it through the existing auth
design: request paths still go through `AuthManager.auth()` and
`UnauthorizedRecovery`, with `core` only choosing when to use a
provider-backed bearer-only `AuthManager`.
## Scope
To keep this PR reviewable, `/models` only uses provider auth for the
initial request in this change. It does **not** add a dedicated `401`
retry path for `/models`; that can be follow-up work if we still need it
after landing the main provider-token support.
## Example Usage
```toml
model_provider = "corp-openai"
[model_providers.corp-openai]
name = "Corp OpenAI"
base_url = "https://gateway.example.com/openai"
requires_openai_auth = false
[model_providers.corp-openai.auth]
command = "gcloud"
args = ["auth", "print-access-token"]
timeout_ms = 5000
refresh_interval_ms = 300000
```
The command contract is intentionally small:
- write the bearer token to `stdout`
- exit `0`
- any leading or trailing whitespace is trimmed before the token is used
## What Changed
- add `model_providers.<id>.auth` to the config model and generated
schema
- validate that command-backed provider auth is mutually exclusive with
`env_key`, `experimental_bearer_token`, and `requires_openai_auth`
- build a bearer-only `AuthManager` for `ModelClient` and
`ModelsManager` when a provider configures `auth`
- let normal Responses requests and realtime websocket connects use the
provider-backed bearer source through the same `AuthManager.auth()` path
- allow `/models` online refresh for command-auth providers and attach
the provider token to the initial `/models` request
- keep `auth.cwd` available as an advanced escape hatch and include it
in the generated config schema
## Testing
- `cargo test -p codex-core provider_auth_command`
- `cargo test -p codex-core
refresh_available_models_uses_provider_auth_token`
- `cargo test -p codex-core
test_deserialize_provider_auth_config_defaults`
## Docs
- `developers.openai.com/codex` should document the new
`[model_providers.<id>.auth]` block and the token-command contract
Michael Bolin