## Why
While reviewing https://github.com/openai/codex/pull/17958, the helper
name `is_azure_responses_wire_base_url` looked misleading because the
helper returns true for either the `azure` provider name or an Azure
Responses `base_url`. The new name makes both inputs part of the
contract.
## What
- Rename `is_azure_responses_wire_base_url` to
`is_azure_responses_provider`.
- Move the `openai.azure.` marker into
`matches_azure_responses_base_url` so all base URL marker matching is
centralized.
- Keep `Provider::is_azure_responses_endpoint()` behavior unchanged.
## Verification
- Compared the parent and current implementations.
`name.eq_ignore_ascii_case("azure")` still returns true before
consulting `base_url`, `None` still returns false, base URLs are still
lowercased before marker matching, and the same Azure marker set is
checked.
- Ran `cargo test -p codex-api`.
seeing issues with azure after default-enabling web search: #10071,
#10257.
need to work with azure to fix api-side, for now turning off
default-enable of web_search for azure.
diff is big because i moved logic to reuse
Adds a new feature
`enable_request_compression` that will compress using zstd requests to
the codex-backend. Currently only enabled for codex-backend so only enabled for openai providers when using chatgpt::auth even when the feature is enabled
Added a new info log line too for evaluating the compression ratio and
overhead off compressing before requesting. You can enable with
`RUST_LOG=$RUST_LOG,codex_client::transport=info`
```
2026-01-06T00:09:48.272113Z INFO codex_client::transport: Compressed request body with zstd pre_compression_bytes=28914 post_compression_bytes=11485 compression_duration_ms=0
```
