## Summary
- read optional faster-model metadata from streamed buffering payloads
- use the buffering payload itself to determine whether buffering UI
should be shown
- retain the existing header value as a compatibility fallback when the
payload omits the field
## Behavior
An object-valued buffering signal now enables the buffering UI. The
response event's faster-model field takes precedence when present, while
omitted fields fall back to existing response metadata. An explicit null
leaves the retry target unset.
## Validation
- `just test -p codex-api`
- `just fix -p codex-api`
- `cargo fmt --all -- --check`
- `git diff --check`
## Summary
- read the request-scoped safety-buffering treatment from HTTP response
headers and per-turn WebSocket metadata through one shared header parser
- combine that treatment with Responses API safety-buffering signals
- propagate `showBufferingUi` and nullable `fasterModel` through the
existing `model/safetyBuffering/updated` app-server notification
- update the app-server documentation and generated JSON and TypeScript
schemas
The public implementation contains no model mapping or real model
identifier. Tests and protocol examples use generic `current-model` and
`faster-model` placeholders only.
## Dependencies
- server-side treatment evaluation:
https://github.com/openai/openai/pull/1060247
- initial Responses API safety-buffering propagation:
https://github.com/openai/codex/pull/29371
- Codex App UI: https://github.com/openai/openai/pull/1057789
## Validation
- Codex API tests: 129 passed
- focused Codex core safety-buffering integration test passed
- app-server protocol tests passed after regenerating schema fixtures
- Clippy fix and repository formatting completed successfully
The broader app-server run compiled all changed crates and completed
with 1,269 passing tests. Its remaining failures were unrelated
environment limitations: macOS sandbox application was denied, one
expected test binary was unavailable, and several existing subprocess
tests timed out as a result.
Francis Chalissery