## Why
Reusable clients need fresh authentication for each request while preserving the credential source and transport policy selected when the client was created.
## What changed
- Add runtime-aware backend client construction and per-request authentication. Allow token refresh within the original credential source, reject credential replacement, and validate destination and account/organization selectors.
- Let runtime authentication finish persisting rotated tokens when the requesting task is cancelled.
- Apply asynchronous authentication to file creation and finalization requests, generating fresh assertions while keeping credentials off blob uploads.
- Preserve direct sandbox routing without enabling legacy custom-CA fallback for protected clients that reject redirects.
- Exclude login account metadata from model cache identities when provider bearer credentials override the login, and record authentication selection outcomes and duration.
## Testing
Add regression coverage for credential refresh and replacement, organization selection, destination restrictions, transport policy preservation, cancellation during token rotation, credential stripping on redirects, and file upload authentication in both runtime authentication modes.
GitOrigin-RevId: d045595e869dfcdfd9f705a6228cf0eb4c2d2c12
## Why
API keys with FedRAMP issuance markers previously used commercial endpoint defaults without a FedRAMP request header.
## What changed
- Recognize `sk-proj-fedramp-` and `sk-svcacct-fedramp-` prefixes as routing hints and send `X-OpenAI-Fedramp: true`, preserving the complete key for authentication.
- Select `https://gov.api.openai.com/v1` for default OpenAI API routing and `https://gov.chatgpt.com/backend-api/` for default ChatGPT backend requests, including model discovery and analytics.
- Preserve explicit endpoint overrides, including an explicitly configured commercial default URL.
- Resolve provider routing and authentication from the same credential snapshot, and apply key-dependent routing to realtime WebSocket startup.
## Testing
Add regression coverage for prefix recognition, unchanged key storage and authorization, provider credential precedence, endpoint overrides, credential rotation, model discovery, analytics routing, and realtime request preparation.
GitOrigin-RevId: a62576ce205c34e067532b8e6c0e431f87a157e2
## Why
Providers need to serve Codex model metadata independently of their inference endpoint. A custom inference `base_url` alone should not opt API-key sessions into remote catalog discovery.
## What changed
- Add `model_catalog_url` to provider configuration and thread-config serialization. Fetch the full catalog URL with provider authentication, headers, query parameters, and `client_version`, while preserving inference routing.
- Require an explicit catalog URL for API-key discovery with a custom base URL. Keep default OpenAI discovery on the Codex backend, and apply `api_key_model_discovery` gating to provider API keys and cached catalogs.
- Include the catalog URL in cache identity so different catalogs do not share cached metadata.
- Limit explicitly configured catalog responses to 1 MiB, reject redirects, and suppress URL and response diagnostics that could expose credentials.
## Testing
Add coverage for catalog configuration round-trips, query encoding, authentication and header reuse, cache identity and discovery gating, oversized responses, and redirect rejection without credential forwarding. Add an integration test verifying that catalog model metadata and instructions reach conversation requests.
GitOrigin-RevId: 7f6ac5eec257278685e1867a6bcebae6514a365a
## What changed
Add a SHA-256 identity derived from provider routing, headers, and authentication scope. Return it with each model catalog response and persist it in `ModelsCacheEntry`. ChatGPT credentials with stable account and user metadata retain the same identity across token refreshes; opaque API credentials contribute to the digest.
## Testing
Add identity tests covering account, user, email, plan, auth mode, provider routing, headers, and API credential changes, plus stability across ChatGPT token refreshes. Update cache tests to include the persisted identity.
GitOrigin-RevId: 3f51c6cabcb01bc03505150a768a61dfe5d6569f
cooper-oai