## What changed
- Read optional workload identity context from `OPENAI_WORKLOAD_IDENTITY_CONTEXT` and forward it unchanged as the `workload_identity_context` token exchange field.
- Treat the context as sensitive by redacting it from session configuration debug output and removing it from model-reachable child environments.
- Include the context in workload identity session fingerprints so sessions with different values cannot share an exchange.
## Testing
- Cover request forwarding, debug redaction, session compatibility, and child-environment scrubbing.
GitOrigin-RevId: fb50700478cf54d9d604944a4ed3e77acc928a0f
## What changed
- Add the `codex-workload-identity` crate for exchanging a file-backed JWT assertion and federation rule ID for short-lived ChatGPT credentials.
- Cache valid access tokens, refresh them before expiry or after rejection, and coalesce concurrent exchanges. Continue using a still-valid cached token when a proactive refresh fails transiently.
- Validate assertion files, token endpoints, and exchange responses; honor outbound proxy policy for HTTPS endpoints and redact access tokens from debug output.
## Testing
- Cover request encoding, assertion rotation, caching, concurrent refreshes, transient-failure fallback, configuration validation, and malformed inputs and responses.
GitOrigin-RevId: 5496851683c2dcf6aaad6840053b97f7c0be076e
cooper-oai