## 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