### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### The Feature

I would like LiteLLM to support an optional cold archive logging callback that writes request/response logs to object storage such as S3 or MinIO, using a reliable queue or stream as a buffer.

Suggested architecture:

1. LiteLLM success/failure callbacks write structured logs to a queue or stream. 2. A background worker uploads logs to S3-compatible object storage. 3. Failed uploads go to a DLQ. 4. A replay tool can retry DLQ items. 5. Retention policy can be configured per model, team, or key.

Suggested retention levels:

- `full` - `metadata_only` - `none`

Desired fields:

- request id - model - virtual key/team/user - status - token usage - spend - timestamps - redacted request/response payload depending on policy - object storage path

### Motivation, pitch

Spend logs and observability integrations are useful for operational dashboards, but some enterprise deployments also need long-term cold archive storage for audit, debugging, compliance, and offline analysis.

Directly writing large payloads from the request path can increase latency a…