### Check for existing issues

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

### What happened?

A managed batch reconciles successfully through `CheckBatchCost` — `batch_processed` becomes `true`, the provider status is recorded — but **no billed spend row is ever written** to `LiteLLM_SpendLogs`. Nothing is logged; there is no error and no warning.

The effect is that managed batch usage is invisible to spend tracking. Per-key and per-team `max_budget` is not enforced for batch workloads, and batch spend does not appear on any spend endpoint or dashboard.

Note that a `LiteLLM_SpendLogs` row with `call_type='aretrieve_batch'` *does* appear, written by non-terminal polls, but it carries `spend=0` and zero tokens. So a query that does not filter on `spend > 0` looks like billing is working when it is not — this is what delayed us noticing.

**Expected:** a completed managed batch writes exactly one spend row carrying the provider's token counts and a non-zero cost, dispatched to the configured success callbacks the same way a normal request's cost event is.

This appears specific to the background poller path. Cost logging for ordinary (no…