Observed

Source-reviewed: cost tracking works in the common path; Azure cost tracking fails on model-name mismatch — Azure returns 'gpt-4' while the deployment is configured as 'azure/gpt-4-1106-preview' and cost calculation uses the response model name (multiple closed issues; the architectural fix request #15851 is marked not-planned); Claude token counts come from LiteLLM's own anthropic_tokenizer.json, whose accuracy against Anthropic's native tokenizer is unverified; multi-replica deployments keep independent spend counters.

1. UPDATE 2026-06-28: a new regression in v1.87.0 pins end_user in SpendLogs to the first request's user for all subsequent requests on a shared virtual key, silently breaking per-user attribution (#31441, open 2026-06-26).