The three modes

ModeProviderPHI policy
Fast defaultExternal LLMPHI Rail aliases identifiers before egress; re-hydrates real values on the response.
PrivateLocal / BAA-approvedPHI stays on-device or on BAA-allowlisted destinations only.
BAAExternal LLM with signed BAAPHI allowed under your BAA. Requires explicit acknowledgement.

Per-call override

Every /run and /openai/chat/completions call accepts a phi_mode param. The response includes phi_mode + phi_reason + phi_guardrail_applied so you can verify which rail fired.

BAA acknowledgement

Turning on BAA mode requires you to tick the box "I have a signed BAA with my chosen provider and I accept responsibility for PHI sent to them."