Create a narrow boundary
Wrap model calls behind a defined application result. Keep pricing, permissions and booking rules outside prompts. Provider changes then become isolated, reviewable work rather than a rewrite of the customer journey.
Test behavioral differences
Check streaming, rate errors, tool calls, null values and output limits. Similar field names can hide different semantics. Preserve operation identity during retries so that a provider fallback does not create duplicate bookings.
Switch gradually
Start with test data, then limited monitored use. Approve the new data-processing path before sending records. Define rollback triggers, such as tool errors or weaker dialect understanding, before migrating.