Treat every model change as a data migration: keep one application credential and one chat-completions-shaped boundary if that simplifies the Node.js service, but never let a routing decision overwrite a previously accepted classification without a versioned schema, provenance, and an explicit promotion rule.
That is the short answer. Replacing several provider integrations with one API key reduces credential exposure in the caller; it does not make models equivalent, and it does not remove the upstream credentials from the trusted routing service. The hard part is preserving the meaning of labels while prompts, models, and adapters change. A response that parses cleanly can still be incompatible with the taxonomy that downstream queries expect.
Storage makes that mistake durable.
Start with the invariant that survives a provider swap
For a tagging workload, the useful abstraction is smaller than a universal AI client. Define a classification command with an immutable item identifier, input text or a controlled reference to it, a taxonomy version, and a deadline class. Define the accepted result as the same item identifier, exactly one allowed label or an explicit abstention, plus the versions of the taxonomy, prompt, route, and model that produced it.
