The Hidden Cost of Model Lock-In

Every team I have consulted with that hard-coded to a single model provider has regretted it. Not because the provider was bad — usually it was great — but because the cost of switching grew linearly with every feature they shipped. Six months in, a deprecation notice or a price change becomes a multi-quarter migration.

Lock-in is rarely a deliberate choice

Nobody sets out to be locked in. It happens one convenient SDK call at a time. You use the provider's function-calling format, its streaming helper, its image endpoint. Each is marginally faster than building an abstraction. The sum total is a codebase that cannot run on any other backend.

The minimal viable abstraction

You do not need a grand multi-provider framework. You need one interface with two implementations:

• complete(messages, config) -> stream of chunks
• embed(text) -> vector

That is it. Behind those two methods you can route to any provider. The config object carries model name, temperature, max tokens — the provider-specific bits live inside the implementation, not your app code.

Keep a shadow provider warm

Once you have the abstraction, run a small percentage of traffic through a second provider in shadow mode. You get free comparative eval data and prove the portability is real, not theoretical. When you need to switch, you already have production traces on the fallback.

Deprecation is a when, not an if

In the last 18 months I have watched three major providers change their model lineup, their pricing, or their terms. The teams that survived unchanged were the ones who never assumed the current model would exist forever. Treat your model choice as a config value, not an architectural decision.

Portability is not about hedging against disaster. It is about keeping the option to optimize — for cost, for latency, for capability — as the landscape shifts. The abstraction is cheap. The optionality is worth a lot.