{"schemaVersion":"1.0","source":"The Workflow Finder","sourceUrl":"https://www.theworkflowfinder.com","license":"Free to use with attribution and a link to the cited page","generated":"2026-08-28","workflow":{"title":"Migrate From a Closed API Model to an Open-Weight Model Without Breaking Your App","slug":"migrate-from-a-closed-model-to-an-open-weight-model","url":"https://www.theworkflowfinder.com/workflows/migrate-from-a-closed-model-to-an-open-weight-model","description":"Swap the model behind a production feature without a rewrite or a silent quality regression, in about half a day.","difficulty":"Intermediate","timeEstimate":"4-6 hours","schemaDuration":"PT6H","expectedResult":"Your application running on an open-weight model instead of a closed API, with evidence the swap didn't degrade output quality and a rollback path if it did.","tags":["Models","Migration","Cost Optimization"]},"steps":[{"position":1,"title":"Baseline Your Current Model's Real Outputs","instructions":"Pull 30-50 real production prompts and their current responses, logged through LangSmith rather than reconstructed from memory. This baseline is what every candidate replacement gets measured against, not a handful of hand-picked examples that flatter whichever model you're hoping to switch to.","input":"Workflow inputs: the topic, goal, or raw materials the user is starting from.","output":"Handoff artifact consumed by Step 2 (\"Test Candidate Models Without Touching Your App's Code\").","ioProvenance":{"input":"structural","output":"structural"},"toolSlots":[{"slug":"langsmith","name":"LangSmith","url":"https://www.theworkflowfinder.com/tools/langsmith","category":"Developer Tools","pricing":"freemium","capabilities":["API integration"]}]},{"position":2,"title":"Test Candidate Models Without Touching Your App's Code","instructions":"Route the same baseline prompts through OpenRouter to a few open-weight candidates side by side. OpenRouter's single API surface means you're comparing model outputs, not rewriting integration code for each candidate.","input":"Output of Step 1 (\"Baseline Your Current Model's Real Outputs\").","output":"Handoff artifact consumed by Step 3 (\"Score the Replacement Against the Baseline\").","ioProvenance":{"input":"structural","output":"structural"},"toolSlots":[{"slug":"openrouter","name":"OpenRouter","url":"https://www.theworkflowfinder.com/tools/openrouter","category":"Developer Tools","pricing":"freemium","capabilities":["API integration"]}]},{"position":3,"title":"Score the Replacement Against the Baseline","instructions":"Use Braintrust to score each candidate's outputs against your baseline on the criteria that actually matter for this feature, correctness, tone, format, whatever you'd have caught in review. A model that's cheaper but scores worse on the dimension your users notice isn't a win.","input":"Output of Step 2 (\"Test Candidate Models Without Touching Your App's Code\").","output":"Handoff artifact consumed by Step 4 (\"Cut Over Gradually With a Rollback Path\").","ioProvenance":{"input":"structural","output":"structural"},"toolSlots":[{"slug":"braintrust","name":"Braintrust","url":"https://www.theworkflowfinder.com/tools/braintrust","category":"Developer Tools","pricing":"freemium","capabilities":["API integration"]}]},{"position":4,"title":"Cut Over Gradually With a Rollback Path","instructions":"Once a candidate wins, route a small percentage of real traffic to it through OpenRouter first, watching error rates and user-facing quality signals before increasing the share. Keep the old model's routing config in place and ready, not deleted, until the new one has run clean for a real stretch of production traffic.","input":"Output of Step 3 (\"Score the Replacement Against the Baseline\").","output":"Final workflow output: Your application running on an open-weight model instead of a closed API, with evidence the swap didn't degrade output quality and a rollback path if it did.","ioProvenance":{"input":"structural","output":"structural"},"toolSlots":[{"slug":"openrouter","name":"OpenRouter","url":"https://www.theworkflowfinder.com/tools/openrouter","category":"Developer Tools","pricing":"freemium","capabilities":["API integration"]}]}]}