Legacy Assistants API Migration
The Assistants API was shut down on 26 August 2026, according to OpenAI's deprecation record↗. This chapter is for maintaining and migrating old code, not starting a new Assistants integration.
#Inventory the old workflow
Identify Assistant instructions/tools, Thread-owned context, Messages and Run orchestration. Include tool loops, retries, human review and any application references to their IDs.
#Understand the conceptual mapping
The migration documentation discusses reusable prompts, Conversations and Responses in place of the older Assistant/Thread/Run model. It is not a guarantee that every stored object has a direct automatic replacement.
#Migrate one complete path
- Select the simplest existing assistant workflow.
- Recreate its intended behavior through supported Responses/Conversations APIs.
- Compare context, tools, outputs, logs and errors.
- Verify access control, stored history and failure recovery.
- Replace more complex paths only after the equivalent flow is accepted.
Do not rewrite the whole repository without understanding what depended on the old orchestration. Preserve needed business records and distinguish migration evidence from merely changing an endpoint.
