When the Assistants API went away, it took the export path with it
Assistants, Threads, and Runs map to Prompts, Conversations, and Responses, and nothing moves the stored history but you.
OpenAI's deprecations page now states it in the past tense: "The Assistants API was officially sunset on August 26, 2026, and is no longer available." The date landed exactly one year after the deprecation notice of August 26, 2025, and the writing had been on the wall longer than that: "When we released the Responses API in March 2025, we announced plans to bring all Assistants API features to the easier to use Responses API, with a sunset date in 2026."
Four objects become four others
The migration guide maps the old model onto the new one:
| Legacy | Replacement | The guide's rationale | |---|---|---| | Assistants | Prompts | "Prompts hold configuration (model, tools, instructions) and are easier to version and update" | | Threads | Conversations | "Streams of items instead of just messages" | | Runs | Responses | "Responses send input items or use a conversation object and receive output items" | | Run steps | Items | "Generalized objects—can be messages, tool calls, outputs, and more" |
Configuration is the easy half: recreate each Assistant's instruction and tool bundle as a named prompt and keep the prompt IDs in source control. The hard half is state.
The export path closed with the API
There is no automated migration tool. The guide's approach to history is manual: read each thread's messages and recreate them as Conversation items, input_text for user turns, output_text for assistant turns. Its code examples show exactly how, and then the guide adds the sentence that matters now: "The Assistants API call that retrieves thread messages no longer works; use your stored messages instead."
That is the trap for anyone who treated OpenAI as the system of record for chat history. Threads lived server-side; that was the feature. A team that kept only thread IDs, planning to export "before the deadline," now holds pointers into an API that no longer answers, and the documented export procedure requires the very calls that were shut off. The guide's fallback, "use your stored messages," only helps if you stored them.
The next clock started the same day
The August 26 changelog entry that recorded the shutdown sits next to a fresh deprecation: whisper-1, gpt-4o-transcribe, gpt-4o-mini-transcribe, and gpt-4o-transcribe-diarize are deprecated with a shutdown date of February 26, 2027, with gpt-live-transcribe or gpt-transcribe as the recommended replacements. Anyone transcribing audio through OpenAI has six months, minus however long the notice goes unread.
The Assistants shutdown is the cleanest demonstration yet of what a platform deprecation means in practice. A year of notice is generous by API standards, and it still stranded data, because the notice period and the export window were the same window. The defensive posture for any vendor API that holds your state: export continuously, not before the deadline. The deadline is when the export tool stops working.
Primary sources: OpenAI API changelog, OpenAI deprecations page, Assistants migration guide, read 2026-09-01.