LLM model/API behavior drift
OpenAI Assistants API Responses API migration deprecation threads runs
A fixture emulates a new capability or lifecycle contract unavailable in the legacy agent workflow.
Agent Quick Fix
Repair against the current OpenAI API contract, then keep the change narrow and source-backed.
Product: OpenAI API
Current-contract area: Assistants-thread workflow must migrate toward Responses API
Likely root cause: A fixture emulates a new capability or lifecycle contract unavailable in the legacy agent workflow.
Repair direction: Verifier checks current model ID, accepted payload, structured output/tool parsing, and behavior under retries.Symptom
A fixture emulates a new capability or lifecycle contract unavailable in the legacy agent workflow.
Why This Happens
SDK types may still accept fields that the selected hosted model rejects; model retirement, tokenizer, thinking, and tool behavior are external and fast-moving.
Common Wrong Fixes
- Changing local code without checking the current external contract.
- Retrying the same install, build, or API call with no version/source change.
- Applying a broad unsafe bypass when a narrow compatibility fix is available.
Codex Search Keywords
These are the search terms observed in a neutral Codex validation run for this failure shape.
site:platform.openai.com/docs Assistants API deprecation Responses API migrate threads runs official OpenAI
OpenAI Assistants API Responses API migration deprecation threads runs
https://platform.openai.com/docs/assistants/migration
'Assistants API is deprecated' in https://platform.openai.com/docs/assistants/migration