Prev Next

AI / Core OpenAI Codex Application Fundamentals Interview Questions

What is the OpenAI Assistants API and what is its deprecation timeline?

The Assistants API was OpenAI's original high-level framework for building stateful, multi-turn AI assistants with persistent threads, file handling, and built-in tools. It introduced key concepts like Threads (conversation state), Runs (execution instances), and Vector Stores (document retrieval).

Assistants API key concepts
ConceptDescription
AssistantA configured AI model with instructions, tools, and optional files
ThreadA persistent conversation history (persisted server-side)
RunAn execution of an assistant on a thread - produces a response
MessageA single turn added to a Thread
Vector StoreA server-side store of embedded documents for file search

Deprecation timeline: OpenAI formally announced the Assistants API deprecation in 2025. The planned sunset date is mid-2026, once full feature parity is achieved in the Responses API. Key migration points:

  • Threads - replaced by previous_response_id chaining or the Conversations API in Responses
  • Vector Stores - now a standalone resource, still used with file_search tool in Responses API
  • Code Interpreter - available as a built-in tool in Responses API
  • Assistant objects - replaced by the system instructions field in Responses calls

Recommendation: all new projects should use the Responses API with the Agents SDK. Existing Assistants API integrations should plan migration before mid-2026 to avoid disruption.

What is the planned sunset date for the OpenAI Assistants API?
In the migration from Assistants API to Responses API, what replaces persistent Thread objects?

More Related questions...

What is OpenAI Codex and how has it evolved from its original form? What are the current recommended models for OpenAI Codex and the API, and when do you choose each? What is the OpenAI Responses API and how does it differ from the Chat Completions API? What are the built-in tools available in the OpenAI Responses API? What is the OpenAI Agents SDK and what are its four core primitives? What is the Codex CLI and what are its key features? What is the Chat Completions API and when should you still use it? What is function calling (tool use) in the OpenAI API and how does it work? What are structured outputs in the OpenAI API and how do you use them? What is the OpenAI Assistants API and what is its deprecation timeline? What is prompt caching in the OpenAI API and how does it reduce costs? What are reasoning models in the OpenAI API and what is the 'effort' parameter? What are OpenAI's key API authentication and security concepts? What are rate limits in the OpenAI API and how do you handle them in production? What is the Batch API and when should you use it? What is streaming in the OpenAI API and how do you implement it? What is OpenAI's Codex Skills feature and what are Automations? What is Model Context Protocol (MCP) and how does it integrate with OpenAI tools? What is fine-tuning in the OpenAI API and when should you use it? What are embeddings in the OpenAI API and what are they used for? What is the OpenAI moderation API and why is it important for application safety? What are OpenAI's image generation models and how do you use them in applications? What is the OpenAI Realtime API and what use cases does it enable? What is retrieval-augmented generation (RAG) and how do you implement it with OpenAI? What is OpenAI's approach to responsible use and safety in the API? What is the OpenAI token system and how do you count and optimise token usage? What are guardrails in the context of OpenAI application development? What is the OpenAI Files API and how is it used for document management? How do you implement multi-agent systems using the OpenAI Agents SDK? What is the OpenAI Evals framework and why is evaluation critical for production applications? How do you implement error handling in OpenAI API applications? What is the OpenAI Codex App and what are its main features for software teams? What are the key differences between OpenAI's o-series reasoning models and the GPT series? How does the Codex IDE extension integrate with development environments? What are the key considerations for building production-grade OpenAI applications? What is the OpenAI Codex and API pricing model and how do you estimate costs? What is the OpenAI computer use capability and what does it enable? How do you use the OpenAI API for code generation, review, and debugging tasks? What is the role of system prompts (instructions) in OpenAI applications and how do you design them effectively? How do you handle context window management in long-running OpenAI applications?
Show more question and Answers...

Merge Mind: The Self Learning AI Code Review Bot Interview Questions

Comments & Discussions

Interviews Questions

About Javapedia.net

Javapedia.net is for Java and J2EE developers, technologist and college students who prepare of interview. Also this site includes many practical examples.

This site is developed using J2EE technologies by Steve Antony, a senior Developer/lead at one of the logistics based company.

Follow Javapedia updates

contact: javatutorials2016[at]gmail[dot]com

Kindly consider donating for maintaining this website. Thanks.

Copyright © 2026, javapedia.net, all rights reserved. · .

DMCA.com Protection Status