OpenAI DevDay Agent Stack
Watch the best official OpenAI DevDay sessions and turn them into a practical agent, Codex, Apps SDK, and ChatGPT workflow.
What You'll Learn
- Understand the current OpenAI builder stack after DevDay 2025
- Choose between Codex, Agents SDK, Apps SDK, Workspace Agents, and ChatGPT agent mode
- Avoid legacy Agent Builder and Evals traps before the November 30, 2026 shutdown
- Design a practical agent workflow with context, tools, approvals, and eval loops
- Connect the workflow to FrankX guides, workbook exercises, and the GenCreator community path
Current Builder Brief
OpenAI DevDay 2025 set the direction for builders: code faster with Codex, ship agents through code, build apps inside ChatGPT, and evaluate production workflows. The important 2026 update is that Agent Builder and Evals are now legacy paths: OpenAI recommends Agents SDK for code-first workflows and ChatGPT Workspace Agents for natural-language team workflows. Use this path as the current FrankX map through the official talks, docs, and migration choices.
Turn DevDay into a build plan
Use the free OpenAI Agent Builder Workbook to pick one workflow, choose the right surface, define guardrails, and ship your first useful agent artifact.
Get the workbookBuilder Stack
Choose the right surface
Developer agent
Codex
General-availability coding agent for terminal, IDE, cloud, Slack, SDK, and team review workflows.
SourceCode-first agents
Agents SDK
Best fit when your application owns orchestration, tool execution, approvals, state, and observability.
SourceChatGPT apps
Apps SDK
Preview framework for building conversational apps with interactive interfaces inside ChatGPT.
SourceTeam agents
Workspace Agents
Trigger published ChatGPT workspace agents from your own systems and share repeatable work with teams.
SourceOperator workflow
ChatGPT agent mode
ChatGPT surface for complex online tasks, files, connectors, browser work, code interpreter, and scheduled runs.
SourceLegacy path
Agent Builder and hosted Evals
OpenAI is winding these down. Use migration guidance before basing a new production workflow on them.
SourceOfficial Timeline
What changed and why it matters
OpenAI DevDay 2025
DevDay introduced Apps in ChatGPT, AgentKit, Sora 2 in the API, Codex GA updates, GPT-5 Pro in the API, realtime mini, and image model updates.
Codex is generally available
Codex added Slack integration, Codex SDK, admin controls, and broader team workflows for local, IDE, cloud, and review loops.
Agent Builder and Evals winding down
OpenAI says Agent Builder and Evals will no longer be available from November 30, 2026; use Agents SDK or Workspace Agents instead.
DevDay 2026 applications are open
OpenAI lists DevDay 2026 for September 29 in San Francisco. This path will be refreshed after that event.
Course Videos
OpenAI DevDay 2025: Opening Keynote with Sam Altman
The official DevDay overview: ChatGPT apps, AgentKit, Codex GA, GPT-5 Pro in the API, Sora 2, realtime, and image model updates.
Developer State Of The Union
Official developer roadmap session covering Codex, gpt-oss, API direction, and how OpenAI expects builders to experiment and scale.
Shipping with Codex
How OpenAI engineers use Codex across local work, cloud delegation, refactors, and merged code review loops.
Context Engineering & Coding Agents with Cursor
Cursor shares context engineering patterns for agent harnesses, autonomous coding, and parallel agent work.
Orchestrating Agents at Scale
The DevDay session on production-grade agent design, orchestration, connectors, and enterprise deployment patterns.
OpenAI on OpenAI: Applying AI to Our Own Workflows
OpenAI shares how it spots and scales high-leverage internal use cases across sales, support, finance, and data workflows.
Evals in Action: From Frontier Research to Production Applications
Useful for evaluation principles, with a 2026 caveat: the hosted Evals product is legacy, so port the habit into code-first traces and tests.
Model Behavior: The Science of AI Style
Behind the scenes of ChatGPT tone, style, and interaction design. Important for builders designing user-facing agents.
Sora, ImageGen, and Codex: The Next Wave of Creative Production
Creative production workflow session for film, media, brand campaigns, and developer-built creative tooling.
Building with Open Models
Official DevDay session on gpt-oss and using open models alongside frontier models for flexible production systems.
Primary Sources
OpenAI
Official channel
Primary source for DevDay keynotes, launch sessions, and product roadmap videos.
OpenAI Developers
Official documentation
Use this for current docs, deprecations, migration guidance, and production checklists.
FrankX
Builder translation layer
Converts official announcements into a practical workbook for creators, operators, and AI architects.
Questions this path answers
What is the current OpenAI agent stack after DevDay 2025?
Use Codex for software work, Agents SDK for code-first product agents, Apps SDK for apps inside ChatGPT, Workspace Agents for repeatable team workflows, and ChatGPT agent mode for operator-style tasks.
Should I start a new workflow in Agent Builder?
No for production work. OpenAI announced on June 3, 2026 that Agent Builder and Evals are winding down and will be unavailable after November 30, 2026. Use Agents SDK or Workspace Agents instead.
What is the best first DevDay video for developers?
Watch Developer State Of The Union first for the platform map, then Shipping with Codex if you build software, or Orchestrating Agents at Scale if you design production agent systems.
Where does the FrankX workbook fit?
The workbook turns the official sessions into a concrete workflow: pick a use case, choose the surface, define tools and permissions, write the agent contract, add evaluation checks, and decide what belongs in the GenCreator community build queue.
Related Resources
Ready for Hands-On Practice?
These free videos give you the foundation. Our guides take you deeper with practical exercises.