Summary

Document the new OpenAI Account (ChatGPT) authentication path added to the OpenAI Chat Model node in n8n-io/n8n#29184.

Pages to update

• docs/integrations/builtin/credentials/openai.md
• docs/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.lmchatopenai/index.md

Details to cover

• OpenAI credentials now support both API key and OpenAI Account (ChatGPT) authentication for the OpenAI Chat Model node.
• OpenAI Account authentication lets users connect a ChatGPT/OpenAI account without entering an API key.
• The connection uses an OpenAI device-code login flow: open the OpenAI login page, enter the shown code, then continue in n8n.
• In the OpenAI Chat Model node, Authentication can be set to API Key or OpenAI Account.
• When using OpenAI Account authentication, n8n loads models from the ChatGPT/Codex account backend and defaults to gpt-5.4-mini.

Related

• n8n PR: feat(OpenAI Chat Model Node): Add OpenAI account OAuth support n8n#29184
• Community request: https://community.n8n.io/t/feature-oauth2-support-for-openai-chatgpt/285451