ChatGPT memory full? How it works and how to add Dexio

Updated 5 min read

ChatGPT remembers details about you across chats, in ways OpenAI describes in its help pages, including what happens when memory fills up. Dexio is a different kind of agent memory: a wiki of linked markdown pages that ChatGPT reads and writes as a custom MCP server, and that your other agents share.

What ChatGPT remembers on its own

With Memory on, ChatGPT can remember preferences and details from your chats. Depending on your plan and region, it can also draw on saved memories, custom instructions, files in Library and connected apps. It does not keep every detail; it decides what is relevant to each response.

The two main settings:

  • Saved memories are details you ask ChatGPT to remember, or that it saves as useful context. They are stored apart from your chats, so deleting a chat does not delete a memory saved from it.
  • Reference chat history lets ChatGPT use relevant parts of past conversations. What it keeps from them can change as ChatGPT updates what is most useful to remember.

You manage both in Settings, then Personalization, then Memory. The memory summary there is a high-level view and may leave details out. You can also ask ChatGPT what it remembers about you. Temporary chats do not create or update memories.

When memory is full

OpenAI says there is no separate storage limit for what ChatGPT can reference through chat history, so a full memory concerns saved memories. Depending on your plan, saved-memory controls include automatic prioritization, which OpenAI describes as keeping the most relevant memories in front so saved memories are less likely to reach capacity.

To make room yourself, open Settings, then Personalization, then Memory, and delete saved memories you no longer need. Deleting one stops ChatGPT using it for personalization, but it does not remove that information from past chats.

ChatGPT’s memory is context about you, kept in your ChatGPT account. A Dexio wiki holds full pages about your work: how a system works, what was decided and why, what the research found. There is no limit on the number of pages, you can read them yourself at app.dexio.wiki, and other agents read and edit the same pages.

Connect ChatGPT to Dexio

ChatGPT adds Dexio as a custom MCP server from Plugins. Do it on chatgpt.com in a browser, since the phone apps can’t add custom servers. On a Business, Enterprise or Education workspace, an admin or owner may have to add it.

  1. In ChatGPT, open Plugins, click +, then Add custom MCP server.
  2. Name it Dexio and paste https://app.dexio.wiki/mcp as the server URL.
  3. Choose OAuth for authentication, tick I understand and want to continue and click Create as a plugin.
  4. On Dexio’s page, sign in or create a free account, then click Allow access.
  5. If Dexio isn’t installed yet, install it from Plugins, under Personal. Then in a new chat, type @ and pick Dexio.

Dexio shows the same steps at app.dexio.wiki/settings/agents?connect=chatgpt.

Check that it works

In a chat with Dexio selected, ask:

What’s in my Dexio wiki?

ChatGPT calls Dexio’s list_pages tool and lists your pages. For actions that change data, ChatGPT may ask you to confirm first, depending on the app’s permissions and the action.

Then have it write your first pages:

Put what you know about the project we’re working on into my Dexio wiki, as a few pages linked together. If you don’t know enough yet, ask me first.

Open app.dexio.wiki. The pages show up in the graph, where every page is a dot and every link a line.

Tell ChatGPT to use the wiki

ChatGPT takes standing instructions from two places:

  • Custom instructions apply to all your chats. On the web, open Settings, then Personalization, check that Enable customization is on, and write in the Custom Instructions field. Plus, Pro, Business, Enterprise and Education plans allow up to 5,000 characters.
  • Project instructions apply only within one project, and override your custom instructions there. Open the project’s ••• menu, then Project settings.

Something like this works in either:

Before answering questions about my work, search my Dexio wiki. When we settle a decision or work something out, write it to the page that covers it, and link related pages.

OpenAI’s help says choosing an app applies to the message you send it with, not the whole conversation. When a later message needs the wiki, type @ and pick Dexio again, or mention it by name.

Troubleshooting

  • Plugins has no Add custom MCP server option. It only appears on chatgpt.com in a browser. On Business, only admins and owners can add a custom MCP server, so ask your workspace admin; our ChatGPT Team plan guide covers who holds those roles. If your settings still show Developer mode (Settings, then Security and login), turn it on and look again.
  • ChatGPT reads the wiki but will not write to it. OpenAI’s two descriptions differ here. Its developer docs say ChatGPT supports read and write tools from a custom MCP server and name no plans. Its help center gives full MCP support, write actions included, to Business, Enterprise and Education, and says Pro connects with read and fetch only. We haven’t tested which plans can write, but if writes are blocked on yours, this is the likely reason. ChatGPT also asks you to confirm each write action unless you let it remember your choice for that conversation.
  • ChatGPT answers without the wiki. Type @ and pick Dexio, or mention Dexio in your message.
  • You want to disconnect ChatGPT. In Dexio, Settings, then Agents lists every connected app, when each was last used, and revokes any of them.

Your other agents share the same wiki

Claude, Claude Code, Codex, Cursor, Hermes, OpenClaw and any other MCP client connect to the same wiki at the same address. Agents that can run commands set themselves up from one message. What ChatGPT writes down, Claude Code can read the next time you open a terminal.

Every agent names itself on every change, so a page’s history shows which agent wrote what, and the person behind it. Setup for each agent is in the guides, and the Claude Code guide is a good next one.

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