If you built a Gem in Gemini or a custom GPT in ChatGPT, it is about to be converted into something else on the vendor's timetable, not yours. Both companies say most of it carries over, but both also list things that do not, and those are the parts you will miss the next time you use it.
I read both help pages today (October 13, 2026). Here is what each one says, what does not make the trip, and what I would copy out this week.
What Google says about Gems
Google's help page "About the transition from Gems to skills" says that starting in November 2026, Gems will transition to skills for personal Google Accounts, and in 2027 for work and school accounts. The page gives March 2027 for Workspace business accounts and June 2027 for education accounts.
When Gems are removed, Google says it will automatically recreate your Gems as skills, along with supported knowledge files. A skill is a set of reusable custom instructions you call by typing a slash and its name in any Gemini chat, and Gemini can also apply one on its own when it thinks it is relevant.
The same page lists what is different:
- Skills do not work with Canvas or Deep Research yet, and most of the default tools a Gem could use (Create video, Create music, Guided learning) are not available to a skill.
- Files a Gem pulled from GitHub are not supported in skills, so they are not converted.
- Sharing a skill, and adding Google Drive files to one, are listed as coming in the coming weeks.
- You can make as many skills as you like but only 100 can be active at once.
So a Gem that was mostly instructions will be fine. A Gem that leaned on Canvas, Deep Research, a GitHub file or a share link to your team will come out the other side missing a piece.
What OpenAI says about custom GPTs
OpenAI's "Custom GPT retirement and migration FAQ" says custom GPTs are scheduled to retire on December 11, 2026 (February 11, 2027 for Enterprise workspaces with an approved deferral), and that the change affects all ChatGPT plans. Creators migrate each GPT to a plugin from My GPTs when the option shows up for their account.
What transfers, per the FAQ: the GPT's instructions become a skill inside the new plugin, connected apps are added as apps, and knowledge files are copied into the plugin's reference files. Your existing conversations with the GPT stay accessible after retirement.
What does not:
- The GPT's selected model does not carry over.
- Custom actions do not transfer. The FAQ says rebuilding one may need a custom MCP server.
- Sharing settings do not carry over. A migrated plugin starts private, and the people who used your GPT do not get access to the replacement automatically.
- Migration uses the latest published version, so drafts and unpublished edits are left behind.
- After you migrate, the original GPT becomes read-only.
OpenAI also says plainly that a migrated plugin may respond differently, and suggests saving a few familiar prompts so you can compare the results before and after.
The pattern in both
The two migrations are not the same, but the same three things hold in both.
The instructions survive. In both cases the text you wrote is the part that converts cleanly.
The wiring does not. Tools, actions, model choice and sharing are the parts each vendor is changing, and they are the parts you cannot export as text.
You do not pick the date. Google gives a month, OpenAI gives a day, and both pages say the timing can differ by account.
That tells you where the work is. The instructions are the asset, and a copy of them in a plain file is worth more than whatever container they sit in this quarter.
What I would copy out this week
This takes about 20 minutes for a handful of assistants.
- Open each Gem and each GPT you still use and paste its name, description and full instructions into a text or markdown file. One file per assistant.
- Download the knowledge files into the same folder. Google's own steps for recreating a Gem as a skill start with exactly this.
- Write down what it depended on that is not text: which model, which tools (Canvas, Deep Research, actions, connected apps) and who it was shared with.
- Save three or four prompts you run often, with an answer you were happy with. OpenAI recommends this for testing a migrated plugin and it works just as well for a skill.
- If a GPT has unpublished edits you care about, publish them before you migrate. Publishing does not require sharing it publicly.
- After the conversion, run the saved prompts and compare. Fix what changed before you rely on it.
One useful detail on the Google side: the help page says you can upload a SKILL.md file to bring in a skill made on another platform, in the Gemini web app and Mac app for now. OpenAI's migration also turns your instructions into a skill. Both vendors are converging on instructions kept as a file, which is one more reason to keep your own copy as one.
Where GPTree fits
I built GPTree, so read this part knowing that. GPTree does not import Gems or GPTs. What it has is personas, and a persona is three plain fields: a name, an optional description, and the instructions. The text you copied out in step 1 pastes straight into the instructions box. You pick a persona per message from the composer, and personas apply per branch, so you can send the same question down two branches under two personas and compare the answers. On the Free plan you can keep one persona of your own, and the built-in ones do not count toward that.
That is not a migration tool and I am not selling it as one. The point of the list above is the same wherever you paste the result.
The next step
Pick the one Gem or GPT you would miss most, and copy its instructions and files into a folder today. Everything else on the list can wait until the migration option shows up in your account.
