You had the conversation. You remember having it. You even remember what the agent found: the one invoice number that was wrong, the paragraph that finally read well, the reason the import wrote duplicate rows. Now you want it back, and the app shows you nothing.

This is not your memory failing. It is the app’s. Most AI tools forget on a schedule, and the schedule is not written where you would look.

Claude Code: 30 days, then gone

Claude Code stores every session as a transcript under ~/.claude/projects/. At startup it deletes transcripts older than 30 days. The setting is cleanupPeriodDays; 0 is not accepted, so “keep for ever” means “set a very large number”. The sweep also takes the tool results, the plans, and the file history that belong to the session. (Claude Code docs: the Claude directory)

Even inside the 30 days you may not find a session. claude --resume lists only sessions from the current folder; sessions from other folders, non-interactive runs and loop sessions are hidden unless you press Ctrl+A or know the id. (Claude Code docs: sessions) And the transcript format “is internal and changes between versions”, so a backup script that worked last month may not work today.

Claude.ai: your copy is not their copy

In the Claude apps, chats stay until you delete them. Since October 2025 you choose: allow training, and de-identified copies are kept for five years; refuse, and the standard period is 30 days. A chat you delete disappears at once and is purged within 30 days. (Anthropic privacy centre, consumer terms update)

So the long memory is theirs, for training. Yours is whatever you have not deleted on an account you still have.

ChatGPT: “temporary” means 30 days

ChatGPT keeps chats until you delete them, and a deleted chat is purged within 30 days. A “temporary chat” is not in your history, but a copy is kept for up to 30 days anyway. (OpenAI help centre) For about five months in 2025 a US court order forced OpenAI to keep every deleted and temporary chat; the order ended on 2025-09-26, and the logs from that window are still held. (Engadget)

The others

Gemini app auto-deletes your activity after 18 months by default. (Google help) Gemini CLI deletes sessions after 30 days, on by default. (Gemini CLI docs)
Cursor does not delete local chats so much as lose them: a failed migration or a changed workspace id leaves them on disk but invisible. Cloud-agent transcripts have no retention limit and no delete button. (Cursor forum)
OpenCode keeps everything, but its session picker showed only the last 30 days, and the request to change that was closed “not planned”. (OpenCode issue #16733)
GitHub Copilot CLI uploads your local sessions to GitHub.com by default. (GitHub docs)
Jean, the app Splitkick is built on, deletes archived sessions after 7 days unless you set archive_retention_days to 0. (Jean docs)

None of this is hidden. It is in the docs. It is also not where you look when a conversation is gone.

What a second brain needs

A second brain has three properties a chat app does not give you:

It is yours. Files on your disk, in a format you can read without the app.
It does not expire. Nothing is deleted because a counter ran out.
You can find things. Search across every project, not the current folder.

What Splitkick does

Splitkick keeps its own copy of every message, plan and result in its session files on your disk. It does not read them back from Claude Code’s transcripts, so the 30-day sweep in Claude Code does not touch your history in Splitkick. Search works across all projects.

One thing we inherited from Jean and changed: archived sessions were deleted after 7 days by default. Since Splitkick 1.0 the default is never, and the import from Jean switches the 7-day setting off. Archive hides; only you delete. Where the files are and how to back them up: Files on disk.

If you want to keep what you already have in Claude Code: set cleanupPeriodDays to a large number in ~/.claude/settings.json today. Then come back for the rest.

Your AI app is your second brain. It has Alzheimer's.