Gemini CLI history: onboarding an engineer

How does someone new find out why this code was written this way?

Why this is hard

A new engineer inherits decisions, not just code. When a large share of the codebase was written with AI, the reasoning lives in conversations rather than in commit messages — and those conversations are on other people's laptops, if they still exist.

What Gemini CLI specifically does to you here

Checkpoints capture conversation state alongside a shadow git repository of snapshots, which is unusually good for reconstructing how something was built — for as long as the 30-day window holds, which is shorter than any onboarding.

ls ~/.gemini/history/ 2>/dev/null | head

Where Gemini CLI keeps this in the first place: ~/.gemini/tmp/<project_hash>/chats/. general.sessionRetention deletes sessions after 30 days, and cleanup is enabled by default.

What a working answer looks like

A working answer means the reasoning behind a file is reachable from the file, by someone who was not there when it was written.

Start by measuring what you have. npx promptwake doctor reports what every AI tool on the machine is holding and how much of it sits inside a deletion window — no account, writes nothing, sends nothing anywhere. If the conclusion is that the record should not depend on one laptop, that is what PromptWake captures: prompt, response and the resulting diff, local by default and synced into a shared timeline on the paid tiers.