Petr's AI School

Session

3 min read

One whiteboard per meeting. When the meeting ends, the board is photographed and stored, and the next meeting starts with a clean one. You can always pull out yesterday’s photo and carry on from it.

A session is one conversation with Claude Code in one project folder. Everything in it, your prompts, the answers, every file it read and every tool result, sits in the context window for that session and nowhere else. The harness saves the whole conversation to your disk as you go, so nothing is lost when you close the window.

Three things you do with sessions:

  • Start a new one. Type /clear. The whiteboard is wiped and the old session is saved. Do this every time you change to an unrelated task; see Attractor effect for why.
  • Come back to an old one. Type /resume and pick from the list. From the terminal, claude -c continues the most recent session in this folder and claude -r shows the picker before Claude starts.
  • Undo file changes. Before it edits a file, the harness takes a snapshot of it. Press Esc twice on an empty line and a rewind menu appears. Pick a point in the conversation and the files go back to how they were then. This works only for files it wrote or edited with its own editing tools. It cannot undo files moved or deleted by a command, an email it sent, or a change in a system outside your folder. Working safely has the full list.

Example

Monday you start a session in Documents\ai-school and work on a summary. Tuesday you open the same folder, type claude -c, and the summary conversation is back, with everything it read still in the context. You decide the summary took a wrong turn after the second draft. Esc Esc, pick the point after the first draft, and the file is back to that version.

Why it matters for you

Sessions take the fear out of trying things. A wrong turn costs a /clear. A file edit you regret costs an Esc Esc. Nothing you do in a session reaches outside the folder unless you asked for it and approved it.

One caution from Usage limits: coming back to a very long session is expensive, because the whole whiteboard is read again on every turn. For a new task, a new session is faster and cheaper than an old one.

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