Agent session
Also called Thread, Conversation
One run of an agent from its first message to its last, with its own growing context. When it ends, that context is gone unless you resume it, or the agent wrote something to a file.
An agent doesn't remember yesterday. Whatever a session decided and didn't write into the repo is lost to the next one, so a good session leaves files behind. Keeping to one task per session also keeps one job's clutter out of the next.
Say it to your agent
“Before we finish this session, write what you learned, what is left and the next step to docs/progress.md, and commit it. The next session will start from that file and nothing else.”