Session

One bounded run of interaction with an agent. Starts empty, accumulates messages, tool results, and files read, and ends when cleared, closed, or compacted into a fresh session. The session is what fills the context window: if the context window is the box, the session is the stuff slowly filling it up. Work too large for a single context window must be split across sessions.

Usage:

"How long can one session run before it falls apart?"

"Depends on the work — a focused refactor stays sharp longer than open-ended research. Once the session bloats, hand off or compact, don't push through."