Claude Code

Sessions, turns, tool calls, and what happens when you type while Claude is working.
Author

Ran Li

Modified

November 9, 2026

Terms follow the Claude Code docs (commands). Terms that are not official are marked informal. Behaviors confirmed by hand are marked tested and link to the tidbit that tested them.

Session

Term Meaning
session One open Claude Code window, holding one conversation
context What Claude remembers in this session. /clear wipes it
turn One round: you send → Claude works → Claude replies. A turn is made of tool calls and reading any text you typed in the meantime. A skill call always starts a new turn
busy / idle (informal) Busy = a turn is running. Idle = no turn running. A background tool call does not keep Claude busy

Tool calls

Term Meaning
tool call One action inside a turn (Bash, Read, Edit, …). A turn can have many
foreground tool call The default. The turn waits for it to finish, so Claude stays busy. To force it, say “wait for it”
background tool call Runs on its own, outside the turn; the turn ends without it, so Claude is idle. A Bash command goes to the background when you ask, when you press Ctrl+B, when it times out, or when it is banned in the foreground (e.g. sleep)
AskUserQuestion A tool call that asks you something and does not finish until you answer. The turn stays busy while the question is pending (tested, tidbit)

Commands

Term Meaning
slash command Anything typed as /something. Either a built-in (/clear, /compact, /model) or a skill from a plugin or the user (/dev-log)
skill A custom slash command defined in a plugin or .claude/skills. Running one starts a new turn

Typing while Claude works

Two questions decide what happens to anything you type:

  1. Is Claude busy? Busy = a turn is running. Idle = no turn running. A background tool call does not count; a pending AskUserQuestion does.
  2. What did you type? Plain text, or a slash command.
Text Slash command
Idle runs now runs now
Busy joins the current turn, at the next gap between tool calls waits; runs after the turn ends

So mid-turn, text always runs before a queued slash command, whatever order you typed them.

Term Meaning
queue One list of everything you typed mid-turn, in the order you typed it
text, queued Handed to Claude at the next gap between tool calls, inside the current turn. So it is answered before the turn ends, and before any queued slash command — whatever order you typed them (tested, tidbit)
slash command, queued Waits in the list and runs after the current turn ends, as its own step. A pending AskUserQuestion keeps the turn alive, so a queued /clear waits for your answer (tested, tidbit)
text, during a pending question Taken as the answer to the question, not queued (tested, tidbit)
immediate commands A few built-ins never queue: /status, /tasks, /usage
send now Ctrl+Enter or Ctrl+X Ctrl+S sends queued input right away instead of waiting. Up from an empty input box takes queued items back into the box