Which Claude Code session is using my limit?

The usage screen shows a total. To find the session responsible, you have to look at the per-session numbers in the logs Claude Code keeps on your Mac.

What to look for

Three numbers per session tell you almost everything:

• Tokens today. The plain total. One session is usually far ahead of the rest.
• Size per turn now. How much the session re-reads every time it replies. This is the number that makes a session expensive from here on.
• Share used by subagents. If most of a session's tokens were spent by helpers, the session you are looking at is not really the problem; the fan-out is.

Doing it by hand

Claude Code writes one log file per session under ~/.claude/projects/. Each reply in the file records how many tokens went in and out. Adding those up per file gives you the per-session totals. Two traps:

• Subagent logs are in a subfolder. Each session's helpers write to <session>/subagents/. If you only read the top-level files you will miss most of a heavy day.
• Replies are written more than once. A single reply appears on several lines, once per part of the reply, each carrying the same token counts. Count each reply once or your totals come out roughly double.

More detail in where Claude Code keeps its logs.

Doing it without the work

Cost Doctor reads those same files and shows the list for you: today's sessions ranked by tokens, each named by its title, with its size per turn, where it started, and one line of advice. It includes the subagent logs and counts each reply once.

What to do once you have found it

• If the session is carrying a lot of history, compact it or start fresh.
• If it started large, trim the connectors and plugins.
• If subagents did most of the spending, rein in the fan-out.