StateSync and /compact

What compaction does

Claude Code sends the whole conversation on every call. Compaction swaps it for a summary, either automatically when the context is nearly full, or when you run /compact with an instruction for what to keep.

• Between tasks it is exactly right. The old transcript is dead weight. /clear is better still if nothing carries over.
• Mid-task it hurts. The transcript is the working state, so the agent reads again what it already had. On a short chat the summary can cost more than it saves.

Compaction makes each later call smaller. It does not make there be fewer of them.

What StateSync does

StateSync runs Claude Code on your own account and acts as each tool result comes back. A command that returns hundreds of lines usually has a few that decide the next edit. StateSync carries those forward, and the whole result is one call away if the agent needs it.

That changes what compaction cannot: how much each result adds, and how many calls the work takes. On the run, fewer calls was most of the saving. 30 percent fewer tokens is 25 percent fewer requests multiplied by a 6 percent smaller average request. The requests are most of it.

Measured by us on the TokenBench 55-task set, on Claude Code with Claude Sonnet 4.6, with one StateSync run per task against the plain agent's earlier runs. See every task, losses included.

Picking a project back up

A compaction summary lives in one session of one agent. StateSync keeps a lighter record of the project's recent tasks and attempts, and it is there the next time you open the project, in whichever agent you pick. It helps most when you are trying approaches. It does not replace reviewing the work.

Side by side

Using both

StateSync does not turn compaction off, and you should keep compacting at a switch. The conversation just grows more slowly inside a task, so automatic compaction comes later or not at all. StateSync was cheaper on 53 of 55 tasks.

Very short tasks save the least. On the 18 tasks the plain agent finished in under two minutes, the cost saving was 27 percent, against 50 percent on longer ones. They are cheap already, and compaction never runs on them either. The free fixes are in the Claude Code guide.