Claude Code Token Economics

What fills the context window, and where the levers are

Claude Code Token Economics What fills the context window, and where the levers are Every turn resends this Fixed Prefix · system + CLAUDE.md + MCP tools · Every turn resends this Fixed Prefix system + CLAUDE.md + MCP tools Conversation History · /clear, /compact, /rewind · Every turn resends this Conversation History /clear, /compact, /rewind Claude Code Session · context window · Architecture component Claude Code Session context window Subagents · own context, returns summary · Architecture component Subagents own context, returns summary Claude API · cache write 1.25x / read 0.1x · Architecture component Claude API cache write 1.25x / read 0.1x Billing Path · Subscription / Console / Bedrock · Architecture component Billing Path Subscription / Console / Bedrock /usage /context /insights · measure before optimizing · Architecture component /usage /context /insights measure before optimizing stable - cacheable grows per turn input tokens usage delegate heavy reads inspect Legend Backend Database Cloud External

Architecture diagram • Built with Archify • Create yours ↗ • Hover to trace • R route • Click to focus • +/− zoom • M radar • T theme • E export