lean-ctx Ships Context OS for AI Development: 60–99% Token Reduction via MCP Server + Shell Hook

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lean-ctx is a Rust-based 'Context OS' that sits between AI coding tools and LLMs, compressing file reads by 60–99% and shell output by 60–95%. Cached re-reads cost only 13 tokens. It works as a standard MCP server with 49 tools across 10 read modes using Tree-sitter AST parsing for 18 languages. Recent updates added CLI/MCP feature parity ensuring both paths trigger identical side effects: session tracking, Context Ledger updates, heatmap recording, and knowledge consolidation. Compatible with Claude Code, Cursor, Copilot, Windsurf, and Codex.