context-os: Open-source tool reduces Claude Code token consumption by 27-42%

context-os is an open-source local context optimizer that hooks into Claude Code automatically to reduce token consumption. The tool was created after hitting usage limits too frequently.

Setup and installation

One command setup: cargo install --path apps/cli followed by context-os init.

Features

• PreToolUse hook intercepts cargo test, npm build, cargo clippy, pytest, and similar commands, compressing the output before Claude sees it
• Auto-saves session state when you stop — next session loads your objective, git state, modified files, decisions, and failed approaches
• Injects compact context (branch, uncommitted files, objective) on every turn so Claude always knows where it is, even after compaction

Performance and specifications

• 27-42% reduction in token consumption depending on content type
• 7/7 gates passing in benchmarks
• 100% protected string recall
• Single Rust binary
• No cloud, no network calls

The tool won't fix the rate limit system itself, but it measurably reduces how many tokens you burn per session on bloated tool output.