arc-copilot

A local-first run cache for the GitHub Copilot CLI. ARC watches a coding agent solve something in your repo, keeps the route that actually worked, and hands it back before the next similar run.

Install

macOS (Apple silicon or Intel), Node 22+:

npm i -g arc-copilot
arc setup
arc split

Linux and Windows builds are coming next.

What it does

arc split opens Copilot next to a live ARC pane in one terminal. As Copilot works, ARC keeps only the verified steps from runs that finished and proved themselves, then injects a compact note before the next similar prompt. It does not change Copilot, store transcripts, or run as a daemon.

A kept capsule is the route, not a transcript:

Capsule: Run the integration test suite
First move: bring up the test db, then run the suite
Reuse when: running or fixing integration tests
Command shapes: docker compose up -d test-db
                pnpm test:integration
Validation probe: "Test Files  12 passed (12)", exit code 0

Common commands

arc split      Copilot plus the live ARC companion pane
arc ui         the standalone dashboard
arc status     injection state, capsule count, recent activity
arc capsules   list kept capsules
arc doctor     plugin, runtime, and split-view readiness

Implementation

The product is the native Rust binary in rust/ — that is what the npm package installs and runs. src/ is a TypeScript reference implementation kept for differential testing: tests/rust_parity.rs runs the Rust binary and the TypeScript side by side and asserts they produce identical behavior. The TypeScript is never shipped or executed at runtime.

License

Apache-2.0. See LICENSE.

Built and maintained by Ayub Mohyadin.