One binary, no runtime.

Requirements

• git — the store is a Git repository and every change is a commit.
• gh — used for authentication and PR operations. Companion reads a token fromCOMPANION_FORGE_TOKEN, forge.token, or gh auth token.
• Go 1.27.3+ — only if you install with go install or build from source.
• Universal Ctags (optional) — adds symbol indexing for non-Go languages. The first line of ctags --version must read Universal Ctags.

Homebrew

The shortest path on macOS and Linux. The formula installs the companion binary and generates shell completions for bash, zsh, and fish.

The formula is named repo-companion and installs the companion command. The fully qualified name repocompanion/tap/…taps the repository and trusts only this formula, not everything in the tap. brew upgrade repo-companion moves it to the next release.

Covered platforms: macOS on Intel and Apple silicon, Linux on x86_64 and arm64. Windows has no formula — use a prebuilt archive or go install.

Prebuilt binary

Every release publishes archives for macOS, Linux, and Windows. Each contains LICENSE, NOTICE, THIRD_PARTY_NOTICES.md, and SECURITY.md, alongside checksums.txt.

gh release download v0.2.0 --repo repocompanion/companion \
  --pattern 'companion_0.2.0_darwin_arm64.tar.gz'
tar -xzf companion_0.2.0_darwin_arm64.tar.gz
sudo mv companion /usr/local/bin/
companion version

On Linux, move the binary to /usr/local/bin or ~/.local/bin. On Windows, extract the zip and add its folder to PATH. Verify a download against checksums.txt with shasum -a 256 -c checksums.txt.

With go install

The fastest path if you already have a Go toolchain. companion version reports the module version for go install builds and the release version for downloaded archives.

Build from source

git clone https://github.com/repocompanion/companion.git
cd companion
make build        # ./companion
make test

The build produces ./companion in the checkout. Nothing is installed outside the repository.

Verify the install

companion version
companion doctor --strict

doctor checks git, the store, authentication, the local mirror, the state directory, and the code providers. --strict turns warnings into a non-zero exit, which makes it usable in CI.

Create your docs store

The store is one private GitHub repository. It can start empty: companion initcreates the initial main commit with .companion/registry.yaml when the repository has no commits.

companion init --remote [email protected]:your-org/docs-store.git
companion context
companion guidance "implement an SQS consumer in Go" --lang go

context shows the resolved project, team, languages, and the source of each value.guidance ranks the patterns, ADRs, and standards that apply to a task, and attaches reference implementations when the code repository is available.

Recommended repository layout, branch protection, CODEOWNERS, and docs CI are covered in Store setup.

Connect a coding agent

The MCP server runs over stdio. No port is opened and no daemon is started.

Claude Code

Cursor

Add the server to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "companion": {
      "command": "companion",
      "args": ["mcp"]
    }
  }
}

Agents without MCP

Export the same context as files the agent can read. agents-md writes a managed block between <!-- companion:begin --> markers, so repeated exports stay idempotent.

companion export agents-md --output AGENTS.md
companion export llms-txt --output llms.txt
companion export context --format markdown --output context.md

Next steps