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Gaffer

Install

Gaffer runs KurrentDB projections locally so you can develop, test, and debug them without standing up a database. This section installs the CLI, walks through writing a first projection end-to-end, and shows how to attach a debugger.

Install the CLI

Section titled “Install the CLI”
Terminal window
npm install -g @kurrent/gaffer

Requires Node.js 22 or later. Platform binaries are pulled in as optional dependencies.

Verify:

Terminal window
gaffer version

If you install the VS Code extension first and skip this step, the extension surfaces a status bar prompt that will run the install for you.

Integrations

Section titled “Integrations”
  • VS Code extension: run/debug lenses on gaffer.toml, breakpoint debugging, and projection-API autocomplete. See the extension.
  • AI assistants (Claude Code, Cursor, Continue, Copilot): point them at gaffer mcp for scaffolding, debugging, and the projection API. See MCP.