Agentic Brownfield Coding (ABC)
This Claude Code plugin repo assists complex software projects in their first steps towards agentic coding:
- Scaffolding and gradually augmenting an existing codebase with an efficient harness setup.
- Learning controlled agentic development workflows with a human-in-the-loop mindset.
Background
The ABC project arose from a dissatisfaction with the built-in /init command of Claude Code,
which tries to derive agent instructions by scanning the existing repository content.
Especially for large and complex codebases, this approach generally leads to poor results,
as summarized comprehensively by Google engineer Addy Osmani.
Another major inspiration was Dexter Horthy's work on AI in Complex Codebases
which has become known for the RPI workflow. Together with co-founder Kyle Mistele, he promotes disciplined harness engineering
and controlled interactive workflows to rein in the non-determinism of coding agents.
Details about the concrete hypotheses and design philosophy behind the ABC solutions
can be found in the full length background essay.
System Requirements
- Linux — natively supported, requires jq installed
- macOS — supported (agent will substitute GNU-only utilities), requires jq installed
- Windows — requires Git Bash and jq on PATH
Installation
claude plugin marketplace add ralfstrobel/agentic-brownfield-coding
claude plugin install abc-init@agentic-brownfield-coding
claude plugin install abc@agentic-brownfield-coding
[!TIP]
The separate init plugin is only required once for scaffolding and can be uninstalled after.
Uninstallation
claude plugin uninstall abc-init@agentic-brownfield-coding
claude plugin uninstall abc@agentic-brownfield-coding
claude plugin marketplace remove agentic-brownfield-coding
Usage
Scaffolding
These commands should be run using Opus as they require complex code base reasoning.
-
/abc-init:standalone – Create initial Claude Code artifacts for single-application projects.
-
/abc-init:monorepo – Create initial Claude Code artifacts for monorepo projects (multiple sub-projects/teams).
-
/abc-init:bashless – (Optional) Create MCP tool wrappers for relevant CLI commands
and disable the Bash tool, in order to prevent inefficient tool choice and harness bypassing via shell.
-
/abc-init:headless – (Optional) Scaffold a driver script for batch execution
of headless agent micro-sessions (repetitive file migrations, doc generation, component analysis...).
[!IMPORTANT]
Content generated by the scaffolding skills includes executable shell scripts (statusline, hooks, MCP server)
that run automatically as part of the Claude Code harness — review and safeguard these files against manipulation!
[!NOTE]
The scaffolding result is not a turnkey solution and requires thorough testing for every new codebase.
As even frontier models sometimes struggle to follow long workflows,
you may want to read the skill yourself and compare it against your output.
Agent instructions produced by agents are notoriously too verbose and often need to be condensed.
Workflows
These commands provide basic examples for agentic workflows during code development.
/abc:build – Controlled agentic development workflow with explicit steps and human-in-the-loop checkpoints./abc:learn – Codify implicit codebase knowledge from current conversation as agent context files.
[!NOTE]
While the commands can be used productively, their main purpose is to be illustrative.
You are encouraged to use them as templates to create your own custom workflows for your needs.
The further reading section below links to various sources for advanced workflow concepts.
Agents
These files provide basic examples for tasks that can easily be delegated to optimized subagents.
FAQ
Why only Claude Code?
At the time of writing, Claude Code is the only major coding assistant to support all artifacts
that form the base of the ABC solutions – primarily custom subagents, commands and hooks.
As long as no suitable standard for these solutions is adopted by a majority of assistants,
the focus will likely remain on Claude Code due to time constraints.
Further Reading
Shoutouts and Related Projects
- superpowers is a well-known plugin for enhanced workflows.
- GET SHIT DONE is a relatively light-weight spec-driven approach for iterative development.
- Think Upfront provides a robust workflow for human-first agentic development.
- Cole Medin's AI Workshop teaches his method for building an AI-first development setup.
Directories
License
This work is licensed under Apache-2.0 on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
Attribution via a link to this repository is appreciated. Feedback and contributors are welcome.
