CopperMCP

CopperMCP is a local-first, open-source PCB automation platform designed for deterministic routing, MCP-based tools, and optional AI policy plugins.

Why this project exists

Existing open autorouters provide useful geometry and negotiated-congestion baselines, but there is no broadly adopted open platform that combines reproducible routing, safe agent tools, learned policy hooks, KiCad-native workflows, and transparent benchmarks. CopperMCP is building that layer without putting an LLM in charge of electrical correctness.

The non-negotiable boundary is simple:

• AI may interpret constraints and propose net ordering, corridors, cost weights, and repairs.

• Deterministic code owns geometry, connectivity, DRC, provenance, and file mutation.

• Generated work remains an immutable candidate until a user validates and explicitly applies it.

Related MCP server: KiCad MCP Server

Current capabilities

• Read-only, bounded inspection of documented .kicad_pcb files.

• Workspace confinement, including protection against parent-path and symlink escapes.

• SHA-256 board revisions and versioned JSON schemas.

• Immutable Board IR 0.1.0 with exact integer units, typed constraints, canonical digests, and a bounded fail-closed converter for a documented KiCad subset.

• Fixed-argument KiCad CLI DRC with source, time, size, schema, and stale-context guards.

• Candidate-manifest validation and correctness-first comparison.

• Bounded integer A* candidates for one two-pad net on a documented rectangular Board IR subset, with independent lattice, search, and obstacle-work ceilings, plus replay-bound serialization to new disposable KiCad bytes when every modeled source geometry object has a native UUID/tstamp. This synthetic-domain reference has no durable export, authoritative candidate-bound DRC evidence, preview, MCP route tool, source mutation, or apply path.

• MCP tools and a stable CLI over the same application services.

• Professional CI, CodeQL, dependency auditing, release automation, issue forms, and project ledgers.

See the roadmap for routing and KiCad IPC milestones.

Audio Board Lab

The Audio Board Lab publishes open KiCad designs that exercise CopperMCP against real audio-PCB workflows. Lab #001 — CopperTone is a 52 mm × 30 mm, two-layer OPA1656 stereo line-buffer preview with checked-in board source, BOM, Gerbers, drill files, STEP assembly, renders, constraints, provenance, and a one-command KiCad 10 validation gate. The recorded KiCad 10.0.5 run reports 0 DRC violations, 0 unconnected items, and 0 unrouted items.

CopperTone is a board-first engineering preview, not a fabrication-approved or electrically validated product. It has no source schematic, ERC, assembled prototype, or audio measurements yet; its hardware sources are separately licensed under CERN-OHL-S-2.0. CopperMCP inspected and validated the artifact but did not autoroute or apply its copper.

Research direction

The open autorouter research package compares current open routing tools and records the evidence behind CopperMCP's CPU-first roadmap: exact integer geometry, A*/maze search, PathFinder-style negotiated congestion, conflict-aware parallelism, bounded exact repair, profiled GPU kernels, and optional typed ML policy hooks. Deterministic code and KiCad validation remain the authority for every copper result.

Quick start

Prerequisites: Python 3.11 or newer.

python3 -m venv .venv
source .venv/bin/activate
python -m pip install -e ".[dev,security]"
make check

Inspect a board without modifying it:

copper-mcp --workspace /absolute/path/to/boards inspect example.kicad_pcb

Run authoritative KiCad DRC and return only bounded aggregate evidence:

export COPPER_MCP_KICAD_CLI=/absolute/path/to/kicad-cli  # optional when discoverable
copper-mcp --workspace /absolute/path/to/boards drc example.kicad_pcb

The DRC adapter never accepts arbitrary KiCad flags and never requests zone refill or board save. It mirrors the board, matching project/rule files, and workspace-local KiCad library assets into a private snapshot; bounds that snapshot cumulatively; limits report growth in the child process; and rejects results when any captured context changes during execution. Context discovery also has file count and wall-clock ceilings, and the pre-run byte snapshot is released before KiCad starts. Keep KiCad projects and their project-relative libraries self-contained below the configured workspace. DRC-clean is not a substitute for electrical, signal-integrity, manufacturability, or hardware review.

Start the local MCP server over standard input/output:

export COPPER_MCP_WORKSPACE=/absolute/path/to/boards
copper-mcp-server

Example MCP client configuration:

{
  "mcpServers": {
    "copper-mcp": {
      "command": "copper-mcp-server",
      "env": {
        "COPPER_MCP_WORKSPACE": "/absolute/path/to/boards",
        "COPPER_MCP_TRANSPORT": "stdio"
      }
    }
  }
}

Never place provider keys or proprietary board contents in committed MCP configuration. See .env.example and the security policy.

Architecture

KiCad IPC / board files        MCP clients / CLI
           \                       /
            \                     /
             Board IR + services
                      |
           deterministic router contract
                      |
          immutable candidate + provenance
                      |
        internal checks + authoritative KiCad DRC
                      |
               explicit user apply

MCP is an external adapter, not an internal dependency of the routing engine. The reference core is currently Python so it is executable and reviewable everywhere; performance-critical Rust or GPU backends will implement the same stable routing contract. Read the architecture overview and ADRs before changing this boundary.

Documentation

• Project charter

• Architecture

• Board IR and KiCad adapter contract

• Deterministic A* baseline

• MCP contract

• Security and threat model

• Development guide

• Autorouter research

• Audio Board Lab

• Roadmap

• Release process

• Project ledgers

Contributing

Contributions are welcome, particularly reproducible boards, geometry tests, routing algorithms, KiCad integration, benchmark infrastructure, and documentation. Please read CONTRIBUTING.md, the Code of Conduct, and existing ADRs first.

Private or customer PCB designs must not be attached to public issues. Use minimal synthetic reproductions or sanitized open designs.

Versioning and status

CopperMCP follows Semantic Versioning and Keep a Changelog. Before 1.0.0, minor releases may intentionally change experimental contracts with migration notes. See CHANGELOG.md and the release ledger.

License

Except where a directory says otherwise, CopperMCP software and documentation are licensed under the Apache License 2.0. Audio Board Lab hardware sources carry their own clearly identified open-hardware license; CopperTone uses CERN-OHL-S-2.0. Test fixtures and contributed datasets must include compatible provenance and licensing metadata.