GateFlow Plugin for Claude Code

AI-powered hardware development platform — design, verify, synthesize, and deploy working RTL with natural language. Supports SystemVerilog, Verilog, and VHDL across the full open-source FPGA toolchain.

Loving hardware doesn't have to be gatekept.

GateFlow brings professional hardware development tooling to Claude Code. Describe what you want to build — including your target board — and get lint-checked, simulated, formally verified, synthesis-ready code with correct pin assignments.

Whether you're writing your first always_ff, formally proving your FIFO never overflows, or synthesizing an SPI controller for your Arty A7, the tools should help you, not fight you.

We can't wait to see what you create. ❤️

• Quick Start — Install in one command
• Usage — Natural language, skills, and commands
• Features — What makes GateFlow different
• Components — All skills, agents, and commands
• Individual Downloads — Grab single components
• Cross-Tool Compatibility — Use with Codex, Cursor, Copilot, Cline, Windsurf
• Configuration — Project-specific settings
• Project Structure — Repo layout
• Troubleshooting — Common issues
• Updates — Changelog
• Releases — Detailed release notes
• Contributing | License | Links

Quick Start

Install

# Option 1: Marketplace (recommended)
claude plugin marketplace add codejunkie99/Gateflow-Plugin
claude plugin install gateflow

# Option 2: Clone and run
git clone https://github.com/codejunkie99/Gateflow-Plugin.git
claude --plugin-dir ./Gateflow-Plugin/plugins/gateflow

# Option 3: Persistent (add to ~/.claude/settings.json)
git clone https://github.com/codejunkie99/Gateflow-Plugin.git ~/.claude-plugins/gateflow-marketplace

For Option 3, add to ~/.claude/settings.json or .claude/settings.json:

{
  "plugins": [
    "~/.claude-plugins/gateflow-marketplace/plugins/gateflow"
  ]
}

Prerequisites

Verify & Update

# Verify installation
/gf-doctor

# Update (marketplace)
# /plugin → Marketplaces → gateflow → Update → restart Claude Code

# Update (local)
# git pull in your plugin folder, then restart Claude Code

Usage

Just Ask

GateFlow understands context. Describe what you need in plain English:

"Create a FIFO and test it"
 → Generates FIFO, creates testbench, runs simulation, fixes issues, delivers working code

"Formally verify that the FIFO never overflows"
 → Generates SVA properties, configures SymbiYosys, runs proof, reports results

"Synthesize my design for the iCEBreaker board"
 → Runs Yosys synthesis, reports LUT/FF/BRAM usage, generates constraint file

"Add an SPI controller to my project"
 → Installs verified SPI master IP block with testbench and formal proofs

"What pins does the Arty A7 PMOD JA have?"
 → Looks up curated board database, shows pin assignments with I/O standards

"Why is my output X?"
 → Analyzes code, traces signal path, identifies root cause

"Plan a DMA controller"
 → Creates detailed design plan with block diagrams, FSMs, interfaces, verification strategy

Skills (Auto-Activating)

Skills activate automatically based on context:

Commands

Local CLI

GateFlow also ships with a command-first local CLI for plugin maintenance and
agent creation:

python3 tools/gateflow_cli.py status
python3 tools/gateflow_cli.py agents list
python3 tools/gateflow_cli.py agents create "CDC Reviewer" \
  --role "clock-domain crossing reviewer" \
  --description "Reviews synchronizers and CDC constraints"
python3 tools/gateflow_cli.py shell
python3 tools/gateflow_cli.py tui

Inside the TUI, press a to create a new agent without leaving the dashboard.

Example Session

$ claude --plugin-dir ./Gateflow-Plugin/plugins/gateflow

You: Create a parameterized counter with enable and test it

Claude: Creating counter module...
✓ Created counter.sv

Running lint check...
✓ Lint clean

Creating testbench...
✓ Created tb_counter.sv

Running simulation...
✓ All tests pass (12 checks)

Done! Created:
- rtl/counter.sv (8-bit parameterized counter with enable)
- tb/tb_counter.sv (Self-checking testbench)

Features

Working Code, Not Just Generated Code

The /gf orchestrator doesn't stop at generation — it verifies:

Create → Lint → Fix → Test → Fix → Formally Verify → Synthesize → Deliver

Formal Verification from Natural Language

Tell GateFlow what to prove in plain English:

"Formally verify that the FIFO never overflows and the pointers are always consistent"
 → Generates SVA assert property statements
 → Configures SymbiYosys (.sby file)
 → Runs bounded model checking
 → Reports proof results or explains counterexamples in English

Yosys Synthesis with Resource Reports

"Synthesize my design for the iCEBreaker"
 → Checks for unsupported SV constructs (warns before failing)
 → Runs Yosys synthesis targeting iCE40
 → Reports: LUTs: 142, FFs: 87, BRAM: 1, DSP: 0

Drop-In IP Library

8 verified, formally proven IP blocks ready to use:

/gf-ip add fifo_sync    → Installs FIFO with RTL + testbench + formal proofs
/gf-ip add uart          → UART TX+RX with configurable baud rate
/gf-ip add axi4lite_slave → AXI4-Lite register interface

Every block is lint-clean, simulation-tested, and formally verified.

Board-Aware Development

GateFlow knows your FPGA board's pinout:

/gf-boards arty-a7-35t pmod-ja  → Shows exact pin assignments

Curated constraint files (.xdc, .pcf, .cst) for popular boards included.

Hardware Design Planning

/gf-plan creates professional design documents:

• Block diagrams (ASCII and Mermaid)
• Module hierarchy and interface specs
• FSM state diagrams
• Clock domain analysis
• Verification strategy and implementation phases

Codebase Intelligence

/gf-architect maps your entire project:

• Module hierarchy and dependencies
• Signal flow analysis and FSM extraction
• Clock domain crossing detection
• Package and type definitions

Comprehensive Coverage

• Memory: FIFOs, dual-port RAM, register files
• Error handling: ECC, watchdogs, TMR
• DFT: Scan chains, JTAG, BIST
• Timing: Retiming, pipelining, SDC
• Verification: SVA, coverage, formal

Smart Hooks

GateFlow watches your workflow and helps proactively:

• After SV edits — reminds you to lint
• Before destructive commands — warns if you're about to delete SV files
• On session end — checks if you forgot to lint or simulate modified files
• Progressive tips — surfaces slash commands you haven't used yet

Components

Skills (27)

Agents (20)

Commands (21)

IP Library (8 verified blocks)

Install with: /gf-ip add fifo_sync or "add a FIFO to my project"

Board Database (4 boards)

Query with: /gf-boards arty-a7-35t or "what pins does the Arty A7 have?"

Agents are automatically invoked by /gf based on your request — you don't need to call them directly.

Individual Downloads

Don't need the full plugin? Grab individual components.

How to download single components

Each component is a standalone .md file. Download and drop into your plugin directory:

your-plugin/
├── .claude-plugin/
│   └── plugin.json
├── agents/          ← agent .md files
├── commands/        ← command .md files
└── skills/
    └── skill-name/  ← SKILL.md files
        └── SKILL.md

curl examples

# Download an agent
curl -O https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md

# Download a skill
mkdir -p skills/gf-plan
curl -o skills/gf-plan/SKILL.md https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/skills/gf-plan/SKILL.md

# Download a command
curl -O https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/commands/gf-lint.md

Note: Some skills (like gf-plan) include reference files in a references/ subdirectory. For full functionality, download the entire skill folder.

Cross-Tool Compatibility

GateFlow's skills and agents are plain Markdown — they work across AI coding tools.

Setup instructions for Codex, Cursor, Copilot, Cline, Windsurf

OpenAI Codex CLI

Codex uses the same SKILL.md format:

# User-global
mkdir -p ~/.codex/skills/gf-plan
curl -o ~/.codex/skills/gf-plan/SKILL.md \
  https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/skills/gf-plan/SKILL.md

# Repo-level
mkdir -p .agents/skills/gf-lint
curl -o .agents/skills/gf-lint/SKILL.md \
  https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/skills/gf-lint/SKILL.md

Cursor

# Append to .cursorrules
curl -s https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md \
  >> .cursorrules

# Or: Settings → Agent Modes → Add Custom Mode → paste agent content

GitHub Copilot CLI

mkdir -p .github
curl -s https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md \
  >> .github/copilot-instructions.md

Cline

curl -s https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md \
  >> .clinerules

Windsurf

# As a rule
mkdir -p .windsurf/rules
curl -o .windsurf/rules/sv-codegen.md \
  https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md

# As a workflow
mkdir -p .windsurf/workflows
curl -o .windsurf/workflows/gf-plan.md \
  https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/skills/gf-plan/SKILL.md

OpenCode

OpenCode supports MCP servers and skill files:

# Add GateFlow skills to your OpenCode config
mkdir -p .opencode/skills/gf-plan
curl -o .opencode/skills/gf-plan/SKILL.md \
  https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/skills/gf-plan/SKILL.md

# Add agent definitions
curl -O https://raw.githubusercontent.com/codejunkie99/Gateflow-Plugin/main/plugins/gateflow/agents/sv-codegen.md

Quick Reference

Configuration

Create .claude/gateflow.local.md in your project for project-specific settings:

---
verilator_flags: ["-Wall", "-Wno-UNUSED"]
top_module: chip_top
clock_freq: 100MHz
---

# Project Notes
- Memory mapped registers at 0x1000
- AXI4-Lite interface for config

Project Structure

Gateflow-Plugin/
├── plugins/gateflow/          # Main plugin source
│   ├── .claude-plugin/        #   Plugin manifest
│   ├── agents/                #   20 specialized AI agents
│   ├── commands/              #   21 slash commands
│   ├── skills/                #   27 auto-activating skills
│   ├── hooks/                 #   Automation hooks + session tracking
│   ├── boards/                #   Curated FPGA board database (4 boards)
│   ├── ip/                    #   Verified IP block library (8 blocks)
│   └── CLAUDE.md              #   SystemVerilog reference
├── agents/                    # Mirrored agent entrypoints (symlinks)
├── skills/                    # Mirrored skill entrypoints (symlinks)
├── docs/                      # Compressed docs index
├── CLAUDE.md                  # SV reference (repo-level)
└── AGENTS.md                  # Docs index for non-Claude agents

Troubleshooting

"Verilator not found"

verilator --version            # Check if installed
brew install verilator         # macOS
sudo apt install verilator     # Linux (Debian/Ubuntu)

"Plugin not loading"

claude --plugin-dir /path/to/Gateflow-Plugin/plugins/gateflow
ls /path/to/Gateflow-Plugin/plugins/gateflow/.claude-plugin/plugin.json

"Agent not found"

Use the gateflow: prefix when spawning agents manually:

gateflow:sv-codegen
gateflow:sv-testbench

Updates

For detailed release notes, see releases.md.

Contributing

Contributions welcome! Areas we'd love help with:

• Board definitions: Add your FPGA board to plugins/gateflow/boards/
• IP blocks: Submit verified blocks to plugins/gateflow/ip/
• Protocol support: AXI4-Full, PCIe, USB, Ethernet, Wishbone
• Tool integrations: Cocotb, FuseSoC, Edalize
• Documentation and examples

License

BSL-1.1 (Business Source License) — see LICENSE for details.

You can: Use, fork, contribute for non-commercial/personal/educational purposes.
Commercial use: Contact us for a license.
After 2028: Converts to Apache 2.0.

Links

• Claude Code Documentation
• Verilator
• SystemVerilog LRM

Star History

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Design. Verify. Ship.