GateFlow Plugin for Claude Code

AI-powered SystemVerilog development assistant — design, verify, debug, and deliver working RTL with natural language.

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Loving hardware doesn't have to be gatekept.

GateFlow brings professional SystemVerilog tooling to Claude Code. Describe what you want to build and get lint-checked, simulated, verified code — not just generated code.

Whether you're writing your first always_ff or architecting a multi-module SoC, the tools should help you, not fight you.

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

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• 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

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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

Tool	Required	macOS	Linux
Claude Code	Yes	See website	See website
Verilator	Yes	brew install verilator	sudo apt install verilator
Verible	Optional	brew tap chipsalliance/verible && brew install verible	See releases

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

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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

"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

"Add assertions to check the handshake protocol"
 → Generates SVA properties for valid/ready handshake

"Explain how the FSM in uart_tx.sv works"
 → Analyzes state machine, explains transitions, creates state diagram

Skills (Auto-Activating)

Skills activate automatically based on context:

Skill	Trigger	What It Does
/gf	Any SV task	Main orchestrator — plan-first, parallel build, verify until working
/gf-plan	"plan", "design", "architect"	RTL implementation plans with ASCII diagrams
/gf-build	"build", "multi-component", "SoC"	Parallel component build orchestration
/gf-architect	"map codebase", "analyze project"	Codebase map with hierarchy, FSMs, clocks, CDC
/gf-viz	"visualize", "show hierarchy"	Terminal ASCII visualization of RTL architecture
/gf-learn	"teach me", "exercise", "practice"	Learning mode with exercises and feedback

Commands

Command	What It Does
/gf-lint	Run Verilator lint with structured output
/gf-fix	Auto-fix lint errors
/gf-sim	Compile and run simulation
/gf-gen	Generate module/testbench scaffolds
/gf-scan	Index project files
/gf-map	Map codebase architecture
/gf-doctor	Check environment and dependencies

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)

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Features

Working Code, Not Just Generated Code

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

Create → Lint → Fix → Test → Fix → Deliver

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

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Components

Skills (12)

Skill	Description	Source
gf	Main orchestrator — plan, build, verify until working	SKILL.md
gf-plan	RTL implementation planning with diagrams	SKILL.md
gf-build	Parallel component build orchestration	SKILL.md
gf-architect	Codebase map with hierarchy, FSMs, clocks, CDC	SKILL.md
gf-lint	Structured Verilator lint checking	SKILL.md
gf-sim	Simulation with auto DUT/TB detection	SKILL.md
gf-viz	Terminal visualization of RTL architecture	SKILL.md
gf-learn	Learning mode — exercises, reviews, hints	SKILL.md
gf-router	Intent classification and routing	SKILL.md
gf-expand	Clarifying questions with trade-offs	SKILL.md
gf-summary	Summarize Verilator/lint output	SKILL.md
tb-best-practices	Testbench best practices reference	SKILL.md

Agents (11)

Agent	Expertise	Source
sv-codegen	RTL architect — synthesizable modules	sv-codegen.md
sv-testbench	Verification engineer — testbenches and stimulus	sv-testbench.md
sv-debug	Debug specialist — simulation failures, X-values	sv-debug.md
sv-verification	Verification methodologist — SVA, coverage, formal	sv-verification.md
sv-understanding	RTL analyst — explains and documents code	sv-understanding.md
sv-planner	Architecture planner — design plans and diagrams	sv-planner.md
sv-orchestrator	Parallel builder — multi-component designs	sv-orchestrator.md
sv-refactor	Code quality — lint fixes, cleanup, optimization	sv-refactor.md
sv-developer	Full-stack RTL — complex multi-file features	sv-developer.md
sv-tutor	Teacher — reviews solutions, gives hints	sv-tutor.md
sv-viz	Terminal visualization of RTL architecture	sv-viz.md

Commands (7)

Command	Description	Source
/gf-doctor	Environment check	gf-doctor.md
/gf-scan	Index project	gf-scan.md
/gf-map	Map codebase	gf-map.md
/gf-lint	Run lint	gf-lint.md
/gf-fix	Fix lint	gf-fix.md
/gf-gen	Generate scaffolds	gf-gen.md
/gf-sim	Run simulation	gf-sim.md

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

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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.

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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

Location	Scope
.agents/skills/	Current repo
~/.codex/skills/	User-global
/etc/codex/skills/	System-wide

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

Quick Reference

Tool	Where to Put Files	Format
Claude Code	Plugin skills/, agents/, commands/	Native
Codex CLI	~/.codex/skills/ or .agents/skills/	SKILL.md
Cursor	.cursorrules or custom agent mode	Append
Copilot CLI	.github/copilot-instructions.md	Append
Cline	.clinerules	Append
Windsurf	.windsurf/rules/ or .windsurf/workflows/	Individual .md

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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

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Project Structure

Gateflow-Plugin/
├── plugins/gateflow/          # Main plugin source
│   ├── .claude-plugin/        #   Plugin manifest
│   ├── agents/                #   11 specialized AI agents
│   ├── commands/              #   7 slash commands
│   ├── skills/                #   12 auto-activating skills
│   ├── hooks/                 #   Automation hooks
│   └── 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

File	For
CLAUDE.md	Claude Code (primary reference)
AGENTS.md	Other AI agents (Cursor, Copilot, etc.)

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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

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Updates

For detailed release notes, see releases.md.

Version	Date	What Changed
1.5.2	2026-02-15	Fix Stop hook JSON validation: replace prompt hook with deterministic command hook (non-blocking reminder)
1.5.0	2025-02-11	Terminal visualization with /gf-viz skill and sv-viz agent
1.4.4	2025-02-11	Individual component downloads, cross-tool install instructions
1.4.3	2025-02-10	Split gf-plan references, validation fixes, docs improvements

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Contributing

Contributions welcome! Areas we'd love help with:

• Additional protocol support (AXI4, PCIe, USB)
• More design patterns
• Tool integrations (Yosys, Vivado, Quartus)
• Documentation and examples

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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.

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Links

• Claude Code Documentation
• Verilator
• SystemVerilog LRM

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Star History

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Built for hardware engineers who want to move faster.
Design. Verify. Ship.