Han: For the Solo Product Engineer
Han is a suite of AI skills and agents for solo (or small-team) product engineers. It combines
evidence-based planning, test-driven implementation, full documentation maintenance, deep code review, and
architectural analysis into a team of specialists you can dispatch from Claude Code.
What this plugin does
Han turns planning, implementation, review, and documentation work that would normally take a team into a
set of deterministic skills you run from Claude Code.
Each skill dispatches specialist agents, such as project managers, adversarial reviewers, investigators,
architectural analysts, and testing and security specialists, to do the judgment-heavy work. It then folds
their findings into an artifact you can trust.
The skills are designed to compose. You can plan a feature, then plan its implementation, then iterate on
the plan, then build it test-first, then review the resulting code, then write the PR description. All
through named skills that hand off to each other cleanly.
Read Concepts for the skill-and-agent model that runs through the whole plugin.
For Solo Product Engineers and Small Teams
Han is purpose-built for solo product engineers and small teams, instead of large teams or enterprise. This
does not mean it can't work in larger teams, though. Read about why
Han's focus is solo product engineers and small teams to understand
Han's positioning and what it does not bring to the table.
Installation
Claude Code
Add the Test Double skills marketplace to Claude Code, then install the plugin:
/plugin marketplace add testdouble/han
/plugin install han@han
Han ships as multiple plugins:
| Plugin | Type | What it brings |
|---|
han | parent | the parent plugin that brings in han-core, han-planning, han-coding, han-github, and han-reporting |
han-core | bundled | research, analysis, and documentation skills plus every agent |
han-planning | bundled | planning skills you reach for before implementation |
han-coding | bundled | coding skills you reach for while working in code |
han-github | bundled | GitHub-facing skills like posting a code review on a PR |
han-reporting | bundled | reporting skills like the stakeholder summary |
han-feedback | opt-in | skill for capturing post-session feedback on Han skill runs |
han-atlassian | opt-in | skills for publishing docs and work items to Atlassian products |
han-linear | opt-in | skill for publishing work items to Linear (requires a Linear MCP server) |
han-plugin-builder | opt-in | carries the guidance and skills for building your own skills, agents, and plugins |
Installing han@han pulls in the bundled suite (the meta-plugin plus han-core, han-planning,
han-coding, han-github, and han-reporting), and is the right choice for most people. If you do
not want the planning, coding, GitHub, or reporting skills, install han-core@han instead, and add other
specific plugins as desired.
For the full picture and a quick "which one do you need?" guide, see Choosing a Han plugin.
Codex
Add this repo as a Codex marketplace:
codex plugin marketplace add testdouble/han
Codex does not yet support meta-plugins like han@han (see openai/codex#23531,) so install the Han packages directly:
codex plugin add han-core@han
codex plugin add han-planning@han
codex plugin add han-coding@han
codex plugin add han-github@han
codex plugin add han-reporting@han
Install han-feedback, han-atlassian, han-linear, or han-plugin-builder
separately when you want those opt-in packages.
Documentation
- Concepts. Skill vs. agent, and how they compose. Read once before using the plugin.
- Choosing a Han plugin. The full suite vs. core only, the
han-planning, han-coding, han-github, and han-reporting dependencies on han-core, and a quick
guide to which one to install.
- Quickstart. Five paths for five common situations. Each path is a short sequence of skills.
- Skills Index. All skills, grouped by purpose.
- Agents Index. All agents, grouped by role.
- Sizing. The small / medium / large model that decides how many agents the swarming
skills dispatch.
- YAGNI. The evidence-based "You Aren't Gonna Need It" rule every planning, review, and
architecture skill applies.
- Evidence. What counts as evidence in Han, how to characterize how strong it is, and
what to do when no evidence exists at all.
- Readability. The shared output standard every reader-facing skill applies as it
writes, so its human-facing deliverable leads with the main point and reads consistently across skills.
- Changelog. What's new in each version of the plugin.
How-To Guides
- How-to guides. End-to-end recipes for planning a feature, revising a plan
after the build starts, accelerating your understanding of unfamiliar code, triaging and investigating a
bug, running an effective code review, and researching a decision. Pick one when you want the full
walkthrough, not only the path.
- How to provide feedback on Han. Send the maintainers structured
feedback on a skill or agent run.
- Extend Han via dependencies. Add your own custom
skills on top of Han.
- Build a plugin that depends on Han. Ship a plugin
that builds on Han's skills and agents.
Contributing to Han
Maintenance and Support
- Maintenance horizon: Indefinitely maintained, best-effort. No SLA.
- Project type: Personal project, with some Test Double support
- How to report issues: GitHub Issues, with expected best effort for response within 2 weeks.
Han is an open source product of Test Double, and maintained by the following people:
LEGAL NOTICES
Copyright 2026 Test Double, Inc. Distributed under the MIT license.
