Han is a suite of AI skills and agents for solo (or small-team) product engineers. It combines evidence-based planning, full documentation maintenance, deep code review, and architectural analysis into a team of specialists you can dispatch from Claude Code.
Han turns planning, 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 (project managers, adversarial reviewers, investigators, architectural analysts, testing and security specialists) to do the judgment-heavy work, 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 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.
- New to han? → Start with Concepts, then the Quickstart.
- Looking for a specific skill? → Skills Index. 15 skills grouped by purpose.
- Looking for a specific agent? → Agents Index. 21 agents grouped by role.
- Wondering how the agent swarms scale? → Sizing. The small / medium / large dispatch model used by
/code-review,/gap-analysis,/iterative-plan-review,/plan-a-feature, and/plan-implementation. - Wondering why a skill said "YAGNI"? → YAGNI. The evidence-based rule every planning, review, and architecture skill applies before committing items to an artifact.
- Writing or editing a skill or agent? → Contributing.
Fifteen skills, grouped by the moment you reach for them. Each category links to the full long-form docs through the Skills Index.
Spec what to build, plan how to build it, sequence it into phases, and stress-test the plan before you commit.
/plan-a-feature. Build a feature specification from scratch through an evidence-based interview./plan-implementation. Turn a feature specification into an implementation plan through a project-manager-led team conversation./plan-a-phased-build. Split a body of work into a numbered sequence of vertical-slice phases, each independently demoable./iterative-plan-review. Stress-test an existing plan through multiple codebase-grounded review passes.
Find out why something is broken, with evidence to back it.
/investigate. Evidence-based investigation of bugs, failures, and unexpected behavior, with adversarial validation of the proposed fix.
Get a second set of eyes on code that already exists.
/code-review. Comprehensive code review of the current branch or specified files./gh-pr-review. Run a code review against a GitHub PR and post the review as comments./architectural-analysis. Deep architectural analysis of a module: coupling, data flow, concurrency, risk, and SOLID alignment./gap-analysis. Compare two artifacts (spec vs. implementation, PRD vs. shipped feature) and produce a plain-language report indexed by stable gap IDs./test-planning. Produce a prioritized test plan for a branch or directory.
Produce reference material every other skill (and future-you) benefits from.
/project-discovery. Scan the repository for languages, frameworks, tooling, and structure./project-documentation. Create and maintain documentation for features, systems, and components.
Codify how the team works.
/coding-standard. Create and update coding standards from existing patterns or evidence-based research./architectural-decision-record. Create, extract, or convert architectural decision records.
Turn work into something shareable outside the repo.
/update-pr-description. Generate a PR description from the current branch's changes.
Not sure which category fits your situation? The Quickstart has path-by-path guidance for the most common ones.
Add the Test Double skills marketplace to Claude Code, then install the plugin:
/plugin marketplace add testdouble/han
/plugin install han@han
- Concepts. Skill vs. agent, and how they compose. Read once before using the plugin.
- Quickstart. Four paths for four common situations. Each path is a short sequence of skills.
- Skills Index. All 15 skills, grouped by purpose.
- Agents Index. All 21 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.
- Contributing. Adding or editing skills, agents, and documentation.
- Changelog. What's new in each version of the plugin.
- 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:
- River Lynn Bailey: Creator, and primary maintainer
Copyright 2026 Test Double, Inc. Distributed under the MIT license.