harness-sdk/CONTRIBUTING.md

Contributing Guidelines

Thank you for your interest in contributing to our project. Whether it's a bug report, new feature, correction, or additional documentation, we greatly value feedback and contributions from our community.

Please read through this document before submitting any issues or pull requests to ensure we have all the necessary information to effectively respond to your bug report or contribution.

Reporting Bugs/Feature Requests

We welcome you to use the Bug Reports file to report bugs or Feature Requests to suggest features.

For a list of known bugs and feature requests:

• Check Bug Reports for currently tracked issues
• See Feature Requests for requested enhancements

When filing an issue, please check for already tracked items

Please try to include as much information as you can. Details like these are incredibly useful:

• A reproducible test case or series of steps
• The version of our code being used (commit ID)
• Any modifications you've made relevant to the bug
• Anything unusual about your environment or deployment

Finding contributions to work on

Looking at the existing issues is a great way to find something to contribute to. We label issues that are well-defined and ready for community contributions with the "ready for contribution" label.

Check our Ready for Contribution issues for items you can work on.

Before starting work on any issue:

1. Check if someone is already assigned or working on it
2. Comment on the issue to express your interest and ask any clarifying questions
3. Wait for maintainer confirmation before beginning significant work

Development Tenets

Our team follows these core principles when designing and implementing features. These tenets help us make consistent decisions, resolve trade-offs, and maintain the quality and coherence of the SDK. When contributing, please consider how your changes align with these principles:

1. Simple at any scale: We believe that simple things should be simple. The same clean abstractions that power a weekend prototype should scale effortlessly to production workloads. We reject the notion that enterprise-grade means enterprise-complicated - Strands remains approachable whether it's your first agent or your millionth.
2. Extensible by design: We allow for as much configuration as possible, from hooks to model providers, session managers, tools, etc. We meet customers where they are with flexible extension points that are simple to integrate with.
3. Composability: Primitives are building blocks with each other. Each feature of Strands is developed with all other features in mind, they are consistent and complement one another.
4. The obvious path is the happy path: Through intuitive naming, helpful error messages, and thoughtful API design, we guide developers toward correct patterns and away from common pitfalls.
5. We are accessible to humans and agents: Strands is designed for both humans and AI to understand equally well. We don’t take shortcuts on curated DX for humans and we go the extra mile to make sure coding assistants can help you use those interfaces the right way.
6. Embrace common standards: We respect what came before, and do not want to reinvent something that is already widely adopted or done better.

When proposing solutions or reviewing code, we reference these principles to guide our decisions. If two approaches seem equally valid, we choose the one that best aligns with our tenets.

The team/ folder holds the rest of our shared context: the full tenets, decision records, the API bar-raising and feature lifecycle processes, and our design proposals. For a significant feature or a breaking change, start with a design proposal in team/designs/ — see its README for the template and process.

Development Environment

This is a monorepo containing the Python SDK, TypeScript SDK, MCP server, and documentation site. Each has its own toolchain:

Area	Directory	Toolchain
Python SDK	strands-py/	hatch
TypeScript SDK	strands-ts/	npm workspace
MCP server	strands-mcp/	hatch
Docs site	site/	Astro (npm)

Python SDK

The Python SDK uses hatchling as the build backend and hatch for development workflow management.

All hatch commands should be run from the strands-py/ subdirectory (where pyproject.toml lives):

cd strands-py

Setting Up Your Development Environment

1. Entering virtual environment using hatch (recommended), then launch your IDE in the new shell.

   hatch shell
   

2. Set up pre-commit hooks:

   pre-commit install -t pre-commit -t commit-msg
   

   This will automatically run formatters and conventional commit checks on your code before each commit.

3. Run code formatters manually:

   hatch fmt --formatter
   

4. Run linters:

   hatch fmt --linter
   

5. Run unit tests:

   hatch test
   

   Or run them with coverage:

   hatch test -c
   

6. Run integration tests:

   hatch run test-integ
   

Pre-commit Hooks

We use pre-commit to automatically run quality checks before each commit. The hook will run hatch run format, hatch run lint, hatch run test, and hatch run cz check when you make a commit, ensuring code consistency.

The pre-commit hook is installed with:

pre-commit install

You can also run the hooks manually on all files:

pre-commit run --all-files

Code Formatting and Style Guidelines

We use the following tools to ensure code quality:

1. ruff - For formatting and linting
2. mypy - For static type checking

These tools are configured in the pyproject.toml file. Please ensure your code passes all linting and type checks before submitting a pull request:

# Run all checks
hatch fmt --formatter
hatch fmt --linter

If you're using an IDE like VS Code or PyCharm, consider configuring it to use these tools automatically.

For additional details on styling, please see our dedicated Style Guide.

TypeScript SDK

The TypeScript SDK uses an npm workspace rooted at the repository root.

npm ci              # install dependencies (from repo root)
npm run build       # build
npm test            # run unit tests
npm run lint        # lint
npm run type-check  # type checking

Running Selective Integration Tests Locally

From the repository root, run only the integration tests relevant to your changes (computed relative to main, including uncommitted edits):

npm run test:integ:selective

This uses Vitest's module graph to run only the integ-node and integ-browser specs that depend on the source files you changed. If you alter a structural file (package.json, package-lock.json, a strands-ts tsconfig, vitest.config.ts, a shared integration fixture under test/integ/__fixtures__/, or a TypeScript CI workflow), the full integration suite runs automatically.

Documentation Site

The documentation site uses Astro with the Starlight theme.

cd site
npm install
npm run dev                # local dev server at http://localhost:4321/
npm run build              # production build
npm run typecheck          # type checking
npm run typecheck:snippets # type check code examples

For docs contribution guidelines, see site/CONTRIBUTING.md.

Using AI Tools

We love AI. We build with coding agents every day, and you're welcome to use them too — they're a great way to move fast and explore a codebase.

That said, you are the author of your pull request, not your agent. Before you open a PR, make sure you understand the code well enough to explain why it works, defend the design choices, and maintain it if asked. If you couldn't walk a reviewer through it line by line, it's not ready yet.

A few things that help us help you:

• Keep changes small and incremental. A focused PR that does one thing is far easier for us to understand, guide, and merge than a large one that touches many areas. When in doubt, split it up.
• Open an issue first for anything significant, so we can align on the approach before you (or your agent) invest the time.
• Review every line your agent generates. Delete what you don't need, simplify what's over-engineered, and make sure tests actually exercise the behavior — not just pass.

High-quality PRs get reviewed faster and are far more likely to be accepted. Taking the time to understand and trim your changes is the single best thing you can do to get them merged.

Contributing via Pull Requests

Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that:

1. You are working against the latest source on the main branch.
2. You check existing open, and recently merged, pull requests to make sure someone else hasn't addressed the problem already.
3. You open an issue to discuss any significant work - we would hate for your time to be wasted.

For guidance on writing effective PR descriptions, see our PR Description Guidelines.

To send us a pull request, please:

1. Create a branch.
2. Modify the source; please focus on the specific change you are contributing. If you also reformat all the code, it will be hard for us to focus on your change.
3. Format your code using hatch fmt --formatter.
4. Run linting checks with hatch fmt --linter.
5. Ensure local tests pass with hatch test and hatch run test-integ.
6. Commit to your branch using clear commit messages following the Conventional Commits specification.
7. Send us a pull request, answering any default questions in the pull request interface.
8. Pay attention to any automated CI failures reported in the pull request, and stay involved in the conversation.

Code of Conduct

This project has adopted the Amazon Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opensource-codeofconduct@amazon.com with any additional questions or comments.

Security issue notifications

If you discover a potential security issue in this project we ask that you notify AWS/Amazon Security via our vulnerability reporting page. Please do not create a public github issue.

Licensing

See the LICENSE.APACHE and LICENSE.MIT files for our project's licensing. We will ask you to confirm the licensing of your contribution.