How to contribute

vLLM is a large, fast-moving project. The official contributor guide lives at https://docs.vllm.ai/en/latest/contributing/; this section summarizes the parts that matter most for navigating this codebase.

Read these first

Before opening anything:

1. AGENTS.md at the repo root. The policy applies to all AI-assisted contributions. Key rules: no pure code-agent PRs, no low-value busywork PRs, run duplicate-work checks, and every PR description for AI-assisted work must explicitly say AI was used and list test commands run.
2. CONTRIBUTING.md — points at the docs site.
3. docs/contributing/ — the canonical instructions, including domain-specific guides (model contributions, multi-modal, attention backends, etc.).

Where to file things

Type	Where
Bug reports & feature requests	https://github.com/vllm-project/vllm/issues
User questions	https://discuss.vllm.ai or #users in the Slack
Coordination & dev chat	Slack
Security issues	GitHub Security Advisories
Partnerships	collaboration@vllm.ai

Definition of done for a typical PR

• All pre-commit hooks pass (pre-commit run --all-files)
• mypy-3.10 passes on the touched files (run via pre-commit run mypy-3.10 --all-files --hook-stage manual)
• New tests added for the changed behavior; existing tests pass
• DCO sign-off (Signed-off-by: Your Name <your.email@example.com>) on every commit. The DCO file is at the repo root.
• For AI-assisted PRs: explicit Co-authored-by: trailer naming the assistant (e.g., Co-authored-by: Claude), and a PR description that lists test commands and acknowledges AI assistance
• For model PRs: passes the tests/models/ registry tests; for kernel PRs: micro-benchmarks attached
• The PR is rebased on a recent main and CI is green on Buildkite

Sub-pages

• Development workflow — install, branch, edit, test, push, PR, review cycle
• Testing — pytest layout, markers, how to run subsets, distributed tests
• Debugging — logs, common errors, troubleshooting techniques
• Patterns and conventions — coding style, error handling, custom-op registration, plugin entry points
• Tooling — pre-commit, ruff, mypy, clang-format, the build system, custom CI scripts