Add `AGENTS.md` (#36877)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

.gitignore

@@ -189,11 +189,9 @@ cython_debug/
 .vscode/
 
 # Claude
-CLAUDE.md
 .claude/
 
 # Codex
-AGENTS.md
 .codex/
 
 # Cursor

.pre-commit-config.yaml

@@ -30,6 +30,7 @@ repos:
   - id: markdownlint-cli2
     language_version: lts
     args: [--fix]
+    exclude: ^CLAUDE\.md$
 - repo: https://github.com/rhysd/actionlint
   rev: v1.7.7
   hooks:

AGENTS.md

+# Agent Instructions for vLLM
+
+> These instructions apply to **all** AI-assisted contributions to `vllm-project/vllm`.
+> Breaching these guidelines can result in automatic banning.
+
+## 1. Contribution Policy (Mandatory)
+
+### Duplicate-work checks
+
+Before proposing a PR, run these checks:
+
+```bash
+gh issue view <issue_number> --repo vllm-project/vllm --comments
+gh pr list --repo vllm-project/vllm --state open --search "<issue_number> in:body"
+gh pr list --repo vllm-project/vllm --state open --search "<short area keywords>"
+```
+
+- If an open PR already addresses the same fix, do not open another.
+- If your approach is materially different, explain the difference in the issue.
+
+### No low-value busywork PRs
+
+Do not open one-off PRs for tiny edits (single typo, isolated style change, one mutable default, etc.). Mechanical cleanups are acceptable only when bundled with substantive work.
+
+### Accountability
+
+- Pure code-agent PRs are **not allowed**. A human submitter must understand and defend the change end-to-end.
+- The submitting human must review every changed line and run relevant tests.
+- PR descriptions for AI-assisted work **must** include:
+    - Why this is not duplicating an existing PR.
+    - Test commands run and results.
+    - Clear statement that AI assistance was used.
+
+### Fail-closed behavior
+
+If work is duplicate/trivial busywork, **do not proceed**. Return a short explanation of what is missing.
+
+---
+
+## 2. Development Workflow
+
+### Environment setup
+
+```bash
+# Install `uv` if you don't have it already:
+curl -LsSf https://astral.sh/uv/install.sh | sh
+
+# Always use `uv` for Python environment management:
+uv venv
+source .venv/bin/activate
+
+# Always make sure `pre-commit` and its hooks are installed:
+uv pip install pre-commit
+pre-commit install
+```
+
+### Installing dependencies
+
+```bash
+# If you are only making Python changes:
+VLLM_USE_PRECOMPILED=1 uv pip install -e .
+
+# If you are also making C/C++ changes:
+uv pip install -e .
+```
+
+### Running tests
+
+Tests require extra dependencies.
+All versions for test dependencies should be read from `requirements/test.txt`
+
+```bash
+# Install bare minimum test dependencies:
+uv pip install pytest==<requirements/test.txt version>
+uv pip install tblib==<requirements/test.txt version>
+
+# Install additional required dependencies from `requirements/test.txt` as needed:
+uv pip install <requirements/test.txt dependency>==<requirements/test.txt version>
+
+# Run specific test from specific test file
+pytest tests/path/to/test.py -v -s -k test_name
+
+# Run all tests in directory
+pytest tests/path/to/dir -v -s
+```
+
+### Running linters
+
+```bash
+# Run all pre-commit hooks on staged files:
+pre-commit run
+
+# Run on all files:
+pre-commit run --all-files
+
+# Run a specific hook:
+pre-commit run ruff-check --all-files
+
+# Run mypy as it is in CI:
+pre-commit run mypy-3.10 --all-files --hook-stage manual
+```
+
+### Commit messages
+
+Add attribution using commit trailers such as `Co-authored-by:` (other projects use `Assisted-by:` or `Generated-by:`). For example:
+
+```text
+Your commit message here
+
+Co-authored-by: GitHub Copilot
+Co-authored-by: Claude
+Co-authored-by: gemini-code-assist
+Signed-off-by: Your Name <your.email@example.com>
+```

CLAUDE.md

+@AGENTS.md

docs/contributing/README.md

@@ -189,6 +189,11 @@ Using `-s` with `git commit` will automatically add this header.
 
 ### AI Assisted Contributions
 
+Before making an AI assisted contribution, you must:
+
+1. **Be involved**: Do not submit "pure agent" PRs. The human submitter is responsible for reviewing all changed lines, validating behavior end-to-end, and running relevant tests.
+2. **Ensure significance**: Avoid one-off "busywork" PRs (single typo, isolated style cleanup, one mutable default fix, etc.). Bundle mechanical cleanups into a clear, systematic scope.
+
 When AI tools provide non-trivial assistance in generating or modifying code, you must:
 
 1. **Review thoroughly**: You remain responsible for all code you submit. Review and understand AI-generated code with the same care as code you write manually.

docs/governance/process.md

@@ -139,9 +139,14 @@ In case where CI didn't pass due to the failure is not related to the PR, the PR
 
 AI tools can accelerate development, but contributors remain fully responsible for all code they submit. Like the Developer Certificate of Origin, this policy centers on accountability: contributors must believe they have the right to submit their contribution under vLLM's open source license, regardless of how the code was created.
 
-All AI-assisted contributions must meet the same quality, testing, and review standards as any other code. Contributors must review and understand AI-generated code before submission—just make sure it is good code.
+All AI-assisted contributions must meet the same quality, testing, and review standards as any other code. Contributors must review and understand AI-generated code before submission—just make sure it is good code:
 
-Attribution preserves legal clarity and community trust. Contributors must disclose AI assistance in pull requests and mark commits with appropriate trailers (e.g. `Co-authored-by:`).
+- Do not submit "pure agent" PRs. The human submitter is responsible for reviewing all changed lines, validating behavior end-to-end, and running relevant tests.
+- Attribution preserves legal clarity and community trust. Contributors must disclose AI assistance in pull requests and mark commits with appropriate trailers (e.g. `Co-authored-by:`).
+- Avoid one-off "busywork" PRs (single typo, isolated style cleanup, one mutable default fix, etc.). Bundle mechanical cleanups into a clear, systematic scope.
+
+!!! warning
+    These topics are outlined for agents in [AGENTS.md](../../AGENTS.md) with instructions for how to autonomously implement them.
 
 ### Slack