--- name: vx-usage description: "Teaches AI agents how to use vx, the universal dev tool manager. Use when the project has vx.toml or .vx/, or when the user mentions vx, tool version management, Git/GitHub operations, or cross-platform setup. vx auto-manages Node.js, Python, Go, Rust, and 142 providers via Starlark DSL provider.star files. Also covers MCP integration patterns and GitHub Actions." --- # VX - Universal Development Tool Manager > **One-sentence summary**: vx = prefix any dev tool command with `vx` → it auto-installs the tool and runs it. vx is a universal development tool manager that automatically installs and manages development tools (Node.js, Python/uv, Go, Rust, etc.) with zero configuration. ## Core Concept Instead of requiring users to manually install tools, prefix any command with `vx`: ```bash vx node --version # Auto-installs Node.js if needed vx uv pip install x # Auto-installs uv if needed vx go build . # Auto-installs Go if needed vx cargo build # Auto-installs Rust if needed vx just test # Auto-installs just if needed ``` vx is fully transparent - same commands, same arguments, just add `vx` prefix. ## Essential Commands ### Tool Execution (most common) ```bash vx [args...] # Run any tool (auto-installs if missing) vx node app.js # Run Node.js vx python script.py # Run Python (via uv) vx npm install # Run npm vx npx create-react-app app # Run npx vx cargo test # Run cargo vx just build # Run just (task runner) vx git status # Run git vx gh pr status # Run GitHub CLI ``` ### Git and GitHub for Codex When Codex or another AI agent works in a vx-managed repository, use vx-managed Git and GitHub CLI commands. Do not run bare `git` or bare `gh`. ```bash vx git status --short --branch vx git fetch origin main vx git checkout -B fix/example origin/main vx git diff --stat vx git add path/to/file vx git commit -m "fix: example" vx gh issue view 123 vx gh pr view 456 --json title,state,headRefName vx gh pr checks 456 vx gh run view 789 --json status,conclusion,jobs ``` ### Token-Efficient Agent Workflows vx is not just an installation wrapper. For agents, it is the stable way to use fast search, structured GitHub queries, JSON filters, and scoped diffs without spending tokens on irrelevant output. Prefer narrow, structured commands before broad dumps: ```bash # Search and file discovery vx rg -n --glob '!target/**' --glob '!node_modules/**' "OutputRenderer" vx rg --files -g '*.rs' -g '!target/**' vx fd provider.star crates/vx-providers # Git context with small output first vx git status --short --branch vx git diff --stat vx git diff --name-only origin/main...HEAD vx git grep -n "CommandOutput" origin/main -- crates/vx-cli # GitHub context with selected fields vx gh issue view 123 --json title,state,labels,body vx gh pr view 456 --json title,state,headRefName,baseRefName,files vx gh pr checks 456 --json name,state,conclusion,link vx gh run view 789 --json status,conclusion,jobs vx gh run view 789 --json jobs --jq '.jobs[] | {name,conclusion,startedAt,completedAt}' vx gh run view 789 --log | vx rg -n -m 80 "error|failed|panic|Traceback|warning" # Structured filtering vx jq -r '.files[].path' pr.json vx yq '.jobs | keys' .github/workflows/ci.yml ``` Token-saving defaults for agents: - Start with `vx rg`, `vx fd`, `vx git diff --stat`, and `vx git diff --name-only`; open full files or full diffs only after locating the relevant surface. - Use `vx gh --json ...` with selected fields, and add `--jq` when a small projection is enough. - Use vx structured output flags when the vx command supports them: `--json`, `--fields`, `--toon`, `--compact`, or `--output-format toon|compact`. - For forwarded runtimes like `vx node`, `vx cargo`, or `vx npm`, use that tool's own quiet, JSON, or filtering flags when available. - Pipe large logs through vx-managed filters such as `vx rg`, `vx jq`, or `vx yq` before reading them. - Use `vx --compact ...` only when you still need broad subprocess output after structured fields and grep-style filters are not enough. It preserves vx transparency unless explicitly requested. - Do not expect default `vx git` or `vx gh` forwarding to shrink output; explicit `--json`, `--jq`, filtering, or `--compact` is what saves tokens. Compression decision tree for CI/log triage: 1. Status only: `vx gh run view --json status,conclusion,jobs --jq '.jobs[] | {name,conclusion}'`. 2. Suspected failure: `vx gh run view --log | vx rg -n -m 80 "error|failed|panic|Traceback|FAILED|warning"`. 3. Broad but bounded context: `vx --compact gh run view --log`. 4. Last resort: full raw logs, preferably saved to a file and searched locally before being pasted into an agent prompt. Observed on a successful 5,589-line GitHub Actions run: selected `gh --json --jq` projection was about 500 tokens, raw `gh --log` output was about 226k tokens, and `vx --compact gh --log` was about 15.9k tokens. That makes semantic selection the default, compact mode the fallback for broad context, and raw logs the exception. ### Agent Operating Principles vx skills should help agents make small, correct, maintainable changes with bounded context. Treat vx as a token-aware execution layer, not just a command prefix. Use this loop for coding tasks: 1. Inspect the narrowest relevant file, symbol, diff, log, or test output first. 2. Prefer existing project patterns over new helpers or abstractions. 3. Make the smallest maintainable change that solves the actual request. 4. Validate with the cheapest useful scoped command for the risk involved. 5. Summarize only what changed, what was checked, and any remaining risk. Context discipline: - Scope before printing. Search paths first, then open focused file sections. - Avoid dumping full files, broad diffs, generated output, or full CI logs unless the task truly requires them. - For unknown or potentially huge output, cap and filter with vx-managed tools. - Do not cap instruction files, skill files, or agent policy files; read the relevant one fully unless it is unexpectedly huge. - If capped output is insufficient, narrow the query before increasing the cap. Examples: ```bash vx rg -n -m 20 "render_token_savings|OutputRenderer" crates/vx-cli crates/vx-metrics vx git diff --stat origin/main...HEAD vx git diff --name-only origin/main...HEAD vx gh run view 789 --json status,conclusion,jobs --jq '.jobs[] | {name,conclusion}' vx gh run view 789 --log | vx rg -n -m 50 "error|failed|panic|Traceback|FAILED" vx --compact gh run view 789 --log vx metrics tokens --last 20 --json ``` Validation discipline: - Use focused checks first, such as `vx cargo test -p vx-cli --test cli_parsing_tests `. - Run broader checks only when the touched surface or release risk justifies it. - Prefer evidence from the actual failing command, CI job, or runtime behavior over speculative fixes. - Do not add wrappers, maps, helper files, or validation layers unless they clearly reduce real complexity. ### Tool Management ```bash vx install node@22 # Install specific version vx install uv go rust # Install multiple tools at once vx list # List all available tools vx list --installed # List installed tools only vx versions node # Show available versions vx switch node@20 # Switch active version vx uninstall go@1.21 # Remove a version ``` ### Project Management ```bash vx init # Initialize vx.toml for project vx sync # Install all tools from vx.toml vx setup # Full project setup (sync + hooks) vx dev # Enter dev environment with all tools vx run test # Run project scripts from vx.toml vx check # Verify tool constraints vx lock # Generate vx.lock for reproducibility ``` ### Environment & Config ```bash vx env list # List environments vx config show # Show configuration vx cache info # Show cache usage vx search # Search available tools vx info # System info and capabilities ``` ## Project Configuration (vx.toml) Projects use `vx.toml` in the root directory: ```toml [tools] node = "22" # Major version go = "1.22" # Minor version uv = "latest" # Always latest rust = "1.80" # Specific version just = "*" # Any version [scripts] dev = "vx npm run dev" test = "vx cargo test" lint = "vx npm run lint && vx cargo clippy" build = "vx just build" [hooks] pre_commit = ["vx run lint"] post_setup = ["vx npm install"] ``` ## AI Skills Maintenance `vx ai setup` installs vx's built-in skills globally by default so every agent session can reuse the same guidance: ```bash vx ai setup # Install/update global agent skills vx ai setup --project # Install project-local skills and record hash in vx.toml vx ai setup --project --force vx ai check # Compare vx.toml [ai].skills_hash with embedded skills ``` For project-local skills, `vx ai setup --project` records the current embedded skills hash in `vx.toml`. If `vx ai check` reports stale skills, refresh them with `vx ai setup --project --force` before continuing project work. ## Legacy Python 2.7/3.7 Projects vx can run modern and legacy Python lines side by side: ```bash vx python@3.12 --version vx python@3.7 --version vx python@2.7 --version ``` Python 3.7+ uses vx-managed CPython builds where available. Python 2.7 uses the vx legacy compatibility path backed by PyPy2.7 portable archives, so mention the PyPy caveat when a project depends on CPython-only native extensions. For virtual environments, keep one environment per Python line. When `uv` receives a simple `--python` version through vx, vx resolves it to the vx-managed interpreter path before forwarding to uv. Python 2.7 is a special legacy case: uv requires Python 3.6+, so `vx uv venv ... --python 2.7` uses PyPA's Python 2.7 `virtualenv.pyz` under the hood while preserving the same command shape: ```bash vx uv venv .venv312 --python 3.12 vx uv venv .venv37 --python 3.7 vx uv venv .venv27 --python 2.7 ``` Use `just` to make the workflow repeatable: ```makefile venv37: vx uv venv .venv37 --python 3.7 vx uv pip install --python .venv37 -r requirements-py37.txt venv27: vx uv venv .venv27 --python 2.7 .venv27/bin/python -m pip install -r requirements-py27.txt test37: venv37 .venv37/bin/python -m pytest test27: venv27 .venv27/bin/python -m pytest test-legacy: test37 test27 ``` On Windows, use `.venv37\Scripts\python.exe` and `.venv27\Scripts\python.exe` in `justfile` recipes. ## Multi-Version Test Matrices For projects that support multiple runtime lines, keep the matrix in `justfile` instead of ad hoc commands. Use explicit runtime versions for Node/npm and explicit virtual environments for Python: ```makefile test-node18: vx node@18 npm test test-node20: vx node@20 npm test test-node22: vx node@22 npm test test-py37: venv37 .venv37/bin/python -m pytest tests/py37 test-py312: venv312 .venv312/bin/python -m pytest tests/py312 test-matrix: test-node18 test-node20 test-node22 test-py37 test-py312 ``` Agents should prefer `vx just test-matrix` or `vx run test-matrix` when a project defines it, and should add a matrix recipe when compatibility support is part of the task. ## Using `--with` for Multi-Runtime When a command needs additional runtimes available: ```bash vx --with bun node app.js # Node.js + Bun in PATH vx --with deno npm test # npm + Deno available ``` ## Package Aliases vx supports **package aliases** — short commands that automatically route to ecosystem packages: ```bash # These are equivalent: vx vite # Same as: vx npm:vite vx vite@5.0 # Same as: vx npm:vite@5.0 vx rez # Same as: vx uv:rez vx pre-commit # Same as: vx uv:pre-commit vx meson # Same as: vx uv:meson vx release-please # Same as: vx npm:release-please ``` **Benefits**: - Simpler commands without remembering ecosystem prefixes - Automatic runtime dependency management (node/python installed as needed) - Respects project `vx.toml` version configuration **Available Aliases**: | Short Command | Equivalent | Ecosystem | |--------------|------------|-----------| | `vx vite` | `vx npm:vite` | npm | | `vx release-please` | `vx npm:release-please` | npm | | `vx rez` | `vx uv:rez` | uv | | `vx pre-commit` | `vx uv:pre-commit` | uv | | `vx meson` | `vx uv:meson` | uv | ## Companion Tool Environment Injection When `vx.toml` includes tools like MSVC, vx automatically injects discovery environment variables into **all** subprocess environments. This allows any tool needing a C/C++ compiler to discover the vx-managed installation. ```toml # vx.toml — MSVC env vars injected for ALL tools [tools] node = "22" cmake = "3.28" rust = "1.82" [tools.msvc] version = "14.42" os = ["windows"] ``` Now tools like node-gyp, CMake, Cargo (cc crate) automatically find MSVC: ```bash # node-gyp finds MSVC via VCINSTALLDIR vx npx node-gyp rebuild # CMake discovers the compiler vx cmake -B build -G "Ninja" # Cargo cc crate finds MSVC for C dependencies vx cargo build ``` **Injected Environment Variables** (MSVC example): | Variable | Purpose | |----------|---------| | `VCINSTALLDIR` | VS install path (node-gyp, CMake) | | `VCToolsInstallDir` | Exact toolchain path | | `VX_MSVC_ROOT` | vx MSVC root path | ## MSVC Build Tools (Windows) Microsoft Visual C++ compiler for Windows development: ```bash # Install MSVC Build Tools vx install msvc@latest vx install msvc 14.40 # Specific version # Using MSVC tools via namespace vx msvc cl main.cpp -o main.exe vx msvc link main.obj vx msvc nmake # Direct aliases vx cl main.cpp # Same as: vx msvc cl vx nmake # Same as: vx msvc nmake # Version-specific usage vx msvc@14.40 cl main.cpp ``` **Available MSVC Tools**: | Tool | Command | Description | |------|---------|-------------| | cl | `vx msvc cl` | C/C++ compiler | | link | `vx msvc link` | Linker | | lib | `vx msvc lib` | Library manager | | nmake | `vx msvc nmake` | Make utility | ## Supported Tools (142 Providers) | Category | Tools | |----------|-------| | **JavaScript** | node, npm, npx, bun, deno, pnpm, yarn, vite, nx, turbo | | **JS Tooling** | oxlint, biome | | **Python** | uv, uvx, python, pip, ruff, maturin, pre-commit | | **Rust** | cargo, rustc, rustup | | **Go** | go, gofmt, gws, goreleaser, golangci-lint | | **System/CLI** | git, bash, curl, pwsh, jq, yq, fd, bat, ripgrep, fzf, starship, jj, sd, eza, dust, duf, xh, atuin, zoxide, tealdeer, gping, delta, hyperfine, watchexec, bottom | | **TUI/Terminal** | helix, yazi, zellij, lazygit, lazydocker, k9s | | **Build Tools** | just, task, cmake, ninja, make, meson, xmake, protoc, buf, conan, vcpkg, spack | | **DevOps** | kubectl, helm, flux, kind, k3d, nerdctl, skaffold, podman, terraform, hadolint, dagu, actionlint | | **Security** | gitleaks, trivy, cosign, grype, syft | | **Cloud CLI** | awscli, azcli, gcloud | | **.NET** | dotnet, msbuild, nuget | | **C/C++** | msvc, llvm, nasm, ccache, buildcache, sccache, rcedit | | **Media** | ffmpeg, imagemagick | | **Java** | java | | **AI** | ollama, openclaw, mcpcall | | **Other Langs** | zig | | **Container** | dive | | **Config Mgmt** | chezmoi, mise | | **Package Managers** | brew, choco, winget | | **Data/API** | duckdb, grpcurl | | **Misc** | gh, prek, actrun, wix, vscode, xcodebuild, systemctl, release-please, rez, 7zip, trippy | ## Provider System (Starlark DSL) All 142 providers are defined using **provider.star** (Starlark DSL) — a declarative, zero-compilation approach. Each provider lives in `crates/vx-providers//provider.star`. vx uses a **two-phase execution model** (inspired by Buck2): 1. **Analysis Phase (Starlark)**: `provider.star` runs as pure computation, returning descriptor dicts. No I/O. 2. **Execution Phase (Rust)**: The Rust runtime interprets descriptors for actual downloads, installs, and process execution. ### How to add a new tool ```starlark # crates/vx-providers/mytool/provider.star load("@vx//stdlib:provider.star", "runtime_def", "github_permissions") load("@vx//stdlib:provider_templates.star", "github_rust_provider") name = "mytool" description = "My awesome tool" ecosystem = "custom" runtimes = [runtime_def("mytool", aliases=["mt"])] permissions = github_permissions() # Use a template — covers 90% of tools _p = github_rust_provider("owner", "mytool", asset = "mytool-{vversion}-{triple}.{ext}") fetch_versions = _p["fetch_versions"] download_url = _p["download_url"] install_layout = _p["install_layout"] store_root = _p["store_root"] get_execute_path = _p["get_execute_path"] environment = _p["environment"] ``` ### Available templates | Template | Use case | Example | |----------|----------|---------| | `github_rust_provider` | Rust tools on GitHub (most common) | ripgrep, fd, bat, just, uv | | `github_go_provider` | Go tools on GitHub (goreleaser style) | gh, task | | `github_binary_provider` | Single binary download (no archive) | kubectl | | `system_provider` | System package manager only | 7zip | ### Template Placeholders | Placeholder | Rust template | Go template | Description | |-------------|---------------|-------------|-------------| | `{version}` | ✓ | ✓ | Version number (e.g., "1.0.0") | | `{vversion}` | ✓ | — | With v-prefix (e.g., "v1.0.0") | | `{triple}` | ✓ | — | Rust target triple (e.g., "x86_64-unknown-linux-musl") | | `{os}` | — | ✓ | Go GOOS (linux, darwin, windows) | | `{arch}` | — | ✓ | Go GOARCH (amd64, arm64) | | `{ext}` | ✓ | ✓ | Archive extension (zip/tar.gz) | | `{exe}` | ✓ | ✓ | Executable suffix (.exe/"") | ### Starlark Standard Library (14 modules) Located in `crates/vx-starlark/stdlib/`. The main entry point is `provider.star` which re-exports everything: ```starlark # Import everything from the unified facade load("@vx//stdlib:provider.star", "runtime_def", "bundled_runtime_def", "dep_def", "github_permissions", "platform_map", "env_set", "env_prepend", "archive_layout", "binary_layout") ``` Key modules: - `provider.star` — Unified facade (re-exports all) - `runtime.star` — `runtime_def`, `bundled_runtime_def`, `dep_def` - `platform.star` — `platform_map`, `platform_select`, `rust_triple`, `go_os_arch` - `env.star` — `env_set`, `env_prepend`, `env_append`, `env_unset` - `layout.star` — `archive_layout`, `binary_layout`, `bin_subdir_layout`, hooks - `provider_templates.star` — High-level templates (4 templates) - `permissions.star` — `github_permissions`, `system_permissions` - `system_install.star` — `winget_install`, `brew_install`, `apt_install` ## Important Rules for AI Agents 1. **Always use `vx` prefix** when running tools in vx-managed projects 2. **Use `vx just`** instead of `just` for task runner commands 3. **Use `vx npm`** instead of `npm` directly 4. **Use `vx cargo`** instead of `cargo` directly 5. **Use `vx git`** instead of `git` for repository operations 6. **Use `vx gh`** instead of `gh` for GitHub issue, PR, checks, and workflow operations 7. **Use `vx rg`, `vx fd`, `vx jq`, and `vx yq`** for scoped search and structured filtering 8. **Prefer token-efficient output**: `--json`, selected fields, `--jq`, `--toon`, `--compact`, `--output-format toon|compact`, and narrow globs 9. **Check `vx.toml`** first to understand project tool requirements 10. **Use `vx run

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