# Ty > Use this skill when type checking Python code or setting up type checking with ty. Activates on mentions of ty, ty check, ty server, Python type checking, type checker, mypy replacement, pyright replacement, type annotations, type errors, type ignore, Python types, LSP, language server, or Python static analysis. - **Type:** Skill - **Install:** `agentstack add skill-hyperb1iss-hyperskills-ty` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [hyperb1iss](https://agentstack.voostack.com/s/hyperb1iss) - **Installs:** 0 - **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [hyperb1iss](https://github.com/hyperb1iss) - **Source:** https://github.com/hyperb1iss/hyperskills/tree/main/skills/ty - **Website:** https://hyperbliss.tech ## Install ```sh agentstack add skill-hyperb1iss-hyperskills-ty ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # ty: Python Type Checker & Language Server ty (v0.0.34, May 2026) is Astral's Rust-based Python type checker and language server. **Beta status:** 0.0.x versioning, breaking changes between versions, and no stable API yet. Astral reports 10-100x faster checks than mypy and Pyright on large projects. **Formerly "Red-Knot"**, renamed May 2025, extracted from the ruff repo to `astral-sh/ty`. ## When to Use ty - `[tool.ty]` section in `pyproject.toml` or `ty.toml` exists - Type checking Python code in any project - Setting up an LSP for Python in your editor **When to wait:** Projects heavily dependent on mypy plugins (Pydantic, Django, SQLAlchemy). ty has no plugin system and no plans to add one, first-class framework support is the stated approach instead. ## How to Invoke ```bash uvx ty check # One-off (latest) uv run ty check # Project dependency ty check # Global install ``` ## CLI Commands ```bash # Type checking ty check # Check current directory ty check path/to/file.py # Specific file ty check src/ tests/ # Multiple directories # Rule severity ty check --error unresolved-import ty check --warn division-by-zero ty check --ignore unresolved-attribute # Python targeting ty check --python-version 3.12 ty check --python-platform linux ty check --python .venv/bin/python # Output formats ty check --output-format full # Rich diagnostics (default) ty check --output-format concise # One line per error ty check --output-format github # GitHub Actions annotations ty check --output-format gitlab # GitLab Code Quality ty check --output-format junit # JUnit XML # Watch mode ty check --watch # Re-check on file changes ty check -W # Short form # Migration helper ty check --add-ignore # Auto-add ty: ignore comments for all errors # Introspection ty explain rule # List all rules ty explain rule invalid-assignment # Explain specific rule # Language server ty server # Start LSP ``` ### Exit Codes | Code | Meaning | | ---- | ------------------------------------------------------------ | | `0` | No errors (warnings don't count unless `--error-on-warning`) | | `1` | Type errors found | | `2` | CLI/configuration error | ## Configuration ty reads from `ty.toml` (takes precedence) or `pyproject.toml` under `[tool.ty]`. ```toml [tool.ty.environment] python-version = "3.12" # 3.7-3.15 allowed; unset falls back to 3.14 python-platform = "linux" # win32|darwin|android|ios|linux|all python = ".venv" # Path to environment/interpreter root = ["src"] # First-party module discovery extra-paths = [] # Additional resolution paths [tool.ty.rules] unresolved-import = "error" division-by-zero = "ignore" possibly-unresolved-reference = "warn" [tool.ty.analysis] allowed-unresolved-imports = ["mypackage._internal.*"] replace-imports-with-any = ["legacy_lib.*"] respect-type-ignore-comments = true [tool.ty.src] include = ["src/**/*.py"] exclude = ["**/migrations/**"] respect-ignore-files = true [tool.ty.terminal] output-format = "full" error-on-warning = false ``` ### Per-File Overrides ```toml [[tool.ty.overrides]] include = ["tests/**", "**/test_*.py"] [tool.ty.overrides.rules] possibly-unresolved-reference = "warn" unresolved-attribute = "ignore" ``` ## Suppression Comments ```python # Preferred: rule-specific x = foo # ty: ignore[possibly-unresolved-reference] # Broad (discouraged) x = foo # ty: ignore # Legacy (honored by default, configurable) x = foo # type: ignore ``` **Rule:** Fix type errors instead of suppressing. Only add ignore comments when explicitly requested. Always prefer rule-specific ignores. ## What Makes ty Unique ### Unknown vs Any ty distinguishes between `Any` (deliberate opt-out) and `Unknown` (inferred gap). This is the "gradual guarantee", all code is checked, but unknowns are treated permissively rather than skipped entirely (mypy skips unannotated functions by default). ### Intersection Types ty supports `A & B` intersection types natively, not available in mypy or pyright. ### Fine-Grained Incrementality Built on Salsa (same framework as rust-analyzer). Changing one function re-parses only that function and its dependents, not the entire file. This powers sub-millisecond editor responses. ### Performance | Project | ty | pyright | mypy | | --------------------- | --------- | ------- | ------ | | home-assistant (cold) | 2.19s | 19.62s | 45.66s | | PyTorch (cold) | 4.04s | 262.74s | — | | PyTorch (incremental) | **4.7ms** | 386ms | — | ## Editor/LSP Setup ty ships a full LSP with go-to-definition, find references, auto-complete with auto-import, rename, inlay hints, and hover. **VS Code:** Install `astral-sh.ty` extension. **Neovim (>=0.11):** ```lua vim.lsp.config('ty', { settings = { ty = {} } }) vim.lsp.enable('ty') ``` **Neovim ( ty check mypy --strict . -> ty check --error-on-warning # (partial) mypy -p mypackage -> ty check src/mypackage/ # paths, not modules mypy --python-version 3.11 -> ty check --python-version 3.11 ``` ### From pyright ```bash pyright . -> ty check pyright path/to/file.py -> ty check path/to/file.py ``` ## Anti-Patterns | Anti-Pattern | Fix | | --------------------------------------------------- | ------------------------------------------------------------ | | Blanket `# ty: ignore` everywhere | Fix errors or use rule-specific ignores | | Using `# type: ignore` in new code | Use `# ty: ignore[rule-name]` | | Expecting mypy plugin behavior | Check limitation table; wait for framework support if needed | | Running ty on unannotated code expecting strictness | Add ruff ANN rules for annotation enforcement | | Pinning to latest without testing | Pin version in CI, test upgrades deliberately | ## What This Skill is NOT - Not a replacement for `ty explain rule ` for rule details - Not for linting or formatting (use ruff) - Not for package management (use uv) - Not a mypy drop-in replacement yet (plugin gap, beta stability) ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [hyperb1iss](https://github.com/hyperb1iss) - **Source:** [hyperb1iss/hyperskills](https://github.com/hyperb1iss/hyperskills) - **License:** MIT - **Homepage:** https://hyperbliss.tech Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-hyperb1iss-hyperskills-ty - Seller: https://agentstack.voostack.com/s/hyperb1iss - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.