feat: add py.typed marker so mypy uses the shipped type hints (#234)

README.md

@@ -46,6 +46,16 @@ To install Together Python Library from PyPI, simply run:
 pip install together
 ```
 
+### Type hints
+
+This package ships inline type annotations and a [PEP 561](https://peps.python.org/pep-0561/) `py.typed` marker, so type checkers such as mypy and pyright use them automatically — no separate stub package and no `follow_untyped_imports` override needed:
+
+```python
+from together import Together
+
+client = Together()  # fully typed
+```
+
 ### Setting up API Key
 
 > 🚧 You will need to create an account with [Together.ai](https://api.together.xyz/) to obtain a Together API Key.

tests/unit/test_py_typed.py

@@ -0,0 +1,14 @@
+from pathlib import Path
+
+import together
+
+
+def test_py_typed_marker_ships_with_package() -> None:
+    """PEP 561 requires the marker to sit inside the installed package.
+
+    Checking it relative to the imported module (rather than the repo tree)
+    means this also fails if the marker is ever dropped from the built
+    distribution.
+    """
+    package_root = Path(together.__file__).parent
+    assert (package_root / "py.typed").is_file()