refactor: type check with mypy

Author: remarkablemark

.github/workflows/lint.yml

@@ -20,6 +20,9 @@ jobs:
       - name: Install dependencies
         run: pip install -e .[lint]
 
+      - name: Type check
+        run: mypy src
+
       - name: Run Black
         run: black --check .
 

.pre-commit-config.yaml

@@ -15,6 +15,11 @@ repos:
       - id: requirements-txt-fixer
       - id: trailing-whitespace
 
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v1.19.1
+    hooks:
+      - id: mypy
+
   - repo: https://github.com/psf/black
     rev: 25.1.0
     hooks:

pyproject.toml

@@ -33,6 +33,7 @@ docs = [
 lint = [
     "black==25.12.0",
     "isort==7.0.0",
+    "mypy==1.19.1",
     "pre-commit==4.5.1",
     "ruff==0.14.13",
 ]
@@ -48,7 +49,13 @@ Issues = "https://github.com/remarkablemark/python-cli-template/issues"
 [tool.black]
 fast = true
 
+[tool.mypy]
+strict = true
+ignore_missing_imports = true
+
 [tool.coverage.run]
 omit = [
+    "*/tests/*",
+    "/opt/*",
     "/tmp/*",
 ]

src/python_cli_template/cli.py

@@ -3,7 +3,7 @@
 from python_cli_template import __version__, hello
 
 
-def main(argv: list[str] = None) -> None:
+def main(argv: list[str] = []) -> None:
     parser = ArgumentParser(description="Python CLI Template")
 
     parser.add_argument(