chore: add pytest test infrastructure

Mirror the layout introduced on feature/438-token_budget: pytest +
pytest-asyncio dev deps, asyncio_mode auto, a tests.* mypy override, and
pytest in the mypy pre-commit hook deps so the tests/ package type-checks.

.pre-commit-config.yaml

@@ -19,6 +19,7 @@ repos:
           types-python-dateutil,
           pydantic,
           fastapi,
+          pytest,
           "openai-agents[litellm]==0.14.6",
         ]
         args: [--install-types, --non-interactive]

pyproject.toml

@@ -55,8 +55,13 @@ dev = [
   "bandit>=1.8.3",
   "pre-commit>=4.2.0",
   "pyinstaller>=6.17.0; python_version >= '3.12' and python_version < '3.15'",
+  "pytest>=8.3",
+  "pytest-asyncio>=0.24",
 ]
 
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+
 [build-system]
 requires = ["hatchling"]
 build-backend = "hatchling.build"
@@ -104,6 +109,10 @@ module = [
 ignore_missing_imports = true
 disable_error_code = ["import-untyped"]
 
+[[tool.mypy.overrides]]
+module = ["tests.*"]
+disallow_untyped_decorators = false
+
 # ============================================================================
 # Ruff Configuration (Fast Python Linter & Formatter)
 # ============================================================================

uv.lock

@@ -775,6 +775,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/a0/d9/a1e041c5e7caa9a05c925f4bdbdfb7f006d1f74996af53467bc394c97be7/importlib_metadata-8.5.0-py3-none-any.whl", hash = "sha256:45e54197d28b7a7f1559e60b95e7c567032b602131fbd588f1497f47880aa68b", size = 26514, upload-time = "2024-09-11T14:56:07.019Z" },
 ]
 
+[[package]]
+name = "iniconfig"
+version = "2.3.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/72/34/14ca021ce8e5dfedc35312d08ba8bf51fdd999c576889fc2c24cb97f4f10/iniconfig-2.3.0.tar.gz", hash = "sha256:c76315c77db068650d49c5b56314774a7804df16fee4402c1f19d6d15d8c4730", size = 20503, upload-time = "2025-10-18T21:55:43.219Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/cb/b1/3846dd7f199d53cb17f49cba7e651e9ce294d8497c8c150530ed11865bb8/iniconfig-2.3.0-py3-none-any.whl", hash = "sha256:f631c04d2c48c52b84d0d0549c99ff3859c98df65b3101406327ecc7d53fbf12", size = 7484, upload-time = "2025-10-18T21:55:41.639Z" },
+]
+
 [[package]]
 name = "jinja2"
 version = "3.1.6"
@@ -1347,6 +1356,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/63/d7/97f7e3a6abb67d8080dd406fd4df842c2be0efaf712d1c899c32a075027c/platformdirs-4.9.4-py3-none-any.whl", hash = "sha256:68a9a4619a666ea6439f2ff250c12a853cd1cbd5158d258bd824a7df6be2f868", size = 21216, upload-time = "2026-03-05T18:34:12.172Z" },
 ]
 
+[[package]]
+name = "pluggy"
+version = "1.6.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/f9/e2/3e91f31a7d2b083fe6ef3fa267035b518369d9511ffab804f839851d2779/pluggy-1.6.0.tar.gz", hash = "sha256:7dcc130b76258d33b90f61b658791dede3486c3e6bfb003ee5c9bfb396dd22f3", size = 69412, upload-time = "2025-05-15T12:30:07.975Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/54/20/4d324d65cc6d9205fabedc306948156824eb9f0ee1633355a8f7ec5c66bf/pluggy-1.6.0-py3-none-any.whl", hash = "sha256:e920276dd6813095e9377c0bc5566d94c932c33b27a3e3945d8389c374dd4746", size = 20538, upload-time = "2025-05-15T12:30:06.134Z" },
+]
+
 [[package]]
 name = "pre-commit"
 version = "4.5.1"
@@ -1633,6 +1651,35 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/0c/82/a2c93e32800940d9573fb28c346772a14778b84ba7524e691b324620ab89/pyright-1.1.408-py3-none-any.whl", hash = "sha256:090b32865f4fdb1e0e6cd82bf5618480d48eecd2eb2e70f960982a3d9a4c17c1", size = 6399144, upload-time = "2026-01-08T08:07:37.082Z" },
 ]
 
+[[package]]
+name = "pytest"
+version = "9.1.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "colorama", marker = "sys_platform == 'win32'" },
+    { name = "iniconfig" },
+    { name = "packaging" },
+    { name = "pluggy" },
+    { name = "pygments" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/84/0e/b5858858d74958632c49b72cb25a3976ff9f632397626715be71c89d3971/pytest-9.1.0.tar.gz", hash = "sha256:41dd9148c08072446394cefd3d79701701335a9f4cae69ba92e39f6c7f5c061c", size = 1634181, upload-time = "2026-06-13T18:52:45.983Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/8b/5a/ba30a81239b909821b3153e303e7def45178bf353da4f72380e6c5e8793b/pytest-9.1.0-py3-none-any.whl", hash = "sha256:8ebb0e7888bdf2bdfc602ec51f8f62d50200af37356c74e503c79a94f5c81f32", size = 386453, upload-time = "2026-06-13T18:52:44.045Z" },
+]
+
+[[package]]
+name = "pytest-asyncio"
+version = "1.4.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pytest" },
+    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/43/7c/d36d04db312ecf4298932ef77e6e4a9e8ad017906e24e34f0b0c361a2473/pytest_asyncio-1.4.0.tar.gz", hash = "sha256:c6c0d2259945122819f171a32ecea2c349ead889ee28176caaf492143424be42", size = 58514, upload-time = "2026-05-26T09:56:04.083Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/03/e2/08a497ef684b88559c9cc5f4ad53a37e7b99e727094a86d6ea32536d5d3c/pytest_asyncio-1.4.0-py3-none-any.whl", hash = "sha256:933ca923a23075a87fb7070c0ec272a6848489824d887c85c812670932835aa1", size = 16930, upload-time = "2026-05-26T09:56:02.576Z" },
+]
+
 [[package]]
 name = "python-discovery"
 version = "1.2.0"
@@ -2056,6 +2103,8 @@ dev = [
     { name = "pre-commit" },
     { name = "pyinstaller", marker = "python_full_version < '3.15'" },
     { name = "pyright" },
+    { name = "pytest" },
+    { name = "pytest-asyncio" },
     { name = "ruff" },
 ]
 
@@ -2079,6 +2128,8 @@ dev = [
     { name = "pre-commit", specifier = ">=4.2.0" },
     { name = "pyinstaller", marker = "python_full_version >= '3.12' and python_full_version < '3.15'", specifier = ">=6.17.0" },
     { name = "pyright", specifier = ">=1.1.401" },
+    { name = "pytest", specifier = ">=8.3" },
+    { name = "pytest-asyncio", specifier = ">=0.24" },
     { name = "ruff", specifier = ">=0.11.13" },
 ]