Replace mypy with ty (#295)

Author: tomvothecoder

.pre-commit-config.yaml

@@ -31,19 +31,14 @@ repos:
         files: ^backend/.*\.py$
 
 
-  - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v1.19.1
+  - repo: local
     hooks:
-      - id: mypy
-        name: mypy (type checking)
-        args:
-          - --config-file=backend/pyproject.toml
-        files: ^backend/.*\.py$
-        additional_dependencies:
-          - fastapi
-          - pydantic
-          - sqlalchemy
-          - types-python-dateutil
+      - id: ty
+        name: ty (type checking)
+        entry: bash -c 'cd backend && uv run ty check'
+        language: system
+        pass_filenames: false
+        files: ^backend/app/.*\.py$
 
   # ------------------------
   # Frontend (Node / TS)

README.md

@@ -58,7 +58,7 @@ Requests to `https://simboard-dev.e3sm.org/api/...` (the frontend origin) return
 - Backend: FastAPI, Pydantic, SQLAlchemy, Alembic
 - Database: PostgreSQL
 - Auth: GitHub OAuth for browser flows, API tokens for service accounts
-- Tooling: `uv`, `pnpm`, `ruff`, `mypy`, `eslint`, `prettier`, `pre-commit`
+- Tooling: `uv`, `pnpm`, `ruff`, `ty`, `eslint`, `prettier`, `pre-commit`
 - CI/CD: GitHub Actions plus NERSC-focused deployment/build docs under `docs/`
 
 ## Documentation Map

backend/.pre-commit-config.yaml

@@ -3,7 +3,6 @@ default_stages: [pre-commit]
 fail_fast: true
 
 # To update pre-commit hooks, run `pre-commit autoupdate` in the terminal.
-# Then update the versions in `conda-env/dev.yml`.
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v6.0.0
@@ -25,9 +24,12 @@ repos:
       # Run the formatter.
       - id: ruff-format
 
-  - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v1.18.2
+  - repo: local
     hooks:
-      - id: mypy
-        args: ["--config=backend/pyproject.toml"]
-        additional_dependencies: [types-requests, pydantic, types-python-dateutil]
+      - id: ty
+        name: ty (type checking)
+        entry: >
+          bash -c 'cd "$(git rev-parse --show-toplevel)/backend" && uv run ty check'
+        language: system
+        pass_filenames: false
+        files: ^(?:backend/)?app/.*\.py$

backend/app/features/assistant/llm_generator.py

@@ -114,24 +114,25 @@ def _build_model(self, http_client: AsyncClient) -> OpenAIChatModel:
         if self.config.provider == "ollama":
             api_key = api_key or _OLLAMA_PLACEHOLDER_API_KEY
 
-        provider_kwargs = {
-            "api_key": api_key,
-            "base_url": self._resolve_base_url(),
-            "http_client": http_client,
-        }
         if self.config.provider == "ollama":
-            provider_kwargs = {
-                "openai_client": AsyncOpenAI(
-                    **provider_kwargs,
+            provider = OpenAIProvider(
+                openai_client=AsyncOpenAI(
+                    api_key=api_key,
+                    base_url=self._resolve_base_url(),
+                    http_client=http_client,
                     max_retries=0,
                     timeout=self.config.timeout_seconds,
                     _enforce_credentials=False,
                 )
-            }
+            )
+        else:
+            provider = OpenAIProvider(
+                api_key=api_key,
+                base_url=self._resolve_base_url(),
+                http_client=http_client,
+            )
 
-        model = OpenAIChatModel(
-            self.config.model_name, provider=OpenAIProvider(**provider_kwargs)
-        )
+        model = OpenAIChatModel(self.config.model_name, provider=provider)
         return model
 
     def _resolve_base_url(self) -> str | None:

backend/app/features/catalog/api.py

@@ -1191,7 +1191,7 @@ def _machine_filter_options(db: Session) -> list[FilterOptionOut]:
 def _creator_filter_options(db: Session) -> list[FilterOptionOut]:
     """Return execution creators with stable IDs and email labels."""
     rows = (
-        db.query(User.id, User.email)
+        db.query(User.id, User.email)  # ty: ignore[no-matching-overload] -- SQLAlchemy mapped descriptors are not recognized as query columns.
         .join(Execution, Execution.created_by == User.id)
         .distinct()
         .order_by(User.email, User.id)

backend/app/features/user/api/oauth.py

@@ -185,7 +185,7 @@ async def github_callback(
     if has_verified_e3sm_membership is not None and hasattr(
         user_manager, "refresh_github_org_membership"
     ):
-        user = await user_manager.refresh_github_org_membership(
+        user = await user_manager.refresh_github_org_membership(  # ty: ignore[call-non-callable] -- FastAPI Users' untyped extension method is narrowed by hasattr.
             user,
             is_verified_member=has_verified_e3sm_membership,
             checked_at=datetime.now(timezone.utc),

backend/app/features/user/api/token.py

@@ -74,7 +74,7 @@ def create_api_token(
             detail="Only administrators can create API tokens",
         )
 
-    stmt = select(User).where(User.id == payload.user_id)
+    stmt = select(User).where(User.id == payload.user_id)  # ty: ignore[invalid-argument-type] -- SQLAlchemy mapped descriptor comparison produces a SQL expression at runtime.
     result = db.execute(stmt)
     target_user = result.scalar_one_or_none()
 
@@ -259,7 +259,7 @@ def create_service_account(
 
     email = f"{payload.service_name}@{settings.domain}"
 
-    existing = db.query(User).filter(User.email == email).first()
+    existing = db.query(User).filter(User.email == email).first()  # ty: ignore[invalid-argument-type] -- SQLAlchemy mapped descriptor comparison produces a SQL expression at runtime.
     if existing is not None:
         return ServiceAccountResponse(
             id=existing.id,

backend/app/features/user/auth/token.py

@@ -97,7 +97,7 @@ def validate_token(
         if datetime.now(timezone.utc) > token.expires_at:
             return None
 
-    user = db.query(User).filter(User.id == token.user_id).first()
+    user = db.query(User).filter(User.id == token.user_id).first()  # ty: ignore[invalid-argument-type] -- SQLAlchemy mapped descriptor comparison produces a SQL expression at runtime.
 
     if not user or not user.is_active:
         return None

backend/app/features/user/manager.py

@@ -19,10 +19,10 @@
 
 
 async def get_user_db(session: AsyncSession = Depends(get_async_session)):  # noqa: B008
-    yield SQLAlchemyUserDatabase(session, User, OAuthAccount)
+    yield SQLAlchemyUserDatabase(session, User, OAuthAccount)  # ty: ignore[invalid-argument-type] -- FastAPI Users' protocol does not support nullable OAuth passwords.
 
 
-class UserManager(UUIDIDMixin, BaseUserManager[User, uuid.UUID]):
+class UserManager(UUIDIDMixin, BaseUserManager[User, uuid.UUID]):  # ty: ignore[invalid-type-arguments] -- OAuth users intentionally have nullable passwords.
     async def on_after_register(self, user: User, request=None):
         logger.info(f"✅ New GitHub user registered: {user.email}")
 
@@ -48,7 +48,7 @@ async def get_user_manager(user_db=Depends(get_user_db)):  # noqa: B008
     yield UserManager(user_db)
 
 
-fastapi_users = FastAPIUsers[User, uuid.UUID](
+fastapi_users = FastAPIUsers[User, uuid.UUID](  # ty: ignore[invalid-type-arguments] -- OAuth users intentionally have nullable passwords.
     get_user_manager, [GITHUB_OAUTH_BACKEND, JWT_BEARER_BACKEND]
 )
 

backend/app/scripts/db/rollback_seed.py

@@ -119,7 +119,7 @@ def rollback_seed(db: Session):
 
         # Remove only the dummy OAuth account/user created by seed.py
         dev_user_id = db.execute(
-            select(User.id).where(User.__table__.c.email == DEV_EMAIL)
+            select(User.id).where(User.__table__.c.email == DEV_EMAIL)  # ty: ignore[no-matching-overload] -- SQLAlchemy declarative table columns are dynamically generated.
         ).scalar_one_or_none()
 
         if dev_user_id: