StreamFlow Mypy Sub-Skill: no-untyped-def

Error: [no-untyped-def] — function or method missing type annotations.

Decision Process

For each function: can all parameters and the return type use concrete types?

• YES → fix it
• NO (any type needs Any, dict[str, Any], etc.) → skip the entire function

Workflow

1. Identify errors:

   uv run mypy path/to/file.py | grep "no-untyped-def"
   

2. Classify each function as FIXABLE or UNFIXABLE (see above)
3. Add annotations to FIXABLE functions only
4. Validate & commit: Load the StreamFlow Mypy Type Checking skill — General Workflow steps 3–5

Key Patterns

# Simple return types
async def close(self) -> None: ...
def is_ready(self) -> bool: ...

# Literal for fixed value sets (preferred over bare str/int)
def get_status(self) -> Literal["pending", "running", "completed", "failed"]: ...
def set_mode(self, mode: Literal["sync", "async"]) -> None: ...

# Broad arguments, narrow returns
from collections.abc import Iterable, Sequence, Mapping

def process(self, items: Iterable[Token]) -> list[str]: ...    # broad arg, narrow return
def validate(self, cfg: Mapping[str, str]) -> bool: ...        # read-only dict arg

# Optional
def get_connector(self, name: str) -> Connector | None: ...

# Self for classmethods
@classmethod
async def load(cls, persistent_id: int) -> Self: ...

# TypedDict for structured dicts (avoids dict[str, Any])
class ConnectorConfig(TypedDict):
    name: str
    enabled: bool

def get_config(self) -> ConnectorConfig: ...

SKIP these — require forbidden types:

def get_config(self): return {"key": self.value}      # needs dict[str, Any]
def get_items(self): return [self.id, self.cfg]        # needs list[Any]
def save(self): return self.config                     # MutableMapping[str, Any]

Common abstract argument types: Iterable[T] (iteration only) · Sequence[T] (indexing) · Mapping[K, V] (read-only dict)

If any return path needs a forbidden type, skip the whole function.

See Also

• StreamFlow Mypy Type Checking skill — General workflow, allowed types reference
• AGENTS.md — Forbidden types list, commit approval rule