Telemetry decorators (df_api_usage etc.) erase type information on all DataFrame methods

[gitovska]

Summary

Three telemetry decorators in snowflake/snowpark/_internal/telemetry.py are completely untyped, causing all DataFrame and RelationalGroupedDataFrame methods they wrap to return Unknown under strict type checkers (pyright, ty).

Root Cause

# telemetry.py — all three follow this pattern
def df_api_usage(func):          # no type variables
    def wrap(*args, **kwargs):   # no type variables
        ...
        return r
    return wrap

df_api_usage is the outermost decorator on DataFrame methods — applied after @publicapi — so it erases the type signature that @publicapi carefully preserves via CallableT:

@df_api_usage       # outer — strips all type information
@publicapi          # inner — uses CallableT correctly, but now overridden
def select(self, *cols) -> "DataFrame":
    ...

The same problem affects df_to_relational_group_df_api_usage and relational_group_df_api_usage.

Fix

Apply the same CallableT pattern used to fix publicapi in #2999:

from typing import TypeVar, Callable

_FuncT = TypeVar("_FuncT", bound=Callable)

def df_api_usage(func: _FuncT) -> _FuncT:
    @functools.wraps(func)
    def wrap(*args, **kwargs):
        ...
        return r
    return wrap  # type: ignore[return-value]

Apply the same fix to df_to_relational_group_df_api_usage and relational_group_df_api_usage.

Affected methods

Every public DataFrame method decorated with @df_api_usage — including select, filter, with_column, join, union, group_by, etc. — and every RelationalGroupedDataFrame aggregation method.

Related

• SNOW-1913150: Type annotations gone #2977 — original type annotation issue (fixed for @publicapi)
• SNOW-1942414: publicapi decorator botches type hints (pyright) #3051 — follow-up (also fixed for @publicapi)
• The telemetry decorators were not addressed in either fix

[AvinashYerra]

Hi maintainers. I want to contribute to this issue.
Would you prefer:

1. Following the existing CallableT pattern used in the earlier @publicapi fixes, or
2. Using a more explicit ParamSpec + TypeVar approach for preserving both parameter and return types in the wrappers? (the one present in the comments of this issue - SNOW-1913150: Type annotations gone #2977