fix(#220): PandasAdapter auto time-column detection was unreachable dead code

[himax12]

Summary

The condition isinstance(df.index, (pd.DatetimeIndex, pd.RangeIndex, pd.Index)) was ALWAYS True because pd.Index is the base class of ALL pandas indexes. This made the 'not' always False, making _detect_time_column() unreachable dead code.

The Fix

Removed pd.Index from the tuple:

• Before: isinstance(df.index, (pd.DatetimeIndex, pd.RangeIndex, pd.Index)) # Always True!
• After: isinstance(df.index, (pd.DatetimeIndex, pd.RangeIndex))

This allows auto-detection to run when index is not DatetimeIndex or RangeIndex.

Changes

• src/sktime_mcp/data/adapters/pandas_adapter.py: Removed pd.Index from the isinstance check

Testing

• DatetimeIndex index -> skip detection (correct)
• RangeIndex index -> skip detection (correct)
• Plain Index (strings/numbers) -> trigger auto-detection (now works!)

[Copilot]

Pull request overview

Fixes unreachable auto time-column detection in PandasAdapter.load() by correcting an isinstance() check that previously always evaluated as true due to inclusion of pd.Index.

Changes:

• Remove pd.Index from the df.index type check so _detect_time_column() can run for non-datetime/non-range indexes.

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[Copilot]

After removing pd.Index from this check, _detect_time_column() will now run when df.index is a pd.PeriodIndex (and other pd.Index subclasses like MultiIndex). Since validate() explicitly treats PeriodIndex as a supported time index, running auto-detection here can unexpectedly overwrite an existing valid time index via df.set_index(time_col). Consider adding pd.PeriodIndex to the tuple (and/or explicitly skipping auto-detection for other already-acceptable index types) so only truly "generic"/non-time-like indexes trigger detection.

Suggested change

	elif not isinstance(df.index, (pd.DatetimeIndex, pd.RangeIndex)):
	# Try to detect time column
	elif not isinstance(df.index, (pd.DatetimeIndex, pd.RangeIndex, pd.PeriodIndex)):
	# Try to detect time column only when there is no already-supported time index