core: fix _parse_google_docstring mishandling continuation lines with colons

[Alvin Tang (alvinttang)]

Description

_parse_google_docstring incorrectly parses multi-line argument descriptions when a continuation line contains a colon. The continuation line is treated as a new argument definition instead of being appended to the current argument's description.

Example

def search(query: str, top_k: int = 5) -> str:
    """Search the knowledge base.

    Args:
        query: The search query to use
            for finding things: important ones
        top_k: Number of results to return
    """

Before (broken): The parser creates 3 args: query, for finding things, top_k
After (fixed): The parser correctly creates 2 args: query (with full description including "for finding things: important ones"), top_k

Root Cause

The parser used if ":" in line to detect new argument lines without considering indentation. In Google-style docstrings, continuation lines have deeper indentation than argument definition lines.

Fix

Detect the base indentation level from the first argument line and treat any line with deeper indentation as a continuation of the current argument's description, regardless of whether it contains a colon.

Issue

Fixes #35679

Dependencies

None.

Testing

Added 4 unit tests in test_function_calling.py::TestParseGoogleDocstring:

• test_continuation_line_with_colon — the core bug scenario
• test_simple_args_still_work — regression check for basic args
• test_continuation_line_without_colon — multi-line descriptions without colons
• test_multiple_continuation_lines_with_colons — multiple continuation lines each containing colons

All tests pass locally with Python 3.12.

[codspeed-hq]

Merging this PR will not alter performance

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✅ 13 untouched benchmarks
⏩ 23 skipped benchmarks¹

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_{Comparing alvinttang:fix/parse-docstring-continuation-colon-v2 (44843a7) with master (f838c78)}

Footnotes

1. 23 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩