fix: PythonCodeSplitter secondary-split pieces missing qualified name context

[GovindhKishore]

Related Issues

• fixes bug: PythonCodeSplitter secondary-split pieces lose function/method identity, hurting retrieval ranking #11874

Proposed Changes:

PythonCodeSplitter._secondary_split() falls back to a plain line-based split for oversized functions/methods/classes. Only the first resulting piece naturally contains the def/class signature line, so every piece after that has no identifying text at all, which hurts retrieval ranking for those pieces.

Fixed by reusing the qualified_name value already computed in _secondary_split() (currently only used in the logger.warning(...) call) and prepending it as a # qualified_name comment line to every piece after the first.

How did you test it?

Manually verified locally with a reproduction script: created a Document with a single function exceeding the oversized threshold, ran it through PythonCodeSplitter().run(...), and confirmed:

• Piece 0 still starts with the original def function_name(...): line (unchanged).
• Pieces 1+ now start with # function_name before the body content (previously had no identifying text at all).

Notes for the reviewer

Open to feedback on the prepended format (comment style, placement) before I finalize with tests and a release note.

Checklist

• I have read the contributors guidelines and the code of conduct.
• I have updated the related issue with new insights and changes.
• I have added unit tests and updated the docstrings.
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I have documented my code.
• I have added a release note file, following the contributors guidelines.
• I have run pre-commit hooks and fixed any issue.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
haystack/components/preprocessors
python_code_splitter.py
Project Total

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