⚡ Bolt: [performance improvement] Avoid eager list materialization during AST traversal

[tachyon-beep]

💡 What: Modified AST traversal functions _assignment_callee and _collect_return_paths in src/wardline/scanner/taint/variable_level.py to accept Iterable[ast.AST] instead of list[ast.AST], removing the eager list() materialization of ast.iter_child_nodes(node) and func_node.body.

🎯 Why: Eagerly converting child node generators to lists at every node during AST traversal creates unnecessary shallow copies and causes excessive memory allocation, which degrades performance especially on large or deep syntax trees.

📊 Impact: Reduces memory overhead and avoids redundant list allocations during static taint analysis traversal. By yielding and iterating directly, the garbage collector has less work to do and memory usage stays flatter.

🔬 Measurement: The optimization preserves exact behavior (verified via the test suite) while improving the efficiency of the compute_return_taint and compute_return_callee analysis paths. Measuring peak memory usage during large codebase scans will show the reduction in memory pressure.

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PR created automatically by Jules for task 3408277797811974874 started by @tachyon-beep

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[Copilot]

Pull request overview

Improves AST traversal performance in the taint scanner by eliminating repeated eager list materialization during recursive walks, reducing per-node allocations and memory churn on large syntax trees.

Changes:

• Updated _assignment_callee and _collect_return_paths to accept Iterable[ast.AST] and pass ast.iter_child_nodes(node) directly (no list(...) copies).
• Removed list(func_node.body) materialization in compute_return_taint and compute_return_callee.
• Added a short performance note in .jules/bolt.md documenting the “avoid eager list materialization” traversal guideline.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/wardline/scanner/taint/variable_level.py	Avoids eager list creation in recursive AST traversal helpers to reduce memory overhead in return-taint analysis paths.
.jules/bolt.md	Documents the learned performance guideline for AST traversal to prevent reintroducing eager list materialization.

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