Multi-candidate selection picked the candidate with the most nodes, but balanced_arrays also collected nested children arrays. For nested-format output (a single root frame whose children array holds 3 nodes), the inner array could outrank the outer (1 node), returning the children and dropping the real root. Flat _parent-style output (what M2.7 emitted in testing) hid it. balanced_arrays now collects only top-level arrays, skipping past each captured span. Adds a regression test. Found by Codex stop-time review.
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