Each sweep takes at most 250 000 segments and 2 million possible crossings (pairs of segments whose bounds overlap, counted in O(n log n)), and a fold at most 4 million segments swept over its steps; past them the operation is refused with PathOpsError::TooComplex before it runs. A boolean group past the caps draws without its result, with a warning once, and the refusal is cached; vector.flatten refuses it instead of dropping it.
BFlat
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