Status: IN
The combined construction techniques (exact arithmetic, sentinel initialization, streaming invariants, ordering independence) achieve correct output for every input within LeetCode's stated constraints.
Construction correctness plus ordering independence should imply universal correctness for constrained inputs — gated on known bugs where construction techniques fail despite valid input
Depends on (SL): correctness-by-construction-not-validation, streaming-needs-no-external-ordering
Unless: zero-input-returns-wrong-result, find-difference-reduce-no-initial-value