fix(ui): replace biased array shuffle with Fisher-Yates algorithm#846
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The search modal tip randomization used `array.sort(() => Math.random() - 0.5)` which produces statistically biased results because comparison-based sorting algorithms require a consistent comparator to work correctly. A random comparator violates this contract, causing some permutations to appear more frequently than others depending on the underlying sort implementation. Replace with a proper Fisher-Yates (Knuth) shuffle that guarantees a uniform distribution of all possible permutations in O(n) time. The new `shuffle()` utility is added to `src/utils/index.ts` for reuse across the codebase. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
array.sort(() => Math.random() - 0.5)with a proper Fisher-Yates (Knuth) shuffle in the search modal's tip randomization (SearchModal.tsline 301).shuffle<T>()utility tosrc/utils/index.tsthat returns a new array without mutating the original.Why this matters
Using
sort()with a random comparator produces statistically biased results. The ECMAScript spec does not define a particular sorting algorithm, so the distribution of permutations depends on the engine's implementation (e.g., V8 uses TimSort). A random comparator violates the requirement that the comparator be consistent and transitive, meaning some orderings appear significantly more often than others.The Fisher-Yates shuffle (also known as the Knuth shuffle) guarantees a uniformly random permutation in O(n) time by iterating backwards through the array and swapping each element with a randomly chosen element from the remaining unprocessed portion.
Changes
src/utils/index.tsshuffle<T>(arr: T[]): T[]utility functionsrc/components/SearchModal.tsshufflefrom utils; replacetips.sort(() => Math.random() - 0.5)withshuffle(tips)Test plan
tsc --noEmit)🤖 Generated with Claude Code