Status: IN
Palindrome construction and permutation problems are specific instantiations of the hash-then-stream pipeline: Counter builds the frequency map in O(n) preprocessing, then a single-pass parity check over frequencies determines constructibility — the same two-phase structure that governs the broader pipeline taxonomy.
palindrome's Counter + parity-scan matches the canonical hash-then-stream decomposition
Depends on (SL): palindrome-construction-reduces-to-frequency-parity, hash-preprocessing-universal-first-step