Status: IN
Palindrome construction and permutation problems in the repo uniformly reduce to frequency-parity analysis: a string can form a palindrome iff at most one character has odd frequency, the longest constructible palindrome sums even portions of each frequency plus at most one center character, and the actual count values are discarded in favor of their parity — the palindrome property is entirely determined by the parity signature of the character frequency distribution.
Depth-1 thematic grouping: four palindrome base beliefs share the same core insight that palindromicity is a parity property of frequencies
Depends on (SL): palindrome-perm-at-most-one-odd, palindrome-greedy-even-portions, palindrome-center-bonus-at-most-once, palindrome-perm-parity-reduction