nx_fec_xor.nx

nx_fec_xor.nx -- sovereign XOR forward-error-correction (FlexFEC family, RFC 8627 re-implemented from spec). Closes the #1 shared gap vs the very best: loss-resilience, behind top esports netcode AND missing for NASA/aerospace-critical streaming. Pure XOR -> integer-only, no field math, branch-light, sovereign (imports only nx_syscalls). Same machinery, three uses: - row (1-D non-interleaved): recovers 1 RANDOM loss per row. - column (1-D interleaved): recovers a BURST of up to D consecutive (they land in distinct columns). - 2-D (row+column): iterative peeling recovers most MIXED loss. - K=1 row == the game REDUNDANT-INPUT window (send last N inputs). THE EXCEED: redundancy is sized adaptively from the REAL per-flow loss estimator (nx_linkqual lq_loss_pct), not a fixed cvar -- caller passes loss_pct to fec_scheme_for_loss. Generalizes the shipped nx_voice_fec redundant-copy concept (CLAUDE.md 15 / review-existing-functionality). Layout: source packets in a flat buffer, packet i at src + i*S (each padded to S bytes). Grid is L columns x D rows, K = L*D source packets, row j cell i = index j*L + i. Row repairs: D x S. Col repairs: L x S. license_tier: ORIGINAL