nx_srcdiff.nx

nx_srcdiff.nx -- IS A DIRECTION MERGE SAFE, OR DOES THIS NEED A UNION? The per-file decision organ. WHY IT EXISTS. The estate's banked law is that A DIVERGENCE'S DIRECTION IS A PER-FILE MEASUREMENT, NEVER A PER-TREE POLICY -- and the 2026-08-03 lane proved it the hard way: BOTH of that session's directional hypotheses INVERTED once someone actually body-diffed the files ("NAS strict superset" hid the laptop's richer state; "local larger => NAS revert" was a missing leak fix). So every convergence needs one question answered first: does adopting one side LOSE anything? That question was being answered ad-hoc, by hand, outside the estate -- four separate times in the 2026-08-06 session alone, in a laptop shell no other seat can run. An analysis that gates a DESTRUCTIVE act and lives only in one operator's scrollback is not a capability the fleet has. WHAT IT REPORTS, and the verdict IS the decision: IDENTICAL -- same line multiset (!!ORDER may still differ; byte identity is nx_filehash's job) A-SUPERSET -- B's lines all appear in A. Adopting A loses NOTHING: a DIRECTION merge is safe. B-SUPERSET -- the mirror. BIDIRECTIONAL -- both sides hold lines the other lacks. A direction merge DESTROYS WORK; UNION. This is exactly the shape that decided the real cases: nx_syscalls.nx came back A-SUPERSET (the only delta was 5 sys_munmap doc lines) so a direction was correct; the 4 same-size gate/quality files came back A-SUPERSET too, with every "laptop-only" line being the SUPERSEDED original of a line the other side replaced -- which a surplus report shows and a size screen cannot. !!A LINE MULTISET IS NOT BYTE IDENTITY. Reordering, and CR-only differences, do not show up as surplus. CR counts are reported per side BECAUSE they are the classic invisible delta (a 2026-08-03 convergence found 742 stray CRs that git's autocrlf hid while a byte gate counted every one). Use nx_filehash/nx_treehash for identity; use THIS to decide which way to merge. DIALECT: plain-if, <=6 params, consts above use. Tables are mmap'd through static POINTERS -- a BSS static ARRAY silently crashes the module at startup (banked gotcha). license_tier: ORIGINAL expect_exit: 0 No hw writes (Rule 26).