nx_record_tsv_gate.nx

nx_record_tsv_gate.nx -- referee for the TSV <-> NXR1 compatibility bridge (seq1326 rung 2). T1 IS THE TOOTH THAT MAKES ADOPTION SAFE: a real tab-delimited line survives tsv -> NXR1 -> tsv BYTE-IDENTICAL. Without that, migrating a plane's physical format silently rewrites its data and every legacy reader is a liar. With it, a plane can be stored as NXR1 today and its existing decoders keep reading the exact same bytes (rule 19) until each is migrated deliberately. T5 IS THE TOOTH THAT KEEPS THE BRIDGE HONEST: a record holding a value TSV cannot represent must be REFUSED at render time, not silently emitted as extra columns. T6 is its non-vacuity partner -- the same record with the offending byte removed MUST render fine, proving T5 refuses because of the TAB and not because rendering is simply broken. license_tier: ORIGINAL expect_exit: 0