nx_log_gate.nx

nx_log_gate.nx -- the gate for the structured logger 32 modules import. WHY: nx_gensota gen-3 worklist. The module's header makes a STRONG, testable promise -- "deterministic by default: monotonic sequence counter, not wall-clock. Tests can snapshot logs BYTE-FOR-BYTE" -- and a byte-for-byte snapshot claim is only true if the format is fixed-width and the counter has no holes. ★THE TOOTH THAT MATTERS (T4): A FILTERED EVENT MUST NOT ADVANCE THE SEQUENCE. If a dropped event consumed a sequence number, every snapshot would depend on the CURRENT LOG LEVEL -- two runs at different verbosity could never be diffed, which is the whole point of the design. Nothing else in the system would notice; the lines still look perfectly well-formed. The context takes an out_fd directly, so this gate writes to a real file and READS THE BYTES BACK -- a writer is only tested by a read-back. ⚠DELIBERATELY NOT TESTED: nx_log_fatal, which exits the process by contract (NX_LOG_EXIT=200). A gate that called it would kill its own harness; its exit path is proven by inspection here and would need a fork to test honestly -- declared, not silently skipped. license_tier: ORIGINAL expect_exit: 0 No hw writes (Rule 26).