按规划继续工作

结论：将现有负向 G-code fixture 纳入 upstream rs274 -g side-by-side 基线，校验错误文本和 absent canonical 事件约束，继续保持解释器语义来源于 LinuxCNC。

wasm-port/docs/drift-report.md

@@ -96,7 +96,9 @@ semantic rewrites:
   select/change/length-offset, canned-cycle, state-tag motion, tool-table
   setup, and O-word subroutine fixtures; it also covers threading/rigid tap,
   NURBS dispatch boundaries, and comparable canonical runtime edge and
-  program-end cleanup calls.
+  program-end cleanup calls. It now also checks the negative fixture set
+  against upstream `rs274 -g` for expected error text and absent canonical
+  event constraints.
   HAL-backed adapter-heavy fixtures, standalone modal-state assertions, and upstream
   `rs274` output gaps such as `WAIT` or hidden NURBS control-point detail still
   need dedicated native LinuxCNC baselines.