按推荐建议，继续执行

结论：记录 LinuxCNC 上游 commit 与本地构建/fixture 基线，新增 upstream baseline 验证并接入 native 验证，确保 vendored 源码同步绑定到明确的 LinuxCNC 源程序版本。

wasm-port/docs/porting-steps-standalone.md

@@ -493,6 +493,10 @@ Current verified progress:
   `vendor/linuxcnc/`. This keeps G-code group conversion on the vendored
   LinuxCNC `interp_convert.cc` path instead of allowing the wrapper layer to
   grow another project-authored conversion implementation.
+- `docs/scope-and-baseline.md` records the current upstream LinuxCNC commit,
+  local tool versions, and fixture baseline. `tools/verify_upstream_baseline.sh`
+  now runs before vendor sync validation so extraction drift is checked against
+  the intended upstream HEAD, not an accidental checkout change.
 
 ## Phase 4: Port INI Parsing Without Editing Upstream