按建议，继续完成后续工作

结论：已新增 OPFS session snapshot store，提供通用 JSON 包络、格式校验和保存/读取往返验证；该层只处理 host-side 持久化，不定义 CNC 机床状态语义。

wasm-port/docs/source-reuse-map.md

@@ -51,7 +51,7 @@ Current validation is intentionally mechanical:
 
 | Dependency | LinuxCNC files that expose it | Standalone treatment |
 | --- | --- | --- |
-| Native file IO | `inifile.cc`, `rs274ngc_pre.cc`, parameter file paths | Allowed in native probes; browser OPFS remains a host-side adapter under `runtime/opfs/`, with path ownership in `runtime/opfs/path-model.js` |
+| Native file IO | `inifile.cc`, `rs274ngc_pre.cc`, parameter file paths | Allowed in native probes; browser OPFS remains a host-side adapter under `runtime/opfs/`, with path ownership in `runtime/opfs/path-model.js` and generic snapshot persistence in `runtime/opfs/snapshot-store.js` |
 | RTAPI | `rtapi_*.h`, TP, posemath, motion headers | Minimal standalone shim in `runtime/core/shims/rtapi.h` |
 | NML transport | `emc.hh`, motion/NML type headers | Transport is not ported; only the status/type edges needed by vendored compute code are exposed through standalone shims and probes |
 | HAL runtime | named parameter lookup, kinematics component lifecycle, and runtime status edges | Standalone HAL adapter under `runtime/core/linuxcnc_wrap/` |
@@ -74,6 +74,8 @@ Current validation is intentionally mechanical:
 - OPFS persistence is connected to the INI panel through the host-side
   `runtime/opfs/file-service.js` adapter. `runtime/opfs/path-model.js` now
   defines paths for INI, tool table, parameter file, G-code program,
-  preview-cache, and session-snapshot targets; semantic loading for tool
-  tables, parameter files, and G-code programs remains future work.
+  preview-cache, and session-snapshot targets. `runtime/opfs/snapshot-store.js`
+  adds a generic JSON session snapshot envelope; semantic loading for tool
+  tables, parameter files, G-code programs, and machine-state restoration
+  remains future work.
 - Native LinuxCNC GUI code remains out of scope for implementation.