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/compatibility-validation.md

@@ -69,7 +69,8 @@ with a Node mock of the browser File System Access handles. It covers nested
 directory creation, text save/load, missing file behavior, invalid relative
 paths, unavailable OPFS storage, and the host-side OPFS path model for INI,
 tool table, parameter, G-code, preview-cache, and session-snapshot storage
-targets.
+targets. It also validates the host-side session snapshot JSON envelope and
+round-trip store without defining CNC machine-state semantics.
 
 The browser smoke script serves `wasm-port/` over localhost and runs Chromium
 headless against a test page that imports the JS SDK, loads the INI WASM
@@ -126,7 +127,7 @@ The validation fails if:
 | Harness | Purpose |
 | --- | --- |
 | `tests/wasm/node/verify_ini_wasm.sh` | Validates the browser-facing INI WASM module can be built from vendored LinuxCNC `inifile.cc`, loaded through the JS SDK in Node, and queried through the exported C ABI. |
-| `tests/opfs/node/verify_file_service.sh` | Validates the host-owned OPFS text-file adapter and path model used by the browser INI panel without moving file persistence into the WASM core. |
+| `tests/opfs/node/verify_file_service.sh` | Validates the host-owned OPFS text-file adapter, path model, and session snapshot store used by the browser INI panel without moving file persistence into the WASM core. |
 | `tests/browser/verify_ini_panel_browser.sh` | Validates the INI SDK, WASM module loading, and OPFS text-file round trip in a real browser runtime. |
 | `tests/host/verify_host_smokes.sh` | Runs the current host-side Node, WASM, OPFS, and browser smoke validation with a single INI WASM build. |
 

wasm-port/docs/drift-report.md

@@ -42,7 +42,7 @@ semantic rewrites:
 | Kinematics component lifecycle | Kinematics modules are initialized through LinuxCNC module entry points where native runtime probes exist, while HAL component init/ready/exit, HAL pin allocation, and RTAPI module metadata are handled by standalone shims. |
 | Go math C/C++ linkage | `genserkins` runtime probing compiles vendored `gomath.c` through a narrow C++ wrapper so LinuxCNC `genserfuncs.c` can link to the upstream Go math symbols without editing vendored source. |
 | Switchkins iterative forward | `genhexkins` runtime probing follows LinuxCNC switchkins iterative-forward behavior, including the first-call warmup path before asserting roundtrip convergence. |
-| Browser storage | OPFS remains outside the native core; `runtime/opfs/file-service.js` owns browser text-file persistence and `runtime/opfs/path-model.js` owns host-side storage paths for INI, tool table, parameter, G-code, preview-cache, and session-snapshot content. |
+| Browser storage | OPFS remains outside the native core; `runtime/opfs/file-service.js` owns browser text-file persistence, `runtime/opfs/path-model.js` owns host-side storage paths for INI, tool table, parameter, G-code, preview-cache, and session-snapshot content, and `runtime/opfs/snapshot-store.js` owns generic JSON session snapshot persistence. |
 
 ## Enforced Non-Drift Rules
 
@@ -61,8 +61,8 @@ semantic rewrites:
 - JS SDK validation is currently limited to the INI WASM wrapper around
   vendored LinuxCNC `inifile.cc`.
 - OPFS validation covers a Node mock of the file-service adapter, the
-  host-side path model, and a Chromium localhost round trip for INI text-file
-  persistence.
+  host-side path model, generic session snapshot storage, and a Chromium
+  localhost round trip for INI text-file persistence.
 - Host-side smoke validation is aggregated by
   `tests/host/verify_host_smokes.sh` so Node, WASM, OPFS, and browser checks
   run from one command.

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.