新增 OPFS session readiness SDK helper

wasm-port/docs/opfs-session-persistence.md

@@ -31,6 +31,7 @@ Session snapshot helpers:
 - `loadSessionSnapshot()`
 - `loadMachineSessionSnapshot()`
 - `validateSessionSnapshot()`
+- `readMachineSessionReadiness()`
 
 Machine file and program helpers:
 
@@ -74,6 +75,11 @@ The browser/UI persistence workflow is host-side only:
    `restoreParameters()`, `saveParameters()`, `loadToolTable()`, and
    `saveToolTable()`.
 
+External callers can run `readMachineSessionReadiness()` before step 4 to get a
+structured `ready`/`blocked` report for persisted INI, parameter, tool-table,
+optional G-code, and optional session snapshot files. This helper only checks
+host file availability and snapshot envelope validity.
+
 This workflow stores host files and stages them into Emscripten FS. It does not
 implement G-code, tool-table, parameter-file, planner, remap, or kinematics
 semantics in JavaScript.
@@ -154,6 +160,8 @@ ENABLE_PYTHON_REMAP_RUNTIME_PROBE=1 bash wasm-port/tests/native/probe_python_rem
 - Invalid OPFS paths are rejected before storage access.
 - Invalid snapshot format, version, session id, payload, or machine id is
   rejected by snapshot validation helpers.
+- `readMachineSessionReadiness()` reports missing files or invalid snapshots as
+  structured blocked checks before callers load a session into WASM.
 - Missing INI, parameter, or tool-table OPFS files remain host persistence
   errors. JavaScript does not synthesize LinuxCNC machine state.
 - Tool, parameter, remap, planner, and kinematics behavior remains owned by