按规划继续工作

结论：补齐显式参数文件 override 路径的浏览器 OPFS 保存和备份读回验证，继续通过 vendored LinuxCNC save_parameters 路径覆盖。

wasm-port/tests/browser/interp_smoke.html

@@ -703,6 +703,64 @@
           "tool_1.comment=browser explicit tool",
         ].join("\n"),
       );
+      const savedExplicitParameters = await saveMachineParametersToOpfs(
+        interp,
+        "browser-ini-override-session",
+        {
+          5161: 51.25,
+          5162: 102.5,
+          5220: 1.0,
+          5221: 7.5,
+          5399: 202,
+        },
+        {
+          opfsPath: loadedIniOverrideSession.parameters.opfsPath,
+          wasmPath: loadedIniOverrideSession.parameters.wasmPath,
+        },
+      );
+      if (
+        savedExplicitParameters.opfsPath !==
+        "linuxcnc/machines/browser-ini-override-session/browser-explicit.var"
+      ) {
+        throw new Error(`unexpected explicit saved parameter path: ${savedExplicitParameters.opfsPath}`);
+      }
+      if (
+        savedExplicitParameters.backupOpfsPath !==
+        "linuxcnc/machines/browser-ini-override-session/browser-explicit.var.bak"
+      ) {
+        throw new Error(`unexpected explicit backup path: ${savedExplicitParameters.backupOpfsPath}`);
+      }
+      verifyExpectedOutput(
+        "opfs_save_explicit_parameter_file",
+        savedExplicitParameters.result,
+        [
+          "save_parameters=0",
+          "parameter_5161=51.25",
+          "parameter_5162=102.5",
+          "parameter_5221=7.5",
+          "parameter_5399=202",
+        ].join("\n"),
+      );
+      verifyExpectedOutput(
+        "opfs_saved_explicit_parameter_text",
+        await loadTextFile(loadedIniOverrideSession.parameters.opfsPath),
+        [
+          "5161\t51.250000",
+          "5162\t102.500000",
+          "5221\t7.500000",
+          "5399\t202.000000",
+        ].join("\n"),
+      );
+      verifyExpectedOutput(
+        "opfs_saved_explicit_parameter_backup_text",
+        await loadTextFile(savedExplicitParameters.backupOpfsPath),
+        [
+          "5161 41.25",
+          "5162 82.5",
+          "5221 6.5",
+          "5399 101",
+        ].join("\n"),
+      );
 
       await saveMachineTextFiles("browser-invalid-param-file-session", {
         ini: [