Guard initial m98m99 staging paths

wasm-port/tests/browser/interp_smoke.html

@@ -7621,6 +7621,14 @@
         "m98m99/03-error-M98-no-P-word",
         "test.ngc",
       );
+      const m98m99InitialStagedNgcFiles = [
+        m98m99BasicsPath,
+        m98m99VariablesPath,
+        m98m99M98NoPWordPath,
+      ].map((path) => path.replace("/work/browser-interp/m98m99/", ""));
+      if (m98m99InitialStagedNgcFiles.join(",") !== m98m99RegressionFiles.slice(0, 3).join(",")) {
+        throw new Error("browser_interp_m98m99_initial_staging_manifest: list drift");
+      }
       verifyExpectedOutput(
         "browser_interp_m98m99_03_error_m98_no_p_word",
         interp.runFile(m98m99M98NoPWordPath),

wasm-port/tests/wasm/node/verify_interp_wasm.mjs

@@ -2533,6 +2533,17 @@ const m98m99M98NoPWordPath = writeInterpRegressionFile(
   "m98m99/03-error-M98-no-P-word",
   "test.ngc",
 );
+assert.deepEqual(
+  [
+    m98m99BasicsPath,
+    m98m99VariablesPath,
+    m98m99M98NoPWordPath,
+  ],
+  m98m99RegressionFiles
+    .slice(0, 3)
+    .map((file) => `/work/interp/m98m99/${file}`),
+  "interp m98m99 initial direct-file staging manifest drift",
+);
 verifyExpectedOutput(
   "interp_m98m99_03_error_m98_no_p_word_wasm",
   interp.runFile(m98m99M98NoPWordPath),