Guard g76 staging paths

wasm-port/tests/browser/interp_smoke.html

@@ -7269,10 +7269,18 @@
         );
       }
 
-      const g76Dir = await writeInterpRegressionFiles(interp, "g76", [
+      const g76Files = [
         "g76only.ngc",
         "test.tbl",
-      ]);
+      ];
+      if (g76Files.length !== 2 || new Set(g76Files).size !== g76Files.length) {
+        throw new Error("browser_interp_g76_fixture_coverage: list drift");
+      }
+      const g76Dir = await writeInterpRegressionFiles(interp, "g76", g76Files);
+      const g76StagedRelativeFiles = g76Files.map((file) => `${g76Dir}/${file}`.replace("/work/browser-interp/g76/", ""));
+      if (g76StagedRelativeFiles.join(",") !== g76Files.join(",")) {
+        throw new Error("browser_interp_g76_staging_manifest: list drift");
+      }
       interp.writeTextFile(
         `${g76Dir}/test.ini`,
         [

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

@@ -2220,7 +2220,21 @@ for (const g71Fixture of g71Fixtures) {
   );
 }
 
-const g76Dir = writeInterpRegressionFiles("g76", ["g76only.ngc", "test.tbl"]);
+const g76Files = [
+  "g76only.ngc",
+  "test.tbl",
+];
+assert.deepEqual(
+  g76Files.filter((file) => file.endsWith(".ngc")),
+  interpRegressionNgcFilesRecursive("g76"),
+  "interp g76 fixture coverage drift",
+);
+const g76Dir = writeInterpRegressionFiles("g76", g76Files);
+assert.deepEqual(
+  g76Files.map((file) => `${g76Dir}/${file}`),
+  g76Files.map((file) => `/work/interp/g76/${file}`),
+  "interp g76 staging manifest drift",
+);
 interp.writeTextFile(
   `${g76Dir}/test.ini`,
   [