Guard cam-nisley staging paths

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

@@ -1491,7 +1491,21 @@ verifyExpectedOutput(
   ].join("\n"),
 );
 
-const camNisleyDir = writeInterpRegressionFiles("cam-nisley", ["cam.ngc", "test.tbl"]);
+const camNisleyFiles = [
+  "cam.ngc",
+  "test.tbl",
+];
+assert.deepEqual(
+  camNisleyFiles.filter((file) => file.endsWith(".ngc")),
+  interpRegressionNgcFilesRecursive("cam-nisley"),
+  "interp cam-nisley fixture coverage drift",
+);
+const camNisleyDir = writeInterpRegressionFiles("cam-nisley", camNisleyFiles);
+assert.deepEqual(
+  camNisleyFiles.map((file) => `${camNisleyDir}/${file}`),
+  camNisleyFiles.map((file) => `/work/interp/cam-nisley/${file}`),
+  "interp cam-nisley staging manifest drift",
+);
 interp.writeTextFile(
   `${camNisleyDir}/test.ini`,
   [