Fail the build when the packaged binding does not match the package version

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "prebuild": "rimraf ./nodejs/dist",
     "build": "tsc",
-    "postbuild": "mkdir ./nodejs/dist/lib/binding && cp ./nodejs/lib/binding/node_setapp_binding.node ./nodejs/dist/lib/binding/node_setapp_binding.node",
+    "postbuild": "mkdir ./nodejs/dist/lib/binding && cp ./nodejs/lib/binding/node_setapp_binding.node ./nodejs/dist/lib/binding/node_setapp_binding.node && node ./scripts/check-binding-version.js",
     "prepublishOnly": "npm run build"
   },
   "dependencies": {

scripts/check-binding-version.js

@@ -0,0 +1,59 @@
+#!/usr/bin/env node
+/**
+ * Fail the build if the packaged N-API binding was compiled against a different
+ * Setapp library than this package version.
+ *
+ * `postbuild` copies `nodejs/lib/binding/node_setapp_binding.node` into
+ * `nodejs/dist/lib/binding/`, and `nodejs/dist` is what `main` loads. That
+ * source directory is gitignored, so on a machine where node-gyp has not run
+ * for the current version it holds a binding left over from an earlier one -
+ * and the copy succeeds silently.
+ *
+ * The binding statically links the Swift library, so the version it was built
+ * against is the version consumers actually run, whatever package.json says.
+ * Nothing downstream can detect or correct that.
+ *
+ * Every Mach-O the framework produces carries an embedded `__scv__<version>`
+ * stamp. This compares that stamp with the package version.
+ */
+const fs = require("fs");
+const path = require("path");
+
+const root = path.join(__dirname, "..");
+const pkg = require(path.join(root, "package.json"));
+const binding = path.join(
+  root, "nodejs", "dist", "lib", "binding", "node_setapp_binding.node",
+);
+
+if (!fs.existsSync(binding)) {
+  console.error(`[check-binding-version] no binding at ${path.relative(root, binding)}`);
+  console.error("  postbuild should have copied it from nodejs/lib/binding.");
+  process.exit(1);
+}
+
+// latin1 so bytes survive decoding; the stamp is plain ASCII inside a binary.
+const stamp = fs.readFileSync(binding, "latin1").match(/__scv__(\d+\.\d+\.\d+)/);
+
+if (!stamp) {
+  console.error(`[check-binding-version] no __scv__ version stamp found in the binding.`);
+  process.exit(1);
+}
+
+if (stamp[1] !== pkg.version) {
+  console.error(
+    `[check-binding-version] the binding is built against Setapp ${stamp[1]}, ` +
+    `but this package is ${pkg.version}.\n` +
+    `\n` +
+    `  ${path.relative(root, binding)}\n` +
+    `\n` +
+    `Publishing this would ship a library ${stamp[1]} runtime as ${pkg.version}: the\n` +
+    `binding statically links the Swift library, so its version is what consumers run,\n` +
+    `and any API added since ${stamp[1]} would be missing with no way to detect it.\n` +
+    `\n` +
+    `Rebuild the native binding for this version, then run the build again:\n` +
+    `  npx node-gyp rebuild && npm run build\n`,
+  );
+  process.exit(1);
+}
+
+console.log(`[check-binding-version] binding matches package (Setapp ${pkg.version})`);