diff --git a/.changeset/declare-node-engines.md b/.changeset/declare-node-engines.md
new file mode 100644
index 000000000..f682ebcd3
--- /dev/null
+++ b/.changeset/declare-node-engines.md
@@ -0,0 +1,9 @@
+---
+'@granite-js/plugin-core': patch
+---
+
+Declare the minimum required Node.js version (`>=22.15.0`) in the `engines` field.
+
+`@granite-js/plugin-core` is a CJS bundle that does `require('c12')`, and c12 v3 is an ESM-only package. Under Yarn PnP, the `require(esm)` module graph is resolved with Node's default ESM resolver on Node.js < 22.15.0, ignoring the PnP loader hooks — so c12's own imports (e.g. `pathe`) fail with `ERR_MODULE_NOT_FOUND` at runtime. Node.js 22.15.0 routes `require(esm)` resolution through registered customization hooks (nodejs/node#55698), which makes it work with Yarn PnP.
+
+Declaring `engines` documents this requirement in a machine-readable way: npm prints an `EBADENGINE` warning at install time, pnpm fails the install with `engine-strict=true`, and deployment platforms and tooling pick up the field. Note that Yarn Berry does not enforce `engines`, so PnP users still need a matching Node.js version at runtime.
diff --git a/packages/plugin-core/package.json b/packages/plugin-core/package.json
index 0ce30c595..b7e4f9b5a 100644
--- a/packages/plugin-core/package.json
+++ b/packages/plugin-core/package.json
@@ -33,6 +33,9 @@
   "files": [
     "dist"
   ],
+  "engines": {
+    "node": ">=22.15.0"
+  },
   "devDependencies": {
     "@types/node": "catalog:tools",
     "@vitest/coverage-v8": "^4.0.12",