diff --git a/.node-version b/.node-version
new file mode 100644
index 0000000..a45fd52
--- /dev/null
+++ b/.node-version
@@ -0,0 +1 @@
+24
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 1d05562..a87f6b9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -20,7 +20,10 @@ mostly about keeping review cheap.
 
 Requirements:
 
-- **Node.js 24** — the version used by CI (`.github/workflows/verify.yml`).
+- **Node.js 24** — the version used by CI (`.github/workflows/verify.yml`) and the
+  only version `package.json`'s `engines` field allows. `.node-version` pins it for
+  version managers (nodenv, asdf, fnm, mise). Do not develop against Node 26
+  Current; Electron 44's runtime is Node 24 as well.
 - **npm** — KnowNote uses npm, not pnpm or yarn. The native-module collector in
   `electron-builder` is built around npm's `node_modules` layout and silently
   drops transitive dependencies under pnpm. See the `//dependencies` comment in
diff --git a/package-lock.json b/package-lock.json
index 1237b31..820e52d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -120,6 +120,9 @@
         "vite": "^7.3.1",
         "zod": "^4.3.6",
         "zustand": "^5.0.10"
+      },
+      "engines": {
+        "node": ">=24 <25"
       }
     },
     "node_modules/@acemir/cssom": {
diff --git a/package.json b/package.json
index 7573bbd..eb4a85e 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,9 @@
   "bugs": {
     "url": "https://github.com/MrSibe/KnowNote/issues"
   },
+  "engines": {
+    "node": ">=24 <25"
+  },
   "scripts": {
     "format": "prettier --write .",
     "lint": "eslint --cache .",