diff --git a/.github/workflows/nightly-compatibility.yml b/.github/workflows/nightly-compatibility.yml
index 52beec49..02a07940 100644
--- a/.github/workflows/nightly-compatibility.yml
+++ b/.github/workflows/nightly-compatibility.yml
@@ -7,9 +7,9 @@ on:
   workflow_dispatch:
     inputs:
       node-version:
-        description: 'Node version (27-nightly by default; use 26.X for comparison)'
+        description: 'Node version (latest Node 27 alpha by default; use 26.X for comparison)'
         required: true
-        default: '27-nightly'
+        default: '>=27.0.0-alpha.0 <27.0.0-beta'
         type: string
 
 permissions:
@@ -21,7 +21,7 @@ defaults:
 
 jobs:
   compatibility:
-    name: Rolling nightly / Node ${{ inputs.node-version || '27-nightly' }} / Ubuntu x64
+    name: Rolling nightly / Node ${{ inputs.node-version || '>=27.0.0-alpha.0 <27.0.0-beta' }} / Ubuntu x64
     runs-on: ubuntu-latest
     timeout-minutes: 45
     container: ubuntu:26.04
@@ -45,7 +45,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v7
         with:
-          node-version: ${{ inputs.node-version || '27-nightly' }}
+          node-version: ${{ inputs.node-version || '>=27.0.0-alpha.0 <27.0.0-beta' }}
           architecture: x64
           check-latest: true
           package-manager-cache: false
diff --git a/README.md b/README.md
index a259ceb1..283cf43a 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@
 
 [![Nightly Compatibility](https://github.com/RobotWebTools/rclnodejs/actions/workflows/nightly-compatibility.yml/badge.svg?branch=develop&event=schedule)](https://github.com/RobotWebTools/rclnodejs/actions/workflows/nightly-compatibility.yml?query=branch%3Adevelop+event%3Aschedule)
 
-*Early-warning checks for ROS Rolling and Node.js 27 nightlies. See the [build documentation](./docs/BUILDING.md#nightly-compatibility-checks).*
+*Early-warning checks for ROS Rolling nightlies using Node.js 27 alpha. See the [build documentation](./docs/BUILDING.md#nightly-compatibility-checks).*
 
 **rclnodejs** is a Node.js client library for [ROS 2](https://www.ros.org/) that provides comprehensive JavaScript and TypeScript APIs for developing ROS 2 solutions.
 
diff --git a/docs/BUILDING.md b/docs/BUILDING.md
index b9fece7c..c2f962bd 100644
--- a/docs/BUILDING.md
+++ b/docs/BUILDING.md
@@ -80,10 +80,10 @@ Windows CI covers Humble, Jazzy, Kilted, and Lyrical, with full tests on Lyrical
 
 ### Nightly compatibility checks
 
-The [Nightly Compatibility workflow](../.github/workflows/nightly-compatibility.yml) builds from source and runs core ROS, TypeScript, and package tests on Ubuntu 26.04 x64 with ROS Rolling nightly, Node 27 nightly, and bundled npm.
+The [Nightly Compatibility workflow](../.github/workflows/nightly-compatibility.yml) builds from source and runs core ROS, TypeScript, and package tests on Ubuntu 26.04 x64 with ROS Rolling nightly, the latest matching Node 27 alpha release, and bundled npm. It primarily tracks ROS nightly compatibility; Node follows published alpha releases rather than daily development builds. Alpha is still a prerelease, not a production-stability guarantee.
 
 - **Scheduled:** daily at 00:00 Asia/Shanghai (16:00 UTC) on the default branch; execution may be delayed.
-- **Manual:** use **Actions > Nightly Compatibility > Run workflow**. The `node-version` input defaults to `27-nightly`; use `26.X` for comparison.
+- **Manual:** use **Actions > Nightly Compatibility > Run workflow**. The `node-version` input defaults to `>=27.0.0-alpha.0 <27.0.0-beta`; use `26.X` for comparison, `27-nightly` to investigate Node development changes, or an exact alpha version to reproduce a result. The default range accepts newer Node 27 alphas but excludes beta, RC, stable, and nightly versions. The resolved runtime version is recorded in the job summary.
 
 For pre-merge testing, enable Actions in your fork and place the workflow on its default branch.