diff --git a/install.ps1 b/install.ps1
index 7a5af5bf..752ac2ec 100644
--- a/install.ps1
+++ b/install.ps1
@@ -34,5 +34,20 @@ while ($true) {
 $scriptDir = Split-Path -Parent $scriptPath
 $installerScript = Join-Path -Path (Join-Path -Path $scriptDir -ChildPath 'scripts') -ChildPath 'install-apply.js'
 
+# Auto-install Node dependencies when running from a git clone
+$nodeModules = Join-Path -Path $scriptDir -ChildPath 'node_modules'
+if (-not (Test-Path -LiteralPath $nodeModules)) {
+    Write-Host '[ECC] Installing dependencies...'
+    Push-Location $scriptDir
+    try {
+        & npm install --no-audit --no-fund --loglevel=error
+        if ($LASTEXITCODE -ne 0) {
+            Write-Error "npm install failed with exit code $LASTEXITCODE"
+            exit $LASTEXITCODE
+        }
+    }
+    finally { Pop-Location }
+}
+
 & node $installerScript @args
 exit $LASTEXITCODE
diff --git a/install.sh b/install.sh
index d0abc14f..31925dde 100755
--- a/install.sh
+++ b/install.sh
@@ -14,4 +14,10 @@ while [ -L "$SCRIPT_PATH" ]; do
 done
 SCRIPT_DIR="$(cd "$(dirname "$SCRIPT_PATH")" && pwd)"
 
+# Auto-install Node dependencies when running from a git clone
+if [ ! -d "$SCRIPT_DIR/node_modules" ]; then
+    echo "[ECC] Installing dependencies..."
+    (cd "$SCRIPT_DIR" && npm install --no-audit --no-fund --loglevel=error)
+fi
+
 exec node "$SCRIPT_DIR/scripts/install-apply.js" "$@"