chore: drop Node.js 18 support (EOL April 2025) (#126)

Node 18 reached end-of-life in April 2025 and no longer receives
security patches. This PR:

- Removes Node 18 from the CI test matrix
- Bumps `engines.node` to `>=20.0.0`
- Updates all docs to reflect the new minimum

This also fixes the flaky Windows/Node 18 CI failures (`AttachConsole
failed` in node-pty).

Author: dorlugasigal

.github/copilot-instructions.md

@@ -91,7 +91,7 @@ TermBeam is a Node.js CLI tool that exposes a local PTY (pseudo-terminal) over H
 - **Minimal dependencies** — prefer built-in Node.js APIs over npm packages
 - **One responsibility per file** — each `src/*.js` module owns a single concern
 - **Prettier formatting** — single quotes, trailing commas, 100 char width, semicolons (`.prettierrc`)
-- **Cross-platform support** — must work on Windows, macOS, and Linux; CI tests on Ubuntu + Windows with Node 18, 20, 22
+- **Cross-platform support** — must work on Windows, macOS, and Linux; CI tests on Ubuntu + Windows with Node 20, 22, 24
 - **PTY session cleanup** — `pty.kill()` is async; the `onExit` callback removes the session from the Map
 - **Coverage exclusion** — `src/tunnel.js` and `src/devtunnel-install.js` are excluded from coverage (requires external DevTunnel CLI)
 - **Connection config** — server writes `~/.termbeam/connection.json` on start (port, host, password) for `termbeam resume` auto-discovery; removed on shutdown

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        node-version: [18, 20, 22]
+        node-version: [20, 22, 24]
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       - uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6

CONTRIBUTING.md

@@ -4,7 +4,7 @@ Thank you for your interest in contributing! Here's everything you need to know.
 
 ## Prerequisites
 
-- **Node.js** ≥ 18
+- **Node.js** ≥ 20
 - **npm** ≥ 9
 - **Git**
 - A terminal (macOS, Linux, or Windows with WSL)
@@ -186,7 +186,7 @@ feat!: require password by default
 1. Push your branch to your fork
 2. Open a PR against `main` on [dorlugasigal/TermBeam](https://github.com/dorlugasigal/TermBeam)
 3. Fill in the PR template (if available)
-4. Ensure CI passes (tests run on Node 18, 20, 22)
+4. Ensure CI passes (tests run on Node 20, 22, 24)
 5. Wait for review — we'll provide feedback if needed
 
 ### PR Checklist

docs/getting-started.md

@@ -7,7 +7,7 @@ description: Install TermBeam and connect to your terminal from any device in un
 
 ## Prerequisites
 
-- **Node.js** 18 or higher
+- **Node.js** 20 or higher
 - A terminal (macOS, Linux, or Windows)
 
 ## Installation

docs/running-in-background.md

@@ -256,7 +256,7 @@ launchctl unload ~/Library/LaunchAgents/com.termbeam.plist
 
 <!-- prettier-ignore -->
 !!! info "Node.js Requirement"
-    TermBeam requires Node.js 18 or higher. Verify with `node --version` before setting up a background service.
+    TermBeam requires Node.js 20 or higher. Verify with `node --version` before setting up a background service.
 
 <!-- prettier-ignore -->
 !!! tip "Which method should I use?"

docs/troubleshooting.md

@@ -120,7 +120,7 @@ curl -H "Authorization: Bearer YOUR_PASSWORD" http://localhost:3456/api/sessions
 - **Ubuntu / Debian:** `sudo apt install build-essential python3`
 - **Windows (Admin PowerShell):** `npm install --global windows-build-tools`
 
-Ensure your Node.js version is 18 or higher — older versions are not supported.
+Ensure your Node.js version is 20 or higher — older versions are not supported.
 
 ### "Port already in use"
 

package-lock.json

@@ -47,7 +47,7 @@
     "url": "https://github.com/dorlugasigal/TermBeam/issues"
   },
   "engines": {
-    "node": ">=18.0.0"
+    "node": ">=20.0.0"
   },
   "files": [
     "bin/",