diff --git a/help.txt b/help.txt
new file mode 100644
index 0000000..7158c7e
--- /dev/null
+++ b/help.txt
@@ -0,0 +1,13 @@
+Ludus CLI (v0.1.0)
+
+The Ludus CLI has five modes: `help`, `version`, `run`, `listen`, and `send`.
+
+* `help`: Output this text and exit.
+
+* `version`: Ouput the current version number.
+
+* `run`: Runs a Ludus script: `ludus run {script}`.
+
+* `listen`: Starts a Ludus "listener" server, which receives Ludus source code on a given port and outputs the results. Similar to a REPL, intended to be used in conjunction with `send`, from a text editor.
+
+* `send`: Sends text from `stdin` to a listening server. Any text editor that can send highlighted text to a command line program can evaluate Ludus source.
diff --git a/index.ts b/index.ts
new file mode 100644
index 0000000..0a7daf5
--- /dev/null
+++ b/index.ts
@@ -0,0 +1,19 @@
+import { listen } from "./listener"
+import { run_file } from "./runner"
+import { send } from "./sender"
+
+const help_text = await Bun.file("./help.txt").text()
+
+export async function main() {
+  const cmd = Bun.argv[2]
+  switch (cmd) {
+    case "listen": { return listen() }
+    case "send": { return send() }
+    case "run": { return run_file(Bun.argv[3]) }
+    case "help": { return console.log(help_text) }
+    case "version": { return console.log("0.1.0") }
+    default: console.log("Usage: ludus {help | version | run | listen | send}")
+  }
+}
+
+await main()
diff --git a/listener.ts b/listener.ts
index ce342be..566052f 100644
--- a/listener.ts
+++ b/listener.ts
@@ -1,29 +1,38 @@
 import { run } from "@ludus/ludus-js-pure"
+import { unlinkSync, readFileSync } from "node:fs"
 
-async function listen() {
+export async function listen () {
   const port = Math.floor((Math.random() * 1000) + 50000)
-
-  const repl_info = { port }
-
-  const repl_file = Bun.file("./.lrepl")
-
+  const session_token = crypto.randomUUID();
+  const repl_file_path = ".lrepl"
+  const repl_info = { port, session: session_token }
+  const repl_file = Bun.file(repl_file_path)
   await Bun.write(repl_file, JSON.stringify(repl_info))
 
   console.log(`Ludus REPL listening on localhost:${port}`)
+  console.log(`Session token: ${session_token}`)
 
   Bun.listen({
     hostname: "localhost",
     port,
     socket: {
-      data: (socket, data) => {
-        console.log("I got data!")
-        const source = data.toString("utf-8")
-        const result = run(source)
-        const msgs = result.console
-        for (const msg of msgs) {
-          console.log(msg)
+      data: (_, data) => {
+        const payload = data.toString("utf-8")
+        let session, source
+        try {
+          const json_msg = JSON.parse(payload)
+          session = json_msg.session
+          source = json_msg.source
+        } catch (e) {
+          console.log("Received malformed message.")
+          return
         }
-        if (!result.errors) console.log(result.result)
+        if (session !== session_token) {
+          console.log("Received message not from this REPL session.")
+          return
+        }
+        const result = run(source)
+        if (!result.errors) console.log("=>", result.result)
         else {
           console.log("Ludus had some errors:")
           console.log(result.errors)
@@ -32,9 +41,33 @@ async function listen() {
       error: (socket, error) => { console.log(error); socket.end() }
     }
   })
+
+
+  process.on("exit", async function () {
+    try { cleanup(repl_file_path, session_token) } catch (e) {}
+    console.log("\nGoodbye.")
+  })
+
+  process.on("SIGINT", () => process.exit())
+
+  // Below here, I'm trying to get ctrl-d to work to close the listener
+  // the while (true) loop locks the listener
+  // see: https://github.com/oven-sh/bun/issues/3255
+  // this should be doable with process.stdin.on("close"...)
+  //const mystdin = Bun.file("/dev/stdin").stream().getReader()
+
+  // while (true) {
+  //   const {done, value} = await mystdin.read()
+  //   if (done) process.exit()
+  //   console.log(value)
+  // }
+
 }
 
-await listen()
-
-
+// Don't delete an .lrepl we don't own
+function cleanup (path: string, session_token: string) {
+  const repl_file = readFileSync(path).toString("utf-8")
+  const {session} = JSON.parse(repl_file)
+  if (session === session_token) unlinkSync(path)
+}
 
diff --git a/package.json b/package.json
index 4f8cd74..1bc82cf 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,11 @@
 {
-  "name": "ludus-repl",
+  "name": "@ludus/cli",
+  "version": "0.1.0",
+  "description": "A CLI interface to Ludus.",
+  "main": "index.ts",
   "module": "index.ts",
   "type": "module",
+  "license": "GPL-3.0",
   "devDependencies": {
     "@types/bun": "latest"
   },
diff --git a/runner.ts b/runner.ts
index b9861b1..9abce73 100644
--- a/runner.ts
+++ b/runner.ts
@@ -1,13 +1,20 @@
-import {run} from "@ludus/ludus-js-pure"
+import { run } from "@ludus/ludus-js-pure"
 
-const script = Bun.argv[2]
-const file = Bun.file(script)
-const source = await file.text()
-console.log(`Source to run:
-${source}`)
-
-const result = run(source)
-
-if (!result.errors) console.log(result.result)
-else console.log(result.errors)
+export async function run_file (path: string): Promise<void> {
+  const handle = Bun.file(path)
+  const file_exists = await handle.exists()
+  if (!file_exists) {
+    console.log(`File not found: ${path}`)
+    return
+  }
+  const source = await handle.text()
+  const output = run(source)
 
+  if (output.errors) {
+    for (const error of output.errors) {
+      console.log(error)
+    }
+  } else {
+    console.log(output.result)
+  }
+}
diff --git a/sender.ts b/sender.ts
index 5ef926e..b0b954b 100644
--- a/sender.ts
+++ b/sender.ts
@@ -1,19 +1,31 @@
-const repl_file = Bun.file("./.lrepl")
-const repl_info = await repl_file.json()
-const port = repl_info.port
-
-const socket = await Bun.connect({
-	hostname: "localhost",
-	port,
-	socket: {
-		data: (_, data) => process.exit()
+export async function send() {
+	const repl_file = Bun.file("./.lrepl")
+	let repl_info
+	try {
+		repl_info = await repl_file.json()
+	} catch (e) {
+		console.log("No .lrepl file found.")
+		process.exit(1)
 	}
-})
+	const port = repl_info.port
+	const session = repl_info.session
 
-for await (const input of Bun.stdin.stream()) {
-	const chunk = Buffer.from(input).toString("utf-8")
-	socket.write(chunk)
-	socket.end()
-	process.exit()
+	const socket = await Bun.connect({
+		hostname: "localhost",
+		port,
+		socket: {
+			data: () => process.exit()
+		}
+	})
+
+	for await (const input of Bun.stdin.stream()) {
+		const chunk = Buffer.from(input).toString("utf-8")
+		const payload = {source: chunk, session}
+		// console.log("Sending:", payload)
+		// console.log(`To: ${port}`)
+		socket.write(JSON.stringify(payload))
+		socket.end()
+		process.exit()
+	}
 }