diff --git a/src/readline.ts b/src/readline.ts
new file mode 100644
index 0000000..2a9c91f
--- /dev/null
+++ b/src/readline.ts
@@ -0,0 +1,19 @@
+import { Turn, Entity, Facet } from './actor.js';
+import readline from 'readline';
+
+export function attachReadline(t: Turn, entity: Partial<Entity>): Facet {
+    const ref = t.ref(entity);
+    return t.facet(t => {
+        let rl: readline.Interface | null =
+            readline.createInterface({ input: process.stdin, output: process.stdout });
+        function shutdown(_t: Turn) {
+            rl?.close();
+            rl = null;
+        }
+        t.assert(ref, true);
+        t.activeFacet.actor.atExit(shutdown);
+        t.activeFacet.onStop(shutdown);
+        rl.on('line', (line: string) => t.freshen(t => t.message(ref, line)));
+        rl.on('close', () => t.freshen(t => t.stop()));
+    });
+}
diff --git a/src/secure-chat-client.ts b/src/secure-chat-client.ts
index 53775c5..9bae5fd 100644
--- a/src/secure-chat-client.ts
+++ b/src/secure-chat-client.ts
@@ -1,7 +1,7 @@
 import { $joinedUser, $says, $user, asJoin, asSays, asUserInfo, fromNickClaim, fromSays, NickClaim, Says, UserId } from "./gen/secure-chat-protocol.js";
 import { during, observe } from "./dataspace.js";
 import { Assertion, Ref, Turn } from "./actor.js";
-import readline from 'readline';
+import { attachReadline } from './readline.js';
 
 export default function (t: Turn, ds: Ref) {
     observe(t, ds, $joinedUser, {
@@ -52,15 +52,14 @@ function runSession(t: Turn, uid: UserId, session: Ref) {
         },
     });
 
-    const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
-
-    rl.on('line', (line: string) => t.freshen(t => {
-        if (line.toLowerCase().startsWith('/nick ')) {
-            updateUsername(t, line.slice(5).trimLeft());
-        } else {
-            t.message(session, fromSays(Says({ who: uid, what: line })));
-        }
-    }));
-
-    rl.on('close', () => t.freshen(t => t.stopActor()));
+    attachReadline(t, {
+        retract(t) { t.stop(); },
+        message(t, line: string) {
+            if (line.toLowerCase().startsWith('/nick ')) {
+                updateUsername(t, line.slice(5).trimLeft());
+            } else {
+                t.message(session, fromSays(Says({ who: uid, what: line })));
+            }
+        },
+    });
 }
diff --git a/src/secure-chat-moderator.ts b/src/secure-chat-moderator.ts
index cd76dd0..2fb7be4 100644
--- a/src/secure-chat-moderator.ts
+++ b/src/secure-chat-moderator.ts
@@ -6,37 +6,33 @@ export default function (t: Turn, ds: Ref) {
     let nextUserId: UserId = 0;
 
     const nicks = new Map<string, UserId>();
-    const users = new Map<UserId, { infoHandle: Handle | undefined, nick: string | undefined }>();
-
-    observe(t, ds, $claimNick, {
-        assert(t: Turn, c0: Assertion): void {
-            const c = asNickClaim(c0);
-            if (nicks.has(c.name)) {
-                t.message(c.k, fromNickConflict(NickConflict()));
-            } else {
-                t.message(c.k, true);
-                let u = users.get(c.uid);
-                if (!u) {
-                    u = { infoHandle: void 0, nick: void 0 };
-                    users.set(c.uid, u);
-                }
-                if (u.nick !== void 0) nicks.delete(u.nick);
-                u.infoHandle = t.replace(ds, u.infoHandle, fromUserInfo(UserInfo(c)));
-                u.nick = c.name;
-                nicks.set(c.name, c.uid);
-            }
-        }
-    });
 
     observe(t, ds, $Observe, during((t, o0) => {
         const o = asObserve(o0);
         if (o.label !== $joinedUser) return null;
 
         const uid: UserId = nextUserId++;
-        const h = t.assert(o.observer, fromJoin(Join({
-            uid,
-            handle: ds,
-        })));
-        return t => t.retract(h);
+        const f = t.facet(t => {
+            t.assert(o.observer, fromJoin(Join({ uid, handle: ds })));
+            let infoHandle: Handle | undefined;
+            let nick: string | undefined;
+            observe(t, ds, $claimNick, {
+                assert(t: Turn, c0: Assertion): void {
+                    const c = asNickClaim(c0);
+                    if (c.uid !== uid) return;
+                    if (nicks.has(c.name)) {
+                        t.message(c.k, fromNickConflict(NickConflict()));
+                    } else {
+                        t.message(c.k, true);
+                        if (nick !== void 0) nicks.delete(nick);
+                        infoHandle = t.replace(ds, infoHandle, fromUserInfo(UserInfo(c)));
+                        nick = c.name;
+                        nicks.set(nick, uid);
+                    }
+                }
+            });
+        });
+
+        return t => t.stop(f);
     }));
 }
diff --git a/src/simple-chat.ts b/src/simple-chat.ts
index 75bb0b9..7ca746f 100644
--- a/src/simple-chat.ts
+++ b/src/simple-chat.ts
@@ -1,7 +1,7 @@
 import { $Present, $Says, asPresent, asSays, fromPresent, fromSays, Present, Says } from "./gen/simple-chat-protocol.js";
 import { during, observe } from "./dataspace.js";
 import { Assertion, Handle, Ref, Turn } from "./actor.js";
-import readline from 'readline';
+import { attachReadline } from './readline.js';
 
 export default function (t: Turn, ds: Ref) {
     let username = '';
@@ -26,16 +26,14 @@ export default function (t: Turn, ds: Ref) {
         },
     });
 
-    const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
-    t.activeFacet.actor.atExit(_t => rl.close());
-
-    rl.on('line', (line: string) => t.freshen(t => {
-        if (line.toLowerCase().startsWith('/nick ')) {
-            updateUsername(t, line.slice(5).trimLeft());
-        } else {
-            t.message(ds, fromSays(Says({ who: username, what: line })));
-        }
-    }));
-
-    rl.on('close', () => t.freshen(t => t.stopActor()));
+    attachReadline(t, {
+        retract(t) { t.stop(); },
+        message(t, line: string) {
+            if (line.toLowerCase().startsWith('/nick ')) {
+                updateUsername(t, line.slice(5).trimLeft());
+            } else {
+                t.message(ds, fromSays(Says({ who: username, what: line })));
+            }
+        },
+    });
 }