fix: offer a teammate's directory after leaving one instead of Create directory

.lane/memory/apps/app/src/app.tsx/01M4YT6XB7NQ89E6F4P375REE7-all-projects-and-project-vie.md

@@ -4,9 +4,9 @@ anchor: function App
 created: 2026-10-15T03:38:04Z
 norm: '1'
 sig: 063d0f00fea02511
-body_hash: de60f6b6b28752c6
-raw_hash: a19d4ffff16a8faf
-vouched: 2026-10-22T21:17:34Z
+body_hash: cbba38a628c7d858
+raw_hash: a8b8547e68eff2dc
+vouched: 2026-10-22T21:25:00Z
 lines: 235-824
 ---
 

.lane/memory/apps/app/src/app.tsx/01M5JMVG9G87F31FGVV571Y6BJ-the-project-list-is-built-on.md

@@ -4,9 +4,9 @@ anchor: function App
 created: 2026-10-22T20:29:16Z
 norm: '1'
 sig: 063d0f00fea02511
-body_hash: de60f6b6b28752c6
-raw_hash: a19d4ffff16a8faf
-vouched: 2026-10-22T21:17:34Z
+body_hash: cbba38a628c7d858
+raw_hash: a8b8547e68eff2dc
+vouched: 2026-10-22T21:25:00Z
 lines: 330-1237
 ---
 

.lane/memory/apps/host/src/peers.ts/01M5JBDJ536ASQ9VKEE9T4WW7T-a-hello-without-github-leave.md

@@ -4,8 +4,9 @@ anchor: function greet
 created: 2026-10-22T17:44:22Z
 norm: '1'
 sig: 583ffcbd3b791ed2
-body_hash: f003a7d2404a7483
-raw_hash: 18edf8ce741d1310
+body_hash: b38e7bb2f4ff3a8c
+raw_hash: d2d3c4587a57e408
+vouched: 2026-10-22T21:25:00Z
 lines: 76-86
 ---
 

.lane/memory/apps/host/src/peers.ts/01M5JBDT9ZCB6X9ANFR2K7NJBE-a-peer-s-hello-can-arrive-be.md

@@ -4,8 +4,9 @@ anchor: function discover
 created: 2026-10-22T17:44:31Z
 norm: '1'
 sig: ab69f97386d0db50
-body_hash: 687af47f626b9aa1
-raw_hash: ce225aafa3f68775
+body_hash: 9b0a75f289475140
+raw_hash: 4713ceb74c23d1f3
+vouched: 2026-10-22T21:25:00Z
 lines: 37-74
 supersedes: 01M4YX4FKJR9W30M9Y5HVTKBW4
 ---

.lane/memory/apps/host/src/peers.ts/01M5JR1DMRY4D6Q3Z6KTX7JCG5-a-host-with-no-directory-kee.md

@@ -0,0 +1,12 @@
+---
+id: 01M5JR1DMRY4D6Q3Z6KTX7JCG5
+anchor: function discover
+created: 2026-10-22T21:24:56Z
+norm: '1'
+sig: ab69f97386d0db50
+body_hash: 9b0a75f289475140
+raw_hash: 4713ceb74c23d1f3
+lines: 37-75
+---
+
+a host with no directory keeps greeting peers so it learns which directory they name; adopt still never joins after a choice

apps/app/src/app.tsx

@@ -1010,7 +1010,13 @@ export function App() {
 										onClone={cloneUrl}
 									/>
 								)}
-							{card && <DirectoryCard onDismiss={() => setDismissed(true)} />}
+							{card && (
+								<DirectoryCard
+									offered={directory.offered}
+									onDismiss={() => setDismissed(true)}
+									onChange={() => setSettings("team")}
+								/>
+							)}
 							<TeamSetupItem />
 						</Sidebar>
 					)}

apps/app/src/onboarding.tsx

@@ -245,8 +245,33 @@ export function Welcome({ github, onClose }: { github?: string; onClose: () => v
 	);
 }
 
-/** Sidebar footer upsell while the team has no directory. */
-export function DirectoryCard({ onDismiss }: { onDismiss: () => void }) {
+/**
+ * Sidebar footer while this host has no directory: join the one a teammate's host names, or
+ * create one when nobody has.
+ */
+export function DirectoryCard(
+	{ offered, onDismiss, onChange }: {
+		offered?: { url: string; host: string };
+		onDismiss: () => void;
+		onChange: () => void;
+	},
+) {
+	const [joining, setJoining] = useState(false);
+	const [error, setError] = useState("");
+
+	async function join(url: string) {
+		setJoining(true);
+		setError("");
+		try {
+			await host.request({ op: "directory-set", url });
+			window.dispatchEvent(new Event(DIRECTORY_CHANGED));
+		} catch (error) {
+			setError((error as Error).message);
+		} finally {
+			setJoining(false);
+		}
+	}
+
 	return (
 		<div className="m-2 flex shrink-0 flex-col gap-2 rounded-lg border bg-card p-3">
 			<div className="flex items-center gap-2">
@@ -261,17 +286,51 @@ export function DirectoryCard({ onDismiss }: { onDismiss: () => void }) {
 					<IconX className="size-3.5" aria-hidden />
 				</button>
 			</div>
-			<p className="text-xs leading-5 text-muted-foreground">
-				Keep channels listed while Macs are offline, and share projects.
-			</p>
-			<Button
-				size="sm"
-				variant="outline"
-				className="border"
-				onClick={() => window.dispatchEvent(new Event(CREATE_DIRECTORY))}
-			>
-				Create directory
-			</Button>
+			{offered
+				? (
+					<>
+						<p className="text-xs leading-5 text-muted-foreground">
+							{offered.host}{" "}
+							serves your team's directory. This Mac isn't in it, so its channels aren't listed
+							while it's offline.
+						</p>
+						{error && <p role="alert" className="text-xs text-destructive">{error}</p>}
+						<div className="flex gap-2">
+							<Button
+								size="sm"
+								className="flex-1"
+								disabled={joining}
+								onClick={() => void join(offered.url)}
+							>
+								{joining ? "Joining…" : "Join"}
+							</Button>
+							<Button
+								size="sm"
+								variant="outline"
+								className="flex-1 border"
+								disabled={joining}
+								onClick={onChange}
+							>
+								Change…
+							</Button>
+						</div>
+					</>
+				)
+				: (
+					<>
+						<p className="text-xs leading-5 text-muted-foreground">
+							Keep channels listed while Macs are offline, and share projects.
+						</p>
+						<Button
+							size="sm"
+							variant="outline"
+							className="border"
+							onClick={() => window.dispatchEvent(new Event(CREATE_DIRECTORY))}
+						>
+							Create directory
+						</Button>
+					</>
+				)}
 		</div>
 	);
 }
@@ -291,7 +350,7 @@ export function OfflineHost({ name, host: machine }: { name: string; host: strin
 					{name} runs on that Mac. Its chat opens here when the Mac is back.
 				</p>
 			</div>
-			{directory && !directory.url && (
+			{directory && !directory.url && !directory.offered && (
 				<div className="flex max-w-sm flex-col gap-3 rounded-lg border bg-card p-4 text-left">
 					<div className="flex items-start gap-2.5">
 						<IconDatabase className="mt-0.5 size-4 shrink-0 text-primary" aria-hidden />

apps/host/src/diagnostics.ts

@@ -63,6 +63,7 @@ export async function diagnostics(sync?: boolean): Promise<Diagnostics> {
 			serving: served.isServing(),
 			shares: served.shares(),
 			hosts: hosts.map(({ address: _, ...host }) => host),
+			offered: directory.offered(),
 		},
 		shell: { ...environment },
 		web: web.address,

apps/host/src/directory.ts

@@ -119,6 +119,21 @@ export function isChosen(): boolean {
 	return existsSync(config) || !!process.env.ACE_DIRECTORY;
 }
 
+/** The directory each peer's host names, so a host without one can offer to join it. */
+const offers = new Map<string, string>();
+
+export function offer(peer: string, value: string | undefined): void {
+	if (value) offers.set(peer, value);
+	else offers.delete(peer);
+}
+
+/** A directory a peer's host names while this host has none, as after leaving one. */
+export function offered(): { url: string; host: string } | undefined {
+	if (url()) return;
+	const [host, value] = offers.entries().next().value ?? [];
+	return host && value ? { url: value, host } : undefined;
+}
+
 /**
  * When each URL a peer named last failed without a secret, so discovery doesn't ask every 15
  * seconds; its host may only be offline, so it's asked again later.

apps/host/src/peers.ts

@@ -41,6 +41,7 @@ async function discover(signal: AbortSignal) {
 		if (online.get(name)?.address === host.machine.address) continue;
 		host.client.close();
 		hosts.delete(name);
+		directory.offer(name, undefined);
 		log("info", "peer.gone", { peer: name });
 		emit();
 	}
@@ -65,16 +66,17 @@ async function discover(signal: AbortSignal) {
 		});
 		hosts.set(name, host);
 	}
-	// A teammate can start a directory after this host first greeted them, and a peer that answered
-	// before `gh` resolved has a login to give.
-	const chosen = directory.isChosen();
+	// A teammate can start a directory after this host first greeted them, a host that left one
+	// offers a teammate's instead, and a peer that answered before `gh` resolved has a login to give.
+	const listening = !directory.isChosen() || !directory.url();
 	for (const [name, { client, machine }] of hosts) {
-		if (client.status === "open" && (!chosen || unnamed.has(name))) greet(client, machine);
+		if (client.status === "open" && (listening || unnamed.has(name))) greet(client, machine);
 	}
 }
 
 function greet(client: GatewayClient, machine: Machine) {
 	client.request<Hello>({ op: "hello" }).then((hello) => {
+		directory.offer(machine.name, hello.directory);
 		if (hello.directory) void directory.adopt(hello.directory);
 		// A freshly started peer answers before `gh` has told it its owner's login, which may have changed.
 		if (!hello.github) return void unnamed.add(machine.name);

apps/host/src/protocol.ts

@@ -70,6 +70,8 @@ export type Diagnostics = {
 		shares: Share[];
 		/** Hosts in the directory's last answer, and when each last published to it; older hosts omit it. */
 		hosts?: DirectoryHost[];
+		/** A directory a teammate's host names while this host has none, such as after leaving it. */
+		offered?: { url: string; host: string };
 	};
 	/** Whether the helper loaded the login shell's environment; `pending` while it retries. */
 	shell: { state: "adopted" | "pending" | "failed"; error?: string };