feat: phone login via QR when the saved Mudfish login expires

When autologin is rejected the panel offers '휴대폰으로 로그인 (QR)'. It opens
a 5-minute LAN relay to the launcher UI guarded by a one-time token (first
phone to open the QR URL is the only client allowed) and shows the URL as a
QR code. The relay closes as soon as a new session appears, on cancel, on
expiry, and on unload.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

main.py

@@ -2,6 +2,7 @@ import asyncio
 import logging
 import os
 import sys
+import urllib.parse
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), "py_modules"))
 
@@ -10,9 +11,11 @@ import decky  # noqa: E402
 from mudfish_decky import system  # noqa: E402
 from mudfish_decky.client import MudfishClient  # noqa: E402
 from mudfish_decky.controller import Controller  # noqa: E402
+from mudfish_decky.relay import LoginRelay  # noqa: E402
 from mudfish_decky.store import Store  # noqa: E402
 
 RESUME_POLL_SECONDS = 2
+LOGIN_RELAY_SECONDS = 300
 
 
 class Plugin:
@@ -23,9 +26,19 @@ class Plugin:
             installed = system.find_mudfish()
             base = system.api_base(installed[1]) if installed else system.DEFAULT_API
             store = Store(os.path.join(decky.DECKY_PLUGIN_SETTINGS_DIR, "settings.json"))
-            self.controller = Controller(MudfishClient(base), system, store)
+            target = urllib.parse.urlsplit(base)
+            self.controller = Controller(
+                MudfishClient(base), system, store,
+                relay_factory=lambda: LoginRelay(target=(target.hostname, target.port or 80), ttl=LOGIN_RELAY_SECONDS),
+            )
         return self.controller
 
+    async def start_login(self) -> dict:
+        return await asyncio.to_thread(self._get_controller().start_login)
+
+    async def stop_login(self) -> dict:
+        return await asyncio.to_thread(self._get_controller().stop_login)
+
     async def get_state(self) -> dict:
         return await asyncio.to_thread(self._get_controller().state)
 

package.json

@@ -20,6 +20,7 @@
   },
   "dependencies": {
     "@decky/api": "^1.1.3",
+    "qrcode-generator": "1.4.4",
     "react-icons": "^5.3.0",
     "tslib": "^2.7.0"
   },

pnpm-lock.yaml

@@ -11,6 +11,9 @@ importers:
       '@decky/api':
         specifier: ^1.1.3
         version: 1.1.3
+      qrcode-generator:
+        specifier: 1.4.4
+        version: 1.4.4
       react-icons:
         specifier: ^5.3.0
         version: 5.7.0(react@19.3.1)
@@ -771,6 +774,9 @@ packages:
     resolution: {integrity: sha512-qcJu88Q2IWqJsDD529JKMdwGm/dvInW4HvQnRwiH9JtihJvzGOscDtHE3x1pBKeUOTysQ8kVmLnJ2kJu7yhcGA==}
     engines: {node: '>=12'}
 
+  qrcode-generator@1.4.4:
+    resolution: {integrity: sha512-HM7yY8O2ilqhmULxGMpcHSF1EhJJ9yBj8gvDEuZ6M+KGJ0YY2hKpnXvRD+hZPLrDVck3ExIGhmPtSdcjC+guuw==}
+
   queue-microtask@1.2.3:
     resolution: {integrity: sha512-NuaNSa6flKT5JaSYQzJok04JzTL1CA6aGhv5rfLW3PgqA+M2ChpZQnAC8h8i4ZFkBS8X5RqkDBHA7r4hej3K9A==}
 
@@ -1599,6 +1605,8 @@ snapshots:
 
   picomatch@4.0.7: {}
 
+  qrcode-generator@1.4.4: {}
+
   queue-microtask@1.2.3: {}
 
   react-icons@5.7.0(react@19.3.1):

py_modules/mudfish_decky/controller.py

@@ -21,6 +21,8 @@ MSG_MISSING = "데스크탑 모드에서 미꾸라지를 설치하세요 (docs.m
 MSG_STILL_UP = "터널이 아직 남아 있어요. 끄기를 다시 눌러 주세요"
 MSG_NO_RESPONSE = "미꾸라지가 응답하지 않아요. 터널이 남아 있을 수 있으니 끄기를 눌러 주세요"
 MSG_SLEEP = "절전에서 깨어나 VPN을 껐어요. 필요하면 다시 켜 주세요"
+MSG_LOGGED_IN = "로그인됐어요. 이제 켤 수 있어요"
+MSG_NO_LAN = "와이파이 주소를 찾지 못해 휴대폰 로그인을 열 수 없어요"
 
 CONNECT_TIMEOUT = 30
 DISCONNECT_TIMEOUT = 10
@@ -32,15 +34,20 @@ log = logging.getLogger("mudfish_decky")
 
 
 class Controller:
-    def __init__(self, client, system, store, clock=time.time, sleep=time.sleep):
+    def __init__(self, client, system, store, clock=time.time, sleep=time.sleep, relay_factory=None):
         self.client = client
         self.system = system
         self.store = store
         self.clock = clock
         self.sleep = sleep
+        self.relay_factory = relay_factory
         self._lock = threading.Lock()
         self._error: Optional[str] = None
         self._notice: Optional[str] = None
+        self._need_login = False
+        self._failed_jwt: Optional[str] = None
+        self._relay = None
+        self._relay_url: Optional[str] = None
         self._static: Optional[list] = None
         self._ip_cache = (0.0, None)
         self._sleep_offset: Optional[float] = None
@@ -60,6 +67,10 @@ class Controller:
             try:
                 st = self._signed_in(installed)
                 self._static_nodes(st)
+            except SigninError as e:
+                log.warning("prepare: saved login rejected: %s", e)
+                self._error = MSG_RELOGIN
+                self._mark_need_login()
             except Exception as e:
                 log.warning("prepare: %s", e)
 
@@ -77,6 +88,7 @@ class Controller:
             started = False
             try:
                 st = self._signed_in(installed)
+                self._need_login = False
                 if self._is_on(st):
                     return self._state()
                 self._refresh_rtts()
@@ -116,6 +128,7 @@ class Controller:
                 if self._is_on(st):
                     self._reapply(st)
             except SigninError:
+                self._mark_need_login()
                 return self._fail(MSG_RELOGIN)
             except Exception as e:
                 log.exception("node change failed")
@@ -137,9 +150,31 @@ class Controller:
                     self._error = MSG_STILL_UP
             return True
 
-    def shutdown(self) -> None:
-        """Plugin unload (Deck shutdown/restart, Decky restart): never leave a tunnel behind."""
+    def start_login(self) -> dict:
+        """Open the short-lived LAN relay to the launcher UI; the panel shows its URL as a QR code."""
         with self._lock:
+            if self._relay is not None and self._relay.active:
+                return self._state()
+            ip = self.system.lan_ip()
+            if not ip or self.relay_factory is None:
+                self._notice = MSG_NO_LAN
+                return self._state()
+            relay = self.relay_factory()
+            port = relay.start()
+            self._relay = relay
+            self._relay_url = f"http://{ip}:{port}/_mfd/{relay.token}"
+            log.info("login relay open on %s:%d for %ss", ip, port, int(relay.expires_at - self.clock()))
+            return self._state()
+
+    def stop_login(self) -> dict:
+        with self._lock:
+            self._close_relay()
+            return self._state()
+
+    def shutdown(self) -> None:
+        """Plugin unload (Deck shutdown/restart, Decky restart): never leave a tunnel or relay behind."""
+        with self._lock:
+            self._close_relay()
             if self._tunnel_present():
                 log.info("unload; turning VPN off")
                 self._teardown()
@@ -150,11 +185,42 @@ class Controller:
         self._error = message
         return self._state()
 
+    def _mark_need_login(self) -> None:
+        """Remember which session failed so state() can tell when a new login (e.g. from the phone) lands."""
+        self._need_login = True
+        try:
+            st = self.client.status()
+            self._failed_jwt = st.get("jwt") if st.get("isSignedIn") else None
+        except Exception:
+            self._failed_jwt = None
+
     def _abort(self, started: bool, message: str) -> dict:
+        if message == MSG_RELOGIN:
+            self._mark_need_login()
         if started and not self._teardown():
             message = MSG_STILL_UP
         return self._fail(message)
 
+    def _track_login(self, st: Optional[dict]) -> None:
+        """Drop an expired relay; once a new session appears after a failed login, close the relay."""
+        if self._relay is not None and not self._relay.active:
+            self._close_relay()
+        if not (self._need_login and st and st.get("isSignedIn") and st.get("jwt")):
+            return
+        if st["jwt"] == self._failed_jwt:
+            return
+        self._need_login = False
+        self._failed_jwt = None
+        if self._error == MSG_RELOGIN:
+            self._error = None
+        self._close_relay()
+        self._notice = MSG_LOGGED_IN
+
+    def _close_relay(self) -> None:
+        if self._relay is not None:
+            self._relay.stop()
+        self._relay = self._relay_url = None
+
     def _wait(self, cond, seconds) -> bool:
         for _ in range(seconds):
             if cond():
@@ -291,7 +357,8 @@ class Controller:
     def _state(self) -> dict:
         data = self.store.load()
         out = {"phase": "off", "message": None, "node_mode": data.get("node_mode") or "auto", "node": None,
-               "ip": None, "country": None, "connected_since": None, "tunnel": False}
+               "ip": None, "country": None, "connected_since": None, "tunnel": False,
+               "need_login": False, "login": None}
         if not self.system.find_mudfish():
             out.update(phase="missing", message=MSG_MISSING)
             return out
@@ -299,6 +366,10 @@ class Controller:
             st = self.client.status()
         except Exception:
             st = None
+        self._track_login(st)
+        out["need_login"] = self._need_login
+        if self._relay is not None:
+            out["login"] = {"url": self._relay_url, "expires_at": self._relay.expires_at}
         tap = self.system.tap_up()
         on = bool(st) and self._is_on(st)
         out["tunnel"] = tap or bool(st and st.get("core_running"))

py_modules/mudfish_decky/relay.py

@@ -0,0 +1,151 @@
+"""Short-lived LAN relay to the Mudfish launcher UI so a phone can log in by scanning a QR code.
+
+The launcher only listens on 127.0.0.1. While a login is pending we open a random LAN port that
+forwards raw TCP to it, guarded by a one-time token: the first client to request /_mfd/<token> becomes
+the only client allowed through; everyone else gets 403. The relay closes itself after `ttl` seconds.
+"""
+import logging
+import secrets
+import socket
+import threading
+import time
+from typing import Optional
+
+TOKEN_PREFIX = "/_mfd/"
+PEEK_TIMEOUT = 10
+
+log = logging.getLogger("mudfish_decky")
+
+_REDIRECT = b"HTTP/1.1 302 Found\r\nLocation: /\r\nContent-Length: 0\r\nConnection: close\r\n\r\n"
+_FORBIDDEN = b"HTTP/1.1 403 Forbidden\r\nContent-Length: 9\r\nConnection: close\r\n\r\nForbidden"
+
+
+def parse_request_path(data: bytes) -> Optional[str]:
+    """Path from an HTTP request line, or None if the first line is incomplete or not HTTP."""
+    line, sep, _ = data.partition(b"\r\n")
+    if not sep:
+        return None
+    parts = line.split(b" ")
+    if len(parts) != 3 or not parts[2].startswith(b"HTTP/"):
+        return None
+    try:
+        return parts[1].decode("ascii")
+    except UnicodeDecodeError:
+        return None
+
+
+class Gate:
+    def __init__(self, token: str):
+        self.token = token
+        self.client: Optional[str] = None
+        self._lock = threading.Lock()
+
+    def decide(self, ip: str, path: Optional[str]) -> str:
+        is_token = path is not None and path.split("?", 1)[0] == TOKEN_PREFIX + self.token
+        with self._lock:
+            if self.client is None and is_token:
+                self.client = ip
+            if ip != self.client:
+                return "deny"
+            return "authorize" if is_token else "pipe"
+
+
+def _pipe(src, dst):
+    try:
+        while True:
+            data = src.recv(65536)
+            if not data:
+                break
+            dst.sendall(data)
+    except OSError:
+        pass
+    finally:
+        for s in (src, dst):
+            try:
+                s.shutdown(socket.SHUT_RDWR)
+            except OSError:
+                pass
+
+
+class LoginRelay:
+    def __init__(self, target=("127.0.0.1", 8282), ttl: int = 300, clock=time.time):
+        self.target = target
+        self.ttl = ttl
+        self.clock = clock
+        self.token = secrets.token_urlsafe(16)
+        self.gate = Gate(self.token)
+        self.expires_at = 0.0
+        self._srv: Optional[socket.socket] = None
+        self._stopped = threading.Event()
+        self._conns = set()
+        self._conns_lock = threading.Lock()
+
+    @property
+    def active(self) -> bool:
+        return self._srv is not None and not self._stopped.is_set() and self.clock() < self.expires_at
+
+    def start(self, host: str = "0.0.0.0") -> int:
+        self._srv = socket.create_server((host, 0))
+        self._srv.settimeout(1)
+        self.expires_at = self.clock() + self.ttl
+        threading.Thread(target=self._serve, daemon=True).start()
+        return self._srv.getsockname()[1]
+
+    def stop(self) -> None:
+        self._stopped.set()
+        if self._srv is not None:
+            # shutdown() first: close() alone does not stop a listener another thread is blocked on.
+            for op in (lambda: self._srv.shutdown(socket.SHUT_RDWR), self._srv.close):
+                try:
+                    op()
+                except OSError:
+                    pass
+        with self._conns_lock:
+            conns, self._conns = self._conns, set()
+        for c in conns:
+            try:
+                c.close()
+            except OSError:
+                pass
+
+    def _track(self, sock):
+        with self._conns_lock:
+            self._conns.add(sock)
+
+    def _serve(self):
+        while self.active:
+            try:
+                conn, addr = self._srv.accept()
+            except socket.timeout:
+                continue
+            except OSError:
+                break
+            self._track(conn)
+            threading.Thread(target=self._handle, args=(conn, addr[0]), daemon=True).start()
+        self.stop()
+        log.info("login relay closed")
+
+    def _handle(self, conn, ip):
+        try:
+            conn.settimeout(PEEK_TIMEOUT)
+            path = parse_request_path(conn.recv(4096, socket.MSG_PEEK))
+            decision = self.gate.decide(ip, path)
+            if decision in ("authorize", "deny"):
+                conn.recv(4096)  # consume the request; closing with unread data would send RST
+                conn.sendall(_REDIRECT if decision == "authorize" else _FORBIDDEN)
+                conn.shutdown(socket.SHUT_WR)
+                conn.close()
+                if decision == "authorize":
+                    log.info("login relay: phone %s authorized", ip)
+                return
+            conn.settimeout(None)
+            upstream = socket.create_connection(self.target, timeout=5)
+            upstream.settimeout(None)
+            self._track(upstream)
+            threading.Thread(target=_pipe, args=(conn, upstream), daemon=True).start()
+            _pipe(upstream, conn)
+        except OSError:
+            try:
+                conn.close()
+            except OSError:
+                pass

py_modules/mudfish_decky/system.py

@@ -71,6 +71,16 @@ def route_text(run=subprocess.run) -> str:
     return run(["ip", "-4", "route"], capture_output=True, text=True, timeout=5).stdout
 
 
+def lan_ip(run=subprocess.run) -> Optional[str]:
+    """The Deck's source address for outbound traffic (its Wi-Fi/LAN IP when the VPN is off)."""
+    try:
+        out = run(["ip", "-4", "route", "get", "1.1.1.1"], capture_output=True, text=True, timeout=5).stdout
+    except Exception:
+        return None
+    parts = out.split()
+    return parts[parts.index("src") + 1] if "src" in parts[:-1] else None
+
+
 def public_ip() -> Optional[dict]:
     try:
         with urllib.request.urlopen("https://ipinfo.io/json", timeout=8, context=ssl_context()) as resp:

src/LoginModal.tsx

@@ -0,0 +1,88 @@
+import { DialogButton, ModalRoot } from "@decky/ui";
+import qrcode from "qrcode-generator";
+import { ReactElement, useEffect, useState } from "react";
+import { getState, startLogin, stopLogin, VpnState } from "./backend";
+
+const POLL_MS = 2000;
+
+function QrSvg({ text, size }: { text: string; size: number }) {
+  const qr = qrcode(0, "M");
+  qr.addData(text);
+  qr.make();
+  const count = qr.getModuleCount();
+  const quiet = 2;
+  const cells: ReactElement[] = [];
+  for (let r = 0; r < count; r++) {
+    for (let c = 0; c < count; c++) {
+      if (qr.isDark(r, c)) cells.push(<rect key={`${r}-${c}`} x={c + quiet} y={r + quiet} width={1} height={1} />);
+    }
+  }
+  const dim = count + quiet * 2;
+  return (
+    <svg width={size} height={size} viewBox={`0 0 ${dim} ${dim}`} shapeRendering="crispEdges">
+      <rect width={dim} height={dim} fill="#fff" />
+      <g fill="#000">{cells}</g>
+    </svg>
+  );
+}
+
+function remaining(expiresAt: number): string {
+  const s = Math.max(0, Math.round(expiresAt - Date.now() / 1000));
+  return `${Math.floor(s / 60)}:${String(s % 60).padStart(2, "0")}`;
+}
+
+export function LoginModal({ closeModal }: { closeModal?: () => void }) {
+  const [state, setState] = useState<VpnState | null>(null);
+  const [, tick] = useState(0);
+
+  useEffect(() => {
+    let alive = true;
+    startLogin().then((s) => alive && setState(s));
+    const id = setInterval(async () => {
+      try {
+        const s = await getState();
+        if (!alive) return;
+        setState(s);
+        if (!s.need_login) closeModal?.(); // logged in: backend already closed the relay
+      } catch (e) {
+        console.error("mudfish: getState failed", e);
+      }
+      tick((n) => n + 1);
+    }, POLL_MS);
+    return () => {
+      alive = false;
+      clearInterval(id);
+    };
+  }, []);
+
+  const cancel = () => {
+    stopLogin();
+    closeModal?.();
+  };
+
+  const login = state?.login;
+  return (
+    <ModalRoot onCancel={cancel} closeModal={cancel}>
+      <div style={{ display: "flex", gap: "24px", alignItems: "center" }}>
+        <div style={{ flex: "0 0 auto" }}>
+          {login ? <QrSvg text={login.url} size={240} /> : <div style={{ width: 240, height: 240 }} />}
+        </div>
+        <div style={{ display: "flex", flexDirection: "column", gap: "10px" }}>
+          <div style={{ fontSize: "20px", fontWeight: "bold" }}>휴대폰으로 미꾸라지 로그인</div>
+          {login ? (
+            <>
+              <div>1. 스팀덱과 같은 와이파이에 연결된 휴대폰으로 QR을 찍으세요.</div>
+              <div>2. 열린 미꾸라지 화면에서 <b>'로그인 기억하기'를 체크</b>하고 로그인하세요.</div>
+              <div>3. 로그인이 확인되면 이 창은 자동으로 닫혀요.</div>
+              <div style={{ opacity: 0.6, fontSize: "12px", wordBreak: "break-all" }}>{login.url}</div>
+              <div style={{ opacity: 0.8 }}>{`남은 시간 ${remaining(login.expires_at)} · 처음 QR을 찍은 휴대폰만 접속할 수 있어요`}</div>
+            </>
+          ) : (
+            <div>{state?.message ?? "로그인 창을 여는 중…"}</div>
+          )}
+          <DialogButton onClick={cancel}>닫기</DialogButton>
+        </div>
+      </div>
+    </ModalRoot>
+  );
+}

src/Panel.tsx

@@ -4,8 +4,10 @@ import {
   Field,
   PanelSection,
   PanelSectionRow,
+  showModal,
   ToggleField,
 } from "@decky/ui";
+import { LoginModal } from "./LoginModal";
 import { useEffect, useRef, useState } from "react";
 import {
   connect,
@@ -158,6 +160,13 @@ export function Panel() {
           <Field focusable={false} description={state.message} />
         </PanelSectionRow>
       )}
+      {state.need_login && (
+        <PanelSectionRow>
+          <ButtonItem layout="below" onClick={() => showModal(<LoginModal />)}>
+            휴대폰으로 로그인 (QR)
+          </ButtonItem>
+        </PanelSectionRow>
+      )}
       <PanelSectionRow>
         <ButtonItem layout="below" onClick={() => setAdvanced(!advanced)}>
           {advanced ? "고급 ▾" : "고급 ▸"}

src/backend.ts

@@ -17,6 +17,8 @@ export interface VpnState {
   country: string | null;
   connected_since: number | null;
   tunnel: boolean;
+  need_login: boolean;
+  login: { url: string; expires_at: number } | null;
 }
 
 export const getState = callable<[], VpnState>("get_state");
@@ -24,3 +26,5 @@ export const connect = callable<[], VpnState>("connect");
 export const disconnect = callable<[], VpnState>("disconnect");
 export const setNode = callable<[choice: string], VpnState>("set_node");
 export const listNodes = callable<[], NodeInfo[]>("list_nodes");
+export const startLogin = callable<[], VpnState>("start_login");
+export const stopLogin = callable<[], VpnState>("stop_login");

tests/test_controller.py

@@ -3,8 +3,8 @@ import tempfile
 import unittest
 
 from mudfish_decky.client import AuthError, SigninError
-from mudfish_decky.controller import (MSG_MISSING, MSG_NO_RESPONSE, MSG_RELOGIN, MSG_RTT, MSG_SLEEP, MSG_STILL_UP,
-                                      MSG_TIMEOUT, Controller)
+from mudfish_decky.controller import (MSG_LOGGED_IN, MSG_MISSING, MSG_NO_LAN, MSG_NO_RESPONSE, MSG_RELOGIN, MSG_RTT,
+                                      MSG_SLEEP, MSG_STILL_UP, MSG_TIMEOUT, Controller)
 from mudfish_decky.store import Store
 from tests.test_nodes import STATIC
 
@@ -20,6 +20,10 @@ class FakeSystem:
         self.deleted = []
         self.daemon_calls = 0
         self.ip = {"ip": "13.73.234.162", "country": "JP"}
+        self.lan = "192.168.1.50"
+
+    def lan_ip(self):
+        return self.lan
 
     def find_mudfish(self):
         return ("/opt/mudfish/6.6.0/bin/mudrun-headless", "/opt/mudfish/6.6.0/var") if self.installed else None
@@ -41,6 +45,25 @@ class FakeSystem:
         return self.ip
 
 
+class FakeRelay:
+    token = "tok"
+    expires_at = 1300.0
+
+    def __init__(self):
+        self.active = False
+        self.started = False
+        self.start_calls = 0
+
+    def start(self, host="0.0.0.0"):
+        self.started = True
+        self.active = True
+        self.start_calls += 1
+        return 40123
+
+    def stop(self):
+        self.active = False
+
+
 class FakeClient:
     def __init__(self, system):
         self.system = system
@@ -333,6 +356,86 @@ class ControllerTest(unittest.TestCase):
         self.assertEqual(st["message"], MSG_RTT)
         self.assertEqual(self.client.start_calls, 0)
 
+    # ---- phone (QR) login --------------------------------------------------------------------
+
+    def make_with_relay(self):
+        self.relay = FakeRelay()
+        return Controller(self.client, self.system, Store(self.path), clock=lambda: self.now,
+                          sleep=lambda s: None, relay_factory=lambda: self.relay)
+
+    def test_connect_signin_failure_flags_need_login(self):
+        self.client.signin_error = SigninError("401")
+        self.assertTrue(self.make().connect()["need_login"])
+
+    def test_prepare_signin_failure_flags_need_login(self):
+        self.client.signin_error = SigninError("401")
+        c = self.make()
+        c.prepare()
+        st = c.state()
+        self.assertTrue(st["need_login"])
+        self.assertEqual(st["message"], MSG_RELOGIN)
+
+    def test_prepare_network_failure_does_not_flag_need_login(self):
+        self.client.signin_error = OSError("name resolution")
+        c = self.make()
+        c.prepare()
+        self.assertFalse(c.state()["need_login"])
+
+    def test_need_login_false_by_default(self):
+        self.assertFalse(self.make().state()["need_login"])
+
+    def test_start_login_exposes_qr_url(self):
+        c = self.make_with_relay()
+        st = c.start_login()
+        self.assertEqual(st["login"], {"url": "http://192.168.1.50:40123/_mfd/tok", "expires_at": 1300.0})
+        self.assertTrue(self.relay.started)
+        self.assertEqual(self.client.start_calls, 0)
+
+    def test_start_login_reuses_active_relay(self):
+        c = self.make_with_relay()
+        c.start_login()
+        c.start_login()
+        self.assertEqual(self.relay.start_calls, 1)
+
+    def test_start_login_without_lan_ip_shows_message(self):
+        self.system.lan = None
+        st = self.make_with_relay().start_login()
+        self.assertIsNone(st["login"])
+        self.assertEqual(st["message"], MSG_NO_LAN)
+        self.assertFalse(self.relay.started)
+
+    def test_state_closes_relay_after_signin(self):
+        self.client.signin_error = SigninError("401")
+        self.client.st["isSignedIn"] = False
+        c = self.make_with_relay()
+        c.connect()
+        c.start_login()
+        self.client.st["isSignedIn"] = True  # user logged in from the phone
+        st = c.state()
+        self.assertFalse(self.relay.active)
+        self.assertIsNone(st["login"])
+        self.assertFalse(st["need_login"])
+        self.assertEqual(st["phase"], "off")
+        self.assertEqual(st["message"], MSG_LOGGED_IN)
+
+    def test_stop_login_closes_relay(self):
+        c = self.make_with_relay()
+        c.start_login()
+        self.assertIsNone(c.stop_login()["login"])
+        self.assertFalse(self.relay.active)
+
+    def test_expired_relay_drops_from_state(self):
+        c = self.make_with_relay()
+        c.start_login()
+        self.relay.active = False
+        self.assertIsNone(c.state()["login"])
+
+    def test_shutdown_closes_relay(self):
+        c = self.make_with_relay()
+        c.start_login()
+        c.shutdown()
+        self.assertFalse(self.relay.active)
+
     # ---- sleep / shutdown --------------------------------------------------------------------
 
     def test_resume_jump_turns_tunnel_off_with_notice(self):

tests/test_relay.py

@@ -0,0 +1,111 @@
+import socket
+import threading
+import unittest
+
+from mudfish_decky.relay import Gate, LoginRelay, parse_request_path
+
+
+def http_get(port, path):
+    with socket.create_connection(("127.0.0.1", port), timeout=5) as s:
+        s.sendall(f"GET {path} HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n".encode())
+        chunks = []
+        while True:
+            data = s.recv(4096)
+            if not data:
+                break
+            chunks.append(data)
+    return b"".join(chunks).decode()
+
+
+class FakeTarget:
+    """Minimal HTTP server standing in for the Mudfish launcher."""
+
+    def __init__(self):
+        self.srv = socket.create_server(("127.0.0.1", 0))
+        self.port = self.srv.getsockname()[1]
+        threading.Thread(target=self._serve, daemon=True).start()
+
+    def _serve(self):
+        while True:
+            try:
+                conn, _ = self.srv.accept()
+            except OSError:
+                return
+            with conn:
+                conn.recv(4096)
+                conn.sendall(b"HTTP/1.1 200 OK\r\nContent-Length: 5\r\nConnection: close\r\n\r\nhello")
+
+    def close(self):
+        self.srv.close()
+
+
+class GateTest(unittest.TestCase):
+    def test_denies_until_token_seen(self):
+        g = Gate("tok")
+        self.assertEqual(g.decide("10.0.0.2", "/"), "deny")
+        self.assertEqual(g.decide("10.0.0.2", "/_mfd/wrong"), "deny")
+
+    def test_first_token_holder_is_the_only_client(self):
+        g = Gate("tok")
+        self.assertEqual(g.decide("10.0.0.2", "/_mfd/tok"), "authorize")
+        self.assertEqual(g.decide("10.0.0.2", "/do/mudrun/status"), "pipe")
+        self.assertEqual(g.decide("10.0.0.3", "/_mfd/tok"), "deny")
+        self.assertEqual(g.decide("10.0.0.3", "/"), "deny")
+
+    def test_query_string_on_token_path(self):
+        self.assertEqual(Gate("tok").decide("10.0.0.2", "/_mfd/tok?x=1"), "authorize")
+
+
+class ParseTest(unittest.TestCase):
+    def test_parse_request_path(self):
+        self.assertEqual(parse_request_path(b"GET /_mfd/tok HTTP/1.1\r\nHost: x\r\n\r\n"), "/_mfd/tok")
+
+    def test_parse_partial_or_garbage(self):
+        self.assertIsNone(parse_request_path(b"GET /incomplete"))
+        self.assertIsNone(parse_request_path(b"\x16\x03\x01binary"))
+
+
+class LoginRelayTest(unittest.TestCase):
+    def setUp(self):
+        self.target = FakeTarget()
+        self.relay = LoginRelay(target=("127.0.0.1", self.target.port), ttl=60)
+        self.port = self.relay.start(host="127.0.0.1")
+
+    def tearDown(self):
+        self.relay.stop()
+        self.target.close()
+
+    def test_token_is_random_and_url_safe(self):
+        other = LoginRelay(target=("127.0.0.1", 1))
+        self.assertNotEqual(self.relay.token, other.token)
+        self.assertGreaterEqual(len(self.relay.token), 16)
+        self.assertRegex(self.relay.token, r"^[A-Za-z0-9_-]+$")
+
+    def test_forbidden_before_token(self):
+        self.assertIn("403", http_get(self.port, "/").splitlines()[0])
+
+    def test_token_redirects_then_proxies(self):
+        first = http_get(self.port, f"/_mfd/{self.relay.token}")
+        self.assertIn("302", first.splitlines()[0])
+        self.assertIn("Location: /", first)
+        self.assertTrue(http_get(self.port, "/").endswith("hello"))
+
+    def test_stop_closes_port(self):
+        self.relay.stop()
+        self.assertFalse(self.relay.active)
+        with self.assertRaises(OSError):
+            socket.create_connection(("127.0.0.1", self.port), timeout=2).close()
+
+    def test_expires_after_ttl(self):
+        now = [1000.0]
+        relay = LoginRelay(target=("127.0.0.1", self.target.port), ttl=300, clock=lambda: now[0])
+        relay.start(host="127.0.0.1")
+        self.assertEqual(relay.expires_at, 1300.0)
+        self.assertTrue(relay.active)
+        now[0] = 1301.0
+        self.assertFalse(relay.active)
+        relay.stop()
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_system.py

@@ -35,6 +35,16 @@ class SystemTest(unittest.TestCase):
         with tempfile.TemporaryDirectory() as var:
             self.assertEqual(api_base(var), "http://127.0.0.1:8282")
 
+    def test_lan_ip_from_route_get(self):
+        from mudfish_decky.system import lan_ip
+        out = "1.1.1.1 via 192.168.1.1 dev wlan0 src 192.168.1.50 uid 0 \n    cache \n"
+        self.assertEqual(lan_ip(run=lambda cmd, **kw: types.SimpleNamespace(stdout=out, returncode=0)),
+                         "192.168.1.50")
+
+    def test_lan_ip_none_without_route(self):
+        from mudfish_decky.system import lan_ip
+        self.assertIsNone(lan_ip(run=lambda cmd, **kw: types.SimpleNamespace(stdout="", returncode=2)))
+
     def test_sleep_offset_is_boottime_minus_monotonic(self):
         from mudfish_decky.system import sleep_offset
         clocks = {"boot": 500.0, "mono": 420.0}