Add UGS Sessions online hosting with no port-forwarding

Players can now host and join over the internet without port-forwarding
via Unity Gaming Services Relay + Lobby, exposed through the unified
Multiplayer Services SDK (Sessions API).

- OnlineSessionManager: anonymous auth, CreateSessionAsync (public,
  relay-backed), QuerySessionsAsync server browser, JoinSessionByIdAsync,
  and session leave wired into the existing net-stop teardown.
- Per-install auth profile derived from the project path
  (mirror_<sha1(dataPath)>) so junction-mirror clones get distinct UGS
  player ids, avoiding the same-machine 409 LobbyConflict on join.
- Install com.unity.services.multiplayer 2.2.4 (pulls Relay/Lobby/
  Authentication/Core) and attach OnlineSessionManager to the
  NetworkManager in Main.

Loopback dev flow (NetworkBootstrap H/C/J/K) is left untouched; the
online path is additive. MatchManager and gameplay are unchanged since
Sessions starts the host/client through NGO as before.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/OnlineSessionManager.cs

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+using System;
+using System.Collections.Generic;
+using Unity.Netcode;
+using Unity.Services.Authentication;
+using Unity.Services.Core;
+using Unity.Services.Multiplayer;
+using UnityEngine;
+
+/// <summary>
+/// Online hosting/joining over Unity Gaming Services so players can connect across the internet
+/// without port forwarding. Uses the unified Multiplayer Services "Sessions" API, which bundles
+/// Relay (NAT-free messaging via Unity's relay servers) + Lobby (the public server list) + anonymous
+/// Authentication behind single calls, and configures + starts the NGO transport itself - so we do
+/// NOT call <see cref="NetworkManager.StartHost"/>/<c>StartClient</c> here; CreateSessionAsync starts
+/// the host and JoinSession* starts the client.
+///
+/// Terminology: the UGS "session" is the entry in the public server list (network layer). It is a
+/// different thing from the in-game "Lobby" scene (the pre-match staging area that <see cref="MatchManager"/>
+/// loads after the connection is up). This component does not touch the match flow at all - the usual
+/// NetworkManager callbacks fire exactly as they do for loopback hosting, so MatchManager, spawning and
+/// authority are unaffected.
+///
+/// This is a quick IMGUI server browser for clone testing; replace with proper uGUI later. The loopback
+/// dev path (see <see cref="NetworkBootstrap"/>, H/C/J/K) stays for fast local testing - online is additive.
+/// Requires the project to be linked to a UGS cloud project (Project Settings > Services) with Relay,
+/// Lobby and Authentication (Anonymous) enabled; otherwise sign-in fails with a clear status message.
+/// Attach to the same GameObject as the NetworkManager.
+/// </summary>
+[RequireComponent(typeof(NetworkManager))]
+[DisallowMultipleComponent]
+public class OnlineSessionManager : MonoBehaviour
+{
+    [Tooltip("Maximum players per hosted session (host included).")]
+    public int maxPlayers = 8;
+
+    [Tooltip("Draw the on-screen online server-browser panel (below the dev panel).")]
+    public bool showGui = true;
+
+    private NetworkManager _net;
+    private ISession _session;                 // active session (host or client); null when not in one
+    private IList<ISessionInfo> _browse = new List<ISessionInfo>();
+    private string _hostName = "";
+    private string _status = "Idle";
+    private bool _busy;
+    private bool _leaving;                      // suppress the defensive leave while an explicit leave is in flight
+    private Vector2 _scroll;
+
+    private void Awake()
+    {
+        _net = GetComponent<NetworkManager>();
+        _hostName = $"{SystemInfo.deviceName} game";
+    }
+
+    private void OnEnable()
+    {
+        if (!_net) return;
+        _net.OnServerStopped += OnNetworkStopped;
+        _net.OnClientStopped += OnNetworkStopped;
+    }
+
+    private void OnDisable()
+    {
+        if (!_net) return;
+        _net.OnServerStopped -= OnNetworkStopped;
+        _net.OnClientStopped -= OnNetworkStopped;
+    }
+
+    // The match-end / disconnect / Shutdown paths stop the NetworkManager without telling UGS. Leave the
+    // session here too so the Relay allocation and the public lobby entry are released.
+    private void OnNetworkStopped(bool _)
+    {
+        var stale = _session;
+        _session = null;
+        if (stale != null && !_leaving) LeaveSilently(stale);
+    }
+
+    private async void LeaveSilently(ISession session)
+    {
+        try { await session.LeaveAsync(); }
+        catch (Exception e) { Debug.LogWarning($"[OnlineSession] leave-on-stop failed: {e.Message}"); }
+    }
+
+    private async System.Threading.Tasks.Task EnsureSignedInAsync()
+    {
+        if (UnityServices.State != ServicesInitializationState.Initialized)
+        {
+            // Anonymous tokens are cached per machine under company/product, NOT per project path - so
+            // junction-mirror clones (shared ProjectSettings) would otherwise resolve to one UGS player id
+            // and collide on join (409 LobbyConflict). Namespacing the auth cache by a hash of this install's
+            // path gives each clone a stable, distinct identity. Harmless in production - separate machines
+            // already have separate caches; this only matters for same-machine clone testing.
+            var options = new InitializationOptions();
+            options.SetProfile(ProfileForThisInstall());
+            await UnityServices.InitializeAsync(options);
+        }
+        if (!AuthenticationService.Instance.IsSignedIn)
+            await AuthenticationService.Instance.SignInAnonymouslyAsync();
+    }
+
+    // Deterministic, regex-safe (^[a-zA-Z0-9_-]{1,30}$) profile derived from the install path, so the same
+    // clone is always the same UGS player across restarts - no random per-launch identity, no orphaned ghost
+    // players/lobbies piling up. SHA1 over dataPath -> "mirror_" + 12 hex chars = 19 chars (fits the limit).
+    private static string ProfileForThisInstall()
+    {
+        using (var sha1 = System.Security.Cryptography.SHA1.Create())
+        {
+            var bytes = sha1.ComputeHash(System.Text.Encoding.UTF8.GetBytes(Application.dataPath));
+            var name = new System.Text.StringBuilder("mirror_", 19);
+            for (int i = 0; i < 6; i++) name.Append(bytes[i].ToString("x2"));
+            return name.ToString();
+        }
+    }
+
+    private async void HostAsync()
+    {
+        if (_busy) return;
+        _busy = true;
+        try
+        {
+            _status = "Signing in…";
+            await EnsureSignedInAsync();
+            _status = "Creating session…";
+            var options = new SessionOptions
+            {
+                Name = string.IsNullOrWhiteSpace(_hostName) ? "Chameleon game" : _hostName.Trim(),
+                MaxPlayers = Mathf.Max(2, maxPlayers)
+            }.WithRelayNetwork();
+            _session = await MultiplayerService.Instance.CreateSessionAsync(options);
+            _status = $"Hosting \"{_session.Name}\" (code {_session.Code})";
+        }
+        catch (Exception e)
+        {
+            _status = $"Host failed: {e.Message}";
+            Debug.LogException(e);
+        }
+        finally { _busy = false; }
+    }
+
+    private async void RefreshAsync()
+    {
+        if (_busy) return;
+        _busy = true;
+        try
+        {
+            _status = "Signing in…";
+            await EnsureSignedInAsync();
+            _status = "Querying sessions…";
+            var results = await MultiplayerService.Instance.QuerySessionsAsync(new QuerySessionsOptions());
+            _browse = results.Sessions;
+            _status = $"{_browse.Count} session(s) found";
+        }
+        catch (Exception e)
+        {
+            _status = $"Refresh failed: {e.Message}";
+            Debug.LogException(e);
+        }
+        finally { _busy = false; }
+    }
+
+    private async void JoinAsync(string sessionId)
+    {
+        if (_busy) return;
+        _busy = true;
+        try
+        {
+            _status = "Signing in…";
+            await EnsureSignedInAsync();
+            _status = "Joining session…";
+            _session = await MultiplayerService.Instance.JoinSessionByIdAsync(sessionId);
+            _status = $"Joined \"{_session.Name}\"";
+        }
+        catch (Exception e)
+        {
+            _status = $"Join failed: {e.Message}";
+            Debug.LogException(e);
+        }
+        finally { _busy = false; }
+    }
+
+    private async void LeaveAsync()
+    {
+        if (_busy || _session == null) return;
+        _busy = true;
+        _leaving = true;
+        try
+        {
+            _status = "Leaving…";
+            await _session.LeaveAsync();   // also tears down the NGO connection
+            _status = "Left session";
+        }
+        catch (Exception e)
+        {
+            _status = $"Leave failed: {e.Message}";
+            Debug.LogException(e);
+        }
+        finally { _session = null; _leaving = false; _busy = false; }
+    }
+
+    private void OnGUI()
+    {
+        if (!showGui || !_net) return;
+
+        GUILayout.BeginArea(new Rect(10, 180, 340, 360), GUI.skin.box);
+        GUILayout.Label("Online (UGS Relay + Lobby)");
+        GUILayout.Label(_status);
+
+        GUI.enabled = !_busy;
+        if (!_net.IsListening)
+        {
+            GUILayout.Label("Session name:");
+            _hostName = GUILayout.TextField(_hostName);
+            if (GUILayout.Button("Host Online")) HostAsync();
+
+            GUILayout.Space(6);
+            if (GUILayout.Button("Refresh List")) RefreshAsync();
+
+            _scroll = GUILayout.BeginScrollView(_scroll, GUILayout.Height(180));
+            if (_browse.Count == 0)
+                GUILayout.Label("No sessions. Click Refresh.");
+            foreach (var s in _browse)
+            {
+                GUILayout.BeginHorizontal();
+                int taken = Mathf.Max(0, s.MaxPlayers - s.AvailableSlots);
+                GUILayout.Label($"{s.Name}  ({taken}/{s.MaxPlayers})");
+                if (GUILayout.Button("Join", GUILayout.Width(60))) JoinAsync(s.Id);
+                GUILayout.EndHorizontal();
+            }
+            GUILayout.EndScrollView();
+        }
+        else if (_session != null)
+        {
+            GUILayout.Label($"In session: {_session.Name}");
+            if (GUILayout.Button("Leave Session")) LeaveAsync();
+        }
+        else
+        {
+            GUILayout.Label("Local (loopback) session active.");
+        }
+        GUI.enabled = true;
+
+        GUILayout.EndArea();
+    }
+}

Assets/Scripts/OnlineSessionManager.cs.meta

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+fileFormatVersion: 2
+guid: 64babb133b483be49972dd184b31d84b