Import december-2020-12-18 from private repo (scrubbed 2026-05-27)

Targets Rec Room 2020.12.18 client.

Re-import after adding:
- DorkNet.ClientMod/dorknet-clientmod.json.template — config schema
  the launcher's manifest-driven patcher renders into UserData/.
- tools/build-patcher-zip.ps1 — produces the dorknet-clientpatch-{key}.zip
  Release asset the launcher fetches.
- .github/workflows/release.yml — auto-publishes both Release assets
  on v1-december-* tag push.

Scrubbed via maintainer-side scrub-for-public.ps1: same drop rules as
the prior import, plus build-patcher-zip.ps1 added to the tools/
allow-list so it survives the scrub.

DorkNet.Models/GameSessions/GameSession.cs

@@ -0,0 +1,73 @@
+using System.Text.Json.Serialization;
+
+namespace DorkNet.Models.GameSessions;
+
+public class GameSession
+{
+    [JsonPropertyName("GameSessionId")]
+    public long GameSessionId { get; set; }
+
+    [JsonPropertyName("RegionId")]
+    public string RegionId { get; set; } = "us";
+
+    [JsonPropertyName("RoomId")]
+    public string RoomId { get; set; } = string.Empty;
+
+    [JsonPropertyName("RoomName")]
+    public string RoomName { get; set; } = string.Empty;
+
+    [JsonPropertyName("ActivityLevelId")]
+    public string ActivityLevelId { get; set; } = string.Empty;
+
+    [JsonPropertyName("EventId")]
+    public long? EventId { get; set; }
+
+    [JsonPropertyName("Private")]
+    public bool Private { get; set; }
+
+    [JsonPropertyName("GameInProgress")]
+    public bool GameInProgress { get; set; }
+
+    [JsonPropertyName("MaxCapacity")]
+    public int MaxCapacity { get; set; } = 8;
+
+    [JsonPropertyName("IsFull")]
+    public bool IsFull { get; set; }
+
+    [JsonPropertyName("PlayerCount")]
+    public int PlayerCount { get; set; }
+
+    [JsonPropertyName("PhotonRoomName")]
+    public string PhotonRoomName { get; set; } = string.Empty;
+}
+
+public class JoinRandomGameSessionRequest
+{
+    [JsonPropertyName("RoomId")]
+    public string? RoomId { get; set; }
+
+    [JsonPropertyName("ActivityLevelId")]
+    public string? ActivityLevelId { get; set; }
+
+    [JsonPropertyName("RegionId")]
+    public string RegionId { get; set; } = "us";
+}
+
+public class JoinGameSessionResponse
+{
+    [JsonPropertyName("Result")]
+    public JoinGameErrorCode Result { get; set; } = JoinGameErrorCode.Success;
+
+    [JsonPropertyName("GameSession")]
+    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
+    public GameSession? GameSession { get; set; }
+}
+
+public enum JoinGameErrorCode
+{
+    Success = 0,
+    Full = 1,
+    NotFound = 2,
+    Banned = 3,
+    Error = 4,
+}