diff --git a/SVSim.Database/Services/Guild/GuildChatService.cs b/SVSim.Database/Services/Guild/GuildChatService.cs
new file mode 100644
index 00000000..4e96decf
--- /dev/null
+++ b/SVSim.Database/Services/Guild/GuildChatService.cs
@@ -0,0 +1,55 @@
+using SVSim.Database.Repositories.Guild;
+using SVSim.Database.Services;
+
+namespace SVSim.Database.Services.Guild;
+
+public sealed class GuildChatService : IGuildChatService
+{
+    private readonly IGuildRepository _guilds;
+    private readonly IGuildMemberRepository _members;
+    private readonly IGuildInviteRepository _invites;
+    private readonly IGuildJoinRequestRepository _joinRequests;
+    private readonly IGuildChatMessageRepository _chatMessages;
+    private readonly IGameConfigService _config;
+
+    public GuildChatService(
+        IGuildRepository guilds,
+        IGuildMemberRepository members,
+        IGuildInviteRepository invites,
+        IGuildJoinRequestRepository joinRequests,
+        IGuildChatMessageRepository chatMessages,
+        IGameConfigService config)
+    {
+        _guilds = guilds;
+        _members = members;
+        _invites = invites;
+        _joinRequests = joinRequests;
+        _chatMessages = chatMessages;
+        _config = config;
+    }
+
+    public Task<ChatWindow> GetWindowAsync(long viewerId, int startMessageId, int direction, int waitIntervalHint, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<ChatPostResult> PostTextOrStampAsync(long viewerId, int type, string message, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<ChatPostResult> PostDeckAsync(long viewerId, string deckPayloadJson, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<bool> DeleteDeckAsync(long viewerId, int messageId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<ChatPostResult> PostReplayAsync(long viewerId, string replayPayloadJson, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<string?> GetReplayDetailAsync(long viewerId, int messageId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<string?> GetDeckLogAsync(long viewerId, int messageId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    // No-op skeleton — will be wired in Phase 5.
+    public Task EmitSystemEventAsync(int guildId, long actorViewerId, Entities.Guild.GuildChatMessageType type, string? body = null, CancellationToken ct = default)
+        => Task.CompletedTask;
+}
diff --git a/SVSim.Database/Services/Guild/GuildService.cs b/SVSim.Database/Services/Guild/GuildService.cs
new file mode 100644
index 00000000..b6cc2b93
--- /dev/null
+++ b/SVSim.Database/Services/Guild/GuildService.cs
@@ -0,0 +1,91 @@
+using SVSim.Database.Repositories.Guild;
+using SVSim.Database.Services;
+
+namespace SVSim.Database.Services.Guild;
+
+public sealed class GuildService : IGuildService
+{
+    private readonly IGuildRepository _guilds;
+    private readonly IGuildMemberRepository _members;
+    private readonly IGuildInviteRepository _invites;
+    private readonly IGuildJoinRequestRepository _joinRequests;
+    private readonly IGuildChatMessageRepository _chatMessages;
+    private readonly IGameConfigService _config;
+
+    public GuildService(
+        IGuildRepository guilds,
+        IGuildMemberRepository members,
+        IGuildInviteRepository invites,
+        IGuildJoinRequestRepository joinRequests,
+        IGuildChatMessageRepository chatMessages,
+        IGameConfigService config)
+    {
+        _guilds = guilds;
+        _members = members;
+        _invites = invites;
+        _joinRequests = joinRequests;
+        _chatMessages = chatMessages;
+        _config = config;
+    }
+
+    // Returns null so /guild/info can short-circuit to a non-joined response in Phase 1.
+    public Task<GuildFullView?> GetMyGuildAsync(long viewerId, CancellationToken ct = default)
+        => Task.FromResult<GuildFullView?>(null);
+
+    public Task<Entities.Guild.Guild?> GetActiveAsync(int guildId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<IReadOnlyList<GuildSearchEntry>> SearchAsync(string name, int activity, int joinCondition, int memberBucket, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> CreateAsync(long viewerId, CreateGuildRequest req, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> UpdateAsync(long viewerId, UpdateGuildRequest req, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> UpdateDescriptionAsync(long viewerId, string description, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> UpdateEmblemAsync(long viewerId, long emblemId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> BreakupAsync(long viewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> InviteAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> CancelInviteAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> RejectInviteAsync(long callerViewerId, int guildId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> JoinAsync(long viewerId, int guildId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> CancelJoinRequestAsync(long viewerId, int guildId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> AcceptJoinRequestAsync(long callerViewerId, long applicantViewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> RejectJoinRequestAsync(long callerViewerId, long applicantViewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> LeaveAsync(long viewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> RemoveAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<GuildOpResult> ChangeRoleAsync(long callerViewerId, long targetViewerId, int newRoleId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<IReadOnlyList<Entities.Guild.GuildInvite>> ListPendingInvitesForMeAsync(long viewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
+    public Task<IReadOnlyList<Entities.Guild.GuildJoinRequest>> ListPendingJoinRequestsForMyGuildAsync(long viewerId, CancellationToken ct = default)
+        => throw new NotImplementedException();
+}
diff --git a/SVSim.Database/Services/Guild/GuildServiceTypes.cs b/SVSim.Database/Services/Guild/GuildServiceTypes.cs
new file mode 100644
index 00000000..04ac0083
--- /dev/null
+++ b/SVSim.Database/Services/Guild/GuildServiceTypes.cs
@@ -0,0 +1,40 @@
+using SVSim.Database.Entities.Guild;
+
+namespace SVSim.Database.Services.Guild;
+
+public enum GuildOpResultCode
+{
+    Ok = 0,
+    NotInGuild,
+    AlreadyInGuild,
+    GuildNotFound,
+    NameTaken,
+    NameInvalid,
+    MemberCapReached,
+    SubLeaderCapReached,
+    PermissionDenied,
+    InviteNotFound,
+    InviteAlreadyResolved,
+    JoinRequestNotFound,
+    JoinRequestAlreadyResolved,
+    TargetNotInGuild,
+    LeaderLeaveBlocked,        // leader cannot leave while other members remain
+    InvalidRoleTransition,
+}
+
+public sealed record GuildOpResult(GuildOpResultCode Code, int? GuildId = null, string? Detail = null)
+{
+    public static readonly GuildOpResult Ok = new(GuildOpResultCode.Ok);
+    public bool IsOk => Code == GuildOpResultCode.Ok;
+}
+
+public sealed record GuildFullView(
+    Entities.Guild.Guild Guild,
+    IReadOnlyList<GuildMember> Members,
+    int JoinRequestCount,
+    int InviteCount);
+
+public sealed record GuildSearchEntry(Entities.Guild.Guild Guild, int MemberNum);
+
+public sealed record CreateGuildRequest(string Name, int Activity, int JoinCondition);
+public sealed record UpdateGuildRequest(int? Activity, int? JoinCondition);
diff --git a/SVSim.Database/Services/Guild/IGuildChatService.cs b/SVSim.Database/Services/Guild/IGuildChatService.cs
new file mode 100644
index 00000000..1f15c2a4
--- /dev/null
+++ b/SVSim.Database/Services/Guild/IGuildChatService.cs
@@ -0,0 +1,18 @@
+namespace SVSim.Database.Services.Guild;
+
+public sealed record ChatWindow(IReadOnlyList<Entities.Guild.GuildChatMessage> Messages, int WaitIntervalSeconds);
+public sealed record ChatPostResult(bool Ok, int? AssignedMessageId);
+
+public interface IGuildChatService
+{
+    Task<ChatWindow> GetWindowAsync(long viewerId, int startMessageId, int direction, int waitIntervalHint, CancellationToken ct = default);
+    Task<ChatPostResult> PostTextOrStampAsync(long viewerId, int type, string message, CancellationToken ct = default);
+    Task<ChatPostResult> PostDeckAsync(long viewerId, string deckPayloadJson, CancellationToken ct = default);
+    Task<bool> DeleteDeckAsync(long viewerId, int messageId, CancellationToken ct = default);
+    Task<ChatPostResult> PostReplayAsync(long viewerId, string replayPayloadJson, CancellationToken ct = default);
+    Task<string?> GetReplayDetailAsync(long viewerId, int messageId, CancellationToken ct = default);
+    Task<string?> GetDeckLogAsync(long viewerId, int messageId, CancellationToken ct = default);
+
+    /// <summary>Emit a system-event row. Called by IGuildService at create/join/leave/remove/role-change/description-change.</summary>
+    Task EmitSystemEventAsync(int guildId, long actorViewerId, Entities.Guild.GuildChatMessageType type, string? body = null, CancellationToken ct = default);
+}
diff --git a/SVSim.Database/Services/Guild/IGuildService.cs b/SVSim.Database/Services/Guild/IGuildService.cs
new file mode 100644
index 00000000..0c53b38e
--- /dev/null
+++ b/SVSim.Database/Services/Guild/IGuildService.cs
@@ -0,0 +1,40 @@
+namespace SVSim.Database.Services.Guild;
+
+/// <summary>
+/// Single dispatch surface for guild business operations. Enforces:
+///   - one viewer ≤1 guild
+///   - MaxMemberNum / MaxSubLeaderNum caps (from GuildConfig)
+///   - role-based permissions per docs/superpowers/specs/2026-06-27-guild-functionality-design.md
+///   - leader-leaves-with-members blocked
+///   - auto-routing single-member leader leave -> breakup
+///   - clear pending invites + cancel pending join_requests on successful join
+///   - emit system chat events via IGuildChatService
+/// </summary>
+public interface IGuildService
+{
+    Task<GuildFullView?> GetMyGuildAsync(long viewerId, CancellationToken ct = default);
+    Task<Entities.Guild.Guild?> GetActiveAsync(int guildId, CancellationToken ct = default);
+    Task<IReadOnlyList<GuildSearchEntry>> SearchAsync(string name, int activity, int joinCondition, int memberBucket, CancellationToken ct = default);
+
+    Task<GuildOpResult> CreateAsync(long viewerId, CreateGuildRequest req, CancellationToken ct = default);
+    Task<GuildOpResult> UpdateAsync(long viewerId, UpdateGuildRequest req, CancellationToken ct = default);
+    Task<GuildOpResult> UpdateDescriptionAsync(long viewerId, string description, CancellationToken ct = default);
+    Task<GuildOpResult> UpdateEmblemAsync(long viewerId, long emblemId, CancellationToken ct = default);
+    Task<GuildOpResult> BreakupAsync(long viewerId, CancellationToken ct = default);
+
+    Task<GuildOpResult> InviteAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default);
+    Task<GuildOpResult> CancelInviteAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default);
+    Task<GuildOpResult> RejectInviteAsync(long callerViewerId, int guildId, CancellationToken ct = default);
+
+    Task<GuildOpResult> JoinAsync(long viewerId, int guildId, CancellationToken ct = default);
+    Task<GuildOpResult> CancelJoinRequestAsync(long viewerId, int guildId, CancellationToken ct = default);
+    Task<GuildOpResult> AcceptJoinRequestAsync(long callerViewerId, long applicantViewerId, CancellationToken ct = default);
+    Task<GuildOpResult> RejectJoinRequestAsync(long callerViewerId, long applicantViewerId, CancellationToken ct = default);
+
+    Task<GuildOpResult> LeaveAsync(long viewerId, CancellationToken ct = default);
+    Task<GuildOpResult> RemoveAsync(long callerViewerId, long targetViewerId, CancellationToken ct = default);
+    Task<GuildOpResult> ChangeRoleAsync(long callerViewerId, long targetViewerId, int newRoleId, CancellationToken ct = default);
+
+    Task<IReadOnlyList<Entities.Guild.GuildInvite>> ListPendingInvitesForMeAsync(long viewerId, CancellationToken ct = default);
+    Task<IReadOnlyList<Entities.Guild.GuildJoinRequest>> ListPendingJoinRequestsForMyGuildAsync(long viewerId, CancellationToken ct = default);
+}
diff --git a/SVSim.EmulatedEntrypoint/Program.cs b/SVSim.EmulatedEntrypoint/Program.cs
index 4c635f8b..fbc55a3b 100644
--- a/SVSim.EmulatedEntrypoint/Program.cs
+++ b/SVSim.EmulatedEntrypoint/Program.cs
@@ -121,6 +121,14 @@ public class Program
         builder.Services.AddScoped<IFriendService, FriendService>();
         builder.Services.AddScoped<IPlayedTogetherWriter, FriendService>();
 
+        builder.Services.AddScoped<SVSim.Database.Repositories.Guild.IGuildRepository, SVSim.Database.Repositories.Guild.GuildRepository>();
+        builder.Services.AddScoped<SVSim.Database.Repositories.Guild.IGuildMemberRepository, SVSim.Database.Repositories.Guild.GuildMemberRepository>();
+        builder.Services.AddScoped<SVSim.Database.Repositories.Guild.IGuildInviteRepository, SVSim.Database.Repositories.Guild.GuildInviteRepository>();
+        builder.Services.AddScoped<SVSim.Database.Repositories.Guild.IGuildJoinRequestRepository, SVSim.Database.Repositories.Guild.GuildJoinRequestRepository>();
+        builder.Services.AddScoped<SVSim.Database.Repositories.Guild.IGuildChatMessageRepository, SVSim.Database.Repositories.Guild.GuildChatMessageRepository>();
+        builder.Services.AddScoped<SVSim.Database.Services.Guild.IGuildService, SVSim.Database.Services.Guild.GuildService>();
+        builder.Services.AddScoped<SVSim.Database.Services.Guild.IGuildChatService, SVSim.Database.Services.Guild.GuildChatService>();
+
         builder.Services.AddSingleton<IBattleContextStore, InMemoryBattleContextStore>();
         builder.Services.AddScoped<IBattleHistoryWriter, BattleHistoryWriter>();
         builder.Services.AddScoped<IReplayHistoryReader, ReplayHistoryReader>();