Phase 5D Collaboration Foundation

PlotLine/Controllers/ProjectCollaboratorsController.cs

@@ -0,0 +1,50 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using PlotLine.Services;
+using PlotLine.ViewModels;
+
+namespace PlotLine.Controllers;
+
+[Authorize]
+public sealed class ProjectCollaboratorsController(IProjectCollaborationService collaboration) : Controller
+{
+    public async Task<IActionResult> Index(int projectId)
+    {
+        var model = await collaboration.GetCollaboratorsAsync(projectId);
+        return model is null ? NotFound() : View(model);
+    }
+
+    [HttpPost]
+    [ValidateAntiForgeryToken]
+    public async Task<IActionResult> Add(ProjectCollaboratorInviteViewModel model)
+    {
+        if (!ModelState.IsValid)
+        {
+            TempData["CollaborationError"] = "Enter a valid collaborator email address.";
+            return RedirectToAction(nameof(Index), new { projectId = model.ProjectID });
+        }
+
+        var result = await collaboration.AddCollaboratorAsync(model);
+        if (result.NotFound)
+        {
+            return NotFound();
+        }
+
+        TempData[result.Succeeded ? "CollaborationMessage" : "CollaborationError"] = result.Message;
+        return RedirectToAction(nameof(Index), new { projectId = model.ProjectID });
+    }
+
+    [HttpPost]
+    [ValidateAntiForgeryToken]
+    public async Task<IActionResult> Remove(int projectId, int userId)
+    {
+        var result = await collaboration.RemoveCollaboratorAsync(projectId, userId);
+        if (result.NotFound)
+        {
+            return NotFound();
+        }
+
+        TempData[result.Succeeded ? "CollaborationMessage" : "CollaborationError"] = result.Message;
+        return RedirectToAction(nameof(Index), new { projectId });
+    }
+}

PlotLine/Data/Repositories.cs

@@ -18,6 +18,17 @@ public interface IProjectRepository
     Task ArchiveForUserAsync(int projectId, int userId);
 }
 
+public interface IProjectCollaborationRepository
+{
+    Task<int?> GetOwnerUserIdAsync(int projectId);
+    Task<IReadOnlyList<ProjectCollaborator>> ListCollaboratorsAsync(int projectId);
+    Task<IReadOnlyList<ProjectInvitation>> ListPendingInvitationsAsync(int projectId);
+    Task<bool> CollaboratorCountsForOwnerAsync(int ownerUserId, int collaboratorUserId);
+    Task<bool> AddCollaboratorAsync(int projectId, int userId, int invitedByUserId);
+    Task<bool> RemoveCollaboratorAsync(int projectId, int userId);
+    Task<int> CreatePendingInvitationAsync(int projectId, string emailAddress, int invitedByUserId);
+}
+
 public interface IBookRepository
 {
     Task<IReadOnlyList<Book>> ListByProjectAsync(int projectId);
@@ -1227,6 +1238,74 @@ public sealed class ProjectRepository(ISqlConnectionFactory connectionFactory) :
     }
 }
 
+public sealed class ProjectCollaborationRepository(ISqlConnectionFactory connectionFactory) : IProjectCollaborationRepository
+{
+    public async Task<int?> GetOwnerUserIdAsync(int projectId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        return await connection.QuerySingleOrDefaultAsync<int?>(
+            "dbo.ProjectCollaboration_GetOwner",
+            new { ProjectID = projectId },
+            commandType: CommandType.StoredProcedure);
+    }
+
+    public async Task<IReadOnlyList<ProjectCollaborator>> ListCollaboratorsAsync(int projectId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        var rows = await connection.QueryAsync<ProjectCollaborator>(
+            "dbo.ProjectCollaboration_ListCollaborators",
+            new { ProjectID = projectId },
+            commandType: CommandType.StoredProcedure);
+        return rows.ToList();
+    }
+
+    public async Task<IReadOnlyList<ProjectInvitation>> ListPendingInvitationsAsync(int projectId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        var rows = await connection.QueryAsync<ProjectInvitation>(
+            "dbo.ProjectCollaboration_ListPendingInvitations",
+            new { ProjectID = projectId },
+            commandType: CommandType.StoredProcedure);
+        return rows.ToList();
+    }
+
+    public async Task<bool> CollaboratorCountsForOwnerAsync(int ownerUserId, int collaboratorUserId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        return await connection.QuerySingleAsync<bool>(
+            "dbo.ProjectCollaboration_CollaboratorCountsForOwner",
+            new { OwnerUserID = ownerUserId, CollaboratorUserID = collaboratorUserId },
+            commandType: CommandType.StoredProcedure);
+    }
+
+    public async Task<bool> AddCollaboratorAsync(int projectId, int userId, int invitedByUserId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        return await connection.QuerySingleAsync<bool>(
+            "dbo.ProjectCollaboration_AddCollaborator",
+            new { ProjectID = projectId, UserID = userId, InvitedByUserID = invitedByUserId },
+            commandType: CommandType.StoredProcedure);
+    }
+
+    public async Task<bool> RemoveCollaboratorAsync(int projectId, int userId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        return await connection.QuerySingleAsync<bool>(
+            "dbo.ProjectCollaboration_RemoveCollaborator",
+            new { ProjectID = projectId, UserID = userId },
+            commandType: CommandType.StoredProcedure);
+    }
+
+    public async Task<int> CreatePendingInvitationAsync(int projectId, string emailAddress, int invitedByUserId)
+    {
+        using var connection = connectionFactory.CreateConnection();
+        return await connection.QuerySingleAsync<int>(
+            "dbo.ProjectCollaboration_CreatePendingInvitation",
+            new { ProjectID = projectId, EmailAddress = emailAddress, InvitedByUserID = invitedByUserId },
+            commandType: CommandType.StoredProcedure);
+    }
+}
+
 public sealed class BookRepository(ISqlConnectionFactory connectionFactory) : IBookRepository
 {
     public async Task<IReadOnlyList<Book>> ListByProjectAsync(int projectId)

PlotLine/Models/CoreModels.cs

@@ -10,6 +10,40 @@ public sealed class Project
     public bool IsArchived { get; set; }
     public DateTime? ArchivedDate { get; set; }
     public string? ArchivedReason { get; set; }
+    public string AccessRole { get; set; } = "Owner";
+    public bool IsOwner => string.Equals(AccessRole, "Owner", StringComparison.OrdinalIgnoreCase);
+}
+
+public sealed class ProjectCollaborator
+{
+    public int ProjectUserAccessID { get; set; }
+    public int ProjectID { get; set; }
+    public int UserID { get; set; }
+    public string Email { get; set; } = string.Empty;
+    public string DisplayName { get; set; } = string.Empty;
+    public string AccessRole { get; set; } = "Collaborator";
+    public int? InvitedByUserID { get; set; }
+    public string? InvitedByDisplayName { get; set; }
+    public DateTime? InvitedDateUTC { get; set; }
+    public DateTime? AcceptedDateUTC { get; set; }
+    public bool IsActive { get; set; }
+}
+
+public sealed class ProjectInvitation
+{
+    public int ProjectInvitationID { get; set; }
+    public int ProjectID { get; set; }
+    public string EmailAddress { get; set; } = string.Empty;
+    public string AccessRole { get; set; } = "Collaborator";
+    public Guid InvitationToken { get; set; }
+    public int InvitedByUserID { get; set; }
+    public string? InvitedByDisplayName { get; set; }
+    public DateTime InvitedDateUTC { get; set; }
+    public DateTime? AcceptedDateUTC { get; set; }
+    public int? AcceptedByUserID { get; set; }
+    public bool IsAccepted { get; set; }
+    public bool IsCancelled { get; set; }
+    public DateTime? CancelledDateUTC { get; set; }
 }
 
 public sealed class GenreMetricPreset

PlotLine/Program.cs

@@ -103,8 +103,10 @@ public class Program
         builder.Services.AddScoped<IAcceptanceRepository, AcceptanceRepository>();
         builder.Services.AddScoped<IImportRepository, ImportRepository>();
         builder.Services.AddScoped<IProjectAccessRepository, ProjectAccessRepository>();
+        builder.Services.AddScoped<IProjectCollaborationRepository, ProjectCollaborationRepository>();
         builder.Services.AddScoped<ISubscriptionRepository, SubscriptionRepository>();
         builder.Services.AddScoped<IProjectService, ProjectService>();
+        builder.Services.AddScoped<IProjectCollaborationService, ProjectCollaborationService>();
         builder.Services.AddScoped<IBookService, BookService>();
         builder.Services.AddScoped<IChapterService, ChapterService>();
         builder.Services.AddScoped<ISceneService, SceneService>();

PlotLine/Services/CoreServices.cs

@@ -2,6 +2,7 @@ using System.Diagnostics;
 using System.Net;
 using System.Text;
 using Microsoft.AspNetCore.Mvc.Rendering;
+using Microsoft.Extensions.Options;
 using PlotLine.Data;
 using PlotLine.Models;
 using PlotLine.ViewModels;
@@ -19,6 +20,24 @@ public interface IProjectService
     Task ArchiveAsync(int projectId);
 }
 
+public interface IProjectCollaborationService
+{
+    Task<ProjectCollaboratorsViewModel?> GetCollaboratorsAsync(int projectId);
+    Task<ProjectCollaborationResult> AddCollaboratorAsync(ProjectCollaboratorInviteViewModel model);
+    Task<ProjectCollaborationResult> RemoveCollaboratorAsync(int projectId, int userId);
+}
+
+public sealed class ProjectCollaborationResult
+{
+    public bool Succeeded { get; init; }
+    public bool NotFound { get; init; }
+    public string Message { get; init; } = string.Empty;
+
+    public static ProjectCollaborationResult Success(string message) => new() { Succeeded = true, Message = message };
+    public static ProjectCollaborationResult Failure(string message) => new() { Message = message };
+    public static ProjectCollaborationResult Inaccessible() => new() { NotFound = true, Message = "Project not found." };
+}
+
 public interface IBookService
 {
     Task<BookDetailViewModel?> GetDetailAsync(int bookId);
@@ -303,6 +322,185 @@ public sealed class ProjectService(IProjectRepository projects, IBookRepository
         => currentUser.UserId.HasValue ? projects.ArchiveForUserAsync(projectId, currentUser.UserId.Value) : Task.CompletedTask;
 }
 
+public sealed class ProjectCollaborationService(
+    IProjectRepository projects,
+    IProjectCollaborationRepository collaboration,
+    IUserRepository users,
+    IProjectAccessService access,
+    ISubscriptionService subscriptions,
+    IEmailQueueRepository emailQueue,
+    ICurrentUserService currentUser,
+    IOptions<EmailSettings> emailOptions,
+    ILogger<ProjectCollaborationService> logger) : IProjectCollaborationService
+{
+    private readonly EmailSettings _emailSettings = emailOptions.Value;
+
+    public async Task<ProjectCollaboratorsViewModel?> GetCollaboratorsAsync(int projectId)
+    {
+        if (!await access.CanOwnProjectAsync(projectId))
+        {
+            return null;
+        }
+
+        var project = currentUser.UserId.HasValue ? await projects.GetForUserAsync(projectId, currentUser.UserId.Value) : null;
+        if (project is null)
+        {
+            return null;
+        }
+
+        return new ProjectCollaboratorsViewModel
+        {
+            Project = project,
+            Collaborators = await collaboration.ListCollaboratorsAsync(projectId),
+            PendingInvitations = await collaboration.ListPendingInvitationsAsync(projectId),
+            Invite = new ProjectCollaboratorInviteViewModel { ProjectID = projectId }
+        };
+    }
+
+    public async Task<ProjectCollaborationResult> AddCollaboratorAsync(ProjectCollaboratorInviteViewModel model)
+    {
+        if (!currentUser.UserId.HasValue || !await access.CanOwnProjectAsync(model.ProjectID))
+        {
+            return ProjectCollaborationResult.Inaccessible();
+        }
+
+        var ownerUserId = await collaboration.GetOwnerUserIdAsync(model.ProjectID);
+        if (!ownerUserId.HasValue || ownerUserId.Value != currentUser.UserId.Value)
+        {
+            return ProjectCollaborationResult.Inaccessible();
+        }
+
+        var email = NormalizeEmail(model.EmailAddress);
+        if (string.IsNullOrWhiteSpace(email))
+        {
+            return ProjectCollaborationResult.Failure("Enter a valid collaborator email address.");
+        }
+
+        if (string.Equals(email, currentUser.Email, StringComparison.OrdinalIgnoreCase))
+        {
+            return ProjectCollaborationResult.Failure("Owners already have access to their own projects.");
+        }
+
+        var user = await users.GetByEmailAsync(email);
+        if (user is not null)
+        {
+            if (user.UserID == ownerUserId.Value)
+            {
+                return ProjectCollaborationResult.Failure("Owners already have access to their own projects.");
+            }
+
+            var existingCollaborators = await collaboration.ListCollaboratorsAsync(model.ProjectID);
+            if (existingCollaborators.Any(x => x.UserID == user.UserID))
+            {
+                return ProjectCollaborationResult.Success("That user already has collaborator access.");
+            }
+
+            if (!await collaboration.CollaboratorCountsForOwnerAsync(ownerUserId.Value, user.UserID))
+            {
+                var limit = await subscriptions.CanInviteCollaboratorAsync(ownerUserId.Value);
+                if (!limit.Allowed)
+                {
+                    return ProjectCollaborationResult.Failure(limit.Message);
+                }
+            }
+
+            await collaboration.AddCollaboratorAsync(model.ProjectID, user.UserID, currentUser.UserId.Value);
+            await QueueInvitationNotificationAsync(user, model.ProjectID);
+            return ProjectCollaborationResult.Success("Collaborator added.");
+        }
+
+        var pendingLimit = await subscriptions.CanInviteCollaboratorAsync(ownerUserId.Value);
+        if (!pendingLimit.Allowed)
+        {
+            return ProjectCollaborationResult.Failure(pendingLimit.Message);
+        }
+
+        await collaboration.CreatePendingInvitationAsync(model.ProjectID, email, currentUser.UserId.Value);
+        return ProjectCollaborationResult.Success("Pending invitation recorded. When that person creates an account, this invitation can be completed in the collaboration workflow.");
+    }
+
+    public async Task<ProjectCollaborationResult> RemoveCollaboratorAsync(int projectId, int userId)
+    {
+        if (!currentUser.UserId.HasValue || !await access.CanOwnProjectAsync(projectId))
+        {
+            return ProjectCollaborationResult.Inaccessible();
+        }
+
+        var ownerUserId = await collaboration.GetOwnerUserIdAsync(projectId);
+        if (!ownerUserId.HasValue || ownerUserId.Value != currentUser.UserId.Value)
+        {
+            return ProjectCollaborationResult.Inaccessible();
+        }
+
+        if (userId == ownerUserId.Value)
+        {
+            return ProjectCollaborationResult.Failure("Project owners cannot be removed as collaborators.");
+        }
+
+        var removed = await collaboration.RemoveCollaboratorAsync(projectId, userId);
+        return removed
+            ? ProjectCollaborationResult.Success("Collaborator removed.")
+            : ProjectCollaborationResult.Failure("Collaborator access was not found.");
+    }
+
+    private async Task QueueInvitationNotificationAsync(AppUser user, int projectId)
+    {
+        var project = currentUser.UserId.HasValue ? await projects.GetForUserAsync(projectId, currentUser.UserId.Value) : null;
+        var projectName = project?.ProjectName ?? "a project";
+        var inviterName = CleanDisplayName(currentUser.DisplayName);
+        var subject = $"You have been added to {projectName} in PlotWeaver Studio";
+        var plainText = $"""
+            You have been added as a collaborator.
+
+            Hello {CleanDisplayName(user.DisplayName)},
+
+            {inviterName} added you as a collaborator on "{projectName}" in PlotWeaver Studio. Sign in to PlotWeaver Studio to open the shared project.
+            """;
+        var html = $"""
+            <!doctype html>
+            <html>
+            <body style="font-family:Segoe UI,Arial,sans-serif;background:#f7f1e8;margin:0;padding:32px;color:#251c17;">
+                <div style="max-width:620px;margin:0 auto;background:#fffaf2;border:1px solid #e4d4bd;border-radius:10px;padding:28px;">
+                    <p style="margin:0 0 8px;text-transform:uppercase;letter-spacing:.08em;color:#7a5b3b;font-size:12px;font-weight:700;">PlotWeaver Studio</p>
+                    <h1 style="margin:0 0 16px;font-size:24px;">You have been added as a collaborator</h1>
+                    <p>Hello {WebUtility.HtmlEncode(CleanDisplayName(user.DisplayName))},</p>
+                    <p>{WebUtility.HtmlEncode(inviterName)} added you as a collaborator on <strong>{WebUtility.HtmlEncode(projectName)}</strong>.</p>
+                    <p>Sign in to PlotWeaver Studio to open the shared project.</p>
+                </div>
+            </body>
+            </html>
+            """;
+
+        var emailQueueId = await emailQueue.CreateAsync(new EmailQueueItem
+        {
+            ToEmail = user.Email,
+            ToName = CleanDisplayName(user.DisplayName),
+            FromEmail = GetFromAddress(),
+            FromName = CleanDisplayName(_emailSettings.FromName),
+            Subject = subject,
+            PlainTextBody = plainText,
+            HtmlBody = html,
+            MaxAttempts = 5
+        });
+
+        logger.LogInformation("Queued collaborator invitation email {EmailQueueID} for user {UserID}.", emailQueueId, user.UserID);
+    }
+
+    private static string NormalizeEmail(string? value) => value?.Trim().ToLowerInvariant() ?? string.Empty;
+
+    private static string CleanDisplayName(string? value)
+    {
+        return string.IsNullOrWhiteSpace(value) ? "PlotWeaver Studio" : value.Trim();
+    }
+
+    private string GetFromAddress()
+    {
+        return string.IsNullOrWhiteSpace(_emailSettings.FromAddress)
+            ? "hello@plotweaver.studio"
+            : _emailSettings.FromAddress.Trim();
+    }
+}
+
 internal static class SubscriptionLimitGuards
 {
     public static async Task EnsureAllowedAsync(Func<int, Task<SubscriptionLimitResult>> validateAsync, int? userId)

PlotLine/Services/ProjectAccessFilter.cs

@@ -58,6 +58,7 @@ public sealed class ProjectAccessFilter(IProjectAccessService access, ICurrentUs
     private static readonly Dictionary<string, Dictionary<string, string>> ControllerParameterEntities = new(StringComparer.OrdinalIgnoreCase)
     {
         ["Projects"] = new(StringComparer.OrdinalIgnoreCase) { ["id"] = "Project", ["projectId"] = "Project" },
+        ["ProjectCollaborators"] = new(StringComparer.OrdinalIgnoreCase) { ["projectId"] = "Project" },
         ["Books"] = new(StringComparer.OrdinalIgnoreCase) { ["id"] = "Book", ["bookId"] = "Book", ["projectId"] = "Project" },
         ["Chapters"] = new(StringComparer.OrdinalIgnoreCase) { ["id"] = "Chapter", ["chapterId"] = "Chapter", ["bookId"] = "Book" },
         ["Characters"] = new(StringComparer.OrdinalIgnoreCase) { ["id"] = "Character", ["characterId"] = "Character", ["projectId"] = "Project" },
@@ -81,6 +82,13 @@ public sealed class ProjectAccessFilter(IProjectAccessService access, ICurrentUs
         ["StoryBible"] = new(StringComparer.OrdinalIgnoreCase) { ["projectId"] = "Project" }
     };
 
+    private static readonly Dictionary<string, HashSet<string>> OwnerOnlyProjectActions = new(StringComparer.OrdinalIgnoreCase)
+    {
+        ["Projects"] = new(StringComparer.OrdinalIgnoreCase) { "Archive" },
+        ["ProjectCollaborators"] = new(StringComparer.OrdinalIgnoreCase) { "Index", "Add", "Remove" },
+        ["Exports"] = new(StringComparer.OrdinalIgnoreCase) { "ProjectBackup" }
+    };
+
     private static readonly Dictionary<string, Dictionary<string, string>> ActionIdEntities = new(StringComparer.OrdinalIgnoreCase)
     {
         ["Characters"] = new(StringComparer.OrdinalIgnoreCase) { ["ArchiveRelationship"] = "CharacterRelationship" },
@@ -146,7 +154,7 @@ public sealed class ProjectAccessFilter(IProjectAccessService access, ICurrentUs
         foreach (var requirement in requirements)
         {
             var allowed = requirement.EntityType == "Project"
-                ? await access.CanAccessProjectAsync(requirement.EntityId)
+                ? await CheckProjectRequirementAsync(controllerName, descriptor.ActionName, requirement.EntityId)
                 : await access.CanAccessEntityAsync(requirement.EntityType, requirement.EntityId);
 
             if (!allowed)
@@ -159,6 +167,13 @@ public sealed class ProjectAccessFilter(IProjectAccessService access, ICurrentUs
         await next();
     }
 
+    private Task<bool> CheckProjectRequirementAsync(string controllerName, string actionName, int projectId)
+    {
+        return OwnerOnlyProjectActions.TryGetValue(controllerName, out var ownerOnlyActions) && ownerOnlyActions.Contains(actionName)
+            ? access.CanOwnProjectAsync(projectId)
+            : access.CanAccessProjectAsync(projectId);
+    }
+
     private static HashSet<AccessRequirement> CollectRequirements(string controllerName, string actionName, IDictionary<string, object?> arguments)
     {
         var requirements = new HashSet<AccessRequirement>();

PlotLine/Sql/045_Phase5D_CollaborationFoundation.sql

@@ -0,0 +1,252 @@
+SET ANSI_NULLS ON;
+GO
+SET QUOTED_IDENTIFIER ON;
+GO
+
+IF OBJECT_ID(N'dbo.ProjectInvitation', N'U') IS NULL
+BEGIN
+    CREATE TABLE dbo.ProjectInvitation
+    (
+        ProjectInvitationID int IDENTITY(1,1) NOT NULL CONSTRAINT PK_ProjectInvitation PRIMARY KEY,
+        ProjectID int NOT NULL,
+        EmailAddress nvarchar(256) NOT NULL,
+        AccessRole nvarchar(50) NOT NULL,
+        InvitationToken uniqueidentifier NOT NULL CONSTRAINT DF_ProjectInvitation_InvitationToken DEFAULT NEWID(),
+        InvitedByUserID int NOT NULL,
+        InvitedDateUTC datetime2 NOT NULL CONSTRAINT DF_ProjectInvitation_InvitedDateUTC DEFAULT SYSUTCDATETIME(),
+        AcceptedDateUTC datetime2 NULL,
+        AcceptedByUserID int NULL,
+        IsAccepted bit NOT NULL CONSTRAINT DF_ProjectInvitation_IsAccepted DEFAULT 0,
+        IsCancelled bit NOT NULL CONSTRAINT DF_ProjectInvitation_IsCancelled DEFAULT 0,
+        CancelledDateUTC datetime2 NULL,
+        CONSTRAINT FK_ProjectInvitation_Project FOREIGN KEY (ProjectID) REFERENCES dbo.Projects(ProjectID),
+        CONSTRAINT FK_ProjectInvitation_InvitedByUser FOREIGN KEY (InvitedByUserID) REFERENCES dbo.AppUser(UserID),
+        CONSTRAINT FK_ProjectInvitation_AcceptedByUser FOREIGN KEY (AcceptedByUserID) REFERENCES dbo.AppUser(UserID),
+        CONSTRAINT CK_ProjectInvitation_AccessRole CHECK (AccessRole IN (N'Collaborator'))
+    );
+END;
+GO
+
+IF NOT EXISTS (SELECT 1 FROM sys.indexes WHERE name = N'IX_ProjectInvitation_Project_Status' AND object_id = OBJECT_ID(N'dbo.ProjectInvitation'))
+    CREATE INDEX IX_ProjectInvitation_Project_Status ON dbo.ProjectInvitation(ProjectID, IsAccepted, IsCancelled, InvitedDateUTC DESC);
+GO
+
+IF NOT EXISTS (SELECT 1 FROM sys.indexes WHERE name = N'IX_ProjectInvitation_Email_Status' AND object_id = OBJECT_ID(N'dbo.ProjectInvitation'))
+    CREATE INDEX IX_ProjectInvitation_Email_Status ON dbo.ProjectInvitation(EmailAddress, IsAccepted, IsCancelled);
+GO
+
+IF NOT EXISTS (SELECT 1 FROM sys.indexes WHERE name = N'UX_ProjectInvitation_Project_Email_Pending' AND object_id = OBJECT_ID(N'dbo.ProjectInvitation'))
+    CREATE UNIQUE INDEX UX_ProjectInvitation_Project_Email_Pending ON dbo.ProjectInvitation(ProjectID, EmailAddress) WHERE IsAccepted = 0 AND IsCancelled = 0;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.Project_ListForUser
+    @UserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT p.ProjectID, p.ProjectName, p.Description, p.CreatedDate, p.UpdatedDate, p.IsArchived,
+        pua.AccessRole
+    FROM dbo.Projects p
+    INNER JOIN dbo.ProjectUserAccess pua ON pua.ProjectID = p.ProjectID
+    WHERE p.IsArchived = 0
+        AND pua.UserID = @UserID
+        AND pua.IsActive = 1
+    ORDER BY p.ProjectName;
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.Project_GetForUser
+    @ProjectID int,
+    @UserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT p.ProjectID, p.ProjectName, p.Description, p.CreatedDate, p.UpdatedDate, p.IsArchived,
+        pua.AccessRole
+    FROM dbo.Projects p
+    INNER JOIN dbo.ProjectUserAccess pua ON pua.ProjectID = p.ProjectID
+    WHERE p.ProjectID = @ProjectID
+        AND p.IsArchived = 0
+        AND pua.UserID = @UserID
+        AND pua.IsActive = 1;
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_GetOwner
+    @ProjectID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT TOP (1) pua.UserID
+    FROM dbo.ProjectUserAccess pua
+    WHERE pua.ProjectID = @ProjectID
+        AND pua.AccessRole = N'Owner'
+        AND pua.IsActive = 1
+    ORDER BY pua.ProjectUserAccessID;
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_ListCollaborators
+    @ProjectID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT pua.ProjectUserAccessID, pua.ProjectID, pua.UserID, u.Email, u.DisplayName,
+        pua.AccessRole, pua.InvitedByUserID, invitedBy.DisplayName AS InvitedByDisplayName,
+        pua.InvitedDateUTC, pua.AcceptedDateUTC, pua.IsActive
+    FROM dbo.ProjectUserAccess pua
+    INNER JOIN dbo.AppUser u ON u.UserID = pua.UserID
+    LEFT JOIN dbo.AppUser invitedBy ON invitedBy.UserID = pua.InvitedByUserID
+    WHERE pua.ProjectID = @ProjectID
+        AND pua.AccessRole = N'Collaborator'
+        AND pua.IsActive = 1
+    ORDER BY u.DisplayName, u.Email;
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_ListPendingInvitations
+    @ProjectID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT pi.ProjectInvitationID, pi.ProjectID, pi.EmailAddress, pi.AccessRole, pi.InvitationToken,
+        pi.InvitedByUserID, invitedBy.DisplayName AS InvitedByDisplayName, pi.InvitedDateUTC,
+        pi.AcceptedDateUTC, pi.AcceptedByUserID, pi.IsAccepted, pi.IsCancelled, pi.CancelledDateUTC
+    FROM dbo.ProjectInvitation pi
+    INNER JOIN dbo.AppUser invitedBy ON invitedBy.UserID = pi.InvitedByUserID
+    WHERE pi.ProjectID = @ProjectID
+        AND pi.IsAccepted = 0
+        AND pi.IsCancelled = 0
+    ORDER BY pi.InvitedDateUTC DESC;
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_AddCollaborator
+    @ProjectID int,
+    @UserID int,
+    @InvitedByUserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    IF EXISTS
+    (
+        SELECT 1
+        FROM dbo.ProjectUserAccess
+        WHERE ProjectID = @ProjectID
+            AND UserID = @UserID
+            AND AccessRole = N'Collaborator'
+    )
+    BEGIN
+        UPDATE dbo.ProjectUserAccess
+        SET IsActive = 1,
+            InvitedByUserID = @InvitedByUserID,
+            InvitedDateUTC = COALESCE(InvitedDateUTC, SYSUTCDATETIME()),
+            AcceptedDateUTC = COALESCE(AcceptedDateUTC, SYSUTCDATETIME())
+        WHERE ProjectID = @ProjectID
+            AND UserID = @UserID
+            AND AccessRole = N'Collaborator';
+    END
+    ELSE
+    BEGIN
+        INSERT INTO dbo.ProjectUserAccess (ProjectID, UserID, AccessRole, InvitedByUserID, InvitedDateUTC, AcceptedDateUTC, IsActive)
+        VALUES (@ProjectID, @UserID, N'Collaborator', @InvitedByUserID, SYSUTCDATETIME(), SYSUTCDATETIME(), 1);
+    END;
+
+    UPDATE pi
+    SET IsAccepted = 1,
+        AcceptedDateUTC = COALESCE(AcceptedDateUTC, SYSUTCDATETIME()),
+        AcceptedByUserID = @UserID
+    FROM dbo.ProjectInvitation pi
+    INNER JOIN dbo.AppUser u ON u.Email = pi.EmailAddress
+    WHERE pi.ProjectID = @ProjectID
+        AND u.UserID = @UserID
+        AND pi.IsAccepted = 0
+        AND pi.IsCancelled = 0;
+
+    SELECT CAST(1 AS bit);
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_RemoveCollaborator
+    @ProjectID int,
+    @UserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    UPDATE dbo.ProjectUserAccess
+    SET IsActive = 0
+    WHERE ProjectID = @ProjectID
+        AND UserID = @UserID
+        AND AccessRole = N'Collaborator'
+        AND IsActive = 1;
+
+    SELECT CAST(CASE WHEN @@ROWCOUNT = 1 THEN 1 ELSE 0 END AS bit);
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_CreatePendingInvitation
+    @ProjectID int,
+    @EmailAddress nvarchar(256),
+    @InvitedByUserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    IF EXISTS
+    (
+        SELECT 1
+        FROM dbo.ProjectInvitation
+        WHERE ProjectID = @ProjectID
+            AND EmailAddress = @EmailAddress
+            AND IsAccepted = 0
+            AND IsCancelled = 0
+    )
+    BEGIN
+        SELECT TOP (1) ProjectInvitationID
+        FROM dbo.ProjectInvitation
+        WHERE ProjectID = @ProjectID
+            AND EmailAddress = @EmailAddress
+            AND IsAccepted = 0
+            AND IsCancelled = 0
+        ORDER BY ProjectInvitationID DESC;
+        RETURN;
+    END;
+
+    INSERT INTO dbo.ProjectInvitation (ProjectID, EmailAddress, AccessRole, InvitedByUserID)
+    VALUES (@ProjectID, @EmailAddress, N'Collaborator', @InvitedByUserID);
+
+    SELECT CAST(SCOPE_IDENTITY() AS int);
+END;
+GO
+
+CREATE OR ALTER PROCEDURE dbo.ProjectCollaboration_CollaboratorCountsForOwner
+    @OwnerUserID int,
+    @CollaboratorUserID int
+AS
+BEGIN
+    SET NOCOUNT ON;
+
+    SELECT CAST(CASE WHEN EXISTS
+    (
+        SELECT 1
+        FROM dbo.ProjectUserAccess ownerAccess
+        INNER JOIN dbo.ProjectUserAccess collaboratorAccess ON collaboratorAccess.ProjectID = ownerAccess.ProjectID
+        INNER JOIN dbo.Projects p ON p.ProjectID = ownerAccess.ProjectID
+        WHERE ownerAccess.UserID = @OwnerUserID
+            AND ownerAccess.AccessRole = N'Owner'
+            AND ownerAccess.IsActive = 1
+            AND collaboratorAccess.UserID = @CollaboratorUserID
+            AND collaboratorAccess.AccessRole = N'Collaborator'
+            AND collaboratorAccess.IsActive = 1
+            AND p.IsArchived = 0
+    )
+    THEN 1 ELSE 0 END AS bit);
+END;
+GO

PlotLine/ViewModels/CoreViewModels.cs

@@ -27,6 +27,23 @@ public sealed class ProjectDetailViewModel
     public IReadOnlyList<Book> Books { get; set; } = [];
 }
 
+public sealed class ProjectCollaboratorsViewModel
+{
+    public Project Project { get; set; } = new();
+    public IReadOnlyList<ProjectCollaborator> Collaborators { get; set; } = [];
+    public IReadOnlyList<ProjectInvitation> PendingInvitations { get; set; } = [];
+    public ProjectCollaboratorInviteViewModel Invite { get; set; } = new();
+}
+
+public sealed class ProjectCollaboratorInviteViewModel
+{
+    public int ProjectID { get; set; }
+
+    [Required, EmailAddress, StringLength(256)]
+    [Display(Name = "Collaborator email")]
+    public string EmailAddress { get; set; } = string.Empty;
+}
+
 public sealed class BookEditViewModel
 {
     public int BookID { get; set; }

PlotLine/Views/ProjectCollaborators/Index.cshtml

@@ -0,0 +1,109 @@
+@model ProjectCollaboratorsViewModel
+@{
+    ViewData["Title"] = "Collaborators";
+}
+
+<nav class="breadcrumb-trail" aria-label="Breadcrumb">
+    <a asp-controller="Projects" asp-action="Index">Projects</a>
+    <a asp-controller="Projects" asp-action="Details" asp-route-id="@Model.Project.ProjectID">@Model.Project.ProjectName</a>
+    <span>Collaborators</span>
+</nav>
+
+<div class="page-heading">
+    <div>
+        <p class="eyebrow">Project access</p>
+        <h1>Collaborators</h1>
+    </div>
+    <div class="button-row">
+        <a class="btn btn-outline-secondary" asp-controller="Projects" asp-action="Details" asp-route-id="@Model.Project.ProjectID">Back to project</a>
+    </div>
+</div>
+
+@if (TempData["CollaborationMessage"] is string collaborationMessage)
+{
+    <div class="alert alert-success">@collaborationMessage</div>
+}
+
+@if (TempData["CollaborationError"] is string collaborationError)
+{
+    <div class="alert alert-warning">@collaborationError</div>
+}
+
+<section class="edit-panel">
+    <form asp-action="Add" method="post" class="row g-3 align-items-end">
+        <input type="hidden" name="ProjectID" value="@Model.Project.ProjectID" />
+        <div class="col-md-8">
+            <label class="form-label" for="EmailAddress">Collaborator email</label>
+            <input class="form-control" id="EmailAddress" name="EmailAddress" value="@Model.Invite.EmailAddress" autocomplete="email" />
+        </div>
+        <div class="col-md-4">
+            <button class="btn btn-primary" type="submit">Add collaborator</button>
+        </div>
+    </form>
+</section>
+
+<section class="list-section">
+    <h2>Current collaborators</h2>
+    @if (!Model.Collaborators.Any())
+    {
+        <p class="muted">No collaborators have access to this project yet.</p>
+    }
+    else
+    {
+        <div class="table-responsive">
+            <table class="table align-middle">
+                <thead>
+                    <tr>
+                        <th>Name</th>
+                        <th>Email</th>
+                        <th>Added</th>
+                        <th></th>
+                    </tr>
+                </thead>
+                <tbody>
+                    @foreach (var collaborator in Model.Collaborators)
+                    {
+                        <tr>
+                            <td>@collaborator.DisplayName</td>
+                            <td>@collaborator.Email</td>
+                            <td>@collaborator.InvitedDateUTC?.ToString("dd MMM yyyy")</td>
+                            <td class="text-end">
+                                <form asp-action="Remove" method="post" class="archive-button-form" data-confirm-message="Remove collaborator access for this project?">
+                                    <input type="hidden" name="projectId" value="@Model.Project.ProjectID" />
+                                    <input type="hidden" name="userId" value="@collaborator.UserID" />
+                                    <button class="btn btn-outline-danger btn-sm" type="submit">Remove</button>
+                                </form>
+                            </td>
+                        </tr>
+                    }
+                </tbody>
+            </table>
+        </div>
+    }
+</section>
+
+@if (Model.PendingInvitations.Any())
+{
+    <section class="list-section">
+        <h2>Pending invitations</h2>
+        <div class="table-responsive">
+            <table class="table align-middle">
+                <thead>
+                    <tr>
+                        <th>Email</th>
+                        <th>Invited</th>
+                    </tr>
+                </thead>
+                <tbody>
+                    @foreach (var invitation in Model.PendingInvitations)
+                    {
+                        <tr>
+                            <td>@invitation.EmailAddress</td>
+                            <td>@invitation.InvitedDateUTC.ToString("dd MMM yyyy")</td>
+                        </tr>
+                    }
+                </tbody>
+            </table>
+        </div>
+    </section>
+}

PlotLine/Views/Projects/Details.cshtml

@@ -44,6 +44,10 @@
     </div>
     <div class="button-row">
         <a class="btn btn-outline-secondary" asp-action="Edit" asp-route-id="@Model.Project.ProjectID">Edit project</a>
+        @if (Model.Project.IsOwner)
+        {
+            <a class="btn btn-outline-secondary" asp-controller="ProjectCollaborators" asp-action="Index" asp-route-projectId="@Model.Project.ProjectID">Collaborators</a>
+        }
         <a class="btn btn-outline-primary" asp-controller="Timeline" asp-action="Index" asp-route-projectId="@Model.Project.ProjectID">Timeline</a>
         <a class="btn btn-outline-secondary" asp-controller="Timeline" asp-action="Settings" asp-route-projectId="@Model.Project.ProjectID">Timeline Settings</a>
         <a class="btn btn-outline-secondary" asp-controller="ProjectMetrics" asp-action="Index" asp-route-projectId="@Model.Project.ProjectID">Scene Metrics</a>
@@ -61,13 +65,19 @@
         <a class="btn btn-outline-primary" asp-controller="Dynamics" asp-action="Story" asp-route-projectId="@Model.Project.ProjectID">Story dynamics</a>
         <a class="btn btn-outline-secondary" asp-controller="Acceptance" asp-action="Phase1" asp-route-projectId="@Model.Project.ProjectID">Phase 1 Checklist</a>
         <a class="btn btn-outline-secondary" asp-controller="Archives" asp-action="Index" asp-route-projectId="@Model.Project.ProjectID">Archived Items</a>
+        @if (Model.Project.IsOwner)
+        {
             <a class="btn btn-outline-secondary" asp-controller="Exports" asp-action="ProjectBackup" asp-route-projectId="@Model.Project.ProjectID">Download Project Backup</a>
+        }
         <a class="btn btn-outline-secondary" asp-controller="ProjectRestorePoints" asp-action="Index" asp-route-projectId="@Model.Project.ProjectID">Restore Points</a>
         <a class="btn btn-primary" asp-controller="Books" asp-action="Create" asp-route-projectId="@Model.Project.ProjectID">Add book</a>
+        @if (Model.Project.IsOwner)
+        {
             <form asp-action="Archive" method="post" class="archive-button-form" data-confirm-message="Archive this project?&#10;&#10;This will hide it from active lists and timelines, but the data will be kept and can be restored later.">
                 <input type="hidden" name="id" value="@Model.Project.ProjectID" />
                 <button class="btn btn-outline-danger" type="submit">Archive Project</button>
             </form>
+        }
     </div>
 </div>
 

PlotLine/Views/Projects/Index.cshtml

@@ -29,14 +29,18 @@ else
         {
             <article class="plain-card">
                 <h2>@project.ProjectName</h2>
+                <p class="eyebrow">@project.AccessRole</p>
                 <p>@(string.IsNullOrWhiteSpace(project.Description) ? "No description yet." : project.Description)</p>
                 <div class="button-row">
                     <a class="btn btn-outline-primary btn-sm" asp-action="Details" asp-route-id="@project.ProjectID">Open</a>
                     <a class="btn btn-outline-secondary btn-sm" asp-action="Edit" asp-route-id="@project.ProjectID">Edit</a>
+                    @if (project.IsOwner)
+                    {
                         <form asp-action="Archive" method="post" class="archive-button-form" data-confirm-message="Archive this project?&#10;&#10;This will hide it from active lists and timelines, but the data will be kept and can be restored later.">
                             <input type="hidden" name="id" value="@project.ProjectID" />
                             <button class="btn btn-outline-danger btn-sm" type="submit">Archive</button>
                         </form>
+                    }
                 </div>
             </article>
         }