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+# PlotWeaver Studio
+
+# Phase 5 -- Multi-User, Collaboration & Subscription Architecture
+
+Version: 1.0\
+Status: Approved Architecture Document\
+Date: June 2026
+
+## Purpose
+
+Phase 5 introduces multi-user support, subscriptions, collaboration
+capabilities, storage management, auditing, and monetisation foundations
+to PlotWeaver Studio.
+
+The goal is to transform PlotWeaver Studio from a single-user authoring
+platform into a secure SaaS application while preserving its core
+philosophy as a planning and writing workspace for authors.
+
+## Core Principles
+
+-   PlotWeaver Studio is an active workspace, not a permanent archive.
+-   Security takes precedence over convenience.
+-   Collaboration supports planning, not real-time writing.
+-   Subscription limits should be generous but prevent abuse.
+
+## Definitions
+
+### User
+
+Authenticated account holder within PlotWeaver Studio.
+
+### Project
+
+Highest-level container which may represent a standalone book or an
+entire series.
+
+### Book
+
+A single book within a project. Subscription limits are enforced against
+books.
+
+### Owner
+
+The user who created a project and manages collaborators.
+
+### Collaborator
+
+A user granted edit access to another user's project.
+
+### Subscription
+
+Defines usage limits and capabilities.
+
+## Security Architecture
+
+Project access shall be determined through ProjectUserAccess records.
+
+Access checks must answer:
+
+> Can this user access this project?
+
+Not:
+
+> Does this user own this project?
+
+### Access Roles
+
+#### Owner
+
+-   Full project access
+-   Invite/remove collaborators
+-   Delete projects
+-   Export projects
+
+#### Collaborator
+
+-   View projects
+-   Edit projects
+
+Restrictions: - Cannot delete projects - Cannot invite collaborators -
+Cannot transfer ownership - Cannot manage subscriptions
+
+Viewer-only access is explicitly excluded from Phase 5.
+
+### ProjectUserAccess
+
+Fields:
+
+-   ProjectUserAccessID
+-   ProjectID
+-   UserID
+-   AccessRole
+-   InvitedByUserID
+-   InvitedDateUTC
+-   AcceptedDateUTC
+-   IsActive
+
+All project-scoped operations must validate user access.
+
+Protected areas include:
+
+-   Projects
+-   Books
+-   Chapters
+-   Scenes
+-   Timeline
+-   Characters
+-   Assets
+-   Locations
+-   Plot Lines
+-   Relationships
+-   Workspace
+-   Imports
+-   Exports
+-   Attachments
+
+## Subscription Levels
+
+### Draft Desk
+
+-   Books: 2
+-   Chapters per Book: 75
+-   Scenes per Book: 300
+-   Characters per Project: 75
+-   Storage: 100 MB
+-   Collaborators: 0
+
+### Writing Room
+
+-   Books: 10
+-   Chapters per Book: 150
+-   Scenes per Book: 1000
+-   Characters per Project: 250
+-   Storage: 1 GB
+-   Collaborators: 1
+
+### Story Forge
+
+-   Books: 30
+-   Chapters per Book: 200
+-   Scenes per Book: 2000
+-   Characters per Project: 500
+-   Storage: 5 GB
+-   Collaborators: 3
+
+### Author Studio
+
+-   Books: Practical unlimited
+-   Chapters: Practical unlimited
+-   Scenes: Practical unlimited
+-   Characters: Practical unlimited
+-   Storage: 20 GB
+-   Collaborators: 10
+
+## Collaboration Requirements
+
+Supported:
+
+-   Invite collaborators
+-   Remove collaborators
+-   View collaborator lists
+
+Excluded:
+
+-   Real-time editing
+-   Internal messaging
+-   Viewer-only roles
+-   Conflict resolution
+-   Ownership transfer
+
+## Audit Requirements
+
+Major entities should support:
+
+-   CreatedByUserID
+-   CreatedDateUTC
+-   ModifiedByUserID
+-   ModifiedDateUTC
+
+Track activity for:
+
+-   Projects
+-   Books
+-   Chapters
+-   Scenes
+-   Characters
+-   Assets
+-   Locations
+-   Plot Lines
+-   Relationships
+
+The audit system should answer:
+
+> Who changed what and when?
+
+## Storage Management
+
+-   Storage tracked per user
+-   Limits enforced by subscription
+-   Restrict file types
+-   Resize uploaded images
+-   Convert images to WebP
+-   Remove unnecessary metadata
+
+Timeline and planning interfaces should remain fast and primarily
+text-based.
+
+## Export and Archiving
+
+Projects should support export including:
+
+-   Project data
+-   Images
+-   Attachments
+
+Archive workflow:
+
+1.  Export project
+2.  Offer download
+3.  Remove from active workspace
+
+## Payment Integration
+
+Stripe will be introduced only after:
+
+-   Security is complete
+-   Subscription infrastructure exists
+-   Limit enforcement is operational
+
+## Phase 5 Implementation Order
+
+1.  Phase 5A -- Project Ownership & Security
+2.  Phase 5B -- Subscription Infrastructure
+3.  Phase 5C -- Subscription Limit Enforcement
+4.  Phase 5D -- Collaboration Foundation
+5.  Phase 5E -- Audit History & Activity Tracking
+6.  Phase 5F -- Storage Management
+7.  Phase 5G -- Export & Archiving
+8.  Phase 5H -- Subscription Management UI
+9.  Phase 5I -- Stripe Payment Integration
+
+## Out of Scope
+
+-   Real-time collaborative editing
+-   Internal messaging systems
+-   Viewer-only roles
+-   AI collaboration workflows
+-   Team organisations
+-   Ownership transfer
+-   Conflict resolution systems
+
+## Success Criteria
+
+Phase 5 is complete when:
+
+-   Project access is secure
+-   Subscription limits are enforced
+-   Collaboration functions safely
+-   Audit history is available
+-   Storage limits are operational
+-   Projects can be exported and archived
+-   Payment processing is integrated successfully