# IT-10: Collaborative Editing & Multiplayer Sessions

**Priority**: P2 (High value, non-blocking)  
**Status**: 📋 Planned  
**Estimated Effort**: 12-15 hours  
**Dependencies**: IT-05 (Test Introspection), IT-08 (Screenshot Capture)  
**Target**: Enable real-time collaborative ROM editing with AI assistance

---

## Vision

Enable multiple users to connect to the same YAZE session, see each other's edits in real-time, and collaborate with AI agents together. Think "Google Docs for ROM hacking" where users can:

- **Connect to each other's sessions** over the network
- **See real-time edits** (tiles, sprites, map changes)
- **Share AI assistance** (one user asks AI, all users see results)
- **Coordinate workflows** (e.g., one user edits dungeons, another edits overworld)
- **Review changes together** with live cursors and annotations

---

## User Stories

### US-1: Session Host & Join

**As a ROM hacker**, I want to host a collaborative editing session so my teammates can join and work together.

```bash
# Host creates a session
$ z3ed collab host --port 5000 --password "dev123"
✅ Collaborative session started
   Session ID: yaze-collab-f3a9b2c1
   URL: yaze://connect/localhost:5000?session=yaze-collab-f3a9b2c1
   Password: dev123
   
👥 Waiting for collaborators...

# Remote user joins
$ z3ed collab join yaze://connect/192.168.1.100:5000?session=yaze-collab-f3a9b2c1
🔐 Enter session password: ***
✅ Connected to session (Host: Alice)
👥 Active users: Alice (host), Bob (you)
```

**Acceptance Criteria**:
- Host can create session with optional password
- Clients can discover and join sessions
- Connection state visible in GUI status bar
- Maximum 8 concurrent users per session

---

### US-2: Real-Time Edit Synchronization

**As a collaborator**, I want to see other users' edits in real-time so we stay synchronized.

**Scenario**: Alice edits a tile in Overworld Editor
```
Alice's GUI:
  - Draws tile at (10, 15) → Sends edit event to all clients
  
Bob's GUI (auto-update):
  - Receives edit event → Redraws tile at (10, 15)
  - Shows Alice's cursor/selection indicator
```

**Acceptance Criteria**:
- Edits appear on all clients within 100ms
- Conflict resolution for simultaneous edits
- Undo/redo synchronized across sessions
- Cursor positions visible for all users

---

### US-3: Shared AI Agent

**As a team lead**, I want to use AI agents with my team so we can all benefit from automation.

```bash
# Alice (host) runs an AI agent test
$ z3ed agent test --prompt "Add treasure chest to room 12" --share

🤖 AI Agent: Analyzing request...
   Action: Click "Dungeon Editor" tab
   Action: Select Room 12
   Action: Add object type 0x12 (treasure chest) at (5, 8)
   
✅ Proposal generated (ID: prop_3f8a)

# All connected users see the proposal in their GUI
Bob's Screen:
  ┌─────────────────────────────────────────┐
  │ 🤖 AI Proposal from Alice               │
  │                                         │
  │ Add treasure chest to room 12           │
  │   • Click "Dungeon Editor" tab          │
  │   • Select Room 12                      │
  │   • Add treasure chest at (5, 8)        │
  │                                         │
  │ [Accept] [Reject] [Discuss]             │
  └─────────────────────────────────────────┘

# Team vote: 2/3 accept → Proposal executes for all users
```

**Acceptance Criteria**:
- AI agent results broadcast to all session members
- Proposals require majority approval (configurable threshold)
- All users see agent execution in real-time
- Failed operations rollback for all users

---

### US-4: Live Cursors & Annotations

**As a collaborator**, I want to see where other users are working so we don't conflict.

**Visual Indicators**:
```
┌─────────────────────────────────────────────┐
│ Overworld Editor                            │
│                                             │
│   🟦 (Alice's cursor at map 0x40)           │
│   🟩 (Bob's cursor at map 0x41)             │
│   🟥 (Charlie editing palette)              │
│                                             │
│ Active Editors:                             │
│   • Alice: Overworld (read-write)           │
│   • Bob: Overworld (read-write)             │
│   • Charlie: Palette Editor (read-only)     │
└─────────────────────────────────────────────┘
```

**Acceptance Criteria**:
- Each user has unique color-coded cursor
- Active editor window highlighted for each user
- Text chat overlay for quick communication
- Annotation tools (pins, comments, highlights)

---

### US-5: Session Recording & Replay

**As a project manager**, I want to record collaborative sessions so we can review work later.

```bash
# Host enables session recording
$ z3ed collab host --record session_2025_10_02.yaml

# Recording captures:
# - All edit operations (tiles, sprites, maps)
# - AI agent proposals and votes
# - Chat messages and annotations
# - User join/leave events
# - Timestamps for audit trail

# Later: Replay the session
$ z3ed collab replay session_2025_10_02.yaml --speed 2x

# Replay shows:
# - Timeline of all edits
# - User activity heatmap
# - Decision points (proposals accepted/rejected)
# - Final ROM state comparison
```

**Acceptance Criteria**:
- All session activity recorded in structured format (YAML/JSON)
- Replay supports speed control (0.5x - 10x)
- Export to video format (optional, uses screenshots)
- Audit log for compliance/review

---

## Architecture

### Components

#### 1. Collaboration Server (New)

**Location**: `src/app/core/collab/collab_server.{h,cc}`

**Responsibilities**:
- Manage WebSocket connections from clients
- Broadcast edit events to all connected clients
- Handle session authentication (password, tokens)
- Enforce access control (read-only vs read-write)
- Maintain session state (active users, current ROM)

**Technology**:
- **WebSocket** for low-latency bidirectional communication
- **Protocol Buffers** for efficient serialization
- **JWT tokens** for session authentication
- **Redis** (optional) for distributed sessions

**Key APIs**:
```cpp
class CollabServer {
 public:
  // Start server on specified port
  absl::Status Start(int port, const std::string& password);
  
  // Handle new client connection
  void OnClientConnected(ClientConnection* client);
  
  // Broadcast edit event to all clients
  void BroadcastEdit(const EditEvent& event, ClientConnection* sender);
  
  // Handle AI proposal from client
  void BroadcastProposal(const AgentProposal& proposal);
  
  // Get active users in session
  std::vector<UserInfo> GetActiveUsers() const;
  
 private:
  std::unique_ptr<WebSocketServer> ws_server_;
  absl::Mutex clients_mutex_;
  std::vector<std::unique_ptr<ClientConnection>> clients_;
  SessionState session_state_;
};
```

---

#### 2. Collaboration Client (New)

**Location**: `src/app/core/collab/collab_client.{h,cc}`

**Responsibilities**:
- Connect to remote collaboration server
- Send local edits to server
- Receive and apply remote edits
- Sync ROM state on join
- Handle disconnection/reconnection

**Key APIs**:
```cpp
class CollabClient {
 public:
  // Connect to session
  absl::Status Connect(const std::string& url, const std::string& password);
  
  // Send local edit to server
  void SendEdit(const EditEvent& event);
  
  // Callback when remote edit received
  void OnRemoteEdit(const EditEvent& event);
  
  // Get list of active users
  std::vector<UserInfo> GetUsers() const;
  
  // Disconnect from session
  void Disconnect();
  
 private:
  std::unique_ptr<WebSocketClient> ws_client_;
  CollabEventHandler* event_handler_;
  SessionInfo session_info_;
};
```

---

#### 3. Edit Event Protocol (New)

**Location**: `src/app/core/proto/collab_events.proto`

**Message Definitions**:
```protobuf
syntax = "proto3";

package yaze.collab;

// Generic edit event
message EditEvent {
  string event_id = 1;        // Unique event ID
  string user_id = 2;         // User who made the edit
  int64 timestamp_ms = 3;     // Unix timestamp
  
  oneof event_type {
    TileEdit tile_edit = 10;
    SpriteEdit sprite_edit = 11;
    PaletteEdit palette_edit = 12;
    MapEdit map_edit = 13;
    ObjectEdit object_edit = 14;
  }
}

// Tile edit (Tile16 Editor, Tilemap)
message TileEdit {
  string editor = 1;          // "tile16", "tilemap"
  int32 x = 2;
  int32 y = 3;
  int32 layer = 4;
  bytes tile_data = 5;        // Tile pixel data or ID
}

// Sprite edit
message SpriteEdit {
  int32 sprite_id = 1;
  int32 x = 2;
  int32 y = 3;
  bytes sprite_data = 4;
}

// Map edit (Overworld/Dungeon)
message MapEdit {
  string map_type = 1;        // "overworld", "dungeon"
  int32 map_id = 2;
  bytes map_data = 3;
}

// User cursor position
message CursorEvent {
  string user_id = 1;
  string editor = 2;          // Active editor window
  int32 x = 3;
  int32 y = 4;
  string color = 5;           // Cursor color (hex)
}

// AI proposal event
message ProposalEvent {
  string proposal_id = 1;
  string user_id = 2;         // User who initiated agent
  string prompt = 3;
  repeated ProposalAction actions = 4;
  
  enum ProposalStatus {
    PENDING = 0;
    ACCEPTED = 1;
    REJECTED = 2;
    EXECUTING = 3;
    COMPLETED = 4;
  }
  ProposalStatus status = 5;
  
  // Voting
  map<string, bool> votes = 6;  // user_id -> accept/reject
  int32 votes_needed = 7;
}

message ProposalAction {
  string action_type = 1;     // "click", "type", "edit"
  map<string, string> params = 2;
}

// Session state
message SessionState {
  string session_id = 1;
  string host_user_id = 2;
  repeated UserInfo users = 3;
  bytes rom_checksum = 4;     // SHA256 of ROM
  int64 session_start_ms = 5;
}

message UserInfo {
  string user_id = 1;
  string username = 2;
  string color = 3;           // User's cursor color
  bool is_host = 4;
  bool read_only = 5;
  string active_editor = 6;
}
```

---

#### 4. Conflict Resolution System

**Challenge**: Multiple users edit the same tile/sprite simultaneously

**Solution**: Operational Transformation (OT) with timestamps

```cpp
class ConflictResolver {
 public:
  // Resolve conflicting edits
  EditEvent ResolveConflict(const EditEvent& local, 
                            const EditEvent& remote);
  
 private:
  // Last-write-wins with timestamp
  EditEvent LastWriteWins(const EditEvent& e1, const EditEvent& e2);
  
  // Merge edits if possible (e.g., different layers)
  std::optional<EditEvent> TryMerge(const EditEvent& e1, 
                                     const EditEvent& e2);
};
```

**Conflict Resolution Rules**:
1. **Same tile, different times**: Last write wins (based on timestamp)
2. **Same tile, same time (<100ms)**: Host user wins (host authority)
3. **Different tiles**: No conflict, apply both
4. **Different layers**: No conflict, apply both
5. **Undo/Redo**: Undo takes precedence (explicit user intent)

---

#### 5. GUI Integration

**Status Bar Indicator**:
```
┌─────────────────────────────────────────────────────────────┐
│ File  Edit  View  Tools  Help          👥 3 users connected │
│                                         🟢 Alice (Host)      │
│                                         🔵 Bob               │
│                                         🟣 Charlie           │
└─────────────────────────────────────────────────────────────┘
```

**Collaboration Panel**:
```
┌─────────────────────────────────┐
│ Collaboration                   │
├─────────────────────────────────┤
│ Session: yaze-collab-f3a9b2c1   │
│ Status: 🟢 Connected            │
│                                 │
│ Users (3):                      │
│  🟢 Alice (Host) - Dungeon      │
│  🔵 Bob (You) - Overworld       │
│  🟣 Charlie - Palette           │
│                                 │
│ Activity:                       │
│  • Alice edited room 12         │
│  • Bob added sprite #23         │
│  • Charlie changed palette 2    │
│                                 │
│ [Chat] [Proposals] [Disconnect] │
└─────────────────────────────────┘
```

**Cursor Overlay**:
```cpp
// In canvas rendering
void OverworldCanvas::DrawCollaborativeCursors() {
  for (const auto& user : collab_client_->GetUsers()) {
    if (user.active_editor == "overworld" && user.user_id != my_user_id) {
      ImVec2 cursor_pos = TileToScreen(user.cursor_x, user.cursor_y);
      ImU32 color = ImGui::GetColorU32(user.color);
      
      // Draw cursor indicator
      draw_list->AddCircleFilled(cursor_pos, 5.0f, color);
      
      // Draw username label
      draw_list->AddText(cursor_pos + ImVec2(10, -5), color, user.username.c_str());
    }
  }
}
```

---

## CLI Commands

### Session Management

```bash
# Host a session
z3ed collab host [options]
  --port <port>           Port to listen on (default: 5000)
  --password <password>   Session password (optional)
  --max-users <n>         Maximum concurrent users (default: 8)
  --read-only <users>     Comma-separated list of read-only users
  --record <file>         Record session to file
  
# Join a session
z3ed collab join <url> [options]
  --password <password>   Session password
  --username <name>       Display name (default: system username)
  --read-only             Join in read-only mode
  
# List active sessions (LAN discovery)
z3ed collab list
  
# Disconnect from session
z3ed collab disconnect

# Kick user (host only)
z3ed collab kick <user-id>
```

### Session Replay

```bash
# Replay recorded session
z3ed collab replay <file> [options]
  --speed <n>             Playback speed multiplier (default: 1.0)
  --start-time <time>     Start at specific timestamp
  --end-time <time>       End at specific timestamp
  --export-video <file>   Export to video (requires ffmpeg)
  
# Export session timeline
z3ed collab export <file> [options]
  --format <format>       Output format: json, yaml, csv (default: json)
  --include-chat          Include chat messages
  --include-proposals     Include AI proposals
```

---

## Implementation Plan

### Phase 1: Core Networking (4-5 hours)

**Tasks**:
1. Set up WebSocket server (using `libwebsockets` or `Boost.Beast`)
2. Implement client connection handling
3. Define `EditEvent` protobuf messages
4. Implement basic message routing (send/receive)
5. Test with 2 clients: edit on one, see on other

**Deliverables**:
- `collab_server.{h,cc}` with basic WebSocket handling
- `collab_client.{h,cc}` with connection management
- `collab_events.proto` with edit event definitions

**Validation**:
- Client A connects to host
- Client A sends test edit event
- Host receives and broadcasts to Client B
- Client B receives edit event

---

### Phase 2: Edit Synchronization (3-4 hours)

**Tasks**:
1. Hook into editor event system (Overworld, Dungeon, Tile16, Palette)
2. Capture local edits and convert to `EditEvent` messages
3. Apply remote `EditEvent` messages to local ROM
4. Implement conflict resolution (last-write-wins)
5. Add undo/redo synchronization

**Deliverables**:
- Edit event capture hooks in all editors
- Edit event application logic
- Conflict resolver implementation

**Validation**:
- User A edits tile → User B sees tile change
- User A edits palette → User B sees palette change
- Simultaneous edits resolve correctly (no data corruption)

---

### Phase 3: GUI Integration (2-3 hours)

**Tasks**:
1. Add status bar indicator (connected users count)
2. Create Collaboration panel (ImGui window)
3. Implement live cursor rendering
4. Add user color assignment (unique per user)
5. Display active editor for each user

**Deliverables**:
- Status bar widget showing connection status
- Collaboration panel showing user list and activity
- Cursor overlay in canvas editors

**Validation**:
- User can see who's connected
- User can see other users' cursor positions
- User can see what editor others are using

---

### Phase 4: AI Agent Sharing (2-3 hours)

**Tasks**:
1. Broadcast AI proposals to all session members
2. Implement proposal voting system (majority rule)
3. Synchronize agent execution across clients
4. Handle proposal rejection/timeout
5. Add proposal history to Collaboration panel

**Deliverables**:
- `ProposalEvent` protobuf messages
- Voting UI in GUI (Accept/Reject/Discuss buttons)
- Proposal broadcast and execution logic

**Validation**:
- User A runs agent → All users see proposal
- Users vote on proposal → Executes if majority accepts
- Proposal execution synchronized (all users see same result)

---

### Phase 5: Session Recording & Replay (1-2 hours)

**Tasks**:
1. Implement session recorder (capture all events to file)
2. Create replay engine (read events from file, re-apply)
3. Add timeline UI for replay (seek, pause, speed control)
4. Export session to JSON/YAML for analysis

**Deliverables**:
- `session_recorder.{h,cc}` with file I/O
- `session_player.{h,cc}` with playback control
- CLI commands for replay

**Validation**:
- Record session → All events captured
- Replay session → ROM state matches original
- Seek/speed control works correctly

---

## Security & Safety Considerations

### Authentication

**Password Protection**:
- Session host sets optional password
- Clients must provide password to join
- Passwords hashed with bcrypt (never transmitted in plaintext)

**Token-Based Auth** (Future):
- Host generates JWT tokens for trusted users
- Tokens expire after session ends
- Revocation list for kicked users

---

### Authorization

**Access Levels**:
1. **Host**: Full control (read-write, kick users, end session)
2. **Editor**: Read-write access to ROM
3. **Viewer**: Read-only access (can see edits, can't make edits)

**Permission Model**:
```cpp
enum class AccessLevel {
  kHost,       // Full control
  kEditor,     // Read-write
  kViewer      // Read-only
};

class SessionPermissions {
 public:
  bool CanEdit(const std::string& user_id) const;
  bool CanKick(const std::string& user_id) const;
  bool CanEndSession(const std::string& user_id) const;
  
  void SetAccessLevel(const std::string& user_id, AccessLevel level);
};
```

---

### Data Integrity

**ROM Checksum Verification**:
- Host broadcasts ROM checksum (SHA256) on session start
- Clients verify their ROM matches host's ROM
- Mismatched ROMs rejected (prevents desyncs)

**Edit Validation**:
- Server validates edit events before broadcasting
- Invalid edits rejected (e.g., out-of-bounds tile index)
- Clients trust server's validation (reduces client-side checks)

---

### Network Security

**Encryption** (Optional, for public internet sessions):
- Use WSS (WebSocket Secure) with TLS/SSL
- Self-signed certificates for LAN (trust on first use)
- Let's Encrypt certificates for public servers

**Rate Limiting**:
- Max 100 edit events per second per user
- Max 10 AI proposals per minute per session
- Prevents spam/DOS attacks

---

## Testing Strategy

### Unit Tests

**Conflict Resolution**:
```cpp
TEST(ConflictResolverTest, LastWriteWins) {
  ConflictResolver resolver;
  
  EditEvent e1 = MakeTileEdit(10, 15, /*timestamp=*/1000);
  EditEvent e2 = MakeTileEdit(10, 15, /*timestamp=*/2000);
  
  EditEvent resolved = resolver.ResolveConflict(e1, e2);
  
  EXPECT_EQ(resolved.timestamp_ms(), 2000);  // e2 wins
}

TEST(ConflictResolverTest, MergeDifferentLayers) {
  ConflictResolver resolver;
  
  EditEvent e1 = MakeTileEdit(10, 15, /*layer=*/0, /*timestamp=*/1000);
  EditEvent e2 = MakeTileEdit(10, 15, /*layer=*/1, /*timestamp=*/1000);
  
  auto merged = resolver.TryMerge(e1, e2);
  
  ASSERT_TRUE(merged.has_value());
  // Both edits should be applied (different layers)
}
```

---

### Integration Tests

**Session Connection**:
```cpp
TEST(CollabServerTest, ClientConnection) {
  CollabServer server;
  server.Start(5000, "password123");
  
  CollabClient client;
  auto status = client.Connect("ws://localhost:5000", "password123");
  
  EXPECT_TRUE(status.ok());
  EXPECT_EQ(server.GetActiveUsers().size(), 1);
}

TEST(CollabServerTest, EditBroadcast) {
  CollabServer server;
  server.Start(5000, "password123");
  
  CollabClient client1, client2;
  client1.Connect("ws://localhost:5000", "password123");
  client2.Connect("ws://localhost:5000", "password123");
  
  // Client 1 sends edit
  EditEvent edit = MakeTileEdit(10, 15, 1000);
  client1.SendEdit(edit);
  
  // Wait for broadcast
  std::this_thread::sleep_for(std::chrono::milliseconds(100));
  
  // Client 2 should receive edit
  EXPECT_TRUE(client2.HasReceivedEdit(edit.event_id()));
}
```

---

### E2E Tests

**Collaborative Workflow**:
```bash
#!/bin/bash
# tests/e2e/test_collab_workflow.sh

# Start host in background
z3ed collab host --port 5000 --password test &
HOST_PID=$!
sleep 2

# Client 1 joins
z3ed collab join ws://localhost:5000 --password test --username Alice &
CLIENT1_PID=$!
sleep 1

# Client 2 joins
z3ed collab join ws://localhost:5000 --password test --username Bob &
CLIENT2_PID=$!
sleep 1

# Verify 3 users connected (host + 2 clients)
USERS=$(z3ed collab users --json | jq '. | length')
if [ "$USERS" -ne 3 ]; then
  echo "❌ Expected 3 users, got $USERS"
  exit 1
fi

# Client 1 makes edit via CLI
z3ed project overworld edit --map 0x40 --tile-x 10 --tile-y 15 --tile-id 0x123

# Wait for sync
sleep 0.5

# Verify edit appeared on Client 2
TILE_ID=$(z3ed project overworld get --map 0x40 --tile-x 10 --tile-y 15 --json | jq '.tile_id')
if [ "$TILE_ID" != "0x123" ]; then
  echo "❌ Edit not synchronized"
  exit 1
fi

echo "✅ Collaborative workflow test passed"

# Cleanup
kill $HOST_PID $CLIENT1_PID $CLIENT2_PID
```

---

## Performance Considerations

### Bandwidth Usage

**Typical Edit Event Size**:
- TileEdit: ~50 bytes (protobuf encoded)
- CursorEvent: ~30 bytes
- ProposalEvent: ~500 bytes (with actions)

**Estimated Bandwidth** (3 users, moderate activity):
- Edit events: 10/sec × 50 bytes = 500 bytes/sec
- Cursor updates: 30/sec × 30 bytes = 900 bytes/sec
- **Total**: ~1.4 KB/sec per client (~11 Kbps)

**Optimization**:
- Batch cursor updates (send every 50ms instead of every frame)
- Delta compression for tile data (send only changed pixels)
- Message prioritization (edits > cursors > chat)

---

### Latency Targets

| Metric | Target | Acceptable | Critical |
|--------|--------|------------|----------|
| Edit propagation | <50ms | <100ms | >200ms |
| Cursor update | <16ms | <33ms | >100ms |
| Proposal broadcast | <100ms | <200ms | >500ms |
| Connection timeout | - | - | >5s |

**Optimization Strategies**:
- WebSocket for low-latency bidirectional communication
- Protobuf for efficient serialization (vs JSON)
- Message batching for cursor updates
- Predictive rendering (interpolate remote cursors)

---

## Future Enhancements

### Voice Chat Integration

**Idea**: Embed WebRTC voice chat for real-time communication

```bash
z3ed collab host --voice --voice-codec opus
```

**Benefits**:
- Faster coordination than text chat
- Enhances team collaboration
- Optional (users can disable if not needed)

---

### Persistent Sessions

**Idea**: Sessions persist across host disconnects (using Redis)

**Architecture**:
```
┌──────────┐     ┌───────────┐     ┌──────────┐
│ Client A ├────►│ Redis     │◄────┤ Client B │
└──────────┘     │ (session  │     └──────────┘
                 │  state)   │
┌──────────┐     │           │     ┌──────────┐
│ Client C ├────►│           │◄────┤ Client D │
└──────────┘     └───────────┘     └──────────┘
```

**Benefits**:
- Host can disconnect without ending session
- Any user can become new host (elected automatically)
- Session state preserved (users, edits, proposals)

---

### Cloud-Hosted Sessions

**Idea**: Deploy collab server to cloud for public access

```bash
# Deploy to AWS/GCP/Azure
z3ed collab deploy --provider aws --region us-east-1

# Join cloud session
z3ed collab join wss://yaze-collab.example.com/session/abc123
```

**Benefits**:
- No port forwarding required
- Better uptime and reliability
- Centralized session management

---

### Integration with Version Control

**Idea**: Auto-commit edits to Git during collaborative sessions

```bash
z3ed collab host --git-auto-commit --git-interval 5m
```

**Behavior**:
- Every 5 minutes, commit current ROM state to Git
- Commit message includes user activity summary
- Creates audit trail for rollback/review

---

## Success Metrics

### Adoption Metrics
- **Active Sessions**: 50+ concurrent sessions within 3 months
- **User Retention**: 60% of users who try collab use it again
- **Session Duration**: Average 30+ minutes per session

### Technical Metrics
- **Edit Latency**: <100ms p99 (99th percentile)
- **Uptime**: >99.5% (excluding client disconnects)
- **Conflict Rate**: <1% of edits result in conflicts
- **Bandwidth**: <5 KB/sec per client average

### User Satisfaction
- **NPS Score**: 40+ (Net Promoter Score)
- **Bug Reports**: <5 critical bugs per 1000 sessions
- **Support Tickets**: <10 per month related to collab features

---

## Risks & Mitigation

### Risk 1: Network Latency

**Impact**: High latency (>200ms) degrades user experience

**Mitigation**:
- Implement client-side prediction (apply edits immediately, rollback if rejected)
- Show latency indicator in GUI (yellow/red warning)
- Suggest LAN-only for high-latency users

---

### Risk 2: Data Corruption

**Impact**: Conflicting edits corrupt ROM data

**Mitigation**:
- Validate all edits server-side before broadcasting
- Implement robust conflict resolution (last-write-wins with timestamps)
- Periodic checksum verification (every 60 seconds)
- Auto-save backups every 5 minutes (local + server)

---

### Risk 3: Security Vulnerabilities

**Impact**: Malicious users could inject invalid edits or DOS the server

**Mitigation**:
- Rate limiting (100 edits/sec per user)
- Input validation (all edit events validated before broadcast)
- Optional authentication (password or JWT tokens)
- Audit logging (all events logged for forensics)

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### Risk 4: Scalability

**Impact**: Server struggles with 8+ concurrent users

**Mitigation**:
- Load testing with 20+ simulated users
- Message batching (reduce per-message overhead)
- Horizontal scaling with Redis (future enhancement)
- Hard cap at 8 users per session (prevents overload)

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## Summary

IT-10 brings **real-time collaborative editing** to YAZE, enabling teams to work together on ROM hacks with AI assistance. Key features:

✅ **Session Hosting**: Host collaborative sessions with password protection  
✅ **Real-Time Sync**: Edits appear on all clients within 100ms  
✅ **Shared AI Agents**: Team votes on AI proposals before execution  
✅ **Live Cursors**: See where teammates are working  
✅ **Session Recording**: Replay sessions for review and audit  

**Estimated Effort**: 12-15 hours  
**Dependencies**: IT-05 (Introspection), IT-08 (Screenshot Capture)  
**Priority**: P2 (High value, but not blocking other work)

**Recommended Timeline**:
- **After IT-09 Complete**: Once CI/CD integration is done
- **Before Agent Workflow (Phase A3)**: Collab enhances agent workflows (team AI usage)

**Next Steps**: 
1. Finalize IT-08 (Enhanced Error Reporting)
2. Complete IT-09 (CI/CD Integration)
3. Prototype collab server with 2-client test
4. Gather user feedback on collaborative workflows

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**Document Created**: October 2, 2025  
**Author**: GitHub Copilot (AI Assistant)  
**Project**: YAZE - Yet Another Zelda3 Editor  
**Component**: z3ed CLI Tool - Collaborative Editing