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Real-Time Editing

Work on documents simultaneously with co-authors, seeing each other's changes as they happen.

How It Works

Opus uses CRDT (Conflict-free Replicated Data Type) technology for real-time collaboration. This means:

  • No conflicts - Multiple people can edit the same line
  • No locks - Nobody gets "locked out"
  • Instant sync - Changes appear within milliseconds
  • Works offline - Edits sync when you reconnect

Getting Started

Automatic Activation

Real-time editing activates automatically when multiple people open the same document. No setup required.

Seeing Collaborators

When others are viewing or editing:

  • Their avatar appears in the top-right
  • A colored cursor shows their position
  • Their name appears when they select text

Presence Indicators

Avatars

See who's currently in the document:

  • Solid ring - Actively editing
  • Faded - Viewing but idle
  • Number badge - More collaborators than can display

Click avatars to see the full list.

Cursors

Each collaborator has a colored cursor:

  • Cursor shows their exact position
  • Name label appears above cursor
  • Selection highlights in their color

Following

Click a collaborator's avatar to jump to their location. Click again to "follow" them—your view scrolls as they move.

Editing Together

Simultaneous Editing

Multiple people can edit:

  • Different sections - No interference
  • Same paragraph - Changes merge automatically
  • Same line - Both edits preserved

Example

If Alice types "The quick brown fox" and Bob simultaneously changes "quick" to "fast":

  • Both see the merge: "The fast brown fox"
  • No conflict dialog
  • No one loses work

Edge Cases

In rare cases where edits truly conflict:

  • Both versions are preserved
  • Opus highlights the conflict
  • Collaborators discuss and resolve

Communication

Comments

Use comments for discussions:

  1. Select text
  2. Click Comment
  3. Type your message
  4. Collaborators are notified

Mentions

Tag collaborators with @:

@alice What do you think about this phrasing?

They receive a notification.

Track Changes

For formal review:

  1. Enable Track Changes
  2. Make suggestions instead of direct edits
  3. Document owner accepts/rejects

Working Offline

Offline Mode

When you lose connection:

  • You can continue editing
  • Changes save locally
  • "Offline" indicator appears

Reconnecting

When connection returns:

  • Local changes sync automatically
  • Remote changes appear
  • Conflicts (rare) are highlighted

Conflict Resolution

If offline edits conflict:

  1. Both versions are shown
  2. Choose which to keep
  3. Or manually merge

Performance

Large Documents

Real-time sync works on documents up to:

  • 100,000+ words
  • Hundreds of images
  • Complex equations

Larger documents may have slight lag.

Many Collaborators

Opus supports up to 50 simultaneous editors. Beyond that:

  • Performance may degrade
  • Consider working in shifts
  • Or split into sections

Slow Connections

On slow connections:

  • Edits may lag slightly
  • Presence updates may delay
  • All changes still sync fully

Privacy & Visibility

What Collaborators See

Depending on their permission:

  • Viewers - Final document only
  • Suggesters - Document + their suggestions
  • Editors - Everything including all edits

What's Tracked

The activity log shows:

  • Who made changes
  • When changes occurred
  • What was changed

Accessible to Editors and Owner.

Best Practices

Before Collaborative Sessions

  • Agree on who edits which sections
  • Set up communication (chat, video call)
  • Ensure everyone has appropriate permissions

During Collaborative Sessions

  • Check who's editing before making major changes
  • Use comments for discussions
  • Follow standard track changes workflow for reviews

Etiquette

  • Don't edit text someone is actively typing
  • Use @ mentions instead of external messages
  • Resolve comments when addressed

Troubleshooting

Can't See Collaborator's Changes

  • Refresh the page
  • Check your internet connection
  • Verify they have edit permission

Seeing Lag

  • Check your internet speed
  • Close other tabs/applications
  • Try a different browser

Duplicate Content

Very rare, but if it happens:

  • One person should stop editing
  • Manually remove duplicates
  • Refresh both browsers

Technical Details

Sync Protocol

Opus uses:

  • Y.js for CRDT operations
  • WebSockets for real-time communication
  • Hocuspocus for server-side sync

Data Persistence

Changes are saved:

  • Immediately to server
  • Every keystroke synced
  • Full history preserved

Next Steps