DAG Visual Editor Design

Design modern, intuitive DAG and workflow visual editors following the LEGO philosophy: snap blocks together simply rather than wire complex ports.

DECISION POINTS

Layout Algorithm Selection

Node Count < 20 AND Simple Flow?
├─ YES → Force-directed layout (React Flow default)
│         • Fast rendering
│         • Good for exploring connections
│
└─ NO → Node Count > 100?
    ├─ YES → Hierarchical (Dagre) + Virtualization
    │        • Set viewport culling
    │        • Lazy load node details
    │
    └─ NO → Branch Factor > 3 per node?
        ├─ YES → ELK Layered Algorithm
        │        • Handles complex routing
        │        • Minimizes edge crossings
        │
        └─ NO → Dagre LR (Left-Right)
                • Standard choice
                • rankdir: 'LR', ranksep: 80

Node Connection Strategy

Data Type Diversity?
├─ Single type (e.g., JSON) → Implicit connections
│   • No handles visible by default
│   • Snap zones on hover
│
├─ 2-3 types → Color-coded handles
│   • Red: Error streams
│   • Blue: Data streams  
│   • Green: Success/completion
│
└─ 4+ types → Bundled connections
    • Group related channels
    • Label bundles clearly
    • Consider type coercion nodes

Editing Mode Selection

User Skill Level?
├─ Beginner → Canvas + Sidebar
│   • Drag nodes from categorized list
│   • Template-based workflows
│
├─ Intermediate → Quick Add (Slash Commands)
│   • Type "/" for node search
│   • Context-aware suggestions
│
└─ Expert → Keyboard First
    • Hotkeys for common nodes
    • Text-based node creation
    • Batch operations

FAILURE MODES

Spaghetti Graph Syndrome

Symptoms: Edges crossing everywhere, impossible to follow data flow, users getting lost Detection: If >30% of edges cross other edges, or users spend >20s tracing a path Fix:

• Force hierarchical layout (Dagre/ELK)
• Add intermediate junction nodes to break long connections
• Implement edge bundling for parallel data flows

Zoom Desert Problem

Symptoms: Pan/zoom feels broken, users can't find their content, minimap unhelpful Detection: Users hitting zoom limits frequently, >5 seconds to locate nodes after navigation Fix:

• Implement fit-to-view on double-click background
• Add breadcrumb navigation for nested groups
• Set proper zoom bounds: min 0.1x, max 3x
• Show node labels at all zoom levels >0.5x

Handle Ambiguity Confusion

Symptoms: Users connecting wrong ports, type errors, unexpected data flow Detection: >20% connection error rate, frequent undo of connections Fix:

• Show handle compatibility on hover (green=valid, red=invalid)
• Add connection preview with data type labels
• Implement smart handle snapping within 20px radius

Performance Cliff Rendering

Symptoms: Editor freezes with >50 nodes, stuttering during pan/zoom Detection: Frame rate drops below 30fps, render times >100ms Fix:

• Enable React Flow viewport culling
• Virtualize node lists in sidebar
• Debounce layout recalculation (300ms delay)
• Cache node measurements between renders

No-Feedback Execution Black Box

Symptoms: Users don't know if workflow is running, what failed, or why it stopped Detection: Users asking "is it working?" or clicking run button multiple times Fix:

• Animate edges during execution (flowing dots)
• Add node status indicators: idle/running/success/error
• Show execution time and data throughput
• Highlight current execution path

WORKED EXAMPLES

Example: Data Processing Pipeline Editor

Scenario: Design editor for CSV → Transform → Database pipeline

Step 1: Choose Layout

• 5 nodes total, linear flow → Use Dagre LR
• Set rankdir: 'LR', ranksep: 120 for readable spacing

Step 2: Design Node Structure

const TransformNode = ({ data }) => (
  <div className="w-64 border-2 border-gray-200 rounded-lg bg-white">
    <div className="bg-blue-50 px-3 py-2 border-b">
      <h3>🔄 Transform Data</h3>
    </div>
    <div className="p-3">
      <div className="text-sm">Filter: {data.filter}</div>
      <div className="text-sm">Sort: {data.sort}</div>
    </div>
    <Handle type="target" position={Position.Left} />
    <Handle type="source" position={Position.Right} />
  </div>
);

Step 3: Connection Logic

• Single data type (tabular) → One handle per side
• Show preview of first 3 rows on edge hover
• Animate data flow during execution

Novice Miss: Would add separate handles for each column Expert Catch: Keeps single connection, shows column mapping in node detail

QUALITY GATES

• Pan latency <50ms (measure with performance.now())
• Zoom smoothness: no frame drops during scroll zoom
• Handle discoverability: New users find connection points within 30s
• Edge routing: <20% of edges cross other edges in auto-layout
• Node search: Find any node within 3 keystrokes
• Execution feedback: Status visible during all async operations
• Mobile usability: Touch targets ≥44px, pinch zoom works
• Undo reliability: Can undo/redo any operation without corruption
• Save performance: Workflow JSON serialization <500ms for 100 nodes
• Error clarity: Failed connections show specific reason (type mismatch, circular reference)

NOT-FOR Boundaries

Don't use DAG editors for:

• Text-heavy content → Use document editors instead
• Real-time collaboration → Use [collaborative-editing] skill for conflict resolution
• Complex mathematical expressions → Use formula builders instead
• Timeline-based workflows → Use [gantt-chart-design] for scheduling
• State machines with loops → Use dedicated state diagram tools

Delegate to other skills:

• Performance optimization → Use [react-performance-optimization] for >1000 nodes
• Accessibility compliance → Use [web-accessibility] for screen reader support
• Animation design → Use [micro-interactions] for execution visualizations