OTM Layout and Positioning Guidance

When to Use This Skill

Call this skill when you need detailed guidance on:

• •Creating initial layout from scratch (new threat models)
• •Positioning components in OTM diagrams
• •Calculating parent container sizes
• •Preserving existing layout when updating
• •Handling nested component hierarchies

Layout for New vs Updating

For NEW Threat Models

Create simple, organized layout:

• •Start external components at left (x: 100-300)
• •Flow left-to-right (users → load balancer → services → databases)
• •Use consistent spacing (80-100px between components)
• •Group related components vertically
• •Leaf components: 85x85 pixels
• •Calculate container sizes from children

For UPDATES (Existing layout present)

🚨 CRITICAL: sync() BEFORE reading existing layout. Users frequently adjust component positions and sizes in the IriusRisk web interface. A local current-threat-model.otm file may contain outdated layout that does NOT reflect changes made in the UI. You MUST call sync() to download the latest OTM before reading or preserving any layout data — even if the file already exists locally.

Preserve existing layout (from freshly synced OTM):

• •Keep existing component positions (x, y)
• •Keep existing component sizes (width, height)
• •Add new components with calculated positions that fit
• •Recalculate parent container sizes when adding children

Component Sizes

Standard sizes:

• •Leaf components (services, databases, APIs): 85x85 pixels
• •Container components (infrastructure): Calculated from children

Spacing Guidelines

• •Minimum spacing between unrelated components: 50 pixels
• •Comfortable spacing: 80-100 pixels
• •Visual grouping: Related components can be closer (30-40 pixels)
• •Padding inside containers: 30-40 pixels from parent edges

Cascading Size Calculation Algorithm

When adding components to nested hierarchies, recalculate sizes bottom-up:

Algorithm (work from leaf nodes up to root):

Step 1: Identify leaf components (no children):

• •Set size to 85x85 pixels

Step 2: For each parent component (contains other components):

child_area_width = max(child.x + child.width) - min(child.x)
child_area_height = max(child.y + child.height) - min(child.y)

parent.width = child_area_width + (2 * 40)  # 40px padding
parent.height = child_area_height + (2 * 40)

# Minimum size for containers
parent.width = max(parent.width, 200)
parent.height = max(parent.height, 200)

Step 3: Repeat for each level moving up the hierarchy

Layout Patterns

Pattern A: Adding Infrastructure Around Applications

# Existing: API service at x:200, y:200, size 85x85
# Adding: ECS cluster to contain it

# Calculate ECS cluster:
# Child occupies x:200-285, y:200-285
# Add padding: 85 + (2*40) = 165x165
# Position 40px left/above: x:160, y:160

- id: "ecs-cluster"
  representation:
    position: {x: 160, y: 160}
    size: {width: 165, height: 165}

- id: "api-service"
  parent: {component: "ecs-cluster"}
  representation:
    position: {x: 200, y: 200}  # Original preserved
    size: {width: 85, height: 85}

Pattern B: Adding Peer Services Inside Container

# Existing: auth-service at x:200, y:200 in ecs-cluster
# Adding: payment-service alongside

- id: "payment-service"
  parent: {component: "ecs-cluster"}
  representation:
    position: {x: 335, y: 200}  # 200 + 85 + 50
    size: {width: 85, height: 85}

# Recalculate parent:
# Children occupy x:200-420, y:200-285
# Child area: 220x85
# Add padding: 300x165
- id: "ecs-cluster"
  representation:
    position: {x: 160, y: 160}
    size: {width: 300, height: 200}  # RECALCULATED

Pattern C: Adding Load Balancer (Peer Component)

# Existing: backend at x:300, y:200
# Adding: ALB upstream

- id: "alb"
  representation:
    position: {x: 150, y: 200}  # To the left
    size: {width: 85, height: 85}

- id: "backend"
  representation:
    position: {x: 300, y: 200}  # Original preserved
    size: {width: 85, height: 85}

Layout Reset Option

If reset_layout=True or auto_reset_layout: true in config:

• •DO NOT calculate positions
• •DO NOT include representation sections
• •Backend strips all layout data
• •IriusRisk auto-layouts from scratch

Key Rules

DO:

• •✅ Calculate container sizes from children (bottom-up)
• •✅ Preserve existing positions when updating
• •✅ Add 40px padding around children
• •✅ Use 85x85 for leaf components
• •✅ Recalculate ALL ancestors when adding to nested hierarchy

DON'T:

• •❌ Use fixed sizes for containers
• •❌ Forget to recalculate parent sizes
• •❌ Overlap components (unless parent/child)
• •❌ Place at x:0, y:0 unless intentional
• •❌ Stop at one level - cascade up entire tree