Test LikeC4 Model

Use this skill when validating LikeC4 model correctness and integrity.

Validation Workflow

1. Project Structure Validation (REQUIRED)

Use LikeC4 MCP read-project-summary to validate:

• •All element kinds are defined in shared specifications
• •All relationship kinds exist in spec files
• •Tags are properly declared
• •No orphaned elements

2. Element Reference Validation (REQUIRED)

Use LikeC4 MCP search-element to verify:

• •All referenced elements exist
• •FQN usage is correct for nested elements
• •instanceOf references point to valid Containers

3. Relationship Validation (REQUIRED)

Use LikeC4 MCP find-relationships to check:

• •Relationships use valid typed kinds
• •No duplicate relationships between same elements
• •All relationships have descriptive labels
• •No reverse/return relationships exist

4. View Validation (RECOMMENDED)

Use LikeC4 MCP open-view to preview:

• •Views render correctly without errors
• •Include patterns show expected elements
• •Layout hints (rank source/sink) work as intended
• •No unexpected elements appear due to over-broad wildcards

5. Syntax Validation (RECOMMENDED)

Use Context7 MCP query-docs to verify:

• •Relationship syntax is correct
• •View syntax follows LikeC4 DSL standards
• •Deployment instanceOf syntax is proper

Common Issues to Check

Broken References

# Use LikeC4 MCP search-element to find elements
# Verify all referenced elements exist in model

Invalid Element Kinds

# Use LikeC4 MCP read-project-summary
# Check that all element kinds are in spec-*.c4 files

Missing Relationship Labels

❌ api -[calls]-> service          // Missing label
✅ api -[calls]-> service 'Fetches data'

Over-broad View Includes

❌ include **                      // Too broad
✅ include mySystem.*              // Scoped

Testing Checklist

• • Run LikeC4 MCP read-project-summary - verify all element kinds exist
• • Search for all FQN references - use search-element to validate
• • Check relationships - use find-relationships for key connections
• • Preview all views - use open-view for each defined view
• • Verify syntax - use Context7 MCP if uncertain about syntax features
• • Check for compilation errors in VS Code Problems panel
• • Run likec4 start locally to ensure diagrams render

Parent Context Validation

Critical requirement: Every view MUST explicitly include its parent/surrounding element.

For detailed context requirements, see PARENT_CONTEXT_REFERENCE.md

Context Checklist for Views

• • C1 Context view: System boundary clearly shown? External systems included?
• • C2 Container view: System boundary shown? Containers appear WITHIN system?
• • C2 Container view: Neighboring containers shown? (include -> vault.* and vault.* ->)
• • C3 Component view: Parent container boundary shown? Components appear WITHIN container?
• • C3 Component view: Neighboring containers shown? (include -> service and service ->)
• • Deployment Zone view: Zone container shown? VMs appear WITHIN zone? Parent environment included?
• • Deployment VM view: VM container shown? Instances appear WITHIN VM? Parent zone included?
• • Dynamic/Sequence view: Initiating actor shown at start? Causality clear?

Common mistakes:

• •❌ C3 view without parent container boundary
• •❌ C2 view without system boundary
• •❌ Deployment VM without parent zone
• •❌ Sequence without initiating actor
• •✅ Every view contextualized by showing what contains it

Output

Comprehensive validation report identifying:

• •Broken or invalid references
• •Syntax errors or warnings
• •Missing or incorrect metadata
• •Views that don't render as expected