Feature samples

Small single-purpose snippets, each demonstrating one feature.

Minimal valid input

// Demonstrates: the smallest valid .krs input — system + 2 services + sync/async edges.
// Use this as a baseline when isolating rendering bugs.

system Minimal {
  label "Minimal System"

  service Frontend {
    label "Frontend"
  }

  service Backend {
    label "Backend"
  }

  Frontend ->  Backend "sync call"
  Frontend --> Backend "async call"
}

User nodes ([human] / [ai])

// Demonstrates: [human] and [ai] user nodes with role and description properties.

system UserSample {
  label "User Node Sample"

  user Customer [human] {
    label "Customer"
    role "Places orders and tracks shipments"
    description "A human user who interacts with the storefront."
  }

  user SupportAgent [human] {
    label "Support Agent"
    role "Handles customer inquiries"
  }

  user RecommendBot [ai] {
    label "Recommendation Bot"
    role "Generates personalised product recommendations"
    description "An AI agent that analyses purchase history."
  }

  service Storefront {
    label "Storefront"
  }

  service SupportPortal {
    label "Support Portal"
  }

  Customer      -> Storefront     "browses and orders"
  SupportAgent  -> SupportPortal  "resolves tickets"
  RecommendBot  -> Storefront     "injects recommendations"
}

Sync / async edges

// Demonstrates: sync (->) and async (-->) edges, with and without labels.

system EdgeSample {
  label "Edge Variants"

  service A { label "Service A" }
  service B { label "Service B" }
  service C { label "Service C" }
  service D { label "Service D" }

  // Sync edges
  A -> B "labelled sync call"
  A -> C

  // Async edges
  B --> D "labelled async call"
  C --> D
}

All four annotations

// Demonstrates: all four lifecycle annotations — @deprecated, @new,
// @experimental, @migration_target — individually and combined.

system AnnotationSample {
  label "Annotation Sample"

  service LegacyAuth @deprecated {
    label "Legacy Auth"
    description "Scheduled for removal in Q3."
  }

  service NewAuth @new {
    label "New Auth"
    description "Introduced in the latest release."
  }

  service BetaSearch @experimental {
    label "Beta Search"
    description "Feature-flagged; not yet in general availability."
  }

  service MigrationBridge @deprecated @migration_target {
    label "Migration Bridge"
    description "Deprecated origin that is also the migration target stub."
  }

  LegacyAuth -> MigrationBridge "migrate traffic"
  MigrationBridge -> NewAuth    "forward requests"
  NewAuth -> BetaSearch         "delegate search"
}

[external] tag

// Demonstrates: [external] tag on service and resource nodes.
// External nodes represent components outside the system boundary.

system ExternalSample {
  label "External Nodes"

  service OrderService {
    label "Order Service"

    domain OrderDomain {
      label "Order Domain"

      usecase PlaceOrder {
        label "Place Order"

        resource PaymentAPI [external] {
          label "Payment API"
          description "Third-party payment gateway outside our boundary."
        }

        resource InventoryDB {
          label "Inventory DB"
        }
      }
    }
  }

  service PaymentGateway [external] {
    label "Payment Gateway"
    description "External payment provider — not owned by this team."
  }

  OrderService -> PaymentGateway "charges card"
}

Full drill-down hierarchy

// Demonstrates: full logical hierarchy — system → service → domain → usecase → resource.
// Use this to verify drill-down rendering at every level.

system ECommerce {
  label "EC Platform"

  service OrderService {
    label "Order Service"

    domain OrderDomain {
      label "Order Domain"

      usecase PlaceOrder {
        label "Place Order"

        resource OrderDB {
          label "Order DB"
          description "Primary database for order records."
        }

        resource PaymentAPI [external] {
          label "Payment API"
        }
      }

      usecase CancelOrder {
        label "Cancel Order"

        resource OrderDB {
          label "Order DB"
        }
      }
    }

    domain ShippingDomain {
      label "Shipping Domain"

      usecase TrackShipment {
        label "Track Shipment"

        resource ShippingAPI [external] {
          label "Shipping API"
        }
      }
    }
  }
}

All deploy artifact types

// Demonstrates: all deploy artifact types — war, jar, oci, lambda, function,
// assets, job (one-shot and scheduled), artifact.

system DeploySample {
  label "Deploy Sample"

  service LegacyApp    { label "Legacy App" }
  service ApiServer    { label "API Server" }
  service WorkerApp    { label "Worker App" }
  service WebFrontend  { label "Web Frontend" }
  service DataPipeline { label "Data Pipeline" }
  service BillingJob   { label "Billing Job" }
  service FnHandler    { label "Function Handler" }
  service AzureFn      { label "Azure Function" }
  service LegacyBatch  { label "Legacy Batch" }
}

deploy "Production" {
  war "legacy-app" {
    runtime "Tomcat 10"
    realizes "LegacyApp"
  }

  jar "api-server" {
    runtime "JVM 21"
    realizes "ApiServer"
  }

  oci "worker" {
    image "worker-app:latest"
    runtime "Kubernetes"
    realizes "WorkerApp"
  }

  lambda "fn-handler" {
    runtime "Node.js 22"
    realizes "FnHandler"
  }

  function "azure-fn" {
    runtime "Node.js 20"
    realizes "AzureFn"
  }

  assets "web-frontend" {
    runtime "CloudFront"
    realizes "WebFrontend"
  }

  job "data-pipeline" {
    runtime "JVM 21"
    realizes "DataPipeline"
  }

  job "monthly-billing" {
    runtime "JVM 21"
    schedule "0 0 1 * *"
    realizes "BillingJob"
  }

  artifact "legacy-batch" {
    type "COBOL batch"
    runtime "Mainframe"
    realizes "LegacyBatch"
  }
}

Domain drift warning

// Demonstrates: domain-to-domain edges across and within services.
//
// Cross-service edge (OrderDomain -> PaymentDomain):
//   No explicit service edge exists, so an implicit service edge is derived
//   and rendered in amber dashed style in the system view.
//
// Intra-service edge (OrderDomain -> ShippingDomain within OrderService):
//   Both domains belong to OrderService, so the edge is rendered directly
//   in the service drill-down view.

system DriftSample {
  label "Domain Drift Sample"

  service OrderService {
    label "Order Service"

    domain OrderDomain {
      label "Order Domain"
      description "Depends on PaymentDomain to process payments and ShippingDomain to ship orders."
      OrderDomain -> PaymentDomain "decides payment"
      OrderDomain -> ShippingDomain "triggers shipment"
    }

    domain ShippingDomain {
      label "Shipping Domain"
      description "Handles order shipment."
    }
  }

  service PaymentService {
    label "Payment Service"

    domain PaymentDomain {
      label "Payment Domain"
      description "Handles payment processing for orders."
    }
  }
}

Legend block

// Diagram legend syntax (Issue #833, #1513).
//
// `legend` blocks declare color-meaning pairs that render as a footer band
// below each diagram view. Two entry primitives exist:
//   swatch <hex>  "label"   — explicit color sample
//   ref <target>  "label"   — color from the .krs.style cascade for the
//                              given annotation / tag / id / type
//
// View scope is optional. When omitted, the legend appears on the top level
// of every view. `system` / `deploy` / `org` target a view type; `service` /
// `domain` target drill-down views rooted at that node kind (Issue #1513).
// Matching is exact — each level shows only the legends for its own scope.

system ECPlatform {
  label "EC Platform"

  service ECommerce {
    label "EC Site"

    domain Order {
      label "Order"
      usecase PlaceOrder { label "Place Order" }
    }
  }
  service Payment [external] {
    label "Payment"
  }
  service Legacy @deprecated {
    label "Legacy"
  }
}

deploy Production {
  oci "ec-api"      { realizes ECommerce }
  oci "payment-api" { realizes Payment }
}

organization Acme {
  team Backend {
    label "Backend"
  }
}

// Shown on the top level of every view (system / deploy / org).
legend "Owner team" {
  swatch #2563EB "Team Backend"
  swatch #16A34A "Team Frontend"
  swatch #DC2626 "Third-party"

  ref @deprecated "Deprecated"
  ref [external]  "External system"
  ref service     "Service"
  ref #ECommerce  "EC site (focus)"
}

// Deploy-only legend — physical layer specifics.
legend deploy "Hosting tier" {
  swatch #0EA5E9 "Cloud Run"
  swatch #F59E0B "On-prem"
}

// Shown only on drill-down views rooted at a service (e.g. ECommerce).
legend service "Service internals" {
  swatch #8B5CF6 "Domain"
}

// Shown only on drill-down views rooted at a domain (e.g. Order).
legend domain "Domain vocabulary" {
  swatch #3B82F6 "Usecase"
}

resource operations (CRUD)

// Resource CRUD operations on usecases (Issue #1046) and the
// derived read/write edge differentiation in the usecase view (Issue #1061).
//
// `operations` declares which CRUD verbs the enclosing usecase performs on a
// resource. Recognized verbs are `create` / `read` / `update` / `delete`.
// Unknown verbs still parse (preserved for translate adapters that emit
// `list` / `search` / `execute`) but raise an `unknown-resource-operation`
// warning. Omission keeps the dependency opaque — no diagnostic.
//
// In the usecase drill-down view the renderer derives a write-vs-read
// classification from `operations` and shows it via:
//   - synthesized usecase->resource edge gets a [write] / [read] pseudo-tag
//   - edge label: "W" for write, "R" for read
//   - edge stroke-width: 2 for write, 1.5 for read (default style)
// Hierarchy: read (1.5) < write (2) < cyclic (2.5) keeps cyclic the
// most attention-grabbing axis.
//
// This file is the AT-friendly minimal sample. See `examples/ja/ec-platform/`
// for the same property used in a realistic scenario.

system Demo {
  label "Resource operations demo"

  database OrderDB {
    table OrderTable { label "Orders table" }
  }

  service Backend {
    domain Order {
      // Write usecase: edge renders thicker with "W" label.
      usecase PlaceOrder {
        label "Accept a new order"
        resource OrderDB.OrderTable {
          operations create, read
        }
        resource InventoryAPI [external] {
          label "Inventory check API"
          operations read
        }
      }

      // Multi-line form accumulates verbs; still classified as write
      // because update is in the list.
      usecase UpdateOrder {
        label "Modify an order"
        resource OrderDB.OrderTable {
          operations read
          operations update
        }
      }

      // Pure read usecase: edge renders thinner with "R" label.
      usecase QueryOrder {
        label "Query order status"
        resource OrderDB.OrderTable {
          operations read
        }
      }

      // Omission form — opaque dependency. Renders as read (conservative)
      // with "R" label and the default thin stroke.
      usecase ListOrders {
        label "List recent orders"
        resource OrderDB.OrderTable
      }
    }
  }
}