Imported from Powerworks/K9DatingApp (build-kit-dotnet-es/.claude/skills/learn-eventmodelers-api/SKILL.md). Install upstream with npx skills add Powerworks/K9DatingApp --skill learn-eventmodelers-api. Copyright stays with the author.

Eventmodelers Platform API Reference

You now have complete knowledge of the eventmodelers platform API. Use this reference whenever you need to call, implement, or reason about any endpoint.

Note on scope: this documents the eventmodelers.ai SaaS platform itself (the board/timeline tool the slice.json definitions come from) — the "Architecture Overview" below describes how that external platform is built, not the app this build-kit generates code into. This build-kit's own code-gen skills (build-state-change, build-state-view, build-automation) target a Wolverine.Http + Marten (event-sourced) + RabbitMQ .NET app — see those skills, and your project's own CLAUDE.md, for that side. Everything below is unchanged from the platform's actual API surface, which is language-agnostic from a caller's point of view (plain HTTP/curl).

Architecture Overview

• Framework: Express.js + @event-driven-io/emmett (event sourcing)
• Adapter: @event-driven-io/emmett-expressjs
• Database: PostgreSQL via Knex
• Storage / Auth: Supabase
• Route discovery: Dynamic glob (**/routes{,-*}.js) loaded from dist/src/slices
• Base URL (local): http://localhost:3000

Authentication & Headers

• CORS allowed origins: localhost:3000, localhost:3001, https://app.eventmodelers.ai

Element Types

MODEL_CONTEXT  // Context/domain modeling container
CHAPTER        // Timeline/sequence container
ACTOR          // System participant (swimlane label)
AUTOMATION     // Automated action
API            // External service
SCREEN         // UI screen
COMMAND        // State-changing operation
EVENT          // Domain event
SPEC_ERROR     // Error scenario
TABLE          // Data table
READMODEL      // Query result / materialized view
SCENARIO       // GWT scenario
LANE           // Timeline row
SLICE_BORDER   // Slice boundary marker

Standard HTTP Status Codes

1. Boards

File: src/slices/change/api-boards/routes.ts

POST /api/org/:orgId/boards/:boardId/events

Persist board/timeline row events as an array of mixed event types.

Request body: Array of node, comment, edge, or board events Response: 200 — processed results array

GET /api/boards

List all boards.

Response: 200 — Board[]

DELETE /api/org/:orgId/boards/:boardId

Delete a board.

Response: 204

GET /api/org/:orgId/boards/:boardId/events/search

Search events by node name.

Query params: name (string) Response: 200 — matching event array

GET /api/org/:orgId/boards/:boardId/events

Get all board events in sequence.

Response: 200 — event array

GET /api/org/:orgId/boards/:boardId/nodes/:nodeId/comments

Get all comments for a node.

Response: 200 — comment array

POST /api/org/:orgId/boards/:boardId/bucket

Create a Supabase storage bucket for the board.

Response: 200 — { ok: boolean, bucket: string, alreadyExisted: boolean }

2. Chapters & Timelines

File: src/slices/change/api-chapters/routes.ts

POST /api/org/:orgId/boards/:boardId/chapters

Create a chapter node.

Request body: { position?: { x: number, y: number } } Response: 200 — chapter data

POST /api/org/:orgId/boards/:boardId/timelines/:timelineId/columns

Add a column to a timeline.

Request body: { index?: number } (integer index, optional) Response: 200 — { columnId: string, index: number, totalColumns: number }

DELETE /api/org/:orgId/boards/:boardId/timelines/:timelineId/columns/:columnId

Delete a column from a timeline. Removes the column and all its cells. Cannot delete the last column.

Response:

• 200 — { columnId: string, totalColumns: number }
• 400 — validation error (e.g. last column)
• 404 — timeline or column not found

POST /api/org/:orgId/boards/:boardId/timelines/:timelineId/lanes

Add a lane (row) to a timeline.

Request body:

{
  type: 'actor' | 'interaction' | 'swimlane' | 'spec' | 'feedback'
  label?: string
  index?: number
  height?: number
}

Response: 200 — lane data

POST /api/org/:orgId/boards/:boardId/timelines/:timelineId/cells/:cellId/drop

Drop a node into a timeline cell. Validates placement rules.

Request body: { nodeId: string, nodeType: ElementType }

Placement rules:

• swimlane lane → accepts EVENT
• interaction lane → accepts COMMAND, READMODEL
• actor lane → accepts SCREEN, AUTOMATION
• feedback lane → accepts markdown
• spec lane → accepts SPEC_NODE

Response:

• 200 — drop result
• 400 — placement violation
• 404 — cell or node not found

3. Nodes

File: src/slices/change/api-nodes/routes.ts

All node endpoints require header: x-user-id

POST /api/org/:orgId/boards/:boardId/nodes/events

Submit node change events.

Request body: NodeChangeEvent[]

interface NodeChangeEvent {
  id: string                    // uuid
  eventType: 'node:created' | 'node:changed' | 'node:deleted'
  nodeId: string
  boardId: string
  timestamp: number             // unix ms
  userId?: string
  hash?: string                 // content hash
  changedAttributes?: string[]  // dot-paths e.g. 'meta.title'
  node?: {
    id: string
    data: {
      backgroundColor?: string
      title?: string
      type?: string
      url?: string
      // ...other node data fields
    }
  }
  meta?: {
    type: ElementType
    title?: string
    description?: string
    fields?: Record<string, unknown>
    // ...
  }
  edges?: Array<{
    id: string
    source: string
    target: string
    sourceHandle?: string
    targetHandle?: string
  }>
  chapterId?: string   // for cell placement
  cellName?: string    // spreadsheet-style e.g. "B2"
}

Response: 200 — { hashes: { [eventId: string]: string } }

GET /api/org/:orgId/boards/:boardId/nodes

List all nodes on a board.

Query params: type?: ElementType Response: 200 — node record array

GET /api/org/:orgId/boards/:boardId/nodes/:nodeId

Get a single node.

Response: 200 — node record OR 404

4. Images

File: src/slices/change/api-images/routes.ts

POST /api/org/:orgId/boards/:boardId/images/:imageId

Update a board image.

Request: multipart/form-data — field file (binary) Response: 204

POST /api/org/:orgId/boards/:boardId/imagesnapshots/:imageId

Update an image snapshot.

Request: multipart/form-data — field file (binary) Response: 204

POST /api/org/:orgId/boards/:boardId/image-nodes/:nodeId

Create an image node.

Request: multipart/form-data — fields: file, chapterId, cellName Response: 204

POST /api/org/:orgId/boards/:boardId/images/:imageId/sketch

Render a sketch description to WebP and upload.

Request body:

{
  elements: object[]           // sketch element descriptors
  semanticDescription?: string // human-readable description stored in metadata
}

Response: 204

POST /api/org/:orgId/boards/:boardId/image-nodes/:nodeId/sketch

Create a SCREEN node from a sketch description.

Request body:

{
  chapterId: string
  cellName: string
  description: { elements: object[] }
  semanticDescription?: string
}

Response: 204 OR 400 (validation error)

5. Slices

File: src/slices/change/api-.slices/routes.ts

POST /api/org/:orgId/boards/:boardId/timelines/:timelineId/slices

Create a complete slice (1 column + 3 nodes automatically placed).

Request body:

{
  type: 'state-change' | 'state-view' | 'automation'
  index?: number
  nodes?: {
    actor?: Partial<NodeData>
    interaction?: Partial<NodeData>
    swimlane?: Partial<NodeData>
  }
}

Slice node mapping:

• state-change → SCREEN (actor) + COMMAND (interaction) + EVENT (swimlane)
• state-view → SCREEN (actor) + READMODEL (interaction) + EVENT (swimlane)
• automation → AUTOMATION (actor) + COMMAND (interaction) + EVENT (swimlane)

Response: 200 — slice data

POST /api/org/:orgId/boards/:boardId/timelines/:timelineId/slice-definitions

Create a standalone SLICE_BORDER node spanning an existing column. Unlike the endpoint above, this does not add a column or any actor/interaction/swimlane content nodes — the column must already exist (e.g. created via POST .../slices or the column API) and is referenced by columnId.

Request body:

{
  columnId: string   // id of an existing column on this timeline
  title: string      // slice title — always taken from this field, never derived
  data?: Record<string, unknown>   // optional node.data payload
  meta?: Record<string, unknown>   // optional extra meta fields (type, colId, title are always set explicitly and cannot be overridden here)
}

Response: 200 — { nodeId, timelineId, columnId, title } Errors: 400 missing columnId/title or column not found · 404 timeline not found

6. Specifications (GWT Scenarios)

File: src/slices/change/api-specs/routes.ts

POST /api/org/:orgId/boards/:boardId/contexts/:contextName/slices/:sliceName/scenarios

Append a Given-When-Then scenario to a spec node.

Request body:

{
  id: string
  title: string
  vertical?: boolean
  examples?: unknown[]
  given: string[]   // nodeIds — must be EVENTs from same timeline
  when: string[]    // nodeIds — at most one COMMAND; empty if then has READMODEL
  then: string[]    // nodeIds — EVENTs only OR exactly one READMODEL (not mixed)
}

Validation rules:

• given: only EVENTs from same timeline
• when: max one COMMAND; must be empty when then contains a READMODEL
• then: all EVENTs OR exactly one READMODEL — never mixed
• All referenced nodes must belong to the same chapter/timeline

Response:

• 201 — { scenario, scenarios, specNodeId, isNewNode: boolean }
• 400 — validation error
• 404 — context or slice not found
• 409 — duplicate scenario title

GET /api/org/:orgId/boards/:boardId/contexts/:contextName/spec-info

Get valid elements for a context (by name lookup).

Response: 200 — { chapterId: string, elements: ElementRecord[] }

GET /api/org/:orgId/boards/:boardId/contexts/:contextName/slices/:sliceName/spec-info

Get valid elements for a specific slice.

Response: 200 — { chapterId: string, elements: ElementRecord[] }

7. Config Import

File: src/slices/change/config-import/routes.ts

POST /api/org/:orgId/boards/:boardId/import-config

Import an EventModelingJson config to populate a board.

Request: multipart/form-data with field file OR application/json body:

{ slices: SliceDefinition[] }

Response: 200 — transformed canvas with nodes and edges

8. Slice Data

File: src/slices/slicedata/routes.ts

GET

Build structured slice data from board state.

Query params (one required): contextId OR contextName; optional: sliceId Response: 200 — slice data matching event modeling schema

GET /api/org/:orgId/boards/:boardId/slicedata/slices

List all slices on a board.

Response: 200 — { slices: Array<{ id: string, title: string, status: string }> }

9. Extensions

File: src/slices/extensions/routes.ts

GET /api/org/:orgId/boards/:boardId/extensions

List extension configs for a board.

Response: 200 — extension record array

PUT /api/org/:orgId/boards/:boardId/extensions/:type

Enable or disable an extension.

Request body: { enabled: boolean, config?: object } Response: 200 — updated extension config

10. Snapshots

File: src/slices/Snapshots/routes.ts

All snapshot endpoints require Supabase JWT authentication.

Constraints: max 3 snapshots per user, max 30-day retention, max 50 MB file size.

GET /api/snapshots

List current user's snapshots.

Response: 200 — Array<{ id, name, payload_id, expiry, shared }>

POST /api/snapshots

Create a snapshot.

Request: multipart/form-data — fields: payloadFile (binary), name (string), retention? (days, max 30) Response: 201 — { ok: true, id: string }

GET /api/snapshots/:id

Load a snapshot's payload.

Response: 200 — snapshot payload JSON

PATCH /api/snapshots/:id/share

Share a snapshot (makes it publicly accessible).

Response: 200 — { ok: true }

DELETE /api/snapshots/:id

Delete a snapshot.

Response: 200 — { ok: true }

11. User Management — Commands (Event Sourced)

All commands respond with:

{
  ok: true
  next_expected_stream_version: number
  last_event_global_position: number
}

Optional headers on all: correlation_id, causation_id

POST /api/creategroup

Body: { groupId: string, name: string } Event emitted: GroupCreated

POST /api/inviteuser

Body: { groupId: string, email: string, invitationId: string } Event emitted: UserInvited

POST /api/acceptinvite

Body: { userId: string, groupId: string, invitationId: string } Event emitted: InvitationAccepted

POST /api/assignrole

Body: { userId: string, groupId: string, role: string } Event emitted: RoleAssigned

12. User Management — Read Models (Projections)

All require authentication. Optional query param _id to filter by ID.

GET /api/query/group-details-lookup

Group details. Filter: ?_id=groupId

GET /api/query/open-invites

Pending invitations. Filter: ?_id=invitationId

GET /api/query/user-group-assignments

User-to-group mappings. Filter: ?_id=groupId

GET /api/query/users-to-assign-to-groups

Users available for group assignment. Filter: ?_id=userId

13. Utility

GET /api/user

Get current authenticated user info.

Response: { user_id: string, email: string, metadata: object }

GET /api-docs

Swagger UI (interactive API explorer)

GET /swagger.json

OpenAPI specification (JSON)

Domain Events

Snapshot Events (src/events/SnapshotsEvents.ts)

SnapshotStored          // { name, id, payloadId, expiry }
SnapshotDeleted         // { id }
SnapshotCleanedUp       // { id }
PublishedSnapshotDeleted // { id }
SnapshotShared          // { id }
SnapshotPublished       // { id, payloadId, bucket, path }

User Management Events (src/events/UserManagementEvents.ts)

GroupCreated          // { groupId, owner, name }
UserAssignedToGroup   // { groupId, userId }
UserInvited           // { groupId, invitationId, email }
InvitationAccepted    // { invitationId, groupId, userId }
RoleAssigned          // { groupId, userId, role }

All events support optional metadata: user_id, correlation_id, causation_id

Key Source Files (eventmodelers.ai platform's own repo — not this project)