walkeros-understanding-events

name	walkeros-understanding-events
description	Use when creating walkerOS events, understanding event structure, or working with event properties. Covers entity-action naming, event properties, statelessness, and vendor-agnostic design.

Understanding walkerOS Events

Overview

walkerOS events are self-describing, stateless, vendor-agnostic data structures. They capture user interactions in a standardized format that can be transformed for any destination.

Core principle: Events describe WHAT happened, not WHERE it goes. Stateless. Self-describing. Industry-agnostic.

Entity-Action Naming (Critical)

STRICT REQUIREMENT: All events use "entity action" format with space separation.

// Correct
'page view';
'product add';
'order complete';
'button click';

// Wrong
'page_view'; // underscore
'pageview'; // no separator
'purchase'; // no entity
'add_to_cart'; // wrong format

Parsing: const [entity, action] = event.split(' ')

• Entity: Noun (page, product, user, order, button)
• Action: Verb (view, add, complete, click, login)

Event Properties

See packages/core/src/types/walkeros.ts for canonical types (Event interface, plus event helpers in event.ts).

Property	Type	Purpose	Example
name	string	"entity action" format	"product view"
data	object	Entity-specific properties	{ id: "P123", price: 99 }
context	object	State/environment info (optional)	{ stage: ["checkout", 1] }
globals	object	Global properties	{ language: "en" }
user	object	User identification	{ id: "user123" }
nested	array	Related entities (optional)	[{ entity: "product", data: {...} }]
consent	object	Consent states	{ marketing: true }
id	string	W3C span_id, 16 lowercase hex chars, generated by collector	"0123456789abcdef"
timestamp	number	Auto-generated Unix ms	1647261462000
entity	string	Parsed from name	"product"
action	string	Parsed from name	"view"
source.type	string	Source kind (browser, dataLayer, cookiefirst, ...)	"browser"
source.platform	string	Runtime platform (web, server)	"web"
source.schema	string	Source-emitted schema/version (optional)	"datalayer-v2"
source.trace	string	Run-scoped W3C trace_id, shared by every event of a run	"0123...cdef" (32 hex)
source.count	number	Per-run emission sequence (1, 2, 3, ...)	1
source.release	object	Per-flow config release map, accumulates across crossings	{ web: "3", server: "5" }

data Property

Entity-specific properties. Schema-free but consistent within entity type.

// product entity
data: { id: "P123", name: "Laptop", price: 999, currency: "USD" }

// page entity
data: { title: "Home", path: "/", referrer: "https://..." }

context Property

Hierarchical state information. Format: { name: [value, order] }. Optional.

context: {
  stage: ["checkout", 1],    // checkout stage, first step
  test: ["variant-A", 0],    // A/B test variant
  group: ["premium", 2]      // user segment
}

globals Property

Properties that apply to ALL events in the session.

globals: {
  language: "en",
  currency: "USD",
  environment: "production"
}

nested Property

Related entities captured together. Optional.

// Order with line items
nested: [
  { entity: 'product', data: { id: 'P1', quantity: 2 } },
  { entity: 'product', data: { id: 'P2', quantity: 1 } },
];

user Property

User identification across sessions.

user: {
  id: "user123",        // Your user ID
  device: "device456",  // Device fingerprint
  session: "sess789"    // Session ID
}

source Property

Where the event came from. The collector enriches the event with source data based on which source emitted it.

source: {
  type: 'browser',         // source kind (browser, dataLayer, cookiefirst, ...)
  platform: 'web',         // runtime: 'web' or 'server'
  version: '4.0.0',        // external source-emitter version (collector no longer sets this)
  schema: 'datalayer-v2',  // optional schema/version emitted by the source
  trace: '0123...cdef',    // run-scoped W3C trace_id, groups all events of a run
  count: 1,                // per-run emission sequence (1, 2, 3, ...)
  release: { web: '3' },   // per-flow config release map, accumulates web to server
  url: 'https://...',      // page URL (web only, set by web-context transformer)
  referrer: '...',         // page referrer (web only)
  tool: 'cli',             // tool that produced the event (optional)
  command: 'simulate',     // command name (optional)
}

CMP and other non-page sources do NOT set source.url/source.referrer - that's the responsibility of a web-context transformer.

source.trace is the run grouping key: the collector mints a fresh run-scoped trace_id on each run and stamps it (plus a per-run source.count) on every event when absent. It is preserved unchanged when an event is forwarded from web to server, so the whole pipeline shares one trace.

source.release records which config handled the event, keyed by flow name. Each flow the event passes through adds its own entry (that flow's config release), so an event captured on the web and processed on the server carries both flow releases, and a warehouse row shows exactly which config version touched it. This is distinct from source.version, the source package version set only by external source emitters (the collector no longer stamps it).

Migration from v3

If you have existing v3 events or configs, here is the v4 mapping:

v3	v4
event.id = "<ts>-<rnd>-<seq>"	event.id = W3C span_id (16 lowercase hex chars)
event.version	removed - see source.version and source.schema
event.group	removed - use source.trace (run-scoped trace_id) for correlation
event.count	removed - use source.count (per-run emission sequence)
event.source.id	event.source.url (when it meant page URL)
nested: [{ type, data }]	nested: [{ entity, data }] (Entity.entity replaces .type)

Design Principles

Statelessness

Events are immutable snapshots. They don't reference previous events or maintain state.

Self-Describing

Events contain all context needed to understand them. No external lookups required.

Vendor-Agnostic

Events use generic concepts (product, order) not vendor-specific (GA4 item, FB content).

Transformation to vendor formats happens in mapping, not in event creation.

Creating Events

import { elb } from '@walkeros/collector';

// Basic event
await elb('page view', { title: 'Home', path: '/' });

// With all properties
await elb(
  'product add',
  { id: 'P123', price: 99 }, // data
  { stage: ['cart', 1] }, // context (optional)
  { currency: 'USD' }, // globals (optional)
);

Related Skills

• walkeros-understanding-mapping - Transform events for destinations
• walkeros-understanding-flow - Data flow architecture

Source Files:

• packages/core/src/types/walkeros.ts - Event types
• packages/core/src/schemas/ - Event schemas

Documentation:

• Website: Event Model - User-facing docs
• walkeros.io/docs - Public documentation