My events aren't arriving

When a destination stays silent, you do not need a server or a login to find out why. Run your flow against a single event offline and read the result.

npx walkeros push flow.json -e '{"name":"product add","data":{"id":"ers","price":420}}' --simulate destination.gtag

The simulation reports whether the destination accepted the event, which mapping rule matched, and the vendor calls it would have made:

success: true
  destination.gtag
    mapping: product add
    call window.gtag("event","add_to_cart",{...})
  Duration: 4302ms

mapping: none (skipped before mapping) with no calls means the event never reached the destination's mapping (consent, a filter, or no rule). When consent is the reason, a line says which kind:

• pending: waits for consent (require): the destination has require: ["consent"] and never started. Pass starting consent with --consent '{"functional":true}'.
• skipped: consent (requires marketing; granted functional): the destination started, but the event lacks the consent its consent setting requires. Grant it with --consent or in the event's consent.

See consent in simulate. Add --json to get the same result as machine-readable output, with the recorded calls under simulations (see simulation output). Your flow.json must carry config.platform ("web" or "server"), otherwise bundling throws before the simulation runs.

Symptom to cause

Symptom	Likely cause
No events at all	Source not initialized
A destination is silent	Mapping mismatch
Partial or wrong data	Path does not exist
A destination is skipped	Required consent not granted
A destination throws	Vendor SDK or API error

Log every event at the collector

To confirm events are flowing before you blame a vendor, add an inline console destination. It logs the name of every event the collector processes, so you can see what arrives and when.

const { elb } = await startFlow({
  destinations: {
    debug: {
      code: {
        type: 'console',
        config: {},
        push: (event) => console.log('Event:', event.name),
      },
    },
    // ...your other destinations
  },
});

If you see event names in the console but the real destination stays silent, the problem is downstream of the collector: a mapping mismatch, a missing consent, or a vendor error. If you see nothing, the source is not capturing or the collector never started.

Checklist

1. Any errors in the browser console?
2. Is the event pushed? Add the console destination above to confirm.
3. Does the destination mapping match the entity and action names exactly? Names are case-sensitive (product add, not Product Add).
4. Do the mapped data paths exist on the event? Log the full event and check.
5. Is the required consent granted for the destination?
6. Run npx walkeros validate flow.json to catch a malformed config.

Zero-install equivalent (AI assistant via MCP)

If you use the walkerOS MCP server with an AI assistant, the same offline simulation is one tool call. step is required and uses the type.name form (for example destination.gtag).

flow_simulate({
  configPath: 'flow.json',
  step: 'destination.gtag',
  event: { name: 'product add', data: { id: 'ers', price: 420 } },
})

The response includes _hints.warnings, which flags when no destination received the event, and a destination that sent nothing carries skipped with the reason. Pass state: { consent: { functional: true } } to start a destination that waits for consent. For transformer, collector and destination steps, pass ingest (for example { ip, userAgent }) to simulate the request context an HTTP source would provide. Like the CLI output, the result is scrubbed of credentials.