Triggers

Triggers

Crayon workflows can be triggered via MCP tools, HTTP webhooks, or cron schedules.

MCP Tools (Claude)

Use these to trigger workflows and nodes directly from Claude:

• run_workflow — run a workflow by name with JSON input. Returns run_id, status, and result.
• run_node — run a single node (wrapped in a workflow for durability). Takes optional workflow_name for connection resolution.
• list_runs — list recent workflow runs (optionally filtered by workflow name).
• get_run — get a specific run by ID (supports prefix matching like git short hashes).
• get_trace — get the full execution trace with operation tree and timings.

Webhooks

Two modes for HTTP triggering:

Test Mode

Interactive triggers (CLI, MCP tools) run in test mode by default — side-effect nodes describe what they would do without actually performing the action. Webhooks and cron run live by default. Pass "test_mode": true in the request body to run a webhook in test mode instead.

Async (fire-and-forget)

POST /dev/api/workflows/{workflow_name}/start
Authorization: Bearer {token}
Content-Type: application/json

{"input": {}}

• Runs live by default (side effects are performed)
• Pass "test_mode": true to run in test mode instead
• Returns 202 immediately with { "status": "accepted", "runId": "...", "workflow": "..." }
• The workflow runs in the background
• Poll status via GET /dev/api/runs/{runId} — returns { "status": "SUCCESS" | "ERROR" | "PENDING", ... }

Sync (blocking)

POST /dev/api/workflows/{workflow_name}/run
Authorization: Bearer {token}
Content-Type: application/json

{"input": {}}

• Runs live by default (side effects are performed)
• Pass "test_mode": true to run in test mode instead
• Blocks until the workflow completes
• Returns 200 with { "run_id": "...", "status": "SUCCESS", "result": ... }
• Returns 500 on error with { "status": "ERROR", "error": "..." }
• Connection stays open for the full duration of the workflow

Authentication

Webhook requests require a Bearer token in the Authorization header. Tokens are Ed25519 JWTs signed by the auth-server.

Generate a token via the Dev UI: Open the Trigger tab → click Async or Sync → use the token generator (configurable expiry: 7d, 30d, 90d, 365d).

Generate a token via MCP: generate_webhook_token — specify expiry (7d, 30d, 90d, 365d).

Generate a token via API:

POST /dev/api/webhook-token
Content-Type: application/json

{"expiresIn": "30d"}

Returns { "data": { "token": "...", "expiresAt": "..." } }

URL Format

https://{fly_app_name}.fly.dev/dev/api/workflows/{name}/start

The {workflow_name} must be URL-encoded if it contains special characters.

Cron Scheduling

Workflows can be scheduled to run on a recurring basis via the cron system. The auth-server acts as the external scheduler — it sends HTTP requests to machines at the right times, auto-waking them from Fly.io's auto_stop.

Manage schedules via Dev UI: Open the Schedule tab to create, pause, resume, or delete schedules.

Manage via MCP tools:

• list_cron_jobs — list all scheduled jobs
• create_cron_job — create a new schedule (cron expression + timezone)
• update_cron_job — update schedule, enable/disable
• delete_cron_job — remove a schedule
• list_cron_runs — view execution history for a job

Test mode: Cron jobs run live by default. To run a cron job in test mode, include "test_mode": true in the job's input JSON when creating or updating the job. This value is forwarded to the workflow execution.

Cron behavior:

• Scheduler ticks every 15 seconds
• Jobs that fail 10 consecutive times are automatically disabled
• The cron run status tracks both the trigger (HTTP call) and the workflow outcome (polled from DBOS)
• Run statuses: triggered → success | error | timeout