n8n
Actual coverage
Docker and NPM installation; JSON; APIs; first workflow; weather chat; invoice/reminder workflow; support-ticket workflow; AI-agent workflow; AI-assisted workflow creation; ngrok.
Mental model
A workflow is a directed graph of triggers, transformations, decisions, external calls, and side effects. n8n makes this graph visible and reduces glue code, but it does not remove the need for contracts, credentials, retries, observability, and failure design.
Durable knowledge
- Define the trigger, input schema, output, side effects, and owner before building nodes.
- Keep transformations small and name nodes by intent.
- External API calls need authentication, timeouts, rate-limit handling, retry policy, and safe logging.
- Webhooks require authentication/signature checks, idempotency, replay protection, and a stable public endpoint.
- AI-agent nodes are nondeterministic; constrain tools, validate outputs, and require approval for consequential actions.
- Business workflows need a failure route, dead-letter/manual-review path, and enough execution history to diagnose problems.
Project pattern
Trigger → validate → enrich → decide → act → record → notify. Add an explicit error branch and idempotency key around external side effects.