n8n Workflow Lifecycle

The six stages

PLAN. Gather requirements, ask clarifying questions, search for existing workflows / sub-workflows that already do this.
BUILD. Write SDK code (with skills: subworkflows, node-config, expressions, code-nodes; readability section below).
VALIDATE. validate_workflow + get_workflow_details for connections, then have the user verify per-node credentials and create anything you couldn't (missing credentials, folders, etc).
TEST. test_workflow with prepare_test_pin_data; iterate until output matches intent.
PUBLISH. publish_workflow only after stages 3 and 4 are clean.
HANDOFF. Production handoff: how to trigger it, what it returns, what to watch, what they should know to use it well.

Skipping a stage produces workflows that look done but break in production, or solve the wrong problem entirely. Three most common skips:

Build before plan. "User asked for X, I'll start coding" without confirming what X means, whether the same logic already exists as a sub-workflow, or which folder/project it belongs in. Cheaper to ask one clarifying question than to rebuild after.
Test before user-side wire-up. Running test_workflow before the user has verified credentials per node hits the wrong service or 401s. Get the user-side setup done as part of VALIDATE.
Publish without test. Validation passing means the SDK is well-formed; it does NOT mean the workflow is correct.