UX Research & Flow Design Skill

Use this before generating UI code for any non-trivial feature — a flow designed on the fly in code tends to miss edge states.

Flow-mapping process

Entry points: where does the user arrive from (which page, which trigger)? A flow can have multiple entries (e.g. "upgrade plan" reachable from a paywall, settings, or an email link) — each needs the right context carried through.
Happy path steps: the minimum sequence of screens/states from entry to the user's goal being met.
Decision points & branches: every place the flow forks (e.g. "already has a payment method?", "email already registered?") — enumerate both branches explicitly.
Edge & error states: what happens on network failure, validation error, permission denial, empty data, or the user abandoning mid-flow and returning later? A flow isn't done until these are specified, not left to be improvised while coding.
Exit points: where does the user land after success, after abandoning, after error?

Group navigation/content by user mental model (task-based: "Billing," "Team," "Integrations"), not by internal system structure.
Keep primary navigation to 5-7 top-level items; anything more needs grouping or progressive disclosure.
Every page should answer "where am I, what can I do here, how do I get back" without the user having to think.