Making a feature ready to build

The most expensive place to discover a missing UI state is inside a pull request review.

When we start writing code without mapping edge cases first, the questions arrive late: What does this look like with zero items? How do we handle a failed save? Is this button disabled or hidden? Answering them mid-sprint turns focused feature delivery into a stop-and-go negotiation across design, product, and QA.

A feature is ready to build when edge cases are mapped into concrete UI states, existing platform primitives are accounted for, and the port contract is agreed on before writing production code.

Model observable UI states

Instead of reading a specification as a sequence of pages, we can break it down into the discrete states our interface must present.

For any given workflow, we trace what the user sees across the full lifecycle of the screen:

type MemberListState =
  | { status: 'loading' }
  | { status: 'empty'; reason: 'no-members' | 'no-filter-match' }
  | { status: 'ready'; members: MemberRow[]; canManage: boolean }
  | { status: 'removing'; members: MemberRow[]; pendingId: string }
  | { status: 'error'; message: string; retryable: boolean };

This state map immediately answers questions that static mocks ignore. It distinguishes an empty search filter from an account that has no members at all. It also settles whether the table stays visible while a removal operation is in flight.

Mapping these states gives us a shared checklist. It defines the scenarios our standalone demo should support and clarifies the exact shapes we need for unit tests.

Survey existing infrastructure

Before building from scratch, we should identify which platform primitives our feature will assemble.

That means checking the UI kit and design system for decisions that are already solved: typography scales, color tokens, button variants, accessible dialogs, and structural layout shells. Reusing these building blocks ensures consistent responsive behavior and accessibility baselines out of the box.

Our engineering job for this feature is to assemble those shared primitives around its specific product outcome, without rebuilding standard controls or inventing redundant wrappers.

Draft the port contract

The final readiness gate is drafting the port. Before wiring up backend clients, we should write out the exact interface our feature needs in frontend terms:

export interface MemberListPort {
  loadMembers(): Promise<MemberRow[]>;
  removeMember(id: string): Promise<void>;
}

Drafting this interface decouples frontend implementation from backend readiness. Even if backend endpoints are still being built or debated, we can implement the entire feature—complete with mock data in our demo harness—against this stable contract.

When the observable states are enumerated, the UI kit primitives are chosen, and the port is drafted, development becomes mechanical execution. Ambiguity has been resolved upfront, where it is cheapest to change.