frontend-api-layer

name: frontend-api-layer description: Provides patterns for structuring the API layer in React applications. This skill should be used when setting up API clients, defining API request declarations, or integrating with TanStack Query for data fetching.

Frontend API Layer

Patterns for the API layer in React applications using TanStack Query and type-safe API clients.

Canonical Examples

• API Client: client.ts
• Token Store: token-store.ts
• API Declaration: get-task-templates.ts

See references/api-layer-examples.md for full code examples.

Architecture

Component → TanStack Query Hook → API Declaration → API Client → Backend

Core Rules

1. API Declarations in {feature}/api/*.api.ts files
2. Type Safety: Shared types from @eridu/api-types
3. Query Keys: Centralize using factory pattern with listPrefix + list
4. No FE Data Joins: If a view needs a display field, the primary API must include it. Do not call a second endpoint and join client-side.
5. Canonical Resource Routes: Call canonical collection endpoints with target_type/target_id filters, not deeply nested paths mirroring component placement.
6. Decimal Normalization: Normalize both stored API value and user input through the same money helper before comparing.
7. AbortSignal: Always destructure { signal } from queryFn context and forward to API fetchers.

Query Key Factory Pattern

export const taskTemplateKeys = {
  all: ['task-templates'] as const,
  lists: () => [...taskTemplateKeys.all, 'list'] as const,
  listPrefix: (studioId: string) => [...taskTemplateKeys.lists(), studioId] as const,
  list: (studioId: string, filters?: unknown) => [...taskTemplateKeys.listPrefix(studioId), filters] as const,
  detail: (id: string) => [...taskTemplateKeys.all, 'detail', id] as const,
};

• Use listPrefix for mutation invalidation (clears ALL filter combos for a scope)
• Use list(...) in queryKey for useQuery/useInfiniteQuery
• Memoize query key calls in useMemo when used outside queryKey option

Mutation Patterns

• After success: invalidate with listPrefix, not exact list key
• Write-through cache: setQueriesData for immediate UI, then invalidateQueries
• Silent mutations (autosave): add silent?: boolean to variables, guard invalidation with if (!variables.silent), set meta: { suppressErrorToast: true }

Searchable Lookup Contract

• Build a field-by-field matrix: control name, endpoint, scope, search params, fallback
• Include scope discriminator in query key (studioId ?? 'admin') for dual-scope helpers
• Extract shared useSearchQuery helper when 2+ lookup hooks exist in same file
• Dead onSearch wiring = broken implementation, not acceptable placeholder

Route Loader Prefetch

loader: ({ context: { queryClient }, params: { studioId } }) => {
  void queryClient.prefetchQuery({ queryKey, queryFn });
},

• Use void prefetchQuery (non-blocking), not await ensureQueryData
• Match query keys exactly to component useQuery calls
• Lift queries to parent when child data should be warm before render

Internal Read Freshness Policy

Checklist

• API client configured with Better Auth token management
• All requests in {feature}/api/*.api.ts
• Query keys use factory pattern with listPrefix
• Types from @eridu/api-types
• signal forwarded to API fetchers
• Mutations invalidate via listPrefix, not exact key
• No FE data joins for required display fields
• Money comparisons normalized through same helper

Related Skills

• frontend-state-management — State management patterns
• frontend-error-handling — Error handling
• shared-api-types — Shared API types