---
name: role-fullstack-api-frontend-integration-f65cf7e2f632
description: |
  Integrate APIs with frontend applications using type-safe patterns: tRPC for
  end-to-end type safety, REST client generation (openapi-typescript, orval),
  TanStack Query / SWR for data fetching, optimistic updates, and error handling.
allowed-tools: Read, Grep, Glob, Bash
---

# API-Frontend Integration

## When to Use

Activate when connecting a backend API to a frontend application, setting up data-fetching patterns, implementing optimistic updates, or establishing type-safe API contracts.

## Integration Strategy Selection

| Approach              | Type Safety | Setup Cost | Best For                         |
|-----------------------|-------------|------------|----------------------------------|
| tRPC                  | Full E2E    | Low        | Monorepos, same-team ownership   |
| OpenAPI codegen       | Generated   | Medium     | REST APIs, multi-team            |
| GraphQL + codegen     | Generated   | Medium     | Complex relational data queries  |
| Manual fetch + Zod    | Runtime     | Low        | Simple APIs, third-party services|

## tRPC Integration (Recommended for Monorepos)

1. Define routers in `packages/api/src/routers/` with input validation via Zod.
2. Export the `AppRouter` type -- never the runtime object -- to the frontend.
3. Create a tRPC client with `httpBatchLink` or `httpSubscriptionLink`.
4. Wrap the app with `trpc.Provider` and `QueryClientProvider`.
5. Use `trpc.useQuery()` and `trpc.useMutation()` -- types flow automatically.

## REST Client Generation

- **openapi-typescript** -- generates TypeScript types from OpenAPI 3.x specs. Pair with `openapi-fetch` for typed fetch calls.
- **orval** -- generates React Query hooks, Zod schemas, and mock service workers from OpenAPI specs. Preferred for complex REST APIs.
- Automate generation in CI: `"codegen": "orval --config orval.config.ts"`.

## Data Fetching Patterns (TanStack Query / SWR)

```typescript
// Query with proper typing, stale time, and error handling
const { data, isLoading, error } = useQuery({
  queryKey: ['users', filters],
  queryFn: () => api.users.list(filters),
  staleTime: 5 * 60 * 1000,
  retry: 3,
  retryDelay: (attempt) => Math.min(1000 * 2 ** attempt, 10000),
});
```

## Optimistic Updates

1. Use `onMutate` to snapshot previous data and apply the optimistic change.
2. Use `onError` to rollback to the snapshot on failure.
3. Use `onSettled` to invalidate queries and refetch the authoritative state.
4. Show a subtle indicator (toast, inline badge) so the user knows the change is pending.

## Error Handling Strategy

- **API errors** -- define a shared error shape (`{ code, message, details? }`). Parse with Zod on the client.
- **Network errors** -- distinguish between offline, timeout, and server errors. Show different UI for each.
- **Error boundaries** -- wrap route segments with React Error Boundaries. Provide a "Retry" action.
- **Form validation** -- validate on the client first (Zod + react-hook-form), then re-validate on the server. Surface server-side errors next to the relevant field.

## Loading and Empty States

- Use skeleton loaders (not spinners) for content areas to reduce perceived latency.
- Always handle the empty state: "No results found" with a clear call-to-action.
- Show stale data with a background refresh indicator rather than a full loading state on refetch.

## Common Pitfalls

- Fetching inside `useEffect` without cancellation -- always use TanStack Query or SWR.
- Forgetting to invalidate related queries after a mutation.
- Not deduplicating concurrent identical requests (TanStack Query handles this automatically).
- Ignoring error responses and only checking `data` -- always handle the error path.


---
Source attribution: rnavarych
Original project: https://github.com/rnavarych/alpha-engineer/blob/c5b74102c7fd584af3d344ba7c331a7bbec3c729/plugins/roles/role-fullstack/skills/api-frontend-integration/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2026 Raman Navarych

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: rnavarych
Original project: https://github.com/rnavarych/alpha-engineer/blob/c5b74102c7fd584af3d344ba7c331a7bbec3c729/plugins/roles/role-fullstack/skills/api-frontend-integration/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering, Product Management
Roles: Backend Developer, Frontend Developer, Full-Stack Developer, Product Manager, Technical Product Manager
Specialties: API, Backend, Frontend
Tools: Openapi Typescript, Orval, Swr, Tanstack Query, Trpc
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 017d1593e73575230326c947969f8d21de659e0948c7f03820dc4f2e2c098660