Our review

Provides an advanced methodology for mastering useTransition and useOptimistic in React 19 with Next.js and Playwright in the ArbitrageX monorepo, including a strict doctrine and validated delivery.

Strengths

Rigorous validation doctrine with clear checkpoints at every step
Concrete focus on server actions and optimistic UI in React 19
E2E integration via Playwright with assertions on DEGRADED/UP/DOWN states
Research-oriented approach requiring reproducible benchmarks and comparison with the public state of the art

Limitations

Heavily tied to a private monorepo and internal conventions
Not a general-purpose React 19 tutorial
Assumes a Next.js environment with Playwright already set up

When to use it

When implementing or debugging a server-action-driven form that needs transitions and optimistic updates in a Next.js application.

When not to use it

For projects without server actions, without Next.js, or when the work is not about advanced React 19 usage.

Examples

Optimistic update for server action form

In hefarica/arbitragex-v2, we have a server action form state in frontend/app. Use useTransition and useOptimistic to update the list optimistically while the server action runs, then add Playwright E2E assertions for the optimistic state.

Debug pending useTransition

Why does useTransition stay pending after a server action fails in our Next.js frontend? Trace the issue with React 19, apply the fail-closed doctrine, and add an E2E test for the error path using Playwright.

Benchmark optimistic updates

Document a React 19 useOptimistic/useTransition benchmark with 95% CI and compare against TanStack Query optimistic updates for our Next.js app in the arbitragex-v2 monorepo, following the skill's post-doc doctrine.

name: arbx-g-g005-advanced-react-19-usetransitionuseoptimistic description: "Post-Doc skill alineada al monorepo hefarica/arbitragex-v2 (Frontend Doctrinal (Next.js + Playwright)). Se activa cuando: server actions form state. Doctrina OMEGA Zero-Mocks · Fail-Closed · El Remoto Manda."

G005 — Advanced React 19 useTransition/useOptimistic

Dominio: Frontend Doctrinal (Next.js + Playwright) Nivel: Post-Doc Trigger: server actions form state Repos de referencia: vercel/next.js · facebook/react · microsoft/playwright · TanStack/query · shadcn-ui/ui · radix-ui/primitives · wevm/viem · wagmi-dev/wagmi Archivos del repo: frontend/app/* · frontend/components/* · frontend/tests/e2e/* · packages/schemas/*

Quick Start

ARBX_BUILD_FOR_LOCAL_E2E=1 ARBX_ASSUME_NO_RPC=1 pnpm playwright test --reporter=list,html

Core Workflow

Cargar contexto del repo hefarica/arbitragex-v2 (rama actual, último PR, estado de CI).
Identificar el subsistema impactado dentro de los archivos del repo listados arriba.
Aplicar la doctrina del nivel Post-Doc sin desviaciones.
Validar contra: lint → typecheck → build → tests → audit → E2E → deploy.
Reportar evidencia en formato Markdown forense (logs, traces, métricas, hash de commit).

Doctrina del Nivel

Aporte de investigación: paper o RFC referenciado.
Benchmarks reproducibles con criterio estadístico (95% CI).
Comparativa contra estado del arte público.

Reglas de Ejecución

| Condición | Acción | |-----------|--------| | CI rojo en main | ABORT — fix-forward, nunca skip | | Drift schema producer↔consumer | ABORT — restaurar isomorfismo Zod/struct | | Cobertura E2E < contrato iter 18 | ABORT — añadir testid + assertion DEGRADED/UP/DOWN | | Secret en plaintext fuera de Vault/age | ABORT — rotar y reportar | | Profit neto ≤ gas + flashloan_fee | ABORT (skill C/E) | | Slippage > banda RiskGate | RESIZE o ABORT (skill C/E) |

Activation Triggers (regex parciales)

server actions form state
advanced react 19 usetransition/useoptimistic
arbitragex-v2 g

Output Esperado

Diff atómico (rustfmt aparte de semántica).
Evidencia: gh pr checks <N>, cargo nextest, traces OTel, screenshots Playwright.
ADR si la decisión cambia contrato (docs/adr/NNNN-*.md).

Advanced React 19 Hooks

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