skills

.agents/skills/vercel-react-best-practices/rules/async-cheap-condition-before-await.md

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+---
+title: Check Cheap Conditions Before Async Flags
+impact: HIGH
+impactDescription: avoids unnecessary async work when a synchronous guard already fails
+tags: async, await, feature-flags, short-circuit, conditional
+---
+
+## Check Cheap Conditions Before Async Flags
+
+When a branch uses `await` for a flag or remote value and also requires a **cheap synchronous** condition (local props, request metadata, already-loaded state), evaluate the cheap condition **first**. Otherwise you pay for the async call even when the compound condition can never be true.
+
+This is a specialization of [Defer Await Until Needed](./async-defer-await.md) for `flag && cheapCondition` style checks.
+
+**Incorrect:**
+
+```typescript
+const someFlag = await getFlag()
+
+if (someFlag && someCondition) {
+  // ...
+}
+```
+
+**Correct:**
+
+```typescript
+if (someCondition) {
+  const someFlag = await getFlag()
+  if (someFlag) {
+    // ...
+  }
+}
+```
+
+This matters when `getFlag` hits the network, a feature-flag service, or `React.cache` / DB work: skipping it when `someCondition` is false removes that cost on the cold path.
+
+Keep the original order if `someCondition` is expensive, depends on the flag, or you must run side effects in a fixed order.