Cursor rule

1---
2alwaysApply: false
3---
4 
5## Check Cheap Conditions Before Async Flags
6 
7When 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.
8 
9This is a specialization of [Defer Await Until Needed](./async-defer-await.md) for `flag && cheapCondition` style checks.
10 
11**Incorrect:**
12 
13```typescript
14const someFlag = await getFlag()
15 
16if (someFlag && someCondition) {
17  // ...
18}
19```
20 
21**Correct:**
22 
23```typescript
24if (someCondition) {
25  const someFlag = await getFlag()
26  if (someFlag) {
27    // ...
28  }
29}
30```
31 
32This 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.
33 
34Keep the original order if `someCondition` is expensive, depends on the flag, or you must run side effects in a fixed order.
35