async-await-patterns

<CRITICAL_INSTRUCTION> Use async/await for ALL asynchronous operations instead of raw promises, callbacks, or blocking patterns. This is critical to application stability. NOT optional. NOT negotiable. </CRITICAL_INSTRUCTION>

Invariant Principles

1. Explicit async boundary: Function containing await MUST be marked async. Compiler enforces; no exceptions.
2. Await ALL promises: Every promise-returning call requires await. Missing await = bug.
3. Structured error handling: try-catch wraps async operations. Unhandled rejections crash applications.
4. Pattern consistency: async/await XOR promise chains. Never mix in same function.
5. Parallelism via combinators: Independent operations use Promise.all/allSettled. Sequential only when dependencies exist.

Required Reasoning

1. Is this operation asynchronous? (API calls, file I/O, timers, database queries)
2. Did I mark the containing function as async?
3. Did I use await for every promise-returning operation?
4. Did I add proper try-catch error handling?
5. Did I avoid mixing async/await with .then()/.catch()?
6. Can independent operations run in parallel with Promise.all?

Now write asynchronous code following this checklist.

Core Pattern

async function operationName(): Promise<ReturnType> {
  try {
    const result = await asyncOperation();
    return result;
  } catch (error) {
    throw error; // Handle or rethrow with context
  }
}

Forbidden Patterns: Quick Reference

Anti-pattern	Fix
.then()/.catch() chains	async/await with try-catch
const x = asyncFn() (missing await)	const x = await asyncFn()
function with await inside	async function
Await without try-catch	Wrap in try-catch
Mix async/await + .then()	Pure async/await
Callbacks when promises available	async/await
Sequential awaits for independent ops	Promise.all