docs: enforce Promise.withResolvers() more explicitly.

[WebReflection]

Issue

We keep seeing patterns like this:

const ended: { resolve?: () => void; reject?: (error: Error) => void } = {}
const exit = new Promise<void>((resolve, reject) => {
  ended.resolve = resolve
  ended.reject = reject
})

as opposite of having just this:

const ended = Promise.withResolvers()

which is more explicit and available since 2024 in all runtimes: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/withResolvers#browser_compatibility

Fixes #

Context

This MR makes the wording around preferring Promise.withResolvers() more explicit, hoping that will lead to less LOC shipped for no reason with also flaky guards around (see both resolve? and reject? instantly attached after so that these are a certainity, not a maybe).

Implementation

The wording has been changed to explicitly avoid the mentioned case, hoping we won't see that pattern with runtime created no-ops around.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (1 files)

• AGENTS.md

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_{Reviewed by grok-4.6 · Input: 34.4K · Output: 3.6K · Cached: 165.1K}

_{Review guidance: REVIEW.md from base branch main}