Staging and synthetic runs

​

Ingest endpoint

import { createIngestHandler } from 'crust/ingest'

export const POST = createIngestHandler({
  secret: process.env.CRUST_INGEST_SECRET!,
  dir: '.perf-server/samples',
  ratePerMinute: 60,
})

startCollector({ ingestUrl: '/api/__crust/ingest' })

​

Synthetic runs

npx crust synthetic https://staging.example.com / /products/1 \
  --iterations 5 --cpu 4 --network fast-3g

crust synthetic 01KZ016N3F895E073QFKRWR979  4x cpu · fast-3g · median of 4

/                  ttfb 9 ms  fcp 214 ms  lcp 214 ms  128.2 kB
/products/1        ttfb 10 ms fcp 226 ms  lcp 226 ms  136.7 kB

pnpm add -D playwright && pnpm exec playwright install chromium

​

What makes the numbers comparable

• The first iteration is discarded. A cold start measures the deployment’s morning — server compile caches, CDN misses, JIT warmup — not your code.
• The median is reported, not the mean. A mean is hostage to a single GC pause.
• Throttle and network are pinned into the run’s environment fingerprint.
• The collector and widget are off. A measurement tool competing for the main thread moves the numbers it reports.

​

Server spans

import { registerOTel } from '@vercel/otel'
import { CrustSpanAggregator } from 'crust/otel'

export function register() {
  registerOTel({ serviceName: 'my-app', spanProcessors: [new CrustSpanAggregator()] })
}