chore(api): revert the region-move tracing sampler
Why
The measurement #7388 existed to take is done. Vercel Observability, grouped by function_region:
| p50 TTFB | |
|---|---|
iad1 | 293.5ms |
pdx1 | 41.8ms |
But the sampler was never what produced that. It collected zero spans across twenty minutes of live production traffic — while errors flowed normally, host-service traced fine, quota sat clear, and the config was live and correct on ba4bbec87.
Why revert instead of keeping a trickle
"Keep a small sample" isn't available. The sampler doesn't collect a small number of spans, it collects none — so leaving it in place gives config that looks like it samples and doesn't. The next person to read this file would believe it.
Reverting restores the honest state: tracing is off, and off is a thing you can reason about.
What the note preserves
The comment now records that a narrow sampler was tried and produced nothing, so the next attempt starts from "this app cannot currently be traced, cause unknown" rather than from picking a sample rate. That's the actual finding, and it's worth chasing on its own merits — an untraceable API makes the next production mystery much harder than this one was.
Ruled out so far: quota, org-level span ingestion, DSN rate limits, a stale deploy, and name matching (Sentry's docs confirm name is unparametrized at sampling time, but all three route substrings match that form anyway). Suspect but unconfirmed: @sentry/nextjs 10.68 server instrumentation under Next.js 16.3 + Turbopack.
https://claude.ai/code/session_01Ho5jMfrUs1e65svM8M2Hc6
Summary by cubic
Reverts the region-move tracing sampler now that the measurement is done, restoring the previous state where tracing is off. The sampler collected zero spans across 20 minutes of production traffic, so leaving it would have implied sampling works when it doesn't. The comment now records the failed attempt and notes that the app currently cannot be traced for unknown reasons.
Summary by CodeRabbit
- Bug Fixes
- Disabled span tracing for API routes, including desktop version checks, Gmail push notifications, and tRPC requests.