Vercel shipped always-on tracing for production and preview traffic. In beta, available to all plans.
What changed? You can now configure sampling rules to continuously collect traces from live traffic — not just your own browser session. Rules target an environment (All, Production, Preview) and can scope to a path prefix like /checkout. Infrastructure and outbound fetch spans are captured automatically; framework spans need @vercel/otel. Traces are viewable in Logs or via vercel traces get <request-id>.
Pricing: $0.50 per 1M span units. Retention matches your runtime log retention (1h Hobby, 1d Pro, 3d Enterprise).
Why a builder cares. Session replay only shows what you did. Always-on tracing shows what your users actually hit — the 5xx during checkout, the third-party call that hangs, the preview branch that degrades under load. No more "can you reproduce that?" conversations.