fix(sentry): NEXT_PUBLIC_VERCEL_ENV is unasserted, silently mislabelling preview client events as production

[brianespinosa]

Split out from #86 / PR #198 review.

Problem

src/instrumentation-client.ts tags browser-side Sentry events with:

environment: process.env.NEXT_PUBLIC_VERCEL_ENV || process.env.NODE_ENV

Unlike VERCEL_ENV, Vercel does not populate NEXT_PUBLIC_VERCEL_ENV automatically — it has to be set explicitly in project settings. Nothing in the repo asserts that it is.

If it is missing, the expression falls through to NODE_ENV, which is production in any deployed build. Every client-side error from a preview deployment is then reported to Sentry tagged production.

That is a silent failure with real cost: it pollutes production error rates with preview noise, and makes preview-only regressions invisible when filtering by environment. The server-side configs are unaffected — sentry.server.config.ts and sentry.edge.config.ts use VERCEL_ENV, which Vercel does set.

Verify first

Check whether NEXT_PUBLIC_VERCEL_ENV is actually set in the Vercel project across all three environments. It may already be configured, in which case this is only about preventing regression.

Options

1. Assert it. .env.schema already declares it @optional @public @type=enum(development, preview, production). Tightening to required in preview/production (@required=not(forEnv(development))) would fail the build when it is missing, instead of silently mislabelling. This is the fix the varlock adoption makes cheap.
2. Derive it. Set it from VERCEL_ENV in the schema (NEXT_PUBLIC_VERCEL_ENV=$VERCEL_ENV) so it cannot drift from the server-side value. Removes the manual project-settings step entirely.
3. Document only. Note the requirement and rely on project settings.

Option 2 is probably right — it eliminates the class of error rather than detecting it, and the two values should never legitimately disagree.

References

• src/instrumentation-client.ts — the fallback expression
• src/sentry.server.config.ts, src/sentry.edge.config.ts — server-side equivalents using VERCEL_ENV
• .env.schema — both vars declared