docs(mastra): Document classifier evaluation tracing

[sentry-junior]

DESCRIBE YOUR PR

Document tracing of Mastra Classifier evaluations (for example Jev), which now show up as gen_ai.evaluate spans. The new section in the Mastra guide covers a setup example, the data captured, how Mastra's span output processors filter it, and privacy controls. It follows the Vercel AI Jev section from #19692. The Mastra span mapping table gets a CLASSIFIER_EVALUATION row, and the TypeSafe page now links to the new section.

Shipped in Sentry JavaScript SDK 11.6.0 via getsentry/sentry-javascript#25044. Mastra added Classifier in @mastra/core 1.69.0.

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via Andrei Borza.

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Project	Deployment	Actions	Updated
sentry-docs	Ready	Preview	Oct 9, 2026 12:01pm UTC

1 Skipped Deployment

Project	Deployment	Actions	Updated
develop-docs	Ignored	Preview	Oct 9, 2026 12:01pm UTC

[cursor]

The plan checks page duration, 5xx responses, and error events on the changed guide pages. An issue escalates when 5xx responses appear or error events rise from zero.

Monitoring in production

Services: sentry-docs.

Mention @change-monitor in a comment to update the plan.

Plan

What changed

The Mastra guide now documents Classifier evaluation tracing. Those evaluations now show as gen_ai.evaluate spans. The span map table now includes CLASSIFIER_EVALUATION. The shared span map table also ships on the Mastra Cloudflare guide. The TypeSafe page now links to that Mastra section. sentry-docs must deploy before this text is live.

Risk

A broken include can fail both Mastra guide pages. A markdown fault can fail the TypeSafe page. Readers then see an error page instead of the guide. The blast stays on those JavaScript guide pages.

Intended effect

This change only adds documentation. Telemetry cannot show the new heading or table row. The executor cannot confirm the new text from Sentry. Treat intended_effect as unknown. Absent would mean the live Mastra guide still lacks the Classifier section.

Regression watch

Traces sample at 30 percent. Span counts are sampled. Sitewide /:path*? p50-p95 was 89-907ms in this window. Mastra and TypeSafe page duration should stay inside that band. Mastra pages produced 287 /:path*? spans. TypeSafe pages produced 103. Sitewide /:path*? volume was 1,120,443 spans. Escalate if either page count falls to zero while sitewide volume holds.

Watch	Baseline	Window	Source	Escalate when
5xx on Mastra or TypeSafe URLs	0 responses	2026-10-08T10:00:00Z to 2026-10-09T10:00:00Z	Sentry org sentry project docs. Query environment:production http.status_code:>=500 with http.url matching those paths	any 5xx appears
Error events on Mastra or TypeSafe URLs	0 events	2026-10-08T10:00:00Z to 2026-10-09T10:00:00Z	Sentry org sentry project docs. Query environment:production with url matching /platforms/javascript/guides/mastra/ or /configuration/integrations/typesafe	count rises above 0
Mastra /:path*? p75 duration	241ms, hold inside 89-907ms	2026-10-08T10:00:00Z to 2026-10-09T10:00:00Z	Sentry org sentry project docs. Query environment:production transaction:"/:path*?" with Mastra http.target or http.url	p75 rises above 907ms
TypeSafe /:path*? p75 duration	403ms, hold inside 89-907ms	2026-10-08T10:00:00Z to 2026-10-09T10:00:00Z	Sentry org sentry project docs. Query environment:production transaction:"/:path*?" with TypeSafe http.target or http.url	p75 rises above 907ms

If error events rise, inspect code tabs and MDX render on those pages.

Not observable

Live page content is not in Sentry. The new heading, table row, and anchor are not queryable. Client LCP is not available for these paths. Transactions use the catch-all /:path*? name. Pageload transaction.op returned no rows.