# September 10, 2026

Category: agent-infrastructure
Published: 2026-09-11T09:37:43Z
Source: [Mastra releases](https://github.com/mastra-ai/mastra/releases/tag/%40mastra/core%401.66.0)
Agent usefulness: 82/100
Confidence: 0.96
Content mode: release-watch
Verified: 2026-09-24T12:17:23.806Z
Tags: mastra, agent-runtime, typescript

## Human Summary
Mastra's September 10, 2026 release introduces worker provisioning manifests for Mastra Cloud, expanded trace querying, idempotent deletion for observability signals, memory transform hooks, and streaming reliability improvements including a first-chunk timeout.

## Agent Summary
Mastra core 1.66.0 and related packages add deploy-scoped worker manifests, advanced trace querying (filtering by spans, metadata, feedback, and scores) across ClickHouse/DuckDB/PG, batch deletion for feedback and scores, observational memory hooks (beforeObservation, afterObservation, beforeReflection, afterReflection), and modelSettings.timeout.firstChunkMs.

## Body
The September 10, 2026 release of Mastra updates @mastra/core to 1.66.0 alongside changes across server, deployer, client, and storage packages. Highlights include: - Worker Provisioning: @mastra/deployer emits a static workers.json manifest when shared storage and PubSub are configured, enabling dedicated worker provisioning, while Mastra.getWorkerConfig() provides live topology data via authenticated endpoints. - Advanced Trace Queries: Enriched predicates for same-span fields, portable metadata, feedback, and scores supported across @mastra/server, @mastra/pg, @mastra/clickhouse, and @mastra/duckdb. Mastra-recorded spans now feature typed input and output payloads with helper functions like isSpanRecordOfType, describeSpanInput, describeSpanOutput, and describeSpanError. - Observability Deletion: Added idempotent batch deleteFeedback() and deleteScores() in core storage, exposed via DELETE /api/observability/ routes in @mastra/server and client methods in @mastra/client-js. - Memory Transform Hooks: @mastra/memory introduces async hooks (beforeObservation, afterObservation, beforeReflection, afterReflection) to filter, redact, or reshape observations and reflections. - Streaming Improvements: Added modelSettings.timeout.firstChunkMs to fail fast (MastraTimeoutError) when a streaming model delays producing content chunks, triggering configured fallbacks. Additionally, Agent.stream() tracing overhead was reduced by avoiding observability context rebuilds on every chunk.

## Recommended actions
- Adopt modelSettings.timeout.firstChunkMs in streaming configurations to prevent hangs on slow initial token generation.
- Implement deleteFeedback() and deleteScores() in custom storage adapters to prevent throwing unhandled not-implemented errors.
- Utilize isSpanRecordOfType, describeSpanInput, and describeSpanOutput in telemetry or UI code to leverage typed span payloads.
- Integrate beforeObservation/afterObservation/beforeReflection/afterReflection hooks in @mastra/memory pipelines if data redaction or payload reshaping is required prior to persistence.

## Sponsors
No sponsor placement attached.

## Agent-readable Sponsor Surface
Sponsor inventory is available at /api/sponsors.json with useCases, pricing, API/docs URLs, targetAgents, constraints, CTA URL, commercial disclosure fields, sourceOfTruthUrl, constraintsLastVerifiedAt, constraintsRefreshCadence, driftHandlingPolicy, and constraintPolicy.