September 22, 2026
Mastra's September 22, 2026 release introduces @mastra/mcp@2.0.0 built on the MCP 2026-07-28 spec, adds Azure AI Search and Weaviate vector backends, optimizes durable-agent checkpoints, and delivers breaking changes to streaming message events.
Why this signal matters
The Mastra release on September 22, 2026 brings major architectural and performance updates across core, MCP, and storage packages. Highlights include: - MCP v2 Architecture: @mastra/mcp@2.0.0 migrates strictly to MCP revision 2026-07-28, eliminating initialization handshakes and session headers while adopting context.suspend() and context.resumeData with signed continuation states (requestState). - New Vector Backends: Introduced @mastra/azure-ai-search@0.1.0 and @mastra/weaviate@0.1.0 with rich filtering capabilities. - Durable-Agent Snapshotting: Halts default persistence of running checkpoints to prevent storage churn, preserving pending, paused, and suspended states unless recovery.durableAgents is set to 'auto'. - Memory Trimming: Added token-budgeted messageHistory (maxTokens, atMaxRemoveTokens) that trims the oldest context without deleting stored records. - Observability Improvements: Advanced trace queries gain page-based pagination, delta polling, and root-span summary previews across ClickHouse, DuckDB, and PG adapters. - Core Enhancements: Added extensible workspace grep text extensions, resumable storage prune() execution, server-side orderBy for datasets/experiments, and dataset snapshot integrity helpers. - Breaking Changes: Agent Controller streaming message protocol now sends one start event followed by ID-addressed updates and an ID-only end event. @mastra/mcp@2.0.0 removes legacy transport, handshake, and elicitation surfaces.
Actionable summary
Mastra core and ecosystem packages updated. Key highlights: @mastra/mcp@2.0.0 enforces MCP 2026-07-28 with suspend/resume state handling and drops legacy handshakes; agent controller streaming events now emit start, delta updates by ID, and end with ID only; durable agents stop persisting running checkpoints by default; and new vector stores @mastra/azure-ai-search and @mastra/weaviate are added.
- Agent usefulness
- 82/100
- Confidence
- 96%
- Canonical data
- JSON + Markdown
What builders should check
- Update client-side stream consumers for Agent Controller to handle the new ID-addressed delta updates and ID-only message end events.
- Migrate MCP integrations to @mastra/mcp@2.0.0 by removing legacy handshake/elicitation code and adopting the suspend/resume API.
- Review durable agent configurations: enable recovery.durableAgents: 'auto' or configure shouldPersistSnapshot if running checkpoints must be persisted to storage.
- Optionally update trace query consumers to leverage page-based pagination, delta polling, and root-span preview fields.