October 15, 2026
Mastra v1.78.0 introduces agent scopes for multi-tenant identity and memory routing, an end-to-end trace aggregation API, and typed signal queuing.
Why this signal matters
Mastra core version 1.78.0 delivers several major observability, identity, and reliability improvements. Key highlights include: - Agent Scopes : Agents support multi-tenant identity via scopes ( : ) configurable per call, on the agent definition, or injected via the MASTRA SCOPES KEY context. Memory can derive resource and thread from these scopes (conflicting definitions throw an HTTP 400). Resumed runs retain their original scopes and reject additions. - Trace Aggregation API : Adds full-stack trace aggregation via POST /observability/traces/aggregate , mastraClient.aggregateTraces() , and React's useTraceAggregateAvailable() , accompanied by discovery schemas for valid dimensions and measures. - Typed Signal Queueing : Introduces Agent.queueSignal() and route POST /agents/:agentId/queue-signal to queue typed signals behind active runs without reducing them to plain text, recording signal metadata directly to the AGENT RUN span. - Storage & Trace List Previews : Persists outputPreview and errorPreview at write time (backed by buildPreview and PREVIEW MAX LENGTH ) across ClickHouse, Postgres, and DuckDB to improve trace query performance. - Workflow Reliability : Fixes .foreach() hangs/corruptions on failure, ensures durable agents run properly across step engines, and preserves suspendData through crashes while rejecting invalid resume payloads with AGENT RESUME INVALID DATA . - Breaking Changes : buildInputPreview() and INPUT PREVIEW MAX LENGTH are deprecated in favor of buildPreview() and PREVIEW MAX LENGTH . Factory sessions eliminate Plan/Explore modes, requiring…
Actionable summary
Mastra released @mastra/core@1.78.0 featuring scoped identity ( resource: , thread: , org: ), end-to-end trace aggregation ( POST /observability/traces/aggregate ), typed signal queuing via queueSignal() , and preview caching for trace queries. Breaking changes deprecate buildInputPreview() and alter Factory session and credential resolution.
- Agent usefulness
- 94/100
- Confidence
- 96%
- Canonical data
- JSON + Markdown
What builders should check
- Upgrade @mastra/server in lockstep with @mastra/core@1.78.0 to prevent AGENT SCOPES SERVER OUTDATED (HTTP 400) errors.
- Replace usage of deprecated buildInputPreview() and INPUT PREVIEW MAX LENGTH with buildPreview() and PREVIEW MAX LENGTH from @mastra/core/storage .
- Update Factory session configurations to remove modeDefaults from PUT /web/config/thinking and configure explicit credential scopes instead of relying on orgFirst cross-scope fallbacks.