Mastra `@mastra/core@1.42.0` adds trusted system actor execution and signal framework

Mastra's `@mastra/core@1.42.0` release, published by PaulieScanlon on June 12, 2026, delivers a broad set of new capabilities centered on trusted background execution, signal-driven agent wiring, and storage durability. The headline addition is a trusted "system actor" primitive: by passing an `actor` object with `actorKind: 'system'` to `workflow.execute()`, `tool.execute()`, `agent.generate()/stream()`, or `MastraMemory.checkThreadFGA()`, server-side background processes such as cron jobs and schedulers can bypass JWT and human membership requirements while still respecting tenant-scoped fine-grained authorization (FGA). A new `SignalProvider` framework adds declarative agent signal wiring with built-in subscription tracking, polling lifecycle management, and webhook support; bundled providers include `WebhookSignalProvider` and the higher-level `TaskSignalProvider`.

Tool suspension is now agent-agnostic: `ask_user` and `submit_plan` use the generic tool-suspension primitive and work on any agent, not just Harness.

Tool suspension is now agent-agnostic: `ask_user` and `submit_plan` use the generic tool-suspension primitive and work on any agent, not just Harness. Harness surfaces `tool_suspended` events and resumes via `respondToToolSuspension`, with support for multiple concurrent suspensions. Task tools (`task_write/update/complete/check`) gain durability through a new per-thread `threadState` storage domain keyed by `(threadId, type)`, with `ThreadStateLibSQL` for persistence across restarts. On the infrastructure side, Postgres gains `PostgresStoreVNext` with a partitioned, insert-only observability domain for scalable OLAP spans/logs/metrics; ClickHouse adds opt-in replicated tables for multi-replica clusters; and Harness v1 sessions become durable across backends including new LibSQL support. Three new packages ship: `@mastra/openai` runs OpenAI Agents SDK agents through Mastra's `generate()/stream()` with tracing and usage continuity; `@mastra/railway` provides a WorkspaceSandbox provider for Railway Sandboxes; and `@mastra/voyageai` adds VoyageAI embeddings (including multimodal) and rerankers.

This release includes breaking changes: `harness.respondToQuestion()` is removed in favor of `harness.respondToToolSuspension()`; the `ask_question` event is replaced by `tool_suspended`; question-related Harness APIs and types (`registerQuestion`, `pendingQuestion`, `HarnessQuestion*`) are removed; `pendingSuspension` becomes `pendingSuspensions: Map`; and `harness.respondToPlanApproval()` along with `plan_approval_required/plan_approved` events are removed, with `submit_plan` now resumed via `respondToToolSuspension({ toolCallId, resumeData: { action, feedback } })`.

Key facts

1. 01Trusted `actor` system lets background jobs (cron, schedulers, queues) call `workflow.execute()`, `tool.execute()`, `agent.generate()/stream()`, and memory FGA checks without JWT or human membership.
2. 02New `SignalProvider` abstraction supports subscription tracking, polling lifecycle management, and webhooks; includes `WebhookSignalProvider` and `TaskSignalProvider`.
3. 03`ask_user` and `submit_plan` now use the generic tool-suspension primitive and work on any agent; Harness resumes via `respondToToolSuspension` with multiple concurrent suspension support.
4. 04Task tools store state in a new per-thread `threadState` storage domain; `ThreadStateLibSQL` adds durability across restarts.
5. 05Postgres gains `PostgresStoreVNext` with a partitioned, insert-only observability domain; ClickHouse adds opt-in replicated tables; Harness v1 sessions become durable including LibSQL support.
6. 06Three new packages: `@mastra/openai` (OpenAI Agents SDK), `@mastra/railway` (Railway Sandboxes), `@mastra/voyageai` (embeddings and reranking).
7. 07Breaking changes remove `respondToQuestion`, `ask_question` event, and all Harness question-related APIs in favor of the unified `respondToToolSuspension` API.

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