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Agents tracked: 258 Downloads (7d): 219M up 6.1% GitHub stars: 5.5M VS Code installs: 148M Releases (7d): 293 Agent status: 2 with issues Updated Oct 7, 2026
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Mastra changelog: what's new each month

Every stable Mastra release summarised by month: the highlights, new features, improvements, fixes and anything you need to act on. 3 months covered; the current month updates daily.

October 2026 · so far

2 releases: 1.73.0 → 1.74.0

October brought improvements to agent resilience, stream handling, and memory access, along with fixes for provider failures and chat integrations. The month also included updates to the playground UI and security dependency upgrades.

Action needed
  • ThreadViewByTrace, TraceThreadPanel, and ThreadTrace no longer accept anchorTraceId; use pageSize and onLoadOlder instead.
  • ThreadTrace.LoadMoreSentinel removed; use pageSize and onLoadOlder for pagination control.

Highlights

  • Agents now automatically recover from transient provider failures and other common errors without configuration.
  • Tools can now read the full conversation history directly from the execution context.
  • Durable streams changed to use finishReason and output.tripwire instead of separate tripwire chunks.
  • Fixed Slack agents ignoring mentions after being renamed and failing after server restart.
  • Subagent models can now resolve using the calling run's request context.

New

  • Tool-call-resumed stream chunk emitted when a suspended or approval-gated tool call resumes.
  • agent.getMessages() method added to tool execution context for reading current conversation.
  • Group filtering and sort ordering added to observational memory history queries.
  • Export of findGatewayForModel and getGatewayId from @mastra/core/llm for model routing checks.
  • Optional resolveSubagentModel callback in AgentControllerConfig for custom provider handling.

Improved

  • Invalid tool-call IDs on Anthropic models are now rewritten automatically, avoiding failed calls.
  • Agent abort now completes immediately when rate-limit pause occurs instead of waiting up to 10 seconds.
  • Repository-backed Slack sessions can recover from failed GitHub authentication without restarting.
  • Provider registry and model documentation updated with latest available models and providers.

Fixed

  • Durable streams no longer emit duplicate tripwire information.
  • Chat channel agents now respond to mentions after being renamed.
  • Slack Factory runs no longer fail with credential loading errors after server restart.
  • Provider history incompatibilities handled automatically in agent recovery.

September 2026

9 releases: 1.64.0 → 1.72.0

September brought major updates to observability, workflow capabilities, and UI components, with significant API changes across factory configuration, trace querying, and playground components. The month included a major MCP rewrite and new features for advanced trace aggregation, workflow building, and model selection.

Action needed
  • @mastra/factory: sandbox config must be a callback, not options object; workdir/maxSandboxes removed.
  • @mastra/factory: defineBoard() phases require kind, working phases require role, initialPhase must be resting.
  • @mastra/factory: global rules object removed; use MastraFactory({ rules }) instead.
  • subscribeQueuedMessages replaced with subscribeThreadEvents (listener receives typed events).

Highlights

  • Studio Workflow Builder backend enables visual editing and persistence of workflow definitions.
  • Advanced trace queries now support aggregation, thread grouping, filtering by span names and outcomes, with deterministic cursor pagination.
  • ModelSelectionProcessor lets agents pick different models per request based on a classifier, routing simple requests to cheaper models while keeping a capable default.
  • MCP 2.0 major rewrite with 2026-07-28 protocol support and new suspend/resume APIs replaces legacy handshake.
  • Observability storage gains trace deletion, feedback review status tracking, and per-endpoint discovery features.

New

  • Studio Workflow Builder backend for persisted, visually-authored workflow definitions.
  • Classifier registration and classifier steps with typed answers and token usage in workflows.
  • ModelSelectionProcessor to dynamically select models per request with fallback handling.
  • Advanced trace aggregation via planTraceAggregate() and aggregateTraces() with grouping and measures.
  • Thread query contract (queryTraceThreads/queryThreads) for grouping traces by thread.
  • Cross-agent communication tools and peer thread signal mechanisms (experimental, off by default).
  • Trace filters for span names, model providers, timing, outcomes, and version lineage.
  • Per-endpoint discovery features for observability storage (entity types, services, environments).

Improved

  • Sandbox configuration now uses callbacks (ctx => new E2BSandbox) for dynamic setup.
  • Workflow control-flow entries (.parallel, .branch, .foreach, etc.) now support optional id, description, and metadata.
  • Trace deletion now cascades to spans, scores, feedback, and logs; dataset.deleteExperiment() deletes associated traces.
  • Agent Controller stream messages changed to messagestart plus ID-addressed messageupdate deltas for efficient delivery.
  • Background execution now supports per-call dispositions, awaited calls, and bounded delegated tool execution.
  • Observability feedback now carries reviewStatus (needs-review/reviewed) with filtering and update endpoints.
  • Model timeout control via modelSettings.timeout.firstChunkMs to bound first chunk latency.
  • Consistent, resumable prune() execution for storage adapters with bounded work and cancellation.

Fixed

  • Server-defined toModelOutput now supported for client-side tools without execute functions.
  • Guardrail processors now have configurable error handling instead of always warning and failing open.
  • Observer detach() now works correctly; early exit from fullStream also stops observation.
  • Background task execution fenced with persisted, expiring ownership leases to prevent duplicate execution.
  • Workspace grep now includes .sas, .log, and .jsonl files by default with extensible text-extension whitelist.
  • Model failure in Observer/Reflector no longer ends the run when failurePolicy is 'continue'.

August 2026

8 releases: 1.56.0 → 1.63.0

August brought declarative workflow persistence, improved experiment controls, and foundational changes to how agents handle signals and traces. The month also refined storage efficiency and fixed several memory and session management issues.

Action needed
  • MASTRAPLATFORMSECRETKEY auth removed for workspace providers; use MASTRAPLATFORMACCESSTOKEN or pass accessToken explicitly.
  • Stored workflows renamed to dynamic workflows: addStoredWorkflow → addDynamicWorkflow, StoredWorkflow types → DynamicWorkflow.
  • CostGuardProcessor renamed to TokenCostControl; deprecated aliases will be removed in future major version.
  • Channel agent replies now post as markdown by default; set textFormat: 'plain' to preserve plain-text posting.

Highlights

  • Stored workflows renamed to dynamic workflows with new persistence and loading semantics.
  • Agents now support transient signals that remind the model without retaining history, and can filter tool results through a new processToolResult lifecycle hook.
  • TokenCostControl processor replaces CostGuardProcessor with better reliability, diagnostics, and budgeting options.
  • Caller-driven experiments let external orchestrators own the experiment loop while Mastra tracks results.
  • Channel agents now post replies as markdown by default, with plain-text posting available via configuration.

New

  • Item-level scorer selection for dataset experiments.
  • Batch trace ID filtering in observability metric queries.
  • Per-run controls to keep experiment and score results in memory without writing to storage.
  • Tool definitions now captured in MODELGENERATION span attributes.
  • Transient agent signals that deliver reminders without retaining conversation history.
  • Typed experiment provenance and grouping fields that persist across runs and support filtering.
  • instructions.ts as a code alternative to instructions.md for file-based agents.
  • ProcessHandle.closeStdin() to signal end-of-file to background processes.

Improved

  • Declarative, persistable workflow graphs with strict save-path validation and lenient load-path handling.
  • RegexFilterProcessor now reports what the redact strategy rewrote via the onViolation callback.
  • Browser UI can now import toAISdkMessages without requiring Node.js APIs.
  • AgentController supports live-session deletion with process-local listeners.
  • Cost checks now issue fewer queries against observability storage.
  • Sessions resume existing conversations instead of opening empty threads on startup.
  • MCP tools served over HTTP see the authenticated caller when running behind a Mastra server.
  • Graceful shutdown options for generated servers with configurable drain time.

Fixed

  • Memory leak where suspended agent runs were never released from memory.
  • Sessions opening new empty threads on every start instead of resuming conversation.
  • Traces starting under external parent spans not appearing in Mastra Studio.
  • Resumed agent and workflow runs now properly maintain link to suspended run's trace.
  • Fixed worker processes to discover schedules created after startup without restart.
  • Output stream processor traces remaining open when streams close or cancel before finish.

Summaries are written automatically from the official release notes (full changelog ↗); check the original notes before relying on a detail. Mastra: pricing, features and alternatives · All changelogs