Mastra Changelog 2025-05-01

Our latest release features major workflow updates, support for MongoDB, support for the newest MCP transport type, and more.

vNext workflows: the next generation of Mastra workflows

In case you missed it in our changelog from last week, we’ve given workflows a major overhaul based on user feedback. On Wednesday we released vNext workflows in alpha; now, we’re releasing vNext in stable (0.9.1).

vNext will feature several improvements that largely address 3 big needs: stronger control flow, better type safety, and multi-engine support.

Here’s a code sample that shows the new syntax:

workflow
  .then(fetchWeather)
  .branch([
    [
      async ({ inputData }) => {
        return inputData?.rainChance > 0.5;
      }, // conditional
      planIndoorActivities, // step or workflow
    ],
    [
      async ({ inputData }) => {
        return inputData?.rainChance <= 0.5;
      },
      planActivities, // step or workflow
    ],
  ])
  .commit();

Here are some of the biggest improvements we’ve made around control flows:

• Nested Workflows are now first-class citizens and the first primitive to reach for when composing any nested control flows or circular execution structures
• Looping (while or until) accepts a single Step or Workflow and repeats until conditions are met
• .branch() replaces if/else, providing clearer conditional paths. Each truthy condition executes in parallel. And .parallel() for condition-less parallel execution path branching.
  • Branching creates a visual mental model of forking paths in a tree, which accurately represents workflow conditions
• .then() is now the universal connector (.step() has been retired)
• Mastra primitives, like agents and tools, can be transformed to workflow steps using createStep()
• We no longer have the .after() command; users reported the loop-back syntax was hard to reason about. Now, in vNext, branching and dependencies are encapsulated in child workflows and explicit control flow changes.

Transitioning from legacy to vNext

Next week, we’ll be switching over to vNext during our next official release on May 6th, 2025. That means importing from @mastra/core/workflows will give you the vNext workflows.

If you’re using the legacy workflow system, and you want to upgrade Mastra versions but you’re not yet ready to switch over, you can use the legacy import and prefix, eg:

import { Step, Workflow } from '@mastra/core/workflows/legacy'
import { Mastra } from '@mastra/core/mastra'
const step1 = new Step(...)
const workflow = new Workflow(...).step(step1).commit();

const mastra = new Mastra({
  // registering legacy workflows
  legacy_workflows: {
    myWorkflow: workflow
  }
})

// accessing the workflow through the mastra class:
mastra.legacy_getWorkflow('myWorkflow')

Read the full blogpost to learn all about vNext. Full docs here.

New vectorDB provider: MongoDB

We've added MongoDB as a vector database provider, giving you another solid option for storing and retrieving vector embeddings in your applications. Mastra now has 12 vector DB integrations including Postgres/pgvector, libsql, Chroma, and many others.

MongoDB has been pushing the envelope with vector search since early 2023 and we’re happy that you can now use MongoDB’s vector capabilities directly with Mastra.

Streamable HTTP MCP transport

We now support Streamable HTTP as an MCP transport.

Previously, there were two ways to create an MCP server:

1. Stdio transport (using a program running on your computer for the MCP tools)
2. SSE transport (a web server hosted somewhere where you connect via URL)

MCP deprecated the latter (SSE) and replaced it with Streamable HTTP. We now support this new Streamable HTTP MCP transport type.

Other updates

• We recently added Docker as a new MCP registry option to The MCP registry registry
• We’re hosting the very first Mastra virtual hackathon, MASTRA.BUILD, from May 12th-16h. Cash prizes and tons of hands-on building. Find the schedule & registration on our Lu.ma.

Find the full release log for the past week here.

Happy building and see you next week… 🚀