fix(server): clean up custom route streams on disconnect

[mbenhamd]

What changed

Custom API routes now receive the request abort signal, and Node-based adapters pipe streamed Response bodies through the shared server bridge with backpressure-aware cancellation. Fastify, Express, and Koa now stop reading custom route streams when the client disconnects, while Hono forwards the host runtime's request signal into custom route handlers.

This follows up on #16307 after the built-in Fastify stream cleanup in #16308. It keeps MCP and Bun-specific completed-body behavior out of this PR.

Why

The custom route bridge previously read Web Response.body chunks manually and wrote them to Node responses without backpressure or disconnect cleanup. Long-running custom route streams could keep producing after the client closed the connection.

Validation

• corepack pnpm turbo build --filter ./packages/core
• corepack pnpm turbo build --filter ./packages/server
• corepack pnpm turbo build --filter ./packages/mcp
• corepack pnpm --dir packages/server exec vitest run src/server/server-adapter/index.test.ts --config vitest.config.ts
• focused Fastify, Express, Koa, and Hono adapter test files
• Fastify, Express, Koa, and Hono adapter builds
• git diff --check

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

2 Skipped Deployments

Project	Deployment	Actions	Updated (UTC)
mastra-docs-1.x	Skipped		May 12, 2026 10:39pm
mastra-playground-ui	Skipped		May 12, 2026 10:39pm

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: a4e75b19-be7d-4fd0-b18d-a6407c47efd7

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/custom-route-stream-cleanup

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[changeset-bot]

🦋 Changeset detected

Latest commit: 9ef054b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 23 packages

Name	Type
@mastra/express	Patch
@mastra/fastify	Patch
@mastra/hono	Patch
@mastra/koa	Patch
@mastra/server	Patch
@mastra/deployer	Patch
@mastra/nestjs	Patch
mastra	Patch
@mastra/deployer-cloud	Patch
@mastra/deployer-cloudflare	Patch
@mastra/deployer-netlify	Patch
@mastra/deployer-vercel	Patch
@mastra/temporal	Patch
create-mastra	Patch
@mastra/core	Patch
@internal/playground	Patch
mastracode	Patch
@mastra/mcp-docs-server	Patch
@mastra/client-js	Patch
@mastra/opencode	Patch
@mastra/longmemeval	Patch
@mastra/playground-ui	Patch
@mastra/react	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR