fix: add Transfer-Encoding chunked to SSE responses

[guoyangzhen]

Problem

SSE streams cause HTTP/2 PROTOCOL_ERROR with some HTTP adapters (e.g. @hono/node-server). The adapters buffer small SSE responses and automatically add a Content-Length header. When the SSE stream closes, this causes an HTTP/2 PROTOCOL_ERROR because HTTP/2 does not allow Content-Length with streaming responses.

Fix

Add Transfer-Encoding: chunked header to all 3 SSE response locations in WebStandardStreamableHTTPServerTransport. This prevents HTTP adapters from buffering and adding Content-Length.

Locations

• Line ~453: GET standalone SSE stream
• Line ~507: SSE stream with replay
• Line ~755: POST SSE response stream

[changeset-bot]

🦋 Changeset detected

Latest commit: 73389b9

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

This PR includes changesets to release 4 packages

Name	Type
@modelcontextprotocol/server	Patch
@modelcontextprotocol/express	Patch
@modelcontextprotocol/hono	Patch
@modelcontextprotocol/node	Patch

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