fix: resolve SSE reconnection loop with separate /sse + /messages endpoints (v2.46.1) (#699)

Fix SSE clients entering rapid reconnection loops because POST /mcp
never routed messages to SSEServerTransport.handlePostMessage() (#617).

Root cause: SSE sessions were stored in a separate `this.session` property
invisible to the StreamableHTTP POST handler. The POST handler only
checked `this.transports` (StreamableHTTP map), so SSE messages were
never delivered, causing immediate reconnection and rate limiter exhaustion.

Changes:
- Add GET /sse + POST /messages endpoints following the official MCP SDK
  backward-compatible server pattern (separate endpoints per transport)
- Store SSE transports in the shared this.transports map with instanceof
  guards for type discrimination
- Remove legacy this.session singleton, resetSessionSSE(), and isExpired()
- Extract duplicated auth logic into authenticateRequest() method
- Add Bearer token auth and rate limiting to SSE endpoints
- Add skipSuccessfulRequests to authLimiter to prevent 429 storms
- Mark SSE transport as deprecated (removed in MCP SDK v2.x)

The handleRequest() codepath used by the downstream SaaS backend
(N8NMCPEngine.processRequest()) is unchanged. Session persistence
(exportSessionState/restoreSessionState) is unchanged.

Closes #617

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Romuald Członkowski
2026-04-03 14:00:53 +02:00
committed by GitHub
parent 2d4115530c
commit 12d7d5bdb6
10 changed files with 493 additions and 437 deletions

View File

@@ -1 +1 @@
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