[satoren]

Problem

Cursor fails to connect with:

Client error: Streamable HTTP error: Failed to open SSE stream: Conflict
Client error: Maximum reconnection attempts (2) exceeded.

A second GET SSE stream for a session was refused with 409 Conflict. But a client that drops its GET stream is not noticed until the next write to it — the inactivity ping, up to session_timeout (30s by default) later. Until then the stale stream stays tracked, so a client reconnecting within that window is refused. (The official TypeScript/Python SDK servers also answer 409, but they notice the disconnect immediately, so they never hit a stale stream.)

Change

• A GET for a session that already has a stream now casts :replaced to the existing stream(s), on any node, and takes over as the session's stream.
• The replaced stream sends a closed / replaced event and shuts down.
• The 409 test is replaced with one asserting the takeover.

Notes

• The spec allows multiple streams; the official SDK clients hold one GET stream, so a takeover only happens on reconnect.
• Resource subscriptions held by the replaced stream are dropped, as they were before when the stale stream eventually timed out.

🤖 Generated with Claude Code