SSE event streams leak memory on client disconnect

[brendandebeasi]

Description

SSE event streams in server.ts and routes/global.ts leak memory when clients disconnect. The stream.writeSSE() calls are fire-and-forget, so write failures to dead connections go undetected. Bus listeners and heartbeat intervals keep accumulating across reconnects.

In long-running sessions with many reconnects, this causes steady memory growth (~15+ MB observed) from orphaned listeners and intervals that are never cleaned up.

Steps to reproduce

1. Start the OpenCode server (bun dev serve)
2. Open multiple SSE connections (e.g. via browser tabs or curl)
3. Close the connections abruptly (kill the client without a clean close)
4. Repeat steps 2-3 many times
5. Observe that Bus subscription counts grow and memory usage increases steadily

OpenCode version

Latest dev branch

Operating System

macOS (reproduced), likely affects all platforms

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Memory leak: serve and web commands leak child processes on exit; SSE heartbeat interval leaks on server-initiated close #14091: Specifically covers SSE heartbeat interval leaks when the server closes a stream via stream.close() (Hono's onAbort not firing), and Bus.subscribeAll subscriptions accumulating — which is the same root cause described here
• Memory leak: Uncleaned timeouts, intervals, and subscriptions #9156: Covers uncleaned intervals and Bus.subscribe subscriptions leaking across the codebase

If your issue is already covered by one of those, please consider adding details there instead.

[abrekhov]

+1 — confirmed this is the root cause of the 60GB+ OOM crashes reported in #17908. Added detailed diagnostics and root-cause trace there.

[thdxr]

Closing in favor of #20695 where we're collecting all memory-related problems. Please follow that issue for updates.