SSE /event endpoint does not forward events to clients in v1.14.48 (regression from v1.14.40) #26866

Bug Description

The /event SSE endpoint in opencode 1.14.48 does not forward any internal events to connected clients. The endpoint accepts connections and sends server.connected, but no subsequent events (message.part.updated, message.updated, session.status, session.idle, etc.) are ever delivered.

This worked correctly in v1.14.40 and is broken in v1.14.48.

Environment

• OS: Linux x86_64 (Rocky Linux 9)
• OpenCode version: 1.14.48 (opencode serve --hostname 127.0.0.1 --port 0)
• Connection: direct localhost (no proxy, no tailscale, no reverse proxy)
• Client: curl (also reproduced with Go net/http client)

Steps to Reproduce

# Terminal 1: Start the server
opencode serve --hostname 127.0.0.1 --port 0

# Terminal 2: Connect to SSE event stream
curl -sN "http://127.0.0.1:PORT/event" -H "Accept: text/event-stream"

# Terminal 3: Create session + send prompt
SESSION_ID=$(curl -s http://127.0.0.1:PORT/session -H "Content-Type: application/json" -d "{}" | python3 -c "import json,sys;print(json.load(sys.stdin)['id'])")
curl -s http://127.0.0.1:PORT/session/${SESSION_ID}/prompt_async -H "Content-Type: application/json" -d '{"parts":[{"type":"text","text":"say hello"}]}'

Expected Behavior

Terminal 2 receives SSE events as the prompt is processed:

data: {"type":"server.connected","properties":{}}
data: {"type":"message.updated","properties":{...}}
data: {"type":"message.part.updated","properties":{...}}
data: {"type":"session.idle","properties":{...}}

Actual Behavior

Terminal 2 only receives the initial connection event, nothing else:

data: {"id":"evt_...","type":"server.connected","properties":{}}

No further events appear, even after waiting several minutes.

Evidence

1. Server logs confirm events are published internally:

INFO  service=bus type=message.part.delta publishing
INFO  service=bus type=message.part.updated publishing
INFO  service=bus type=session.idle publishing

2. prompt_async returns 204 — prompt was accepted and processed.

3. Same workflow on v1.14.40 works correctly — SSE events arrive in real-time.

4. Session-specific /session/{id}/event returns HTML (web UI), not SSE — no alternative endpoint.

Impact

Breaks all integrations relying on /event SSE for real-time event delivery. Only workaround is downgrading to v1.14.40.

Related Issues

• Chat response delayed over 1 minute in browser, but /global/event receives LLM reply instantly #19514 — Same symptom (events not delivered), between 1.3.17 and 1.4.2
• Server becomes unresponsive after external client disconnects during SSE streaming #15149 — Server unresponsive after SSE client disconnect
• Memory leak: SSE connections stuck in CLOSE_WAIT cause unbounded AsyncQueue growth (~14 MB/sec) #22198 — SSE CLOSE_WAIT memory leak with AsyncQueue