openclaw - 💡(How to fix) Fix [Regression 2026.5.20] Discord typing indicator severely delayed (20-30s) — session write lock contention

Bug Description

After upgrading from 2026.4.23 to 2026.5.20, Discord message handling has become significantly slower. The delay is not due to LLM inference — the issue occurs before the model is even reached.

Before 2026.5.20: Typing indicator appeared on Discord immediately after sending a message.

After 2026.5.20:

• Ack reaction emojis (👀) arrive promptly
• Warning emoji (⚠️) often appears due to slow pre-dispatch processing
• "Bot is typing..." indicator only appears after 20-30 seconds
• Actual LLM response time is normal once typing starts

Regression Source

Suspected commit from 2026.5.20 changelog:

"Agents/messages: stop message-tool-only turns after a successful source-channel message send while keeping transcript mirrors under the session write lock" (#84289)

Log Evidence

Event loop starvation:

liveness warning: reasons=event_loop_delay,cpu
eventLoopDelayP99Ms=4362.1
eventLoopDelayMaxMs=13396.6
eventLoopUtilization=0.885
cpuCoreRatio=0.919

Session lock contention:

sidecars.session-locks:1715ms
work=[active=agent:main:discord:channel:885761219150086156(
  processing/embedded_run,
  q=1,
  age=27s,
  last=embedded_run:started
)]

Large workspace bootstrap being truncated (injected under lock):

workspace bootstrap file TOOLS.md is 13510 chars (limit 12000)
workspace bootstrap file MEMORY.md is 18142 chars (limit 12000)

Environment

• OpenClaw: 2026.5.20 (e510042)
• Node.js: v25.4.0
• OS: Linux 6.17.0-1012-aws (x64)

Steps to Reproduce

1. Run OpenClaw 2026.5.20 with Discord channel configured
2. Send a message to the bot in a Discord guild channel
3. Observe: ack reactions arrive quickly, but typing indicator is delayed by 20-30s
4. Check gateway logs: eventLoopDelayMaxMs spikes to 10s+, session work queue builds up

Expected Behavior

Typing indicator should appear within 1-2 seconds of message receipt, as it did in 2026.4.23.

Actual Behavior

Typing indicator delayed by 20-30 seconds due to event loop starvation and session write lock contention.

Additional Context

The session write lock introduced in #84289 appears to serialize Discord message processing, creating a bottleneck. The lock acquisition and transcript mirror writes block the event loop, delaying the typing indicator (which signals model dispatch) far beyond acceptable thresholds.