openclaw - 💡(How to fix) Fix feat(plugins): enable plugins to respond to Discord reaction events [1 participants]

Summary

Plugins using the before_agent_start hook cannot effectively respond to Discord reaction events because:

1. Reaction system events don't trigger a new agent turn — they are queued via enqueueSystemEvent() and only injected into context when the user sends a follow-up message. This means a plugin cannot respond to a reaction in real time.
2. No dedicated plugin hook for reactions — the only way to see reactions is by scanning messages in before_agent_start, which requires a separate user message to trigger.

This blocks plugins like emoji-confirm-mvp that map emoji reactions to yes/no confirmations.

Context

We confirmed in #60758 that the full reaction pipeline works: Discord sends MESSAGE_REACTION_ADD → OpenClaw receives it → DiscordReactionListener handles it → enqueueSystemEvent() queues it. But nothing triggers an agent turn from that event, so plugins never see it until the user sends another message.

Suggested approaches (not mutually exclusive)

Option A: Reaction system events trigger an agent turn

When a reaction is queued as a system event, automatically dispatch an agent turn on that session. This would allow existing before_agent_start hooks to see the reaction text in the messages and respond. This is the simpler approach and would work with existing plugins.

Option B: New on_reaction plugin hook

Add a new plugin hook (e.g., on_reaction) that fires directly when a reaction event is received, before it's queued as a system event. This would give plugins direct access to the reaction data (emoji, user ID, message ID, channel) and allow them to return a response or inject context without waiting for an agent turn.

Environment

• OpenClaw 2026.4.2 (d74a122)
• Tested with Discord channel, both DM and guild
• Related: #60758