openclaw - 💡(How to fix) Fix Discord reaction-only inputs should wake the agent

Summary

Feature request / bug: make accepted Discord reaction notifications wake the routed agent session, matching the narrowed Telegram reaction wake behavior in #47687.

Why this matters

Discord reactions are a low-noise control surface for operators. Today OpenClaw can surface reaction notifications as system events, but reaction-only inputs should not depend on a later text message or unrelated heartbeat before the agent sees them.

Requested behavior

• When a Discord reaction passes existing reactionNotifications and sender/channel/guild access checks, enqueue the existing reaction system event and request an immediate heartbeat wake for the routed session.
• Keep the change default-safe by preserving existing reactionNotifications modes (off, own, all, allowlist) and access controls.
• Do not add a per-emoji semantics/config API in code. Emoji meanings should be supplied through preferences/prompt text, with the reaction event carrying enough stable detail for the agent to interpret it.

Scope boundary

This should be a small parity patch, not a broader reaction workflow redesign. No new Discord permissions, no hardcoded emoji-to-action map, and no generated config/schema churn should be needed.

Acceptance criteria

• Accepted Discord reaction notification events request an immediate heartbeat wake only after the system event is successfully queued.
• Existing reaction notification modes and access checks still gate the behavior.
• Focused Discord monitor tests cover enqueue + wake and no wake for ignored/blocked/deduplicated events.

Related: #47677, #47687