From be96f94b41614a07f02616728fe677af53267a1d Mon Sep 17 00:00:00 2001
From: Simon Arlott <sa.me.uk>
Date: Mon, 18 Aug 2025 10:41:43 +0100
Subject: [PATCH] Ignore discord updates when the message hasn't been edited in
 the last 6 hours

Discord sends spurious updates for messages that haven't been edited, or
haven't been edited recently. Messages from as far back as 5 years ago have
been observed to be updated, always with a URL or embedded content.

These need to be ignored because it's confusing when out of date messages
are bridged as new messages with no context to protocols that don't support
edits. Edited messages normally arrive as updates immediately.
---
 bridge/discord/handlers.go | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/bridge/discord/handlers.go b/bridge/discord/handlers.go
index 34cef554..eb169108 100644
--- a/bridge/discord/handlers.go
+++ b/bridge/discord/handlers.go
@@ -1,6 +1,8 @@
 package bdiscord
 
 import (
+	"time"
+
 	"github.com/42wim/matterbridge/bridge/config"
 	"github.com/bwmarrin/discordgo"
 	"github.com/davecgh/go-spew/spew"
@@ -63,6 +65,13 @@ func (b *Bdiscord) messageTyping(s *discordgo.Session, m *discordgo.TypingStart)
 	b.Remote <- rmsg
 }
 
+// Discord sends spurious updates for messages that haven't been edited, or
+// haven't been edited recently. Messages from as far back as 5 years ago have
+// been observed to be updated, always with a URL or embedded content.
+//
+// These need to be ignored because it's confusing when out of date messages
+// are bridged as new messages with no context to protocols that don't support
+// edits. Edited messages normally arrive as updates immediately.
 func (b *Bdiscord) messageUpdate(s *discordgo.Session, m *discordgo.MessageUpdate) { //nolint:unparam
 	if m.GuildID != b.guildID {
 		b.Log.Debugf("Ignoring messageUpdate because it originates from a different guild")
@@ -73,6 +82,12 @@ func (b *Bdiscord) messageUpdate(s *discordgo.Session, m *discordgo.MessageUpdat
 	}
 	// only when message is actually edited
 	if m.Message.EditedTimestamp != nil {
+		// message must have been edited recently
+		delay := time.Now().Sub(*m.Message.EditedTimestamp)
+		if delay >= time.Duration(6) * time.Hour {
+			return
+		}
+
 		b.Log.Debugf("Sending edit message")
 		m.Content += b.GetString("EditSuffix")
 		msg := &discordgo.MessageCreate{