We only want to store TAGMSG that should be persistent. +typing TAGMSG
should be dropped, but +react messages should be kept.

This introduces a whitelist for TAGMSG labels. We only store TAGMSG
having a least one tag in that whitelist.
---
 upstream.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/upstream.go b/upstream.go
index 49e5a76..542d742 100644
--- a/upstream.go
+++ b/upstream.go
@@ -44,6 +44,12 @@ var permanentUpstreamCaps = map[string]bool{
 	"draft/extended-monitor":     true,
 }
 
+// storableMessageTags is the static list of message tags that will cause
+// a TAGMSG to be stored.
+var storableMessageTags = map[string]bool{
+	"+react": true,
+}
+
 type registrationError struct {
 	*irc.Message
 }
@@ -2096,6 +2102,18 @@ func (uc *upstreamConn) appendLog(entity string, msg *irc.Message) (msgID string
 	if uc.user.msgStore == nil {
 		return ""
 	}
+	if msg.Command == "TAGMSG" {
+		store := false
+		for tag := range storableMessageTags {
+			if _, ok := msg.Tags[tag]; ok {
+				store = true
+				break
+			}
+		}
+		if !store {
+			return ""
+		}
+	}
 
 	// Don't store messages with a server mask target
 	if strings.HasPrefix(entity, "$") {

base-commit: 6ddfc943f5a2f77f00ef2fc0a19787918e31999e
-- 
2.17.1

Pushed, thanks!