diff --git a/discord/service/thread_keepalive.go b/discord/service/thread_keepalive.go
index 7ddfb59..2d1d2c2 100644
--- a/discord/service/thread_keepalive.go
+++ b/discord/service/thread_keepalive.go
@@ -1,15 +1,21 @@
 package service
 
 import (
+	"time"
+
 	"github.com/bwmarrin/discordgo"
 	"github.com/gaucho-racing/sentinel/discord/pkg/logger"
 )
 
+const threadReopenNotice = "This thread was archived due to inactivity, so I've automatically reopened it. " +
+	"If this thread is no longer needed, lock it before closing and I'll leave it alone."
+
 // KeepThreadAlive unarchives a thread that Discord just auto-archived and
 // bumps its auto-archive window to the maximum (7 days) so the gateway only
-// re-archives it weekly instead of on the channel's default window. The
-// unarchive is silent — no message is posted and members aren't notified.
-// Requires the bot to have MANAGE_THREADS in the guild.
+// re-archives it weekly instead of on the channel's default window. A notice
+// explaining the reopen and the lock-to-close opt-out is posted in the thread
+// and auto-deleted after an hour. Requires the bot to have MANAGE_THREADS in
+// the guild.
 func KeepThreadAlive(thread *discordgo.Channel) {
 	archived := false
 	_, err := Discord.ChannelEdit(thread.ID, &discordgo.ChannelEdit{
@@ -21,4 +27,5 @@ func KeepThreadAlive(thread *discordgo.Channel) {
 		return
 	}
 	logger.SugarLogger.Infof("thread keepalive: unarchived thread %s (%s)", thread.ID, thread.Name)
+	SendDisappearingMessage(thread.ID, threadReopenNotice, time.Hour)
 }