fix(discord): bump stale threads so they stay in the channel list

discord/commands/handler.go

@@ -219,13 +219,11 @@ func OnUserUpdate(s *discordgo.Session, u *discordgo.UserUpdate) {
 	service.SyncDiscordUserAvatar(u.ID, member.AvatarURL("256"))
 }
 
-// OnThreadUpdate keeps guild threads alive indefinitely. Discord doesn't
-// allow disabling thread auto-archival (7-day window at most), so when a
-// thread flips to archived we immediately flip it back. Unarchiving emits
-// another ThreadUpdate with Archived=false, which falls through the guard
-// below — no loop. Locked threads are left alone: locking is an explicit
-// moderator "this thread is closed" signal, and force-unarchiving those
-// would fight moderation.
+// OnThreadUpdate unarchives guild threads that still auto-archive after the
+// periodic bump missed them (bot was down, 1-hour window elapsed between
+// sweeps). Unarchiving emits another ThreadUpdate with Archived=false, which
+// falls through the guard below — no loop. Locked threads are left alone:
+// locking is an explicit moderator "this thread is closed" signal.
 func OnThreadUpdate(s *discordgo.Session, t *discordgo.ThreadUpdate) {
 	if t.GuildID != config.DiscordGuild {
 		return

discord/main.go

@@ -32,6 +32,7 @@ func main() {
 	service.ConnectDiscord()
 	commands.InitializeBot()
 	service.StartReconcileCron()
+	service.StartThreadKeepaliveCron()
 
 	api.Run()
 }

discord/service/thread_keepalive.go

@@ -1,31 +1,144 @@
 package service
 
 import (
+	"sync/atomic"
 	"time"
 
 	"github.com/bwmarrin/discordgo"
+	"github.com/gaucho-racing/sentinel/discord/config"
 	"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."
+// Discord auto-archive durations, in minutes. Changing auto_archive_duration
+// counts as thread activity, which is how we bump without posting a message.
+const (
+	maxAutoArchiveMinutes = 10080 // 7 days
+	midAutoArchiveMinutes = 4320  // 3 days
+)
+
+// threadBumpInterval is how often we scan active threads. threadBumpLeadTime
+// is how close to Discord's channel-list hide deadline we bump.
+const (
+	threadBumpInterval = 5 * time.Minute
+	threadBumpLeadTime = 30 * time.Minute
+)
 
-// 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. 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.
+var threadSweepRunning atomic.Bool
+
+// KeepThreadAlive unarchives a thread that Discord auto-archived. Archived
+// threads are immutable: Discord rejects any PATCH other than archived=false
+// (error 50083), so the 7-day window is set in a second edit after unarchive
+// succeeds. Requires MANAGE_THREADS in the guild.
 func KeepThreadAlive(thread *discordgo.Channel) {
+	if thread == nil {
+		return
+	}
 	archived := false
-	_, err := Discord.ChannelEdit(thread.ID, &discordgo.ChannelEdit{
-		Archived:            &archived,
-		AutoArchiveDuration: 10080,
-	})
-	if err != nil {
+	if _, err := Discord.ChannelEdit(thread.ID, &discordgo.ChannelEdit{
+		Archived: &archived,
+	}); err != nil {
 		logger.SugarLogger.Errorf("thread keepalive: failed to unarchive thread %s (%s): %v", thread.ID, thread.Name, err)
 		return
 	}
 	logger.SugarLogger.Infof("thread keepalive: unarchived thread %s (%s)", thread.ID, thread.Name)
-	SendDisappearingMessage(thread.ID, threadReopenNotice, time.Hour)
+
+	if thread.ThreadMetadata == nil || thread.ThreadMetadata.AutoArchiveDuration != maxAutoArchiveMinutes {
+		if _, err := Discord.ChannelEdit(thread.ID, &discordgo.ChannelEdit{
+			AutoArchiveDuration: maxAutoArchiveMinutes,
+		}); err != nil {
+			logger.SugarLogger.Errorf("thread keepalive: failed to extend auto-archive on thread %s (%s): %v", thread.ID, thread.Name, err)
+		}
+	}
+}
+
+// StartThreadKeepaliveCron spawns a background goroutine that periodically
+// bumps active threads approaching Discord's channel-list hide deadline.
+// Changing auto_archive_duration counts as activity, so the bump does not
+// post a message. ThreadUpdate unarchives any that still slip through.
+//
+// A first sweep runs immediately so a restart recovers threads that went
+// stale while we were down. If a sweep is still running when the next tick
+// fires, the tick is skipped. The goroutine is leaked on process exit; we
+// don't have graceful-shutdown plumbing for it and the OS reaps everything
+// anyway.
+func StartThreadKeepaliveCron() {
+	logger.SugarLogger.Infof("thread keepalive: cron enabled, interval=%v", threadBumpInterval)
+	go func() {
+		sweepStaleThreads()
+		ticker := time.NewTicker(threadBumpInterval)
+		defer ticker.Stop()
+		for range ticker.C {
+			sweepStaleThreads()
+		}
+	}()
+}
+
+func sweepStaleThreads() {
+	if Discord == nil {
+		return
+	}
+	if !threadSweepRunning.CompareAndSwap(false, true) {
+		return
+	}
+	defer threadSweepRunning.Store(false)
+
+	list, err := Discord.GuildThreadsActive(config.DiscordGuild)
+	if err != nil {
+		logger.SugarLogger.Errorf("thread keepalive: failed to list active threads: %v", err)
+		return
+	}
+	if list == nil {
+		return
+	}
+
+	now := time.Now()
+	bumped := 0
+	for _, thread := range list.Threads {
+		if thread == nil || thread.ThreadMetadata == nil || thread.ThreadMetadata.Locked {
+			continue
+		}
+		if thread.ThreadMetadata.Archived {
+			KeepThreadAlive(thread)
+			continue
+		}
+		if threadIsStale(thread.ThreadMetadata, now) && bumpThread(thread) {
+			bumped++
+		}
+	}
+	if bumped > 0 {
+		logger.SugarLogger.Infof("thread keepalive: bumped %d stale thread(s)", bumped)
+	}
+}
+
+// threadIsStale reports whether the thread will leave the channel list within
+// threadBumpLeadTime, based on Discord's last-activity timestamp.
+func threadIsStale(meta *discordgo.ThreadMetadata, now time.Time) bool {
+	if meta == nil {
+		return false
+	}
+	dur := time.Duration(meta.AutoArchiveDuration) * time.Minute
+	if dur <= 0 {
+		dur = time.Hour
+	}
+	return !now.Before(meta.ArchiveTimestamp.Add(dur - threadBumpLeadTime))
+}
+
+// bumpThread toggles auto_archive_duration. Discord treats that change as
+// activity, which resets the hide timer without posting a message.
+func bumpThread(thread *discordgo.Channel) bool {
+	if thread == nil {
+		return false
+	}
+	next := midAutoArchiveMinutes
+	if thread.ThreadMetadata != nil && thread.ThreadMetadata.AutoArchiveDuration != maxAutoArchiveMinutes {
+		next = maxAutoArchiveMinutes
+	}
+	if _, err := Discord.ChannelEdit(thread.ID, &discordgo.ChannelEdit{
+		AutoArchiveDuration: next,
+	}); err != nil {
+		logger.SugarLogger.Errorf("thread keepalive: failed to bump thread %s (%s): %v", thread.ID, thread.Name, err)
+		return false
+	}
+	logger.SugarLogger.Debugf("thread keepalive: bumped thread %s (%s) auto_archive=%d", thread.ID, thread.Name, next)
+	return true
 }