feat(scheduler): sweepPhantomBusy — clear stuck active_tasks from crashed runs

workspace-server/internal/scheduler/scheduler.go

@@ -17,10 +17,12 @@ import (
 )
 
 const (
-	pollInterval   = 30 * time.Second
-	maxConcurrent  = 10
-	batchLimit     = 50
-	fireTimeout    = 5 * time.Minute
+	pollInterval          = 30 * time.Second
+	maxConcurrent         = 10
+	batchLimit            = 50
+	fireTimeout           = 5 * time.Minute
+	phantomSweepInterval  = 5 * time.Minute
+	phantomStaleThreshold = 10 * time.Minute
 )
 
 // A2AProxy is the interface the scheduler needs to send messages to workspaces.
@@ -63,6 +65,7 @@ type Scheduler struct {
 	// Atomic-ish via the mutex; tick rate is 30s so contention is trivial.
 	mu           sync.RWMutex
 	lastTickAt   time.Time
+	lastSweepAt  time.Time
 	tickInterval time.Duration // defaults to pollInterval; overridable in tests
 }
 
@@ -164,6 +167,7 @@ func (s *Scheduler) Start(ctx context.Context) {
 			return
 		case <-ticker.C:
 			tickWithRecover()
+			s.maybeSweepPhantomBusy(ctx)
 			supervised.Heartbeat("scheduler")
 		}
 	}
@@ -565,6 +569,78 @@ func (s *Scheduler) repairNullNextRunAt(ctx context.Context) {
 	}
 }
 
+// maybeSweepPhantomBusy runs sweepPhantomBusy at most once every
+// phantomSweepInterval (5 min). Called on every tick but gated by a timer
+// so the DB query doesn't run on every 30s poll.
+func (s *Scheduler) maybeSweepPhantomBusy(ctx context.Context) {
+	s.mu.RLock()
+	last := s.lastSweepAt
+	s.mu.RUnlock()
+
+	if time.Since(last) < phantomSweepInterval {
+		return
+	}
+
+	s.sweepPhantomBusy(ctx)
+
+	s.mu.Lock()
+	s.lastSweepAt = time.Now()
+	s.mu.Unlock()
+}
+
+// sweepPhantomBusy finds workspaces stuck with active_tasks > 0 but no
+// recent activity_log entry (within phantomStaleThreshold). This happens
+// when an agent errors out (MiniMax timeout, OOM, etc.) and the finally
+// block fails to decrement active_tasks. Without this sweep the scheduler
+// skips cron fires for those workspaces indefinitely ("workspace busy —
+// retry"), requiring manual DB intervention.
+//
+// The query mirrors the manual fix that was being run every 30 min:
+//
+//	UPDATE workspaces SET active_tasks = 0
+//	WHERE active_tasks > 0
+//	  AND id NOT IN (SELECT DISTINCT workspace_id
+//	                 FROM activity_logs
+//	                 WHERE created_at > NOW() - INTERVAL '10 minutes')
+func (s *Scheduler) sweepPhantomBusy(ctx context.Context) {
+	rows, err := db.DB.QueryContext(ctx, `
+		UPDATE workspaces
+		SET active_tasks = 0,
+		    current_task = '',
+		    updated_at   = now()
+		WHERE active_tasks > 0
+		  AND status != 'removed'
+		  AND id NOT IN (
+		      SELECT DISTINCT workspace_id
+		      FROM activity_logs
+		      WHERE created_at > NOW() - $1::interval
+		  )
+		RETURNING id, name
+	`, fmt.Sprintf("%d minutes", int(phantomStaleThreshold.Minutes())))
+	if err != nil {
+		log.Printf("Scheduler: phantom-busy sweep query error: %v", err)
+		return
+	}
+	defer rows.Close()
+
+	count := 0
+	for rows.Next() {
+		var id, name string
+		if err := rows.Scan(&id, &name); err != nil {
+			log.Printf("Scheduler: phantom-busy sweep scan error: %v", err)
+			continue
+		}
+		log.Printf("Scheduler: phantom-busy sweep — reset %s (no activity in %d min)", name, int(phantomStaleThreshold.Minutes()))
+		count++
+	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Scheduler: phantom-busy sweep rows error: %v", err)
+	}
+	if count > 0 {
+		log.Printf("Scheduler: phantom-busy sweep complete — reset %d workspace(s)", count)
+	}
+}
+
 // isEmptyResponse checks if an A2A response body indicates the agent
 // produced no meaningful output. Catches "(no response generated)" from
 // the workspace runtime + genuinely empty/null responses. Used by the