Update task status handling to reset runner_id on job cancellation and failure

- Modified SQL queries in multiple functions to set runner_id to NULL when updating task statuses for cancelled jobs and failed tasks.
- Ensured that tasks are properly marked as failed with the correct error messages and updated completion timestamps.
- Improved handling of task statuses to prevent potential issues with task assignment and execution.

internal/manager/jobs.go

@@ -944,7 +944,7 @@ func (s *Manager) handleCancelJob(w http.ResponseWriter, r *http.Request) {
 
 		// Cancel all pending tasks
 		_, err = conn.Exec(
-			`UPDATE tasks SET status = ? WHERE job_id = ? AND status = ?`,
+			`UPDATE tasks SET status = ?, runner_id = NULL WHERE job_id = ? AND status = ?`,
 			types.TaskStatusFailed, jobID, types.TaskStatusPending,
 		)
 		return err

internal/manager/runners.go

@@ -390,7 +390,7 @@ func (s *Manager) handleNextJob(w http.ResponseWriter, r *http.Request) {
 			        t.condition
 			 FROM tasks t
 			 JOIN jobs j ON t.job_id = j.id
-			 WHERE t.status = ? AND j.status != ?
+			 WHERE t.status = ? AND t.runner_id IS NULL AND j.status != ?
 			 ORDER BY t.created_at ASC
 			 LIMIT 50`,
 			types.TaskStatusPending, types.JobStatusCancelled,
@@ -1363,7 +1363,7 @@ func (s *Manager) handleRunnerJobWebSocket(w http.ResponseWriter, r *http.Reques
 			log.Printf("Job WebSocket disconnected unexpectedly for task %d, marking as failed", taskID)
 			s.db.With(func(conn *sql.DB) error {
 				_, err := conn.Exec(
-					`UPDATE tasks SET status = ?, error_message = ?, completed_at = ? WHERE id = ?`,
+					`UPDATE tasks SET status = ?, runner_id = NULL, error_message = ?, completed_at = ? WHERE id = ?`,
 					types.TaskStatusFailed, "WebSocket connection lost", time.Now(), taskID,
 				)
 				return err
@@ -1678,11 +1678,10 @@ func (s *Manager) handleWebSocketTaskComplete(runnerID int64, taskUpdate WSTaskU
 	} else {
 		// No retries remaining - mark as failed
 		err = s.db.WithTx(func(tx *sql.Tx) error {
-			_, err := tx.Exec(`UPDATE tasks SET status = ? WHERE id = ?`, types.TaskStatusFailed, taskUpdate.TaskID)
-			if err != nil {
-				return err
-			}
-			_, err = tx.Exec(`UPDATE tasks SET completed_at = ? WHERE id = ?`, now, taskUpdate.TaskID)
+			_, err := tx.Exec(
+				`UPDATE tasks SET status = ?, runner_id = NULL, completed_at = ? WHERE id = ?`,
+				types.TaskStatusFailed, now, taskUpdate.TaskID,
+			)
 			if err != nil {
 				return err
 			}
@@ -1849,7 +1848,7 @@ func (s *Manager) cancelActiveTasksForJob(jobID int64) error {
 	// Tasks don't have a cancelled status - mark them as failed instead
 	err := s.db.With(func(conn *sql.DB) error {
 		_, err := conn.Exec(
-			`UPDATE tasks SET status = ?, error_message = ? WHERE job_id = ? AND status IN (?, ?)`,
+			`UPDATE tasks SET status = ?, runner_id = NULL, error_message = ? WHERE job_id = ? AND status IN (?, ?)`,
 			types.TaskStatusFailed, "Job cancelled", jobID, types.TaskStatusPending, types.TaskStatusRunning,
 		)
 		if err != nil {