Persist merge intent so a restart mid-merge-turn doesn't lose it

internal/store/store.go

@@ -248,6 +248,8 @@ CREATE INDEX lead_inputs_owner ON lead_inputs(owner, id);
 UPDATE users SET focus = json_set(focus, '$.project_id', (SELECT project_id FROM tasks WHERE id = json_extract(users.focus, '$.task_id')))
 WHERE json_extract(focus, '$.task_id') IS NOT NULL;
 DELETE FROM lead_inputs WHERE text LIKE 'The human switched the right pane %' OR text = 'The human cleared the right pane.';
+`}, {"add-task-merging-by", `
+ALTER TABLE tasks ADD COLUMN merging_by TEXT NOT NULL DEFAULT '';
 `}}
 
 type Store struct {
@@ -564,6 +566,29 @@ func (s *Store) SetMergeTitle(ctx context.Context, id, title, actor string) erro
 	})
 }
 
+func (s *Store) SetMergingBy(ctx context.Context, id, login string) error {
+	return s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		_, err := tx.ExecContext(ctx, `UPDATE tasks SET merging_by = ? WHERE id = ?`, login, id)
+		return err
+	})
+}
+
+func (s *Store) TakeMergingBy(ctx context.Context, id string) (string, error) {
+	login := ""
+	err := s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {
+		err := tx.QueryRowContext(ctx, `SELECT merging_by FROM tasks WHERE id = ?`, id).Scan(&login)
+		if errors.Is(err, sql.ErrNoRows) {
+			return ErrNotFound
+		}
+		if err != nil {
+			return err
+		}
+		_, err = tx.ExecContext(ctx, `UPDATE tasks SET merging_by = '' WHERE id = ?`, id)
+		return err
+	})
+	return login, err
+}
+
 func (s *Store) MergeTask(ctx context.Context, id, commit, pushed, actor string) (api.Task, error) {
 	return s.closeTask(ctx, id, api.TaskStatusMerged, commit, actor, "task.merged", map[string]any{"id": id, "commit": commit, "pushed": pushed})
 }