add basis for multiple reps

server.go

@@ -35,6 +35,8 @@ type Store interface {
 	UpsertPeople(users []User, eligible map[string]bool) error
 	LastSync() (int64, error)
 	SetLastSync(ts int64) error
+	RepsFor(chapterID int64, dept string) ([]int64, error)
+	EligibleMembers(chapterID int64, dept string) ([]int64, error)
 }
 
 // ErrLocked is returned by AcquireLock when a run is already in flight

store.go

@@ -57,6 +57,38 @@ func OpenStore(path string) (*SQLStore, error) {
 	return &SQLStore{db: db}, nil
 }
 
+// RepsFor returns the user IDs of every rep for a department, ordered by
+// ID so assignment is deterministic across runs.
+func (s *SQLStore) RepsFor(chapterID int64, dept string) ([]int64, error) {
+	return s.userIDs(`SELECT id FROM people
+		WHERE is_rep = 1 AND chapter_id = ? AND department = ?
+		ORDER BY id`, chapterID, dept)
+}
+
+func (s *SQLStore) EligibleMembers(chapterID int64, dept string) ([]int64, error) {
+	return s.userIDs(`SELECT id FROM people
+		WHERE is_eligible = 1 AND chapter_id = ? AND department = ?
+		ORDER BY id`, chapterID, dept)
+}
+
+func (s *SQLStore) userIDs(query string, args ...any) ([]int64, error) {
+	rows, err := s.db.Query(query, args...)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var out []int64
+	for rows.Next() {
+		var id int64
+		if err := rows.Scan(&id); err != nil {
+			return nil, err
+		}
+		out = append(out, id)
+	}
+	return out, rows.Err()
+}
+
 func (s *SQLStore) AcquireLock(chapterID int64, dept string, repID int64) (int64, error) {
 	res, err := s.db.Exec(
 		`INSERT INTO runs (chapter_id, department, rep_user_id, status)