Retry failed sends with their send_id until the server confirms them

internal/store/migrations/070-index-event-send-ids.sql

@@ -0,0 +1 @@
+CREATE INDEX events_send_id ON events(json_extract(payload, '$.send_id')) WHERE kind IN ('user.queued', 'user.message');

internal/store/store.go

@@ -1356,6 +1356,16 @@ func (s *Store) SessionStarted(ctx context.Context, sessionID string) (bool, err
 	return started, err
 }
 
+func (s *Store) UnusedSession(ctx context.Context, taskID, member string) (string, bool, error) {
+	id := ""
+	err := s.db.QueryRowContext(ctx, `SELECT id FROM agent_sessions WHERE task_id = ? AND member = ? AND role = ? AND state = ? AND started = 0 AND pending = 0 LIMIT 1`,
+		taskID, member, string(api.Implementer), string(api.AgentSessionStateIdle)).Scan(&id)
+	if errors.Is(err, sql.ErrNoRows) {
+		return "", false, nil
+	}
+	return id, err == nil, err
+}
+
 func (s *Store) SessionPending(ctx context.Context, sessionID string) (bool, error) {
 	pending := false
 	err := s.db.QueryRowContext(ctx, `SELECT pending FROM agent_sessions WHERE id = ?`, sessionID).Scan(&pending)

internal/store/taskinputs.go

@@ -45,6 +45,22 @@ func (s *Store) AddTaskInput(ctx context.Context, in TaskInput, projectID, sessi
 	})
 }
 
+func (s *Store) SendSession(ctx context.Context, sendID string) (string, bool, error) {
+	sessionID := sql.NullString{}
+	err := s.db.QueryRowContext(ctx, `SELECT agent_session_id FROM events WHERE kind IN ('user.queued', 'user.message') AND json_extract(payload, '$.send_id') = ? LIMIT 1`, sendID).Scan(&sessionID)
+	if err == nil {
+		return sessionID.String, true, nil
+	}
+	if !errors.Is(err, sql.ErrNoRows) {
+		return "", false, err
+	}
+	err = s.db.QueryRowContext(ctx, `SELECT 1 FROM lead_inputs WHERE send_id = ? LIMIT 1`, sendID).Scan(new(int))
+	if errors.Is(err, sql.ErrNoRows) {
+		return "", false, nil
+	}
+	return "", err == nil, err
+}
+
 func (s *Store) WithdrawTaskInput(ctx context.Context, taskID string, id int64, projectID, actor string) (string, error) {
 	sessionID := ""
 	err := s.write(ctx, func(tx *sql.Tx, emit emitFunc) error {