fix

apps/api/internal/auth/errors.go

@@ -34,7 +34,11 @@ func ClientError(err error) (msg string, ok bool) {
 		errors.Is(err, ErrEmailRequired),
 		errors.Is(err, ErrSyntheticEmail),
 		errors.Is(err, ErrNotEligibleSetPassword),
-		errors.Is(err, ErrEmailMismatch):
+		errors.Is(err, ErrEmailMismatch),
+		errors.Is(err, ErrNotCompanyOwner),
+		errors.Is(err, ErrCannotRemoveOwner),
+		errors.Is(err, ErrTransferSelf),
+		errors.Is(err, ErrOwnerRequired):
 		return err.Error(), true
 	default:
 		return "", false

apps/api/internal/auth/ownership.go

@@ -0,0 +1,95 @@
+package auth
+
+import (
+	"context"
+	"errors"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5"
+)
+
+var (
+	ErrNotCompanyOwner     = errors.New("company owner required")
+	ErrCannotRemoveOwner   = errors.New("transfer ownership before removing the company owner")
+	ErrTransferSelf        = errors.New("user is already the company owner")
+	ErrOwnerRequired       = errors.New("new owner must be an active company member")
+)
+
+// CompanyOwnerID returns the billing representative for the company, if set.
+func (s *Service) CompanyOwnerID(ctx context.Context, companyID uuid.UUID) (uuid.UUID, bool, error) {
+	var owner *uuid.UUID
+	err := s.Pool.QueryRow(ctx, `SELECT owner_user_id FROM companies WHERE id = $1`, companyID).Scan(&owner)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return uuid.Nil, false, ErrCompanyNotFound
+	}
+	if err != nil {
+		return uuid.Nil, false, err
+	}
+	if owner == nil || *owner == uuid.Nil {
+		return uuid.Nil, false, nil
+	}
+	return *owner, true, nil
+}
+
+// IsCompanyOwner reports whether userID is the company's owner_user_id.
+func (s *Service) IsCompanyOwner(ctx context.Context, companyID, userID uuid.UUID) (bool, error) {
+	ownerID, ok, err := s.CompanyOwnerID(ctx, companyID)
+	if err != nil {
+		return false, err
+	}
+	return ok && ownerID == userID, nil
+}
+
+// TransferOwnership sets a new company owner. The target must be an active member.
+// The new owner is promoted to membership admin so they retain team powers.
+func (s *Service) TransferOwnership(ctx context.Context, companyID, newOwnerID uuid.UUID) error {
+	tx, err := s.Pool.Begin(ctx)
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback(ctx)
+
+	var current *uuid.UUID
+	err = tx.QueryRow(ctx, `SELECT owner_user_id FROM companies WHERE id = $1 FOR UPDATE`, companyID).Scan(&current)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return ErrCompanyNotFound
+	}
+	if err != nil {
+		return err
+	}
+	if current != nil && *current == newOwnerID {
+		return ErrTransferSelf
+	}
+
+	var status string
+	err = tx.QueryRow(ctx, `
+		SELECT status FROM memberships
+		WHERE company_id = $1 AND user_id = $2`, companyID, newOwnerID).Scan(&status)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return ErrOwnerRequired
+	}
+	if err != nil {
+		return err
+	}
+	if status != "active" {
+		return ErrOwnerRequired
+	}
+
+	_, err = tx.Exec(ctx, `
+		UPDATE memberships
+		SET role = 'admin', status = 'active', updated_at = now()
+		WHERE company_id = $1 AND user_id = $2`, companyID, newOwnerID)
+	if err != nil {
+		return err
+	}
+
+	tag, err := tx.Exec(ctx, `
+		UPDATE companies SET owner_user_id = $2, updated_at = now() WHERE id = $1`, companyID, newOwnerID)
+	if err != nil {
+		return err
+	}
+	if tag.RowsAffected() == 0 {
+		return ErrCompanyNotFound
+	}
+	return tx.Commit(ctx)
+}

apps/api/internal/auth/ownership_test.go

@@ -0,0 +1,20 @@
+package auth
+
+import (
+	"testing"
+)
+
+func TestOwnershipErrorClientFacing(t *testing.T) {
+	t.Parallel()
+	for _, err := range []error{
+		ErrNotCompanyOwner,
+		ErrCannotRemoveOwner,
+		ErrTransferSelf,
+		ErrOwnerRequired,
+	} {
+		msg, ok := ClientError(err)
+		if !ok || msg == "" {
+			t.Fatalf("expected client error for %v", err)
+		}
+	}
+}

apps/api/internal/auth/service.go

@@ -102,7 +102,8 @@ func (s *Service) Register(ctx context.Context, in RegisterInput) (LoginResult,
 
 	var companyID uuid.UUID
 	err = tx.QueryRow(ctx, `
-		INSERT INTO companies (name) VALUES ($1) RETURNING id`, strings.TrimSpace(in.CompanyName)).Scan(&companyID)
+		INSERT INTO companies (name, owner_user_id) VALUES ($1, $2) RETURNING id`,
+		strings.TrimSpace(in.CompanyName), userID).Scan(&companyID)
 	if err != nil {
 		return LoginResult{}, err
 	}