fix: harden multi-pod delivery and load verification

server/db/mysql/tenant_adapter.go

@@ -8,7 +8,9 @@ import (
 	"crypto/sha256"
 	"database/sql"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -2249,6 +2251,61 @@ func (a *adapter) TenantMessageSave(id t.TenantID, msg *t.Message) error {
 	return err
 }
 
+func (a *adapter) TenantMessageSchemaValidate(tenantIDs []t.TenantID) error {
+	if len(tenantIDs) == 0 {
+		return errors.New("mysql: no active tenants available for message schema validation")
+	}
+	validated := make(map[*adapter]map[string]struct{})
+	for _, tenantID := range tenantIDs {
+		tenantAdp, err := a.routedTenantAdapter(tenantID)
+		if err != nil {
+			return fmt.Errorf("mysql: resolve tenant %d for message schema validation: %w", tenantID, err)
+		}
+		table := tenantMessagesTable(tenantID)
+		if tenantAdp.tenantScopedDB {
+			table = "im_messages"
+		}
+		if validated[tenantAdp] == nil {
+			validated[tenantAdp] = make(map[string]struct{})
+		}
+		if _, ok := validated[tenantAdp][table]; ok {
+			continue
+		}
+		if err = tenantAdp.validateMessageIDColumn(table); err != nil {
+			return err
+		}
+		validated[tenantAdp][table] = struct{}{}
+	}
+	if !a.tenantScopedDB {
+		if err := a.validateMessageIDColumn("im_messages"); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (a *adapter) validateMessageIDColumn(table string) error {
+	if !regexp.MustCompile(`^im_(?:[0-9]+_)?messages$`).MatchString(table) {
+		return fmt.Errorf("mysql: unsafe message table name %q", table)
+	}
+	var dataType, nullable, extra string
+	err := a.db.QueryRow(`SELECT DATA_TYPE,IS_NULLABLE,EXTRA FROM information_schema.COLUMNS
+		WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=? AND COLUMN_NAME='id'`, table).
+		Scan(&dataType, &nullable, &extra)
+	if err == sql.ErrNoRows {
+		return fmt.Errorf("mysql: required message table %s is missing", table)
+	}
+	if err != nil {
+		return fmt.Errorf("mysql: inspect %s.id: %w", table, err)
+	}
+	if !strings.EqualFold(dataType, "bigint") || !strings.EqualFold(nullable, "NO") ||
+		!strings.Contains(strings.ToLower(extra), "auto_increment") {
+		return fmt.Errorf("mysql: incompatible %s.id schema: type=%s nullable=%s extra=%s; want BIGINT NOT NULL AUTO_INCREMENT",
+			table, dataType, nullable, extra)
+	}
+	return nil
+}
+
 func (a *adapter) TenantMessageSaveBatch(id t.TenantID, messages []*t.Message) error {
 	tenantAdp, err := a.routedTenantAdapter(id)
 	if err != nil {