fix: harden identity, live access, drafts and setup (review only)

Source-reviewed hardening changes and regression tests. UNBUILT / UNTESTED: not a deployable release. Go formatting, compilation, automated regression tests, full frontend validation and staging acceptance remain required. See docs/hardening/VALIDATION.md. Main remains the original clean snapshot; no upstream Git history imported.

internal/repositories/customer_identity_repository.go

@@ -1,3 +1,5 @@
+// Modified in the independent hardening fork; see docs/hardening.
+
 package repositories
 
 import (
@@ -6,7 +8,6 @@ import (
 
 	"agent-desk/internal/pkg/httpx/params"
 
-	"github.com/mlogclub/simple/common/strs"
 	"github.com/mlogclub/simple/sqls"
 	"gorm.io/gorm"
 )
@@ -36,14 +37,11 @@ func (r *customerIdentityRepository) Take(db *gorm.DB, where ...interface{}) *mo
 	return ret
 }
 
-// GetBy 按外部来源 + 外部用户标识查询身份映射（与 uk_customer_external 一致）。
+// GetBy is the legacy/internal-integration lookup. Ambiguous mappings fail closed.
 func (r *customerIdentityRepository) GetBy(db *gorm.DB, externalSource enums.ExternalSource, externalID string) *models.CustomerIdentity {
-	if strs.IsAnyBlank(string(externalSource), externalID) {
-		return nil
-	}
-	return r.FindOne(db, sqls.NewCnd().
-		Eq("external_source", externalSource).
-		Eq("external_id", externalID))
+ identity, err := r.GetUniqueBy(db, "", externalSource, externalID)
+ if err != nil { return nil }
+ return identity
 }
 
 func (r *customerIdentityRepository) FindByCustomerID(db *gorm.DB, customerID int64) []models.CustomerIdentity {