diff --git a/apps/builder/messages/ar.json b/apps/builder/messages/ar.json
index ecad7d4a1..afe79620a 100644
--- a/apps/builder/messages/ar.json
+++ b/apps/builder/messages/ar.json
@@ -2293,6 +2293,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "رمز المستخدم"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/da.json b/apps/builder/messages/da.json
index 287328e9f..6f4dcdf1a 100644
--- a/apps/builder/messages/da.json
+++ b/apps/builder/messages/da.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Brugerkode"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/de.json b/apps/builder/messages/de.json
index bddc8b98c..d48ace3f6 100644
--- a/apps/builder/messages/de.json
+++ b/apps/builder/messages/de.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Benutzercode"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/en.json b/apps/builder/messages/en.json
index f30ce4be7..aa4181df5 100644
--- a/apps/builder/messages/en.json
+++ b/apps/builder/messages/en.json
@@ -2293,6 +2293,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "User Code"
     }
   },
   "metaConversions": {
diff --git a/apps/builder/messages/es.json b/apps/builder/messages/es.json
index 3e1de64d8..84448f2f3 100644
--- a/apps/builder/messages/es.json
+++ b/apps/builder/messages/es.json
@@ -2293,6 +2293,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Código de usuario"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/fi.json b/apps/builder/messages/fi.json
index 0543578f8..77f75517a 100644
--- a/apps/builder/messages/fi.json
+++ b/apps/builder/messages/fi.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Käyttäjäkoodi"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/fr.json b/apps/builder/messages/fr.json
index 4b4b61146..9fd81e967 100644
--- a/apps/builder/messages/fr.json
+++ b/apps/builder/messages/fr.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Code utilisateur"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/he.json b/apps/builder/messages/he.json
index 37a3f5380..9dca50feb 100644
--- a/apps/builder/messages/he.json
+++ b/apps/builder/messages/he.json
@@ -4843,6 +4843,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "קוד משתמש"
     }
   },
   "billing": {
diff --git a/apps/builder/messages/id.json b/apps/builder/messages/id.json
index c3fabd3ae..98f84a198 100644
--- a/apps/builder/messages/id.json
+++ b/apps/builder/messages/id.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Kode pengguna"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/it.json b/apps/builder/messages/it.json
index 109d3ae25..b2abddd5f 100644
--- a/apps/builder/messages/it.json
+++ b/apps/builder/messages/it.json
@@ -1458,6 +1458,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Codice utente"
     }
   },
   "actions": {
diff --git a/apps/builder/messages/ja.json b/apps/builder/messages/ja.json
index 519c273c3..b255f1268 100644
--- a/apps/builder/messages/ja.json
+++ b/apps/builder/messages/ja.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "ユーザーコード"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/nl.json b/apps/builder/messages/nl.json
index 96cc1a274..2256fafdd 100644
--- a/apps/builder/messages/nl.json
+++ b/apps/builder/messages/nl.json
@@ -1969,6 +1969,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Gebruikerscode"
     }
   },
   "condition": {
diff --git a/apps/builder/messages/pt-BR.json b/apps/builder/messages/pt-BR.json
index 75f37ecee..b209312a5 100644
--- a/apps/builder/messages/pt-BR.json
+++ b/apps/builder/messages/pt-BR.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Código do usuário"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/pt-PT.json b/apps/builder/messages/pt-PT.json
index da0ef23a2..cea167db2 100644
--- a/apps/builder/messages/pt-PT.json
+++ b/apps/builder/messages/pt-PT.json
@@ -2156,6 +2156,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Código do utilizador"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/ro.json b/apps/builder/messages/ro.json
index 6506f6f9c..856ba6048 100644
--- a/apps/builder/messages/ro.json
+++ b/apps/builder/messages/ro.json
@@ -2940,6 +2940,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Cod utilizator"
     }
   },
   "channels": {
diff --git a/apps/builder/messages/sv.json b/apps/builder/messages/sv.json
index f09a75d30..036b4122c 100644
--- a/apps/builder/messages/sv.json
+++ b/apps/builder/messages/sv.json
@@ -2991,6 +2991,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Användarkod"
     }
   },
   "flowAnalytics": {
diff --git a/apps/builder/messages/tr.json b/apps/builder/messages/tr.json
index efcbb13de..3e62e744b 100644
--- a/apps/builder/messages/tr.json
+++ b/apps/builder/messages/tr.json
@@ -2293,6 +2293,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Kullanıcı kodu"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/vi.json b/apps/builder/messages/vi.json
index 5e06dca0d..1ee106ead 100644
--- a/apps/builder/messages/vi.json
+++ b/apps/builder/messages/vi.json
@@ -2293,6 +2293,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "Mã người dùng"
     }
   },
   "flows": {
diff --git a/apps/builder/messages/zh-CN.json b/apps/builder/messages/zh-CN.json
index 012b977b9..4743a96db 100644
--- a/apps/builder/messages/zh-CN.json
+++ b/apps/builder/messages/zh-CN.json
@@ -2994,6 +2994,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "用户代码"
     }
   },
   "flowAnalytics": {
diff --git a/apps/builder/messages/zh-TW.json b/apps/builder/messages/zh-TW.json
index 64b600ed1..10621e069 100644
--- a/apps/builder/messages/zh-TW.json
+++ b/apps/builder/messages/zh-TW.json
@@ -1458,6 +1458,9 @@
     },
     "adSource": {
       "label": "Ad source"
+    },
+    "userCode": {
+      "label": "使用者代碼"
     }
   },
   "messages": {
diff --git a/apps/builder/src/features/contacts/contact-detail.tsx b/apps/builder/src/features/contacts/contact-detail.tsx
index d648505bd..279682371 100644
--- a/apps/builder/src/features/contacts/contact-detail.tsx
+++ b/apps/builder/src/features/contacts/contact-detail.tsx
@@ -163,6 +163,26 @@ const scopedIdentityRowsByChannel: Partial<
   ],
 }
 
+const buildUserCodeField = (
+  contactInbox: ContactInboxResource | undefined,
+  t: (key: string) => string,
+): ContactEditableField[] => {
+  const value = contactInbox?.sourceId
+  if (!value) {
+    return []
+  }
+  return [
+    {
+      key: "sourceId",
+      icon: PhoneIcon,
+      label: t("fields.userCode.label"),
+      value,
+      type: "shortText",
+      readOnly: true,
+    },
+  ]
+}
+
 const buildScopedIdentityFields = (
   contactInbox: ContactInboxResource | undefined,
   t: (key: string) => string,
@@ -174,8 +194,7 @@ const buildScopedIdentityFields = (
   const rows = scopedIdentityRowsByChannel[parsedChannel.data] ?? []
   return rows.flatMap((row): ContactEditableField[] => {
     const value = contactInbox[row.key]
-    // Skip absent values, and a value that IS the Contact ID shown above
-    // (a scoped-id-keyed contact) — no duplicate row.
+    // Skip absent values, and scoped ids that duplicate {{user_code}} (sourceId).
     if (!value || value === contactInbox.sourceId) {
       return []
     }
@@ -318,7 +337,8 @@ export const ContactDetail = ({
 
       if (conversation?.contact) {
         const activeContactInbox = conversation.contactInboxes[0]
-        const channelContactId = activeContactInbox?.sourceId
+        // {{user_id}} — workspace contact record id for API calls (GET /v1/contacts/id:{id}).
+        const userId = conversation.contact.id
         // The ad the contact clicked from (any ad-attributed inbox), shown as
         // a link right under Contact ID. Guarded to http(s) so a non-navigable
         // / `javascript:` referral value never becomes an anchor href.
@@ -331,13 +351,14 @@ export const ContactDetail = ({
             : null
         const tmpContactFields: ContactEditableField[] = [
           {
-            key: "channelContactId",
+            key: "userId",
             icon: IdCardIcon,
-            label: t("fields.contactId.label"),
-            value: channelContactId,
+            label: t("fields.userId.label"),
+            value: userId,
             type: "shortText",
             readOnly: true,
           },
+          ...buildUserCodeField(activeContactInbox, t),
           ...(adSourceUrl
             ? [
                 {