Keep the arrival UTM when visitors click the site's own UTM links

README.md

@@ -81,7 +81,9 @@ Hellotext.removeEventListener(eventName, callback)
 | Event         | When it fires                                                                                   | Callback payload                                                                                               |
 | ------------- | ----------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
 | `session-set` | The session value is set, including when an existing session is restored during initialization. | The current session value, also available as `Hellotext.session`.                                              |
-| `utm-set`     | UTM parameters are saved.                                                                       | A JSON string containing the saved UTM parameters and `observed_at`. Use `JSON.parse` to read it as an object. |
+| `utm-set`     | The UTM parameters the visitor arrived with are saved.                                          | A JSON string containing the saved UTM parameters and `observed_at`. Use `JSON.parse` to read it as an object. |
+
+UTM parameters on links inside the site (a store's own popup, banner or menu link) do not replace the ones the visitor arrived with and do not fire `utm-set`. They are kept apart and sent with events as `internal_utm_params`. Hellotext's own UTMs always count as an arrival.
 
 See [Understanding Sessions](/docs/sessions.md) and [Tracking Events](/docs/tracking.md).
 

__tests__/models/page_test.js

@@ -194,6 +194,29 @@ describe('Page', () => {
         utm_params: {}
       })
     })
+
+    it('adds the in-site UTM when the visitor clicked one of the site\'s own UTM links', () => {
+      mockUtm.current = { source: 'google', medium: 'cpc' }
+      mockUtm.internal = { source: 'pop_up_tv', medium: 'pop_up_tv', observed_at: '2026-10-24T18:00:00.000Z' }
+
+      const page = new Page()
+
+      expect(page.trackingData).toEqual({
+        page: {
+          url: 'https://example.com/current-page?param=value',
+          title: 'Current Page Title',
+          path: '/current-page'
+        },
+        utm_params: { source: 'google', medium: 'cpc' },
+        internal_utm_params: { source: 'pop_up_tv', medium: 'pop_up_tv', observed_at: '2026-10-24T18:00:00.000Z' }
+      })
+    })
+
+    it('leaves the in-site UTM out when there is none', () => {
+      mockUtm.internal = {}
+
+      expect(new Page().trackingData).not.toHaveProperty('internal_utm_params')
+    })
   })
 
   describe('domain getter', () => {