From 6b69ea7dc1c6964903b1ee27a4dc8d089a239604 Mon Sep 17 00:00:00 2001
From: roo hutton <roo.hutton@overleaf.com>
Date: Fri, 7 Aug 2026 09:18:35 +0100
Subject: [PATCH] Merge pull request #36194 from overleaf/rh-cio-split-tests

[web] send active split test assignments to customer.io

GitOrigin-RevId: 3036d6442e8419326f4b641482d65bd5114fe3da
---
 .../Project/ProjectListController.mjs         | 16 +++++++
 .../SplitTests/SplitTestUserGetter.mjs        |  2 +-
 .../Project/ProjectListController.test.mjs    | 47 +++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/services/web/app/src/Features/Project/ProjectListController.mjs b/services/web/app/src/Features/Project/ProjectListController.mjs
index 53bf7c835c..cb9f6949da 100644
--- a/services/web/app/src/Features/Project/ProjectListController.mjs
+++ b/services/web/app/src/Features/Project/ProjectListController.mjs
@@ -578,6 +578,21 @@ async function projectListPage(req, res, next) {
     }
   }
 
+  let splitTestUserProperties
+  if (isSaas) {
+    try {
+      ;[splitTestUserProperties] = await Modules.promises.hooks.fire(
+        'getSplitTestUserProperties',
+        userId
+      )
+    } catch (err) {
+      logger.error(
+        { err, userId },
+        'Failed to build split test user properties for customer.io'
+      )
+    }
+  }
+
   Modules.promises.hooks
     .fire('setUserProperties', userId, {
       overleaf_id: userId,
@@ -602,6 +617,7 @@ async function projectListPage(req, res, next) {
       ...(groupRole && { group_role: groupRole }),
       is_managed_user: Boolean(user.enrollment?.managedBy),
       ...(user.email && { email: user.email }),
+      ...splitTestUserProperties,
     })
     .catch(err => {
       logger.error({ err }, 'Failed to set user properties for customer.io')
diff --git a/services/web/app/src/Features/SplitTests/SplitTestUserGetter.mjs b/services/web/app/src/Features/SplitTests/SplitTestUserGetter.mjs
index 39c3d43269..7790d556d1 100644
--- a/services/web/app/src/Features/SplitTests/SplitTestUserGetter.mjs
+++ b/services/web/app/src/Features/SplitTests/SplitTestUserGetter.mjs
@@ -45,7 +45,7 @@ function getProjection(splitTestName) {
 
 /**
  * @param id
- * @param {string} splitTestName
+ * @param {string} [splitTestName] test to get; omit to fetch all assignments.
  * @param {string} path
  * @return {Promise<SplitTestUser>}
  */
diff --git a/services/web/test/unit/src/Project/ProjectListController.test.mjs b/services/web/test/unit/src/Project/ProjectListController.test.mjs
index fcbfb7d8d1..780c3de46a 100644
--- a/services/web/test/unit/src/Project/ProjectListController.test.mjs
+++ b/services/web/test/unit/src/Project/ProjectListController.test.mjs
@@ -568,6 +568,53 @@ describe('ProjectListController', function () {
       )
     })
 
+    it('should send packed split test assignments to customer.io', async function (ctx) {
+      ctx.Features.hasFeature.withArgs('saas').returns(true)
+      ctx.Modules.promises.hooks.fire
+        .withArgs('getSplitTestUserProperties', ctx.user._id)
+        .resolves([{ split_test_assignments: { 'test-a': 'variant-1' } }])
+      ctx.res.render = () => {}
+
+      await ctx.ProjectListController.projectListPage(ctx.req, ctx.res)
+
+      expect(ctx.Modules.promises.hooks.fire).to.have.been.calledWith(
+        'setUserProperties',
+        ctx.user._id,
+        sinon.match({
+          split_test_assignments: { 'test-a': 'variant-1' },
+        })
+      )
+    })
+
+    it('should not request split test user properties in a non-saas environment', async function (ctx) {
+      ctx.Features.hasFeature.withArgs('saas').returns(false)
+      ctx.res.render = () => {}
+
+      await ctx.ProjectListController.projectListPage(ctx.req, ctx.res)
+
+      expect(ctx.Modules.promises.hooks.fire).to.not.have.been.calledWith(
+        'getSplitTestUserProperties',
+        sinon.match.any
+      )
+    })
+
+    it('should still send other user properties when building split test assignments fails', async function (ctx) {
+      ctx.Features.hasFeature.withArgs('saas').returns(true)
+      ctx.Modules.promises.hooks.fire
+        .withArgs('getSplitTestUserProperties', ctx.user._id)
+        .rejects(new Error('boom'))
+      ctx.res.render = () => {}
+
+      await ctx.ProjectListController.projectListPage(ctx.req, ctx.res)
+
+      const call = ctx.Modules.promises.hooks.fire
+        .getCalls()
+        .find(call => call.args[0] === 'setUserProperties')
+      expect(call).to.exist
+      expect(call.args[2]).to.not.have.property('split_test_assignments')
+      expect(call.args[2]).to.have.property('overleaf_id', ctx.user._id)
+    })
+
     it('should send enterprise_commons=true when user has commons from an enterprise_commons institution', async function (ctx) {
       ctx.Features.hasFeature.withArgs('saas').returns(true)
       ctx.UserGetter.promises.getUserFullEmails.resolves([