OCA · cvinh · Jul 14, 2026
diff --git a/project_merge/README.rst b/project_merge/README.rst
@@ -1,7 +1,3 @@
-.. image:: https://odoo-community.org/readme-banner-image
-   :target: https://odoo-community.org/get-involved?utm_source=readme
-   :alt: Odoo Community Association
-
 ==================
 Project Task Merge
 ==================
@@ -17,7 +13,7 @@ Project Task Merge
 .. |badge1| image:: https://img.shields.io/badge/maturity-Beta-yellow.png
     :target: https://odoo-community.org/page/development-status
     :alt: Beta
-.. |badge2| image:: https://img.shields.io/badge/license-AGPL--3-blue.png
+.. |badge2| image:: https://img.shields.io/badge/licence-AGPL--3-blue.png
     :target: http://www.gnu.org/licenses/agpl-3.0-standalone.html
     :alt: License: AGPL-3
 .. |badge3| image:: https://img.shields.io/badge/github-OCA%2Fproject-lightgray.png?logo=github
@@ -36,6 +32,9 @@ This module adds a wizard to merge project tasks.
 
 A wizard that can be called from tree view of project task.
 
+Messages, activities and attachments from the merged tasks are also
+moved to the destination task.
+
 **Table of contents**
 
 .. contents::
@@ -48,6 +47,12 @@ To use this module, you need to:
 
 1. Merge Project Task
 
+Known issues / Roadmap
+======================
+
+Task dependencies (Blocked by / Blocking, ``depend_on_ids`` /
+``dependent_ids``) are not transferred to the destination task on merge.
+
 Bug Tracker
 ===========
 
@@ -70,6 +75,7 @@ Contributors
 ------------
 
 - `Onestein <http://www.onestein.eu>`__
+- Cyril VINH-TUNG cyril@invitu.com
 
 Maintainers
 -----------

diff --git a/project_merge/readme/CONTRIBUTORS.md b/project_merge/readme/CONTRIBUTORS.md
@@ -1 +1,2 @@
 - [Onestein](http://www.onestein.eu)
+- Cyril VINH-TUNG <cyril@invitu.com>
diff --git a/project_merge/readme/DESCRIPTION.md b/project_merge/readme/DESCRIPTION.md
@@ -1,3 +1,6 @@
 This module adds a wizard to merge project tasks.
 
 A wizard that can be called from tree view of project task.
+
+Messages, activities and attachments from the merged tasks are also moved
+to the destination task.
diff --git a/project_merge/readme/ROADMAP.md b/project_merge/readme/ROADMAP.md
@@ -0,0 +1,2 @@
+Task dependencies (Blocked by / Blocking, `depend_on_ids` / `dependent_ids`)
+are not transferred to the destination task on merge.
diff --git a/project_merge/static/description/index.html b/project_merge/static/description/index.html
@@ -3,7 +3,7 @@
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <meta name="generator" content="Docutils: https://docutils.sourceforge.io/" />
-<title>README.rst</title>
+<title>Project Task Merge</title>
 <style type="text/css">
 
 /*
@@ -360,67 +360,71 @@
 </style>
 </head>
 <body>
-<div class="document">
+<div class="document" id="project-task-merge">
+<h1 class="title">Project Task Merge</h1>
 
-
-<a class="reference external image-reference" href="https://odoo-community.org/get-involved?utm_source=readme">
-<img alt="Odoo Community Association" src="https://odoo-community.org/readme-banner-image" />
-</a>
-<div class="section" id="project-task-merge">
-<h1>Project Task Merge</h1>
 <!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !! This file is generated by oca-gen-addon-readme !!
 !! changes will be overwritten.                   !!
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !! source digest: sha256:30b988692949c43c5df55046d8bc453864e390e181efcf04191bc289601c4c29
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
-<p><a class="reference external image-reference" href="https://odoo-community.org/page/development-status"><img alt="Beta" src="https://img.shields.io/badge/maturity-Beta-yellow.png" /></a> <a class="reference external image-reference" href="http://www.gnu.org/licenses/agpl-3.0-standalone.html"><img alt="License: AGPL-3" src="https://img.shields.io/badge/license-AGPL--3-blue.png" /></a> <a class="reference external image-reference" href="https://github.com/OCA/project/tree/18.0/project_merge"><img alt="OCA/project" src="https://img.shields.io/badge/github-OCA%2Fproject-lightgray.png?logo=github" /></a> <a class="reference external image-reference" href="https://translation.odoo-community.org/projects/project-18-0/project-18-0-project_merge"><img alt="Translate me on Weblate" src="https://img.shields.io/badge/weblate-Translate%20me-F47D42.png" /></a> <a class="reference external image-reference" href="https://runboat.odoo-community.org/builds?repo=OCA/project&amp;target_branch=18.0"><img alt="Try me on Runboat" src="https://img.shields.io/badge/runboat-Try%20me-875A7B.png" /></a></p>
+<p><a class="reference external image-reference" href="https://odoo-community.org/page/development-status"><img alt="Beta" src="https://img.shields.io/badge/maturity-Beta-yellow.png" /></a> <a class="reference external image-reference" href="http://www.gnu.org/licenses/agpl-3.0-standalone.html"><img alt="License: AGPL-3" src="https://img.shields.io/badge/licence-AGPL--3-blue.png" /></a> <a class="reference external image-reference" href="https://github.com/OCA/project/tree/18.0/project_merge"><img alt="OCA/project" src="https://img.shields.io/badge/github-OCA%2Fproject-lightgray.png?logo=github" /></a> <a class="reference external image-reference" href="https://translation.odoo-community.org/projects/project-18-0/project-18-0-project_merge"><img alt="Translate me on Weblate" src="https://img.shields.io/badge/weblate-Translate%20me-F47D42.png" /></a> <a class="reference external image-reference" href="https://runboat.odoo-community.org/builds?repo=OCA/project&amp;target_branch=18.0"><img alt="Try me on Runboat" src="https://img.shields.io/badge/runboat-Try%20me-875A7B.png" /></a></p>
 <p>This module adds a wizard to merge project tasks.</p>
 <p>A wizard that can be called from tree view of project task.</p>
+<p>Messages, activities and attachments from the merged tasks are also
+moved to the destination task.</p>
 <p><strong>Table of contents</strong></p>
 <div class="contents local topic" id="contents">
 <ul class="simple">
 <li><a class="reference internal" href="#usage" id="toc-entry-1">Usage</a></li>
-<li><a class="reference internal" href="#bug-tracker" id="toc-entry-2">Bug Tracker</a></li>
-<li><a class="reference internal" href="#credits" id="toc-entry-3">Credits</a><ul>
-<li><a class="reference internal" href="#authors" id="toc-entry-4">Authors</a></li>
-<li><a class="reference internal" href="#contributors" id="toc-entry-5">Contributors</a></li>
-<li><a class="reference internal" href="#maintainers" id="toc-entry-6">Maintainers</a></li>
+<li><a class="reference internal" href="#known-issues-roadmap" id="toc-entry-2">Known issues / Roadmap</a></li>
+<li><a class="reference internal" href="#bug-tracker" id="toc-entry-3">Bug Tracker</a></li>
+<li><a class="reference internal" href="#credits" id="toc-entry-4">Credits</a><ul>
+<li><a class="reference internal" href="#authors" id="toc-entry-5">Authors</a></li>
+<li><a class="reference internal" href="#contributors" id="toc-entry-6">Contributors</a></li>
+<li><a class="reference internal" href="#maintainers" id="toc-entry-7">Maintainers</a></li>
 </ul>
 </li>
 </ul>
 </div>
 <div class="section" id="usage">
-<h2><a class="toc-backref" href="#toc-entry-1">Usage</a></h2>
+<h1><a class="toc-backref" href="#toc-entry-1">Usage</a></h1>
 <p>To use this module, you need to:</p>
 <ol class="arabic simple">
 <li>Merge Project Task</li>
 </ol>
 </div>
+<div class="section" id="known-issues-roadmap">
+<h1><a class="toc-backref" href="#toc-entry-2">Known issues / Roadmap</a></h1>
+<p>Task dependencies (Blocked by / Blocking, <tt class="docutils literal">depend_on_ids</tt> /
+<tt class="docutils literal">dependent_ids</tt>) are not transferred to the destination task on merge.</p>
+</div>
 <div class="section" id="bug-tracker">
-<h2><a class="toc-backref" href="#toc-entry-2">Bug Tracker</a></h2>
+<h1><a class="toc-backref" href="#toc-entry-3">Bug Tracker</a></h1>
 <p>Bugs are tracked on <a class="reference external" href="https://github.com/OCA/project/issues">GitHub Issues</a>.
 In case of trouble, please check there if your issue has already been reported.
 If you spotted it first, help us to smash it by providing a detailed and welcomed
 <a class="reference external" href="https://github.com/OCA/project/issues/new?body=module:%20project_merge%0Aversion:%2018.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**">feedback</a>.</p>
 <p>Do not contact contributors directly about support or help with technical issues.</p>
 </div>
 <div class="section" id="credits">
-<h2><a class="toc-backref" href="#toc-entry-3">Credits</a></h2>
+<h1><a class="toc-backref" href="#toc-entry-4">Credits</a></h1>
 <div class="section" id="authors">
-<h3><a class="toc-backref" href="#toc-entry-4">Authors</a></h3>
+<h2><a class="toc-backref" href="#toc-entry-5">Authors</a></h2>
 <ul class="simple">
 <li>Onestein</li>
 </ul>
 </div>
 <div class="section" id="contributors">
-<h3><a class="toc-backref" href="#toc-entry-5">Contributors</a></h3>
+<h2><a class="toc-backref" href="#toc-entry-6">Contributors</a></h2>
 <ul class="simple">
 <li><a class="reference external" href="http://www.onestein.eu">Onestein</a></li>
+<li>Cyril VINH-TUNG <a class="reference external" href="mailto:cyril&#64;invitu.com">cyril&#64;invitu.com</a></li>
 </ul>
 </div>
 <div class="section" id="maintainers">
-<h3><a class="toc-backref" href="#toc-entry-6">Maintainers</a></h3>
+<h2><a class="toc-backref" href="#toc-entry-7">Maintainers</a></h2>
 <p>This module is maintained by the OCA.</p>
 <a class="reference external image-reference" href="https://odoo-community.org">
 <img alt="Odoo Community Association" src="https://odoo-community.org/logo.png" />
@@ -433,6 +437,5 @@ <h3><a class="toc-backref" href="#toc-entry-6">Maintainers</a></h3>
 </div>
 </div>
 </div>
-</div>
 </body>
 </html>
diff --git a/project_merge/tests/test_project_task_merge.py b/project_merge/tests/test_project_task_merge.py
@@ -334,3 +334,55 @@ def test_create_new_task_on_merge(self):
             len(self.task_merge_2.dst_task_id._get_all_subtasks()),
             "Should have 18 subtasks",
         )
+
+    def test_merge_moves_messages_and_activities(self):
+        """messages, activities and attachments of the merged task are
+        moved to the destination task, with a mention of their origin
+        task"""
+        task_A = self.env["project.task"].create(
+            {"name": "Task A", "project_id": self.project_goats.id}
+        )
+        task_B = self.env["project.task"].create(
+            {"name": "Task B", "project_id": self.project_goats.id}
+        )
+        attachment_direct = self.env["ir.attachment"].create(
+            {
+                "name": "doc.txt",
+                "res_model": "project.task",
+                "res_id": task_B.id,
+                "raw": b"some content",
+            }
+        )
+        attachment_message = self.env["ir.attachment"].create(
+            {
+                "name": "message_doc.txt",
+                "res_model": "project.task",
+                "res_id": task_B.id,
+                "raw": b"some content",
+            }
+        )
+        message_B = task_B.message_post(
+            body="Some note on task B",
+            subject="B note",
+            message_type="comment",
+            subtype_xmlid="mail.mt_note",
+            attachment_ids=[attachment_message.id],
+        )
+        activity_B = task_B.activity_schedule(
+            "mail.mail_activity_data_todo", summary="Follow up on task B"
+        )
+
+        task_merge = (
+            self.env["project.task.merge"]
+            .with_context(active_ids=[task_A.id, task_B.id])
+            .create({})
+        )
+        task_merge.merge_tasks()
+
+        self.assertEqual(message_B.res_id, task_merge.dst_task_id.id)
+        self.assertEqual(message_B.subject, "From Task B: B note")
+        self.assertEqual(activity_B.res_id, task_merge.dst_task_id.id)
+        self.assertEqual(attachment_direct.res_id, task_merge.dst_task_id.id)
+        self.assertEqual(attachment_direct.name, "doc.txt (from Task B)")
+        self.assertEqual(attachment_message.res_id, task_merge.dst_task_id.id)
+        self.assertEqual(attachment_message.name, "message_doc.txt (from Task B)")
diff --git a/project_merge/wizard/project_task_merge.py b/project_merge/wizard/project_task_merge.py
@@ -31,11 +31,9 @@ def default_get(self, fields):
 
     def merge_tasks(self):
         tag_ids = self.task_ids.mapped("tag_ids").ids
-        attachment_ids = self.task_ids.mapped("attachment_ids").ids
         values = {
             "description": self._get_merge_description(),
             "tag_ids": [(4, tag_id) for tag_id in tag_ids],
-            "attachment_ids": [(4, attachment_id) for attachment_id in attachment_ids],
             "user_ids": self.user_ids.ids,
         }
         if self.create_new_task:
@@ -56,6 +54,8 @@ def merge_tasks(self):
             self.dst_task_id.write(values)
         merged_tasks = self.task_ids - self.dst_task_id
         self._subscribe_merged_followers(merged_tasks)
+        self._merge_dependences_history(merged_tasks)
+        self._merge_dependences_attachments(merged_tasks)
         for task in merged_tasks:
             self._add_message("to", self.dst_task_id.name, task)
             if task.child_ids:
@@ -85,6 +85,54 @@ def _subscribe_merged_followers(self, merged_tasks):
             partner_ids=(merged_tasks).mapped("message_partner_ids").ids
         )
 
+    def _merge_dependences_history(self, merged_tasks):
+        """Move messages and activities from merged tasks to the destination
+        task, keeping track of their origin.
+        :param merged_tasks : recordset of tasks about to be archived
+        """
+        for task_su in merged_tasks.sudo():
+            for message_su in task_su.message_ids:
+                if message_su.subject:
+                    subject = _(
+                        "From %(source_name)s: %(source_subject)s",
+                        source_name=task_su.name,
+                        source_subject=message_su.subject,
+                    )
+                else:
+                    subject = _("From %(source_name)s", source_name=task_su.name)
+                message_su.write({"res_id": self.dst_task_id.id, "subject": subject})
+        merged_tasks.sudo().activity_ids.write({"res_id": self.dst_task_id.id})
+
+    def _merge_dependences_attachments(self, merged_tasks):
+        """Move attachments of the merged tasks to the destination task, and
+        rename them to keep track of their origin.
+        ir.attachment is reparented directly: project.task.attachment_ids
+        is a non-stored compute field, it can't be written through values.
+        :param merged_tasks : recordset of tasks about to be archived
+        """
+        all_attachments = (
+            self.env["ir.attachment"]
+            .sudo()
+            .search(
+                [
+                    ("res_model", "=", "project.task"),
+                    ("res_id", "in", merged_tasks.ids),
+                ]
+            )
+        )
+        task_name_per_id = {task.id: task.name for task in merged_tasks}
+        for attachment in all_attachments:
+            attachment.write(
+                {
+                    "res_id": self.dst_task_id.id,
+                    "name": _(
+                        "%(attach_name)s (from %(task_name)s)",
+                        attach_name=attachment.name,
+                        task_name=task_name_per_id[attachment.res_id][:20],
+                    ),
+                }
+            )
+
     def _add_message(self, way, task_names, task):
         """Send a message post with to advise the project task about the merge.
         :param way : choice between "from" or "to"
Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		- [Onestein](http://www.onestein.eu)
		- Cyril VINH-TUNG <cyril@invitu.com>
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Task dependencies (Blocked by / Blocking, `depend_on_ids` / `dependent_ids`)
		are not transferred to the destination task on merge.