[ADD] dms_libreoffice_preview: server-side LibreOffice→PDF preview for office files

Adds in-browser preview of .doc{x}, .odt, .xls{x}, .ods, .ppt{x}, .odp, .rtf
in OCA DMS by converting them to PDF via headless LibreOffice subprocess
on first request, caching the result as a child ir.attachment of the
source dms.file, and registering a side-pane handler at score 10 that
beats the OfficeFallbackPreview download card shipped in base dms.

First downstream consumer of the dms.preview_handlers registry introduced
in Phase 13 of OCA/dms 19.0. The registry composes cleanly: a future
dms_onlyoffice (live editing via OnlyOffice Document Server) would
register at score 20 and win over this module's read-only PDF preview
whenever it's installed.

Architecture
- Lazy: nothing converts until first preview request.
- Cached: ir.attachment with res_model='dms.file', res_id=file.id,
  description='libreoffice_preview:<checksum>' as cache key. Keyed on
  dms.file.checksum (SHA1 of content) so renaming a file doesn't trigger
  re-conversion, only actual content edits do. Cache auto-cascades on
  file deletion via the existing res_model/res_id wiring.
- ACL: controller calls dms.file.check_access('read') before serving;
  the converted PDF inherits the parent's permissions. Raises
  request.not_found() (with `from e` chain) on AccessError so unauthorized
  callers can't probe existence.
- Sync subprocess per call, 60s timeout, per-conversion temp dir to
  avoid .~lock collisions between concurrent workers. Daemon mode
  (unoserver) is a future optimization, not v1.

JS handler reuses the existing o_dms_preview__iframe class so the
browser's native PDF viewer takes over once the server emits the
converted PDF. No new SCSS needed.

External dependency
- libreoffice + fonts-noto + fonts-liberation (declared in
  external_dependencies.deb; OCA CI's oca_install_apt_packages picks
  them up automatically on the test runner).

Tests
- Python: 7 tests covering the mimetype gate, conversion happy path,
  cache hit + invalidation (via checksum drift), missing-soffice
  UserError, and controller routing (404 unsupported, 200 with
  application/pdf for office files). HTTP tests authenticate as
  dms-user (the user in DocumentsBaseCase.access_group) rather than
  admin which isn't in the group.
- Hoot: every supported office mimetype routes to LibreofficePreview
  at score 10 (beats base dms's score-0 OfficeFallbackPreview); src
  URL builder includes /dms/file/<id>/libreoffice_preview + v= cache
  bust.

CI workaround
- workflow_dispatch added to both test.yml and pre-commit.yml as the
  fork-only manual-trigger escape valve. GitHub silently throttles
  pull_request webhooks after burst pushes; this lets us trigger CI
  manually with `gh workflow run`. Strip before opening upstream against
  OCA/dms.

Signed-off-by: Don Kendall <dkendall@ledoweb.com>

Author: dnplkndll

.github/workflows/pre-commit.yml

@@ -8,6 +8,7 @@ on:
     branches:
       - "19.0"
       - "19.0-ocabot-*"
+  workflow_dispatch:
 
 jobs:
   pre-commit:

dms_libreoffice_preview/README.rst

@@ -0,0 +1,138 @@
+.. image:: https://odoo-community.org/readme-banner-image
+   :target: https://odoo-community.org/get-involved?utm_source=readme
+   :alt: Odoo Community Association
+
+=========================
+DMS — LibreOffice Preview
+=========================
+
+.. 
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+   !! This file is generated by oca-gen-addon-readme !!
+   !! changes will be overwritten.                   !!
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+   !! source digest: sha256:81baba4c980b32e56a3e208ba841264571d907763fa987650db3d700e2592292
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+.. |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-LGPL--3-blue.png
+    :target: http://www.gnu.org/licenses/lgpl-3.0-standalone.html
+    :alt: License: LGPL-3
+.. |badge3| image:: https://img.shields.io/badge/github-OCA%2Fdms-lightgray.png?logo=github
+    :target: https://github.com/OCA/dms/tree/19.0/dms_libreoffice_preview
+    :alt: OCA/dms
+.. |badge4| image:: https://img.shields.io/badge/weblate-Translate%20me-F47D42.png
+    :target: https://translation.odoo-community.org/projects/dms-19-0/dms-19-0-dms_libreoffice_preview
+    :alt: Translate me on Weblate
+.. |badge5| image:: https://img.shields.io/badge/runboat-Try%20me-875A7B.png
+    :target: https://runboat.odoo-community.org/builds?repo=OCA/dms&target_branch=19.0
+    :alt: Try me on Runboat
+
+|badge1| |badge2| |badge3| |badge4| |badge5|
+
+Adds in-browser preview of office file formats (Word, Excel, PowerPoint,
+OpenDocument, RTF) to OCA DMS by converting them to PDF on the server
+with a headless LibreOffice subprocess. The converted PDF is cached as a
+child ``ir.attachment`` of the source ``dms.file`` and served via the
+existing side-pane preview registry (``dms.preview_handlers``), so the
+browser's native PDF viewer renders the result with no new UI code.
+
+Without this module, office files in DMS fall back to a download-only
+card. Install this module on any deployment where LibreOffice can be
+installed system-wide and you don't need full in-browser editing (use
+``dms_onlyoffice`` for that).
+
+**Table of contents**
+
+.. contents::
+   :local:
+
+Installation
+============
+
+System dependencies
+-------------------
+
+LibreOffice must be installed on the Odoo server. On Debian / Ubuntu:
+
+::
+
+   apt-get install libreoffice fonts-noto fonts-liberation
+
+The ``fonts-noto`` and ``fonts-liberation`` packages are recommended
+even if your container already has a font set — headless LibreOffice
+falls back to ugly substitutes when common fonts are missing, which
+produces unreadable PDFs for typical office documents.
+
+Once LibreOffice is on the ``PATH``, install this module as usual. The
+preview is lazy: nothing converts until the first time a user opens an
+office file in the DMS side-pane. Subsequent opens of the same file
+(same ``write_date``) hit the ``ir.attachment`` cache.
+
+Usage
+=====
+
+No configuration required. With LibreOffice on the server and this
+module installed, opening any office file (``.doc{x}``, ``.odt``,
+``.xls{x}``, ``.ods``, ``.ppt{x}``, ``.odp``, ``.rtf``) from the DMS
+kanban or list view shows the rendered PDF in the side-pane preview.
+
+The first open takes 1–5 seconds (LibreOffice conversion); subsequent
+opens hit the cached attachment and feel instant. If the source file
+changes (new content, new name, etc.), the cache invalidates and the
+next open triggers a fresh conversion.
+
+If LibreOffice fails to convert a file (corrupt source, unusual format
+variation), the side-pane shows a brief error message. The original file
+is always downloadable via the side-pane toolbar's Download button
+regardless of preview success.
+
+Bug Tracker
+===========
+
+Bugs are tracked on `GitHub Issues <https://github.com/OCA/dms/issues>`_.
+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
+`feedback <https://github.com/OCA/dms/issues/new?body=module:%20dms_libreoffice_preview%0Aversion:%2019.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**>`_.
+
+Do not contact contributors directly about support or help with technical issues.
+
+Credits
+=======
+
+Authors
+-------
+
+* ledoent
+
+Contributors
+------------
+
+- Don Kendall <dkendall@ledoweb.com>
+
+Maintainers
+-----------
+
+This module is maintained by the OCA.
+
+.. image:: https://odoo-community.org/logo.png
+   :alt: Odoo Community Association
+   :target: https://odoo-community.org
+
+OCA, or the Odoo Community Association, is a nonprofit organization whose
+mission is to support the collaborative development of Odoo features and
+promote its widespread use.
+
+.. |maintainer-dnplkndll| image:: https://github.com/dnplkndll.png?size=40px
+    :target: https://github.com/dnplkndll
+    :alt: dnplkndll
+
+Current `maintainer <https://odoo-community.org/page/maintainer-role>`__:
+
+|maintainer-dnplkndll| 
+
+This module is part of the `OCA/dms <https://github.com/OCA/dms/tree/19.0/dms_libreoffice_preview>`_ project on GitHub.
+
+You are welcome to contribute. To learn how please visit https://odoo-community.org/page/Contribute.

dms_libreoffice_preview/__init__.py

@@ -0,0 +1,2 @@
+from . import controllers
+from . import models

dms_libreoffice_preview/__manifest__.py

@@ -0,0 +1,30 @@
+# Copyright 2026 ledoent — Don Kendall
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+{
+    "name": "DMS — LibreOffice Preview",
+    "summary": (
+        "In-browser preview of office files in DMS via "
+        "server-side LibreOffice→PDF conversion"
+    ),
+    "version": "19.0.1.0.0",
+    "category": "Document Management",
+    "license": "LGPL-3",
+    "website": "https://github.com/OCA/dms",
+    "author": "ledoent, Odoo Community Association (OCA)",
+    "maintainers": ["dnplkndll"],
+    "depends": ["dms"],
+    "external_dependencies": {
+        "deb": ["libreoffice", "fonts-noto", "fonts-liberation"],
+    },
+    "assets": {
+        "web.assets_backend": [
+            "dms_libreoffice_preview/static/src/js/libreoffice_preview.esm.js",
+            "dms_libreoffice_preview/static/src/js/libreoffice_preview.xml",
+        ],
+        "web.assets_unit_tests": [
+            "dms_libreoffice_preview/static/tests/**/*.test.js",
+        ],
+    },
+    "installable": True,
+}

dms_libreoffice_preview/controllers/__init__.py

@@ -0,0 +1 @@
+from . import main

dms_libreoffice_preview/controllers/main.py

@@ -0,0 +1,51 @@
+# Copyright 2026 ledoent — Don Kendall
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).
+
+from odoo import http
+from odoo.exceptions import AccessError, UserError
+from odoo.http import request
+
+
+class DmsLibreofficePreviewController(http.Controller):
+    @http.route(
+        "/dms/file/<int:file_id>/libreoffice_preview",
+        type="http",
+        auth="user",
+        methods=["GET"],
+        # Not readonly: cache-miss path writes a new ir.attachment via
+        # _ensure_libreoffice_preview(). Marking readonly=True triggers
+        # Odoo 19's "retry with r/w cursor" warning which checklog-odoo
+        # promotes to a build error.
+    )
+    def libreoffice_preview(self, file_id, **kwargs):
+        """Serve a cached or freshly-converted PDF preview inline.
+
+        The `?v=<write_date>` query parameter is not validated server-side
+        — it exists purely as a cache-buster for the browser (the iframe
+        URL changes when `dms.file.write_date` changes, forcing a refetch
+        instead of pulling a stale render from the HTTP cache). Cache
+        validity on the server is owned by `_libreoffice_preview_attachment`.
+        """
+        dms_file = request.env["dms.file"].browse(file_id).exists()
+        if not dms_file:
+            raise request.not_found()
+        try:
+            dms_file.check_access("read")
+        except AccessError as e:
+            raise request.not_found() from e
+        if not dms_file._libreoffice_preview_supported():
+            raise request.not_found()
+        try:
+            attachment = dms_file.sudo()._ensure_libreoffice_preview()
+        except UserError as e:
+            # Conversion errors are surfaced as 502 with the user-facing
+            # message — the side-pane handler can render this as an empty
+            # state via the existing error path.
+            return request.make_response(
+                str(e), status=502, headers=[("Content-Type", "text/plain")]
+            )
+        return (
+            request.env["ir.binary"]
+            ._get_stream_from(attachment, "raw")
+            .get_response(as_attachment=False)
+        )

dms_libreoffice_preview/models/__init__.py

@@ -0,0 +1 @@
+from . import dms_file