A task pane can be enabled without changing Word text

A Word document can carry Office Add-in configuration in package parts that a
text diff never sees. One stored property can change from false
to true while every w:t node remains the same. That
is static review evidence, not proof that an add-in is installed, trusted, or
will run.

Document Change Assurance Benchmark 0.10.0
adds its twenty-first deterministic paired package:
interaction.taskpane_auto_show_setting_enabled. Both packages
retain their members, Word text, content types, internal relationship chain,
task-pane declaration, web-extension reference shape, and property name. Only
word/webextensions/webextension1.xml changes: the stored
Office.AutoShowTaskpaneWithDocument value moves from
false to true.

A stored configuration, not an installed add-in

Microsoft’s Office web-extension XML specification
describes document-borne structures for Office Add-ins. Its task-pane
auto-open guidance
specifies the webextension/taskpane parts and this
property.

That guidance also makes the limit clear: the setting is ignored if the add-in
is not already installed and, as of March 2, 2026, auto-open is supported only
for centrally deployed or sideloaded add-ins. DCAB provides only a syntactic,
internally linked package pair. It supplies no manifest and does not retrieve,
install, authenticate, execute, or assert the opening of an add-in task pane.

One property, a complete internal topology

The pair retains the main-document-to-taskpane relationship, one invisible and
unlocked task pane, the taskpane-to-webextension relationship, fixed synthetic
IDs, an EXCatalog reference shape, one property, no bindings, and
an empty snapshot. The independent verifier checks those parts and
relationships, deterministic bytes, stable members, unchanged Word text, and
the one-member boundary.

Standard python-docx opens all 40 .docx fixtures and
its lower-level OPC reader opens all 42 packages. The optional local
DocFence 0.27.0
adapter reports aggregate taskpane_web_extension_inventory_changed
evidence: all structural counts stay fixed while only the auto-show setting
count moves from 0 to 1. It uses counts and private local signatures, not raw
IDs, store data, or property values.

DCAB 0.10.0 retains fixture schema version 1 and extends the corpus from 20 to
21 cases. It publishes a narrow static-review fact, not a deployment, identity,
trust, client-behavior, or security-policy claim.

The source, generated corpus, and verifier are MIT-licensed on
GitHub. Read the
canonical release note
for the full boundary and install command.