Hooks Viewer

Search in the panel

The HooksViewer panel is now a Vue component with a search field: filter the hooks by name, or inside their arguments.
Each hook links to its entry in the new hook catalog.
The list is only rendered once the panel is opened, so pages with many widgets stay fast.

Hook catalog

New Administration → Diagnostic → Hooks Viewer page, for super users: every known hook with its description and parameters (from the source docblock), the file and line where it is posted, the plugins listening to it, a registerEvents() snippet and a link to the developer reference.
Search, filter by category, show only hooks with listeners, rescan the source code on demand.
Hooks that are listened to but built at runtime (like Controller.CoreHome.index) are listed as dynamic.

Other

Matomo 6 compatibility, and a rebuilt inline output that no longer breaks Matomo's pages and responses.

Compatibility

Requires Matomo >=6.0.0-b1,<7.0.0-b1 and PHP 8.1+ (MySQL 8.0+ or MariaDB 10.6+, as required by Matomo 6).
No more deprecated E_USER_ERROR on PHP 8.4+.
~270 events discovered out of the box on Matomo 6.

Inline panel

Hooks are collected during the request and written once the response is complete, in one collapsible HooksViewer panel: right after <body> on full pages, at the top of widgets and AJAX HTML fragments.
The panel summary shows the number of hooks and the request id used in the log file.
The panel is only visible to super users. The log file still records the hooks of every request.
Panel styles follow the Matomo theme (light and dark).

Fixes

Pages are no longer rendered in quirks mode (markup was printed before the doctype).
JSON controller actions (#[JsonResponse], e.g. Dashboard.getAllDashboards) and graph data (jqPlot data-data) are no longer corrupted by hook markup.
No more "Session must be started before any output" errors: headers, cookies and redirects are sent normally.
Multi-byte strings are truncated without breaking characters, enums are shown as Class::CASE.

Log file

Other

update: README.md

Major rewrite. The plugin now covers (almost) every event Matomo dispatches and renders them inline at their dispatch point.

Hook discovery

New HookCatalog scans core/ and plugins/ for every Piwik::postEvent('…') call site. Same-file self::FOO_EVENT constants are resolved automatically.
Result is cached in tmp/cache/hooksviewer-catalog.php and rebuilt whenever the source tree changes (mtime-based signature, 5 min TTL).
~258 events discovered out of the box on a clean Matomo 5 install, vs. ~210 in the previous hand-maintained list.

Rendering

Events are rendered at the moment they fire, inline in the DOM, as <details><summary>HookName</summary><pre><code>args…</code></pre></details>.
Args are pretty-printed across multiple indented lines (depth-limited, truncated at 30 entries per level / 240 chars per string), so deep arrays and objects stay readable.
Args panel is locked to a dark background with white text so it remains legible regardless of the active Matomo theme.

Safety

Inline emission is suppressed for JSON, XML, CSV, image, and tracker responses: Matomo's API and matomo.php payloads stay byte-exact.
Widget AJAX requests (format=html) keep their inline output, so hooks like ViewDataTable.filterViewDataTable, Visualization.beforeRender, Metrics.isLowerValueBetter, and Widget.filterWidgets are visible inside each widget as it loads.
Every fired hook (HTML or not) is also appended to tmp/logs/hooksviewer.log with timestamp, request id, and args. Watch with tail -f.
Activation/deactivation now flushes Matomo's merged-asset bundle so the plugin's stylesheet is picked up immediately.

Internals

One generic __call() dispatcher replaces 200+ hand-rolled stub methods. The whole plugin is ~340 lines of PHP.
Compatible with Matomo 5.x.

Initial plugin commit.

View Plugin Page