Since Fossil 1.30 it's possible to extend both the CLI and web interface with new functionality / or gimicks. Using --with-th1-hooks for compilation and the th1-hooks repo setting, custom callbacks can be crafted.

Web hooks

Simply craft a webpage_hook function in th1-setup.

 proc webpage_hook {} {
    puts $::web_name;
    continue;
 }

The global var $::web_name is populated with the currently requested pagename. It can be one of the built-in functions (wiki, index, home, artifact, etc) or a new custom name. It should preferrably only engage for custom URL paths of course.

An accompanying webpage_notify can be defined, which would be called after page processing.

• webpage_hook is always invoked first.
• Fossils built-in pages thereafter, and if no break or TH_ERROR was created.
• webpage_notify runs last, if continue, return or TH_OK were returned from the _hook callback.

The vars $::web_args and $::web_flags are mostly useless, and just inherit fossil server/ui/cgi startup args. Use set name [getParameter name ""] instead to get URL params.

Comand hooks

The same process applies to command_hook (called first) and command_notify (called after internal command processing). The variable names $::cmd_name, $::cmd_args, $::$cmd_flags are in particular useful to implement new and custom fossil mycmd stuff.