How to set section title based on section content?

I have a document that has some structures like this:

\starttext

\startsection[title={Animals}]

\event{\input knuth }

\stopsection

\startsection[title={Books}]

\event{\input knuth }

\stopsection

\stoptext

The event macro runs a bunch of conditionals, deciding which content to place inside the section. It places any one of neary 200 possible different types of content there.

Sadly when I wrote the code, I thought generic titles would be okay. Now I realize I need to be more specific, giving titles that match the content inside. I could move the section titles inside the \event macro, but it means rewriting ~200 other macros.

In other words, how do I define a section title by defining it somewhere in the content of the \event macro?

\starttext

\startsection[\whatistitle] %<-- would display "Neon Tetras"

\event{\thetitleis{Neon Tetras}\input knuth }

\stopsection

\startsection[\whatistitle] %<-- would display "Detective Stories"

\event{\thetitleis{Detective Stories}\input knuth }

\stopsection

\stoptext