For a long time I haven't commented on this, because I haven't had any clear ideas or suggestions. Now I have some thoughts. I don't know how relevant it may be (and I don't know your plans in more detail), but here's some ideas, for whatever it's worth. It will be interesting to see how this develops.

Related HHVM error log message:

I've now also checked and yes, it works in Zend PHP.

I've been thinking about it, but not sure what's best. Some thoughts on various options:

I found one bug: PhpTagsException::isFatal() is always false for a HookException, because $this->code is only set according to the error level in the __toString() method. I made change 207888 to solve this, using a small redesign (which seemed the simplest solution). I don't know if the redesign is the way you would prefer to solve it.

It's just an idea to make some code in PhpTags extensions shorter. (It can be simpler to exit a hook by throwing an exception. But currently, throwing instead of pushing will stop the runtime.) It's up to you whether it is worth adding support for this.

The new INFO_ORIGINAL_FULL_NAME is even more convenient. :)

It's everything.

I've thought more about PhpTags Functions, which is the one extension among those you are considering that I didn't mention.

Apart from listing objects, constants, etc., a special page could also provide documentation directly in the wiki. Something similar to the current Reference pages for PhpTags Wiki and PhpTags SMW would be possible to generate automatically from the JSON files.

Merging could also be partial, instead of none or all. For example:

• If basic widgets (wiki lists and tables, etc.) are added to PhpTags, then PhpTags Widgets could still provide additional things. It could have any "extra" widgets that are more specialized, require more Javascript, etc.
• If you add data storage and querying in PhpTags itself, then maybe some PhpTags Wiki features would also make sense to have. (Support for categories, for example.) But there may still be things in PhpTags Wiki that are "extra" features and can be kept separate.