What is this giant insect that just bounced off a second-floor glass door?
Searching the Internet again this morning, I think I may have identified it as a California (Giant) Root-Borer Beetle (https://www.insectidentification.org/insect-description.asp?identification=California-Root-Borer-Beetle). Yes?

They fly, and are active at night.

The disturbing serrated appendages are antennae (whew!).

It looks like I have nothing to fear from it unless I or others panic at its appearance, but it or its progeny may be bad news for nearby deciduous trees.