mapping widget GUIDs to widget names

In developer mode, widgets are fully defined in the file system. The folder structure is defaultwidgets/[FACTORY DEFAULT PROVIDER ID]/[WIDGET ID].xml (if the widget is not theme-versioned)

Assuming your widgets are all in the same factory default provider, they'll all be .XML files within your factory default provider's folder. Note that developer mode is not intended for file system editing, it is primarily for version control. The file naming is to optimize site load time.

In developer mode, widgets are fully defined in the file system. The folder structure is defaultwidgets/[FACTORY DEFAULT PROVIDER ID]/[WIDGET ID].xml (if the widget is not theme-versioned)

Assuming your widgets are all in the same factory default provider, they'll all be .XML files within your factory default provider's folder. Note that developer mode is not intended for file system editing, it is primarily for version control. The file naming is to optimize site load time.

that's close. Those seem to have the name stored in an XML file in the root of each GUID. 

My problem is, I created a new widget that lives under filestorage/widgetfiles/GUID/d. It's this stuff that I'm trying to find the widget name of. Also, I don't see the core content component for any of the widgets in this path. 

This path is used for widgets created outside of developer mode. Widgets created w/ developer mode enabled should be within the defaultwidgets/ folder in the path format I identified.