I believe there's a bug in the Web Component Analyzer library's API when using Lit Element. Specifically, it's analyzeText function.
When using CLI mode, the analyzer will pull in prop definitions from a component's parent class, even if that class was imported from another file. In API mode, this doesn't happen. The analyzeText function will only find props from parent class definitions if the parent class is defined within the same file that the child class is defined.
Run yarn or npm i to install the dependencies.
In the examples/cli folder, there are two files where a class TextField extends class TextFieldParent, which in turn, extends class LitElement.
In the file single.file.ts, both classes are defined with that file itself. But in the file multi.file.ts, only TextField is defined there, with TextFieldParent being imported from the file multi-parent.ts.
The commands
yarn cli-single
yarn cli-multiwill run, respecively, wca in CLI mode over the two files. (Or you can run yarn cli-all to save a bit of typing.) Check the scripts entry in package.json to see the CLI syntaxes used.
In both cases, the terminal output will show that props from both TextField and TextFieldParent are included in the markdown.
The commands
yarn api-single
yarn api-multiwill repeat the two tests, but this time using the analyzeText function from the API rather than using CLI mode. (Again, you can use yarn api-all to save yourself some typing.)
The two api scripts call the files test-api-single.js and test-api-multi.js, which are both in the examples/js folder.
This time, only the single file variant will pull in props from both the TextField and TextFieldParent classes. The multi file version will show only props from TextField but not from TextFieldParent.
Note yarn all-tests will run all four tests in sequence.