Instead of adding it here, I would add it to the ResidentRunner base class and document it. While its technically allowed to add new named parameters to overriden methods on subclasses, I think you should generally avoid that practice. It occasionally leads to surprises when a developer can't autocomplete a parameter due to the static type of a variable.

Can you add a doc comment on what needsFullRestart is for?

Doc comments should go on the method itself. Look at the flutter framework for examples of how parameters are documented. Usually something like:

/// One sentence summary about what foo does
///
/// [bar] is blah blah.
void foo(String bar);
```

I was following this particular example which apparently to have more than one line is acceptable. About going in the method agree I should move this up. https://dart.dev/guides/language/effective-dart/documentation#avoid-redundancy-with-the-surrounding-context

Thats fine, but it needs to go on the method itself and not the parameter

How about something like:

/// Connect to a flutter application.
///
/// [needsFullRestart] defaults to `true`, and controls if the frontend server should
/// compile a full dill. This should be set to `false` if this is called in [ResidentRunner.run], since that method already perfoms an initial compilation.