That makes sense to me but is slightly more complicated because that only works if both branches infer to the same type, unless the fix removes the type annotation.

If the variable is declared with different types in the branches, Mypy flags it as a redefinition:

if randint(0, 3):
    x: int = 4
else:
    x: str = 'q'  # mypy flags as redefined

(It's not even clear whether there is one variable x defined in two places or two separate variables each called x. Yet another reason not to define a variable in branches.)

In this case it would be fine to add a new annotation that is the union of types in the branches:

x: int | str = 4 if randint(0, 3) else 'q'

The problem I see is more about:

if randint(0, 3):
    x: int = 4
else:
    x = 'q'  # mypy flags as redefined

Mypy might also flag this as redefinition but I'd have to check if this is true for every type checker (including red knot). But I could still see us flagging this but we may not want to provide a fix for it.