"Expand Selection" doesn't expand to strings or scopes

I use VScode's "Expand Selection" command a lot to copy strings around, but when I try to use it on Lua strings, it expands the selection a lot more than just the string I'm on.

Actual behavior

Suppose my cursor is inside the word example:

hs.alert(prefix .. " an exam|ple string " .. suffix)

1st call to Expand Selection selects the word:

hs.alert(prefix .. " an example string " .. suffix)

2nd call to Expand Selection selects everything between () instead of the full string:

hs.alert(prefix .. " an example string " .. suffix)

Expected behavior

2nd call to Expand Selection should select just the string:

hs.alert(prefix .. " an example string " .. suffix)

In JavaScript, I noticed it even has two steps for the string, the inner part of the string, then the outer:

alert(prefix + " an example string " + suffix)

alert(prefix + "an example string" + suffix)

alert(prefix + " an example string " + suffix)

That would also work!

Similar scenarios

Scopes are also currently skipped:

local myFunction = function () ret|urn true end

local myFunction = function () return true end <- 1st call selects the word

local myFunction = function () return true end <- expected: 2nd call selects the function scope

local myFunction = function () return true end <- actual: 2nd call selects the line instead

Same for Object.property:

Object.property = true

Object.property = true <- expected

Object.property = true <- actual

Start by locating the Expand Selection implementation and any tests covering selection expansion; the issue does not name specific files or entry points. Reproduce the Lua string, function-scope, and Object.property examples, then add coverage showing that successive expansions select the expected constructs.