Addresses Copilot's round-8 review on #2035 (one inline comment, one
suppressed). Both real.
1. RFC 6570 distinguishes an UNDEFINED variable, which omits its whole
expression, from one defined as the empty string, which expands. The
expander was calling `definedValues` on the way in, collapsing the two --
so `x{?q}` with `{ q: "" }` gave `x` instead of `x?q=`, and there was no
way for any caller, `readResourceFromTemplate` included, to request
either that or `x;q`. Key presence is now honored, including §3.2.7's
rule that the matrix operator drops the `=` for an empty value (`x{;q}`
-> `x;q`, while `?`/`&` keep it).
Dropping blanks is a FORM concern, so it moved to the two form
boundaries: the web panel seeds every declared variable with "" and the
TUI's ink-form returns "" for every untouched field, so neither can tell
"never touched" from "deliberately empty" -- but that is a fact about a
text input, not about the template, and it has no business deciding what
a template means for every other caller.
Six unit tests and one integration test encoded the old collapse and now
assert the corrected meaning. The prototype-collision cases get stronger
rather than weaker: a blank `{?toString}` expands to `?toString=` -- its
OWN empty value -- where the original bug expanded the inherited
function's body.
2. The expansion error is now `role="alert"`. It can appear while typing (a
pasted value that cannot be encoded), and plain text is not announced, so
a screen-reader user met a disabled Read Resource with no stated reason.
npm run ci passes.
Signed-off-by: cliffhall <cliff@futurescale.com>
6acaff70ca