Append a child path suffix to a parent path. When the suffix is
omitted (e.g. transparent wrappers like union options) the parent
path is returned unchanged so the child inherits the parent's id.
Bracketed array indices like "[0]" append directly so tags +
"[0]" becomes tags[0] rather than tags.[0] — matching the
canonical form used by every shared id helper in core/idPath.ts.
Append a child path suffix to a parent path. When the suffix is omitted (e.g. transparent wrappers like union options) the parent path is returned unchanged so the child inherits the parent's id.
Bracketed array indices like
"[0]"append directly sotags+"[0]"becomestags[0]rather thantags.[0]— matching the canonical form used by every shared id helper incore/idPath.ts.