A host that builds its own tree (maps-dev's /cdn build inherits the container env) can bake
absolute embed snippet URLs without a committed config change, the same pattern as
DOXA_SYNC_PATHS. The value is the base without the tree name; a trailing slash is trimmed.
check-embed-targets-exist reads the same effective base. Unset, the tree is byte-identical.
check:embed-targets was already wired into package.json while the file it runs sat
untracked — so a fresh clone got a script that could not execute. It asserts that every
embed.iframe src in the manifest resolves to a file on disk, which is the load-bearing
check for the iframe deployment method: one of only two of the five that are proven.
That assertion matters more now than it did. The build stopped emitting a chooser page
per bundle, which took the recursive leaf count from sixty-three to forty-four, so the
coarse leaf floor no longer distinguishes "nineteen pages deliberately removed" from
"a partial wipe deleted real leaves". This gate does: it names the missing file and the
manifest path that pointed at it.
Negative-tested: hiding one leaf fails with exit 1 naming both the file and its JSON
path; restoring returns to a clean forty-three.
