Every surviving carrier now owns its artifacts: checked mkdir/mkdtemp/
fopen acquisition, one all-exit cleanup funnel per carrier, ENOENT-
tolerant checked unlinks, exact-path deletion (rm -rf only for an
owned pid-keyed dir or a .sepwork beneath one), and cleanup failure
fails a passing carrier without overwriting its diagnostic. In the
same pass the carriers adapt to the driver contract this branch lands:
--sep and WW_PKGCACHE are gone, -S and the /tmp/ww_run_<pid> scratch
contract are asserted, and rows whose runtime or reject coverage moved
to test/wcc/data fixtures or test/lang @test owners are trimmed to the
byte/artifact/diagnostic observations only they can make.
Repair and adaptation ride together because most files interleave both
in the same hunks; splitting would manufacture intermediate carrier
states that never existed and cannot run against either driver.
The --sep producer compiled the ROOT build-target with the .wwi-producer
-I flag, so check_exported_type ran on the root and rejected a real-tool
root's legitimate `export fn f(a: *t)` over an unexported local type t
(the root is terminal — its interface is never imported, and its .wwi is
never consumed). The combined build never passes -I, so it built fine.
For pi==root, invoke w6c with -c -o only, no -I. Both stages (the wwstage
twin builds the shorter root argv). Gates that asserted __root.wwi exists
encoded the buggy behavior; updated to assert __root.s (the consumed
product) while deps' .wwi byte-id is retained.
M3-tail commit-6 prerequisite. Gate 989_seproot_export_run reproduces the
export-fn-over-unexported-type root + proves it sep-builds, with a
non-vacuity leg that the forced -I path still rejects.
