749's cstage-vs-wwstage callsite byte-id compare read back <src>.s, but
separate-compile emits the root .s to <ostem>.sepwork/__root.s, so the read
returned NULL and the `if(cs_asm && ws_asm)` guard left the compare silently
skipped -- green but unverified, the same blind-spot class as the #9/#10/#11
producer bugs.
Switch to the canonical explicit-emit idiom (siblings 925/926/949): emit
each stage's .s directly with `w6c -o <tmpdir>/cs.s` / `w6c_ww -o
<tmpdir>/ws.s`, then read both and run the existing helper_callsite() window
compare. The .s files live inside the driver's rm -rf'd tmpdir (w6c emits no
.sepwork); runtime parity blocks unchanged.
The compare now genuinely fires (749's internal subtest count 6->9) and
passes -- cs and ww callsite windows are byte-identical, no rule-10
divergence was hiding behind the skip. make test: all 402 passed.
Hojun-Cho
2e07e3bfe7