The driver flip moves build artifacts from next-to-source <stem>.s to a
.sepwork/ scratch dir. 29 Pattern-B gates now build `ww build --sep -o <stem>`
and read <stem>.sepwork/__root.s (multi-package gates concat all
<stem>.sepwork/*.s, since cross-package labels live in per-package .s).
All intermediates redirect to /tmp (WW_PKGCACHE + -o), so the corpus runs
parallel-safe with no source-tree pollution. Tests pass now (--sep is live)
and survive the flip.
915 additionally retargeted off strconv's PRIVATE left_shift_table (a let,
not export) — which separate compilation correctly hides — onto a test-local
package that exports its own probe table (#96). The combined path only linked
it via a single-unit private leak; encapsulation is now honored under sep.
Test-only; all 5 *_ww binaries HOLD. 989_m1mangle_run deferred (blocked by
#99, imported-package fn main mangling under sep).
Switch symbol mangling from the import leaf clause to the full dotted import path for directory packages; single-file imports keep package-clause mangling (isdir-gate: imported<=>directory-import). The root build unit's fn main stays bare, every other top-level decl mangles, closing #31's duplicate-main hazard by construction (#32). Both stages, byte-identical.
Single commit, not split: the bare rename (f244af3) is red on its own because it unmasks cross-module resolution gaps that do not reproduce pre-M1, so the fixes are intrinsic to making the rename correct. Included: wwstage fnret/fnparamslookupmod map import alias->path (#199b cross-module union-variant scrutinee resolved the wrong fn's union); cstage use_path prefers the referencing module's import for an ambiguous leaf alias (sha256 crypto.math vs strconv math). Tests table-driven: 989_m1mangle_run/_sym, 989_m1union_run (gate-visible per-arm exit codes + cs==ww byte-id).
