The compiler's post-IR role shrinks to: codegen -> invoke the build callback.
There is NO Zig auto-emit / auto-link anymore; emit + link are sx-called actions.
- emit_object() is now an ACTION (verify + emit via a host BuildHooks vtable),
returning the object path. New query primitives build_output/build_target/
build_frameworks/build_flags (data reads from the merged BuildConfig).
- library/modules/build.sx imports compiler.sx and defines default_pipeline:
emit_object -> gather c_object_paths -> link(objs, output, libs, fws, flags,
target). The std<->build import cycle is handled by the resolver.
- The compiler FORCE-LOWERS default_pipeline (well-known name) and AUTO-INVOKES
it post-codegen when no on_build/set_post_link_callback override was
registered (driver's final fallback: invokeByName default_pipeline).
- Prelude-less programs (e.g. asm tests) don't import build.sx, so the BUILD
path auto-imports modules/build.sx (idempotent if already transitive) so
default_pipeline is always available. JIT sx run is untouched (emits in-process).
- Removed the build cache short-circuits (incompatible with the always-run sx
driver; a future cache can live in default_pipeline).
Benign 37-.ir churn (build.sx grew); zero behavior changes (verified diff is
.ir-only). 705/0 both gates.