Step 5 — `context` resolves through `current_ctx_ref`. The compile-time
emit of the default GPA into the `context` global is gone; entry points
already bind `current_ctx_ref` to `&__sx_default_context` and every
sx-to-sx call forwards it. `allocViaContext` sources from
`current_ctx_ref` too. `matchContextAllocCall` is kept as a comptime
escape hatch: the ct_module spun up by `evalComptimeString` doesn't get
the full Allocator/CAllocator/Context type registration so the protocol-
dispatch chain wouldn't run in the interp; codegen also wins from the
direct libc malloc/free.
Step 6 — `push Context.{...}` stack-discipline rewrite. Allocates a
fresh `Context` slot, binds `current_ctx_ref` to it for the body's
lexical scope, restores on exit. No global, no walk.
Step 7 — interp parity. `defaultContextValue()` builds the Context
aggregate (CAllocator thunks for alloc/dealloc, null data) on demand.
`interp.call` bootstraps slot_ptr(0) when an entry function with
implicit ctx is called sans args; `materializeCtxArg` dereferences the
caller's slot_ptr into the aggregate at every sx-to-sx call boundary so
the callee's `load(ref_0)` lands on the value; `load` of an aggregate
is a passthrough. `.global_addr` of `__sx_default_context` returns the
aggregate directly so exported entries' first-line `global_addr(...)`
runs cleanly in `#run`.
`ct_lowering` inherits `implicit_ctx_enabled` + `has_implicit_ctx` so
functions lowered into the ct module carry ctx like their main-module
twins.
152/152 example tests pass. Snapshots regen.
4bf5908792