*ns* is interned in clojure.core holding the current NAMESPACE OBJECT, kept
in sync by ctx-set-current-ns through a var table cached on the env (one
table put on the hot path; core-bench A/B neutral). A thread binding
(binding [*ns* ...]) shadows the root through var-get as usual. in-ns now
returns the namespace object (Clojure); str renders a namespace as its name
and pr-str as #namespace[name]. The ns-designator helper accepts namespace
objects (they are tagged STRUCTS — the old table?-based check never matched
them), so (ns-aliases *ns*) / (ns-unalias *ns* 'a) work — SCI and the jank
syntax-quote corpus use exactly that shape.
Known divergence (documented): inside an interpreted fn, *ns* reflects the
fn's defining ns (jolt's resolution model rebinds current-ns per call);
top-level and load-time reads match Clojure.
Gate green (conformance 326x3, suite 4572 >= 4540, all batteries,
specs+unit +8 *ns* rows); bench neutral.
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