A second, closed construction channel beside the scalar bind seam
(refs #271): ArgKind (Tz / TimeOfDay / Count — deliberately NOT
ScalarKind, which stays invariant 4's streamed set), ArgSpec, ArgValue,
ConstructionArg (verbatim strict-form strings, the id-bearing twin of
BoundParam), ArgOpError, and an ArgsState on PrimitiveBuilder:
pending(name, doc, specs, make) declares an arg-bearing recipe that is
introspectable but not constructible; try_args validates strictly
(exact IANA name, zero-padded HH:MM, plain positive decimal — the
accepted form IS the canonical form, no normalization layer), then
runs make and returns the configured builder. build() on a pending
builder panics — the bind panic-contract twin; the data path always
goes through try_args.
chrono-tz enters aura-core for the typed Tz value (already a workspace
dependency of four crates; typed values at the seam beat a
validated-string re-parse split across two coupled sites).
One test per ArgOpError variant plus strict-form refusal pins.
claude
f449cb06f2