The construction session gains the use op: Op::Use { ref_id, name, bind }
resolves through a second injected closure (subgraph: &dyn Fn(&str) ->
Option<Composite>, mirroring vocab's closed-lookup posture — the engine never
touches the store) and pushes the fetched composite as BlueprintNode::Composite,
renamed to the instance identifier (names are identity-blind debug symbols),
with path-qualified binds applied at splice time. Port resolution, kind checks,
the eager cycle gate, and the holistic finish gates all walk the existing
Composite arm — the session storage already carried it; the
"sessions only ever add primitives" unreachable! is retired by construction.
Open patterns (ratified mid-cycle, #317 comment 4627): finish() drops the
root-role gate; compile/bootstrap keep it. An op-script's explicit input roles
are a pattern's formal parameters — buildable, registerable, splicable; running
one standalone still refuses at bootstrap. The pinned finish-refusal test flips
to assert the new split (finish OK, compile refuses). No shipped fixture used
the input op; no corpus behaviour moves.
Gang integrity at the use seam (review finding): binding a ganged member's raw
path refused via the new BindOpError::AlreadyGanged { param, gang } (aura-core)
instead of silently de-fusing the gang — membership keyed on the same
(node, original_pos) coordinate collect_params/check_gangs use, per nesting
level. The gang's public knob stays unbindable at the seam (recorded residue).
Correctness oracle: use_op_splices_byte_identical_to_the_rust_built_twin pins
blueprint_to_json byte-equality against the GraphBuilder twin AND a
bit-identical recorded run (C1). Seven further use_op_* tests cover the fault
surfaces; open_input_pattern_finishes_registers_shaped_and_splices covers the
open-pattern round trip build -> serialize -> reload -> splice -> run.
No blueprint-format change: the serialized form already nests composites
recursively; the golden byte pin stays untouched.
refs #317
claude
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