Brummel
4a3ae05db2
#47 — close a coverage gap in the graph model serializer: a single interior producer node backing more than one re-exported output field was never exercised by a fixture (every existing one maps each output to a distinct producer or a single field). The issue was filed at cycle 0022 against `aura-cli/src/graph.rs`'s `render_definition` / `output_binding` helper, which rendered a textual `(n1, n2) := <producer>` tuple binding. That file and helper no longer exist — the textual definition renderer was replaced by the JSON model emission now in `aura-engine/src/graph_model.rs`, where the multi-OutField case is plain flat iteration over `c.output()` (one `[name,kind]` entry + one `#N` boundary binding per `OutField`, by `(node, field)`), not a special tuple-binding arm. So the original branch is gone; this guards the flat emission that replaced it. New test `multi_outfield_producer_emits_one_binding_per_field` (+ two fixtures): a two-field producer (`hi`:f64, `lo`:i64 — distinct kinds, so the per-field `field_kind` lookup is exercised) re-exported as both composite outputs, nested in a root so it renders through `composite_def_json`. Asserts both fields surface with their own kind (`"outputs":[["hi","f64"],["lo","i64"]]`) and both bindings reference the same producer at distinct ordinals (`0.o0`/`#0`, `0.o1`/`#1`). Test-only; no production code touched (the behaviour was already correct). Verified: cargo test -p aura-engine green (237 in the lib suite); clippy clean. closes #47