Value-empty LeafFactory declares no input/output interface pre-build (only params) #43

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2026-06-08T10:12:33+02:00

Brummel commented

2026-06-08 10:12:33 +02:00

A value-empty LeafFactory (crates/aura-core/src/node.rs) declares only its
name, its params: Vec<ParamSpec>, and a build closure. It does not
declare its input/output interface (InputSpec / FieldSpec) — those exist
only on the built Node's schema(), post-build. So nothing can read a
leaf's declared inputs or outputs at the blueprint (pre-build, value-empty)
level.

Where it bites

Typed boundary signature (render). The post-#41 render redesign wants the
composite signature macd(fast:i64, slow:i64, signal:i64) -> (macd:f64, signal:f64, histogram:f64). Param types resolve fine (factory().params() is
pre-build), but the output types (:f64) do not — OutField carries only
{node, field, name}, and the producer leaf is a value-empty factory with no
output schema pre-build. The render cycle therefore ships output names only
(-> (macd, signal, histogram)); the typed arrow depends on this.
Pre-build introspection (mc_4 finding, #42). Surfaced porting
fieldtests/milestone-construction-layer/mc_4_introspect_graph.rs: leaf
introspection can only print label + declared param count — inputs /
output_fields are unavailable until the node is built, so a graph-as-data
walk of a blueprint cannot show a leaf's arity or field shape.
Input-slot typing. The render can derive the count/ordering of a node's
wired input slots from the interior edges (Edge.to/.slot + role targets),
but not their kinds — same root cause.

Shape

Let the value-empty LeafFactory declare its static interface — the InputSpecs
and output FieldSpecs it will build — alongside its ParamSpecs, so
param_space()-style pre-build reads can see inputs and outputs too. Most nodes'
input/output shape is static (independent of the injected params), so this is a
declaration the factory can carry without building.

Relation

Adjacent to #36 (param declared twice): both are about the factory declaring its
full static interface once. #36 is the params half (dedup the double
declaration); this is the inputs/outputs half (declare them at all,
pre-build). A unified "factory declares its complete static schema" change could
subsume both — worth considering together when either is picked up.

Surfaced: #42 (mc_4 port) and the post-#41 render-redesign design discussion.

A value-empty `LeafFactory` (crates/aura-core/src/node.rs) declares only its `name`, its `params: Vec<ParamSpec>`, and a `build` closure. It does **not** declare its input/output interface (`InputSpec` / `FieldSpec`) — those exist only on the *built* `Node`'s `schema()`, post-build. So nothing can read a leaf's declared inputs or outputs at the **blueprint (pre-build, value-empty)** level. ## Where it bites - **Typed boundary signature (render).** The post-#41 render redesign wants the composite signature `macd(fast:i64, slow:i64, signal:i64) -> (macd:f64, signal:f64, histogram:f64)`. Param types resolve fine (`factory().params()` is pre-build), but the **output types** (`:f64`) do not — `OutField` carries only `{node, field, name}`, and the producer leaf is a value-empty factory with no output schema pre-build. The render cycle therefore ships output **names only** (`-> (macd, signal, histogram)`); the typed arrow depends on this. - **Pre-build introspection (mc_4 finding, #42).** Surfaced porting `fieldtests/milestone-construction-layer/mc_4_introspect_graph.rs`: leaf introspection can only print `label + declared param count` — `inputs` / `output_fields` are unavailable until the node is built, so a graph-as-data walk of a blueprint cannot show a leaf's arity or field shape. - **Input-slot typing.** The render can derive the *count*/ordering of a node's wired input slots from the interior edges (`Edge.to`/`.slot` + role targets), but not their kinds — same root cause. ## Shape Let the value-empty `LeafFactory` declare its static interface — the `InputSpec`s and output `FieldSpec`s it will build — alongside its `ParamSpec`s, so `param_space()`-style pre-build reads can see inputs and outputs too. Most nodes' input/output shape is static (independent of the injected params), so this is a declaration the factory can carry without building. ## Relation Adjacent to #36 (param declared twice): both are about the factory declaring its full static interface once. #36 is the **params** half (dedup the double declaration); this is the **inputs/outputs** half (declare them at all, pre-build). A unified "factory declares its complete static schema" change could subsume both — worth considering together when either is picked up. Surfaced: #42 (mc_4 port) and the post-#41 render-redesign design discussion.

Brummel added the feature label 2026-06-08 10:12:33 +02:00

Brummel referenced this issue from a commit

2026-06-08 10:52:25 +02:00

spec: 0020 composite signature render

Brummel referenced this issue from a commit

2026-06-08 10:52:26 +02:00

plan: 0020 composite signature render

Brummel referenced this issue from a commit

2026-06-08 10:52:26 +02:00

feat(aura-cli): composite definition renders as a typed signature

Brummel referenced this issue from a commit

2026-06-08 10:52:26 +02:00