Cycle 0002, the second walking-skeleton slice on top of the 0001 substrate:
the interface every node forever implements (C8), proven end-to-end by a real
node with no engine present.
- `Node` (aura-core) — `schema() -> NodeSchema` declares inputs (kind +
lookback) and the single output kind; `eval(&mut self, Ctx) -> Option<Scalar>`
computes one cycle's output (`None` = filter / not-yet-warmed-up). `&mut self`
so a node may keep its own derived state.
- `Ctx<'a>` (aura-core) — a `Copy` borrow-wrapper handing `eval` zero-copy,
financial-indexed `Window`s per input (`ctx.f64_in(i)[k]`, index 0 = newest).
A kind mismatch panics ("engine bug") — wiring guarantees the kind, so a
mismatch can only mean the wiring layer is broken; this keeps node-author code
clean (`w[k]`, not `w?[k]`).
- `AnyColumn::as_f64/as_i64/as_bool/as_ts` (aura-core) — the read-side mirror of
the existing `as_*_mut`, the mechanism `Ctx` uses to get a typed window from a
type-erased edge. Closes the read-side gap the cycle-0001 audit recorded.
- `Sma` (aura-std) — the skeleton's first real block: a producer node computing
the moving mean of one f64 input, emitting `None` until warmed up. Authored in
a downstream crate (proving aura-core's contract is usable across the crate
boundary) and driven by a hand-written test that mimics exactly what the sim
loop will later generalize: push fresh input, eval, collect.
Deliberately deferred (spec 0002 "Out of scope", recorded as decisions): the
firing policies (C6 — InputSpec carries no firing field yet), the sim loop (C4)
and freshness gating (C5), schema-level tunable params (C12/C19), and the
no-output sink refinement (C8 consumer side).
Gates green: cargo build/test (20: 18 aura-core + 2 aura-std)/clippy -D warnings
all clean; surface-purity grep (no dyn-Any / Rc / RefCell) clean.
refs walking-skeleton
Brummel
77a1d26017