Cycle 0003: aura-engine's first real content — a Sim that runs a wired DAG of
nodes deterministically, cycle by cycle. First point in the project where
authored nodes execute against data, not just under a hand-fed Ctx.
- `Sim` (aura-engine) — a bootstrapped, frozen root graph: a flat Vec<NodeBox>
(each node owns its input columns, the cycle-0002 shape) + an index edge
table, topologically ordered (Kahn). `bootstrap` sizes every input column from
its node's schema, kind-checks each edge and source target, and rejects
directed cycles — C7's "type check paid once at wiring" generalized to the
whole topology (`BootstrapError::{KindMismatch, BadIndex, Cycle}`).
- `run` — the deterministic loop: per record, forward the source value into its
target slots, evaluate nodes in topo order, capture the observed node's output
at eval time, and forward each `Some` output into its consumers' input columns
(a `None` forwards nothing — the structural seed of sample-and-hold). The loop
destructures `&mut self` into disjoint field borrows and allocates nothing on
the per-cycle path. This is the flat, monomorphized sharpening of RustAst's
reference-counted, interior-mutable observer push graph (C1/C7).
- `Edge` / `Target` (aura-engine) — producer->consumer and source->consumer wiring.
- `Sub` (aura-std) — a 2-input f64-difference node, so the loop is proven on a
real fan-out + join DAG (source -> {SMA(2), SMA(4)} -> Sub), with a determinism
assertion (C1: a second identical run is bit-identical).
Engine library depends only on aura-core; a test-only dev-dependency on aura-std
lets the integration test wire real Sma/Sub nodes. Sim carries a hand-written,
node-opaque `Debug` impl (Box<dyn Node> is not Debug; the impl prints
nodes.len() + the index/topology fields, needed by the bootstrap-rejection tests'
`unwrap_err`).
Deliberately deferred (recorded as decisions): freshness-gated recompute /
sample-and-hold (C5 -> cycle 0004, with the second source that makes it testable);
the explicit monotonic cycle_id counter (its first reader is freshness, 0004);
the Source trait + data-server ingestion + k-way merge (C3/C11); the builder API
(C19); the real sink + run registry (C18/C22).
Gates green: cargo build/test (26: 18 aura-core + 3 aura-std + 5 aura-engine)/
clippy -D warnings clean; surface-purity grep (no dyn-Any / Rc / RefCell) clean.
refs walking-skeleton
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
Correct the broker mechanism: a broker is an ordinary downstream consumer node (C8/C9), not an external plugin/subsystem. It consumes the position-event stream + price streams and emits an equity stream; several brokers (e.g. sim-optimal pip + realistic currency) can be attached to the same position table at once, yielding directly comparable equity curves. Updates C10, CLAUDE.md invariant 7, aura-engine/aura-std crate docs, and the day-in-the-life doc.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Refine the structure per interview: aura is the reusable engine, research projects are separate external repos depending on it (C16). Add aura-std (universal standard-node tier) to the workspace; remove nodes/ from the engine (project concept). Record authoring-surface = Claude Code + skills pipeline, no embedded coding-LLM (C17), and project management = one-repo-one-project + Aura-native run registry (C18). Add CLAUDE.md invariants 9-10, code_roots -> [crates], and docs/project-layout.md documenting the day-in-the-life and project repo layout.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Brummel