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
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>
C8: a node is producer/consumer/both — at most one output, pure consumers (sinks: chart/equity/logger) have none; records the node-role taxonomy the substrate requires (was wrongly 'exactly one output', contradicting pure consumers and C14). C3: merge by timestamp, normalizing source-native units (data-server Unix-ms) to the canonical epoch-ns of C7. aura-engine lib doc: broker is a downstream plugin over the position table (sim-optimal pip / realistic currency), not an in-strategy 'broker/portfolio node'. Plus a provenance line-wrap nit.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Cargo workspace aura-core -> aura-engine -> aura-cli (bin `aura`) plus nodes/ for hot-reloadable cdylib node crates. Crate bodies are intentionally API-free; types arrive from the first spec. Adds the skills profile (.claude/dev-cycle-profile.yml), the project CLAUDE.md with the eight domain invariants, and the design-ledger skeleton.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Brummel