claude a5e02ff541 docs: SessionFrankfurt output semantics + declared-tap authoring (#285)
Surfaced by the measurement-milestone fieldtest: a downstream author
reaching for session anchoring or declared taps had no public statement of
either — the semantics lived only in node source / the design ledger.

SessionFrankfurt / Session output semantics:
- glossary `session node`: corrected — it claimed three streams
  (`bars_since_open`, `in_session`, `session_open_ts`), but the shipped node
  emits ONE `i64` field `bars_since_open`. Now states the real contract: the
  count of completed bar-periods since the local (tz-aware, DST-correct)
  session open, close-instant indexed (09:15->1, 09:45->3; pre-open <=0), with
  the Frankfurt 09:00 Europe/Berlin open + `period_minutes` knob + the
  value-ignored `trigger`.
- authoring-guide: a "Session anchoring: the SessionFrankfurt preset"
  subsection — schema (trigger / period_minutes / bars_since_open), the
  close-instant multiples, the EqConst gating pattern, DST handling, and the
  add-snippet. Verified against `aura graph introspect --node SessionFrankfurt`.

Declared-tap authoring (C27 / the #284 tap op):
- authoring-guide: the `tap` op-table row (seven ops -> eight) + a worked
  "declaring a measurement tap" example. The example is verified: piping it
  through `aura graph build` emits
  `taps:[{"name":"spread","from":{"node":2,"field":0}}]`.
- design ledger op-list (INDEX.md): a `tap` bullet (seven verbs -> eight);
  also corrected the `expose` "only verb that keeps `as`" claim — `tap` keeps
  it too.
- README op-kind enumeration: adds `tap`.

Docs only; no code change. Both worked examples were run through the built
`aura` binary; the SessionFrankfurt schema was checked against introspect.

closes #285
2026-07-18 16:31:17 +02:00

aura

aura is a "game engine for traders." It is a Rust framework — and a playground — for authoring trading strategies as composable dataflow nodes, backtesting them deterministically and massively in parallel, validating them (sweep / Monte-Carlo / walk-forward), and freezing a validated strategy into a standalone bot with a broker connection. Its differentiator is the World: a program that constructs and orchestrates whole families of backtests, not the single run.

This README is a discoverability map of the shipped aura CLI — what commands exist and what they do. It deliberately keeps per-flag detail light; the two authoritative sources for exact syntax are always:

  • aura <command> --help — the exhaustive flag grammar.
  • The design ledger (docs/design/INDEX.md) and glossary (docs/glossary.md) — the concepts and invariants behind the surface.

Build & run

aura is a Cargo workspace. Build everything and you get one binary named aura:

cargo build --workspace          # binary at target/debug/aura
cargo build --workspace --release  # optimized, at target/release/aura

Invoke it as aura <command> … (examples below use the plain name).

Concepts in one breath

  • Blueprint — a serialized signal graph as data: a param-generic price → bias node graph. A blueprint file (blueprint.json) is the unit a downstream consumer loads and drives verbs over.
  • Open vs. closed — a blueprint with unbound (free) numeric knobs is open; one with every knob bound is closed. Different verbs want different states (see each verb below).
  • Family — the set of runs one verb produces over a blueprint (a sweep grid, a Monte-Carlo seed set, a walk-forward window sequence). Families are persisted in a content-addressed store and can be listed, ranked, and reproduced.
  • Axis — one named, sweepable knob of a blueprint (e.g. graph.fast.length), bound with a comma-separated value list. A gang fuses several sibling knobs into one axis (one value drives all members).

Running & orchestrating a loaded blueprint

These verbs all take the blueprint file as their first positional argument. Most drive a family of runs over it; graph renders its structure so a mis-wire is visible before a run. walkforward, mc, and generalize share sweep's generic grammar — the blueprint positional plus --real and a repeatable --axis <name>=<csv> (generalize takes --real <SYM1,SYM2,…>, at least two instruments, with a single value per axis) — see --help.

Command Purpose
aura run <bp.json> Run one backtest of a closed blueprint and print its report. An open (free-knob) blueprint is refused with a clean error — bind it, or use sweep.
aura graph <bp.json> Render the blueprint's structure as an interactive HTML DAG so a mis-wire is visible before a run. Omit the file to render the built-in sample; a named-but-unreadable file is a usage error.
aura sweep <bp.json> --list-axes Discover the blueprint's open, sweepable knobs. Prints each as <name>:<kind>. Run this first to learn the axis names.
aura sweep <bp.json> --axis <name>=<csv> [--axis …] Run a grid family over the named axes and persist it.
aura mc <bp.json> --seeds <n> Run a synthetic Monte-Carlo family of n seeded realizations. Wants a closed blueprint (the inverse of sweep).
aura mc <bp.json> --real <sym> --axis <name>=<csv> [--axis …] Run a Monte-Carlo R-bootstrap campaign over recorded data — driven through the same generated-campaign pipeline as sweep; --block-len/--resamples/--seed tune the bootstrap.
aura walkforward <bp.json> --axis <name>=<csv> [--axis …] Run an in-sample-refit walk-forward family — rolling optimize + out-of-sample test across windows, stitched into one verdict + parameter stability. --select chooses the per-window objective.
aura runs families List every persisted family (id, kind, member count).
aura runs family <id> [rank <metric>] List one family's members, optionally ranked best-first by an R metric (e.g. sqn_normalized, expectancy_r).
aura reproduce <family-id> Re-derive every member of a persisted family from the content-addressed store and check it is bit-identical (the C18/C1 determinism guarantee).

Important contract — every open knob is mandatory. On sweep and walkforward, the knobs enumerated by --list-axes are all required: you must supply an --axis for each open knob. There is no default value — pin a knob you don't want to vary with a single-value axis (--axis name=4). Omitting one is a clean error naming the missing knob, not a silent default.

Use aura <cmd> --help for the full data-window (--real/--from/--to), naming (--name), and selection (--select) flags.

Authoring & introspecting topology

A blueprint is authored declaratively from a JSON op-list: an ordered list of by-identifier construction ops replayed against the standard node vocabulary. Adding a new node type to that vocabulary is Rust, not JSON — see docs/authoring-guide.md, §0, "Authoring a new node in Rust".

Command Purpose
aura graph build Read an op-list document on stdin, build the blueprint, and print its canonical JSON to stdout (no trailing newline — it is the content-addressed artifact).
aura graph introspect --vocabulary List every node type available to op-lists.
aura graph introspect --node <T> Show one type's input ports, output fields, and param paths (with the bind-value form).
aura graph introspect --unwired Read a partial op-list on stdin and list its still-open interior slots.
aura graph introspect --content-id Read an op-list on stdin and print the SHA-256 content id of the blueprint it would build.
aura graph introspect --identity-id Read an op-list on stdin and print the SHA-256 identity id — the topology's debug-name-blind id, so two documents (or an op-script and a Rust-built blueprint) expressing the same topology print the same id. Combinable with --content-id (both ids, one per line, content id first).

Op-list shape

Each element is one op, tagged by "op". Node params are bound with the typed Scalar form — a tagged, capitalized-kind object: {"I64": 5}, {"F64": 1.5}, {"Bool": true}. A worked example (an SMA-crossover → bias signal):

[
  {"op":"source","role":"price","kind":"F64"},
  {"op":"add","type":"SMA","name":"fast","bind":{"length":{"I64":2}}},
  {"op":"add","type":"SMA","name":"slow","bind":{"length":{"I64":4}}},
  {"op":"add","type":"Sub"},
  {"op":"add","type":"Bias"},
  {"op":"feed","role":"price","into":["fast.series","slow.series"]},
  {"op":"connect","from":"fast.value","to":"sub.lhs"},
  {"op":"connect","from":"slow.value","to":"sub.rhs"},
  {"op":"connect","from":"sub.value","to":"bias.signal"},
  {"op":"expose","from":"bias.bias","as":"bias"}
]

Piping this document into aura graph build emits a blueprint.json you can then feed to run / sweep / mc / walkforward above:

aura graph build < crossover.ops.json > crossover.bp.json
aura sweep crossover.bp.json --list-axes

The op kinds are source, input, add, feed, connect, expose, tap, and gang (tap declares a recorded measurement point on an interior wire — see the authoring guide). See aura graph introspect --node <T> for a type's exact ports and the op-script grammar in the design ledger for the full semantics.

Where to go deeper

  • aura <command> --help — exhaustive, always-current flag grammar.
  • docs/design/INDEX.md — the design ledger: architecture, invariants, the World.
  • docs/glossary.md — canonical terminology (blueprint, family, axis, sweep / Monte-Carlo / walk-forward, R, content-id, …).
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