Aura/fieldtests/milestone-the-world-param-sweep/mw_3_structural_constant.rs

// Milestone fieldtest — scenario 3: the NEGATIVE-SPACE probe (grounds #55).
//
// The "SMA2-entry" strategy: "the close of the last candle is greater than the
// high of the prior candle, with SMA(2) as the bias." The `2` is DEFINITIONAL —
// it is bound to the two-candle construction. Sweeping it to 5 does not give
// "the same strategy at another point"; it deforms it into a different strategy.
//
// This file tries to express that `2` HONESTLY as a downstream author and
// records where the public surface forces a wrong shape. NOTHING is worked
// around: no `.bind()` is invented, no engine is touched. The deliverable is the
// verbatim friction plus the consumer code I WISH I could write (see the
// `WISHED-FOR` block at the bottom — it does not compile and is commented out).
//
// Public interface only: ledger (C8/C19/C23, C20) + specs 0015/0030 + rustdoc.

use std::sync::mpsc;

use aura_core::{Firing, Scalar, ScalarKind, Timestamp};
use aura_engine::{
    BlueprintNode, Composite, Edge, OutField, ParamAlias, Role, Target,
};
use aura_std::{Exposure, Recorder, SimBroker, Sma, Sub};

fn synthetic_prices() -> Vec<(Timestamp, Scalar)> {
    let prices = [
        1.00, 1.01, 1.02, 1.03, 1.05, 1.08, 1.06, 1.04, 1.02, 1.01, 1.03, 1.07,
    ];
    prices
        .iter()
        .enumerate()
        .map(|(i, &p)| (Timestamp(60_000_000_000 * i as i64), Scalar::F64(p)))
        .collect()
}

// ===========================================================================
// AVENUE (a): leave the definitional length as an OPEN param_space() knob and
// fix it to 2 in the bind vector.
//
// The cross uses two Smas. The "bias" Sma is DEFINITIONALLY SMA(2) — but
// `Sma::builder()` is value-empty: its length is ALWAYS an injected param. So
// the `2` MUST surface as an open param-space knob. There is no way to bake it.
// ===========================================================================
fn sma2_entry_avenue_a() -> Composite {
    Composite::new(
        "sma2_entry",
        vec![
            Sma::builder().into(), // the DEFINITIONAL SMA(2) bias — but it is an OPEN knob
            Sma::builder().into(), // a genuinely-tunable slow leg
            Sub::builder().into(),
        ],
        vec![
            Edge { from: 0, to: 2, slot: 0, from_field: 0 },
            Edge { from: 1, to: 2, slot: 1, from_field: 0 },
        ],
        vec![Role {
            name: "price".into(),
            targets: vec![Target { node: 0, slot: 0 }, Target { node: 1, slot: 0 }],
            source: None,
        }],
        // ALIASES are MANDATORY here: Sub is a fan-in of two same-signature SMAs,
        // each carrying an unaliased param slot -> C9 IndistinguishableFanIn at
        // compile unless aliased. So even avenue (a) is forced to NAME the
        // definitional-2 knob `bias` as if it were tunable.
        vec![
            ParamAlias { name: "bias".into(), node: 0, slot: 0 },
            ParamAlias { name: "slow".into(), node: 1, slot: 0 },
        ],
        vec![OutField { node: 2, field: 0, name: "out".into() }],
    )
}

fn harness_with(inner: Composite, tx: mpsc::Sender<(Timestamp, Vec<Scalar>)>) -> Composite {
    Composite::new(
        "harness",
        vec![
            BlueprintNode::Composite(inner),
            Exposure::builder().into(),
            SimBroker::builder(1e-4).into(),
            Recorder::builder(vec![ScalarKind::F64], Firing::Any, tx).into(),
        ],
        vec![
            Edge { from: 0, to: 1, slot: 0, from_field: 0 },
            Edge { from: 1, to: 2, slot: 0, from_field: 0 },
            Edge { from: 2, to: 3, slot: 0, from_field: 0 },
        ],
        vec![Role {
            name: "price".into(),
            targets: vec![Target { node: 0, slot: 0 }, Target { node: 2, slot: 1 }],
            source: Some(ScalarKind::F64),
        }],
        vec![],
        vec![],
    )
}

fn main() {
    // --- AVENUE (a): the definitional 2 leaks into param_space() as a knob. ---
    let (tx0, _rx0) = mpsc::channel();
    let space = harness_with(sma2_entry_avenue_a(), tx0).param_space();
    println!("AVENUE (a) — param_space() of the SMA2-entry strategy:");
    for p in &space {
        println!("  {} : {:?}", p.name, p.kind);
    }
    println!(
        "\n  >> The DEFINITIONAL SMA(2) length surfaces as `sma2_entry.bias` — an OPEN\n  \
         >> knob, indistinguishable from the genuinely-tunable `sma2_entry.slow`.\n  \
         >> A sweep `.axis(\"sma2_entry.bias\", [2, 5, 10])` would enumerate DEFORMED\n  \
         >> strategies (SMA-5-entry, SMA-10-entry) as valid family members.\n  \
         >> param_space() declares a degree of freedom the strategy's definition\n  \
         >> forbids. (C20: structural axes are NOT sweep params — but nothing here\n  \
         >> distinguishes the two.) NOTE: the alias `bias` was FORCED on this knob\n  \
         >> just to clear C9 IndistinguishableFanIn — so the surface makes me NAME\n  \
         >> the constant as if it were tunable."
    );

    // It still runs — the point is the SHAPE, not a crash:
    let (tx, rx) = mpsc::channel::<(Timestamp, Vec<Scalar>)>();
    let mut h = harness_with(sma2_entry_avenue_a(), tx)
        .bootstrap_with_params(vec![Scalar::I64(2), Scalar::I64(4), Scalar::F64(0.5)])
        .expect("avenue (a) bootstraps");
    h.run(vec![synthetic_prices()]);
    drop(h);
    let rows: Vec<_> = rx.iter().collect();
    println!("\n  (avenue (a) runs: {} recorded rows — it WORKS, but the 2 is fungible)", rows.len());

    // --- AVENUE (b): imitate SimBroker::builder(pip_size) — a value captured
    //     OUTSIDE param_space — for the SMA length. ---------------------------
    println!("\nAVENUE (b) — capture the 2 as a construction constant (SimBroker pattern):");
    println!(
        "  SimBroker::builder(1e-4) bakes pip_size OUTSIDE param_space (it is C10/C15\n  \
         metadata — the broker declares NO param). The SMA2-entry author wants the\n  \
         SAME for the length: a value baked at build, never a knob.\n"
    );
    // Probe: is that pattern reachable for an INDICATOR node?
    //   Sma::builder()          -> takes NO args; length is ALWAYS an injected param.
    //   Sma::new(2)             -> exists, bakes length 2... but is it a BlueprintNode?
    //
    // `Sma::new(2)` returns an `Sma` (a built Node), NOT a `PrimitiveBuilder`.
    // A composite's interior is `Vec<BlueprintNode>` = Primitive(PrimitiveBuilder)
    // | Composite. There is NO `BlueprintNode::from(Sma)` for a built node — the
    // blueprint holds value-empty RECIPES, not built nodes. So a built `Sma::new(2)`
    // cannot be placed into a blueprint at all. The SimBroker escape hatch
    // (`builder(constant)`) exists ONLY because SimBroker::builder TAKES the
    // constant; Sma::builder() does not, and there is no `Sma::builder_with(2)`.
    //
    // The following line, if uncommented, does NOT compile — recorded as the
    // verbatim wall (no `From<Sma> for BlueprintNode`):
    //
    //     let _node: BlueprintNode = Sma::new(2).into();
    //
    println!(
        "  >> WALL: `Sma::builder()` takes no length arg (length is always a param),\n  \
         >> and `Sma::new(2)` returns a built `Sma`, not a `PrimitiveBuilder` /\n  \
         >> `BlueprintNode` — a blueprint holds value-empty RECIPES, not built nodes.\n  \
         >> There is no `Sma::builder_with(2)` analogous to `SimBroker::builder(pip)`.\n  \
         >> The construction-constant escape hatch exists for SimBroker (its builder\n  \
         >> TAKES the constant) but is UNREACHABLE for a stock indicator node."
    );

    // ===================================================================
    // WISHED-FOR consumer code (the acceptance evidence for #55). This does
    // NOT compile against today's surface; it is the code I reached for and
    // could not write. Left here verbatim, commented out, as the empirical
    // grounding for #55's future spec.
    // ===================================================================
    //
    //   // (1) An indicator builder that BAKES a structural constant, removing it
    //   //     from param_space entirely (the opposite of `.with`, reserved `.bind`):
    //   let bias = Sma::builder().bind("length", 2);  // length is now a CONSTANT, not a knob
    //
    //   // ...so param_space() of the strategy contains ONLY the genuinely-tunable
    //   //    knobs, and a sweep CANNOT enumerate a deformed SMA-5-entry:
    //   //   param_space() == ["sma2_entry.slow": I64, "scale": F64]   // no `length`
    //
    //   // (2) equivalently, a recipe-level constructor that takes the constant:
    //   let bias = Sma::builder_with(2);              // length baked at build, no param slot
    //
    // Either makes the definitional `2` a CONSTRUCTION value (C19 "params size
    // nodes but a topology change is a different blueprint"; C20 "structural axes
    // are not numeric sweep params"), distinguishing it from a tunable knob — which
    // is exactly the distinction the SMA2-entry strategy needs and today's surface
    // cannot express.

    println!("\nOK: scenario 3 recorded both wrong avenues + the wished-for code (grounds #55).");
}