# Named param binding — Iteration 2 (sweep axes) — Implementation Plan > **Parent spec:** `docs/specs/0030-named-param-binding.md` > > **For agentic workers:** REQUIRED SUB-SKILL: use the `implement` skill to run > this plan. Steps use `- [ ]` checkboxes for tracking. **Goal:** Add the sweep-axes named-binding layer — `Composite::axis` → `SweepBinder` → `SweepBinder::sweep`, backed by `resolve_axes` (per-element kind-checked, a superset of `GridSpace::new`) — and convert the CLI sample sweep to it. **Architecture:** A pure authoring layer in `aura-engine` over the existing `GridSpace::new` / `sweep` primitives (engine core untouched, C1/C12/C19/C23). `resolve_axes` shares `resolve`'s name→slot mapping (iter 1), adds the `EmptyAxis` check and a per-element axis kind-check; because its validation is a superset of `GridSpace::new`'s, the downstream `GridSpace::new(...).expect(...)` is infallible. The single-run side (iter 1) is done and committed (64b19ab). **Tech Stack:** Rust; `crates/aura-engine/src/blueprint.rs` (new items + tests), `crates/aura-engine/src/lib.rs` (re-export), `crates/aura-cli/src/main.rs` (sweep conversion + drop the orphaned `GridSpace` import). --- **Files this plan creates or modifies:** - Modify: `crates/aura-engine/src/blueprint.rs` — add free `fn resolve_axes` (adjacent to `fn resolve` ~:324-363), `Composite::axis`, `struct SweepBinder` + `impl SweepBinder` (adjacent to `Binder` ~:302-320), a new `use` for the sweep primitives, and iter-2 tests in `#[cfg(test)] mod tests`. - Modify: `crates/aura-engine/src/lib.rs:40-43` — add `SweepBinder` to the `pub use blueprint::{…}` re-export (`BindError, Binder` already present). - Modify: `crates/aura-cli/src/main.rs:226-266` — convert `sweep_family()`'s grid construction to `.axis(…).sweep(…)`; drop the now-unused `GridSpace` from the import at `:13`. - Test: `crates/aura-engine/src/blueprint.rs` (test module) — `resolve_axes` round-trip/parity, `EmptyAxis`, `MissingKnob` (sweep), per-element `KindMismatch` (resolve-direct, mixed axis), a builder no-panic wrong-kind test, and a GridSpace `.points()` parity test. - Unchanged (content-pin twins — stay green, no edit): `crates/aura-cli/src/main.rs:541-544` and `crates/aura-cli/tests/cli_run.rs:214` (sweep JSON param goldens — the conversion preserves names/values/order). --- ## Task 1: Engine — `resolve_axes`, `Composite::axis`, `SweepBinder` **Files:** - Modify: `crates/aura-engine/src/blueprint.rs` (new items near the iter-1 `Binder`/`resolve` block ~:300-363; new `use`; tests) - Modify: `crates/aura-engine/src/lib.rs:40-43` - [ ] **Step 1: Add the skeleton (axis, SweepBinder, stubbed `resolve_axes`) + imports + re-export** In `crates/aura-engine/src/blueprint.rs`, add a `use` for the sweep primitives near the existing `use crate::harness::{…};` (~line 21). Use the collision-free forms (`sweep` is both a module and a re-exported fn at the crate root): ```rust use crate::sweep::sweep; use crate::{GridSpace, RunReport, SweepFamily}; ``` Add `Composite::axis` inside an `impl Composite` block (e.g. just after `Composite::with`, ~line 274): ```rust /// Begin binding this blueprint's knobs **by name** as sweep axes (the fluent /// authoring alternative to a positional `GridSpace`). The bound name is the /// exact `param_space()` name (path-qualified for a composite-interior knob, /// bare for a root-level knob). pub fn axis(self, name: &str, vals: impl IntoIterator>) -> SweepBinder { let axis = vals.into_iter().map(Into::into).collect(); SweepBinder { bp: self, axes: vec![(name.to_string(), axis)] } } ``` Add the `SweepBinder` type + impl adjacent to `Binder` (~after line 320), with a stubbed `resolve_axes` (filled in Step 3): ```rust /// A fluent accumulator of named sweep axes, terminated by [`SweepBinder::sweep`]. /// Axes are resolved against `param_space()` once, at the terminal; resolution is a /// superset of `GridSpace::new`'s checks, so the grid it builds cannot fail. pub struct SweepBinder { bp: Composite, axes: Vec<(String, Vec)>, } impl SweepBinder { /// Bind one more sweep axis by name; raw literals lower via `Into`. pub fn axis(mut self, name: &str, vals: impl IntoIterator>) -> SweepBinder { self.axes.push((name.to_string(), vals.into_iter().map(Into::into).collect())); self } /// Resolve the named axes against `param_space()` into a positional grid and /// run the disjoint sweep. pub fn sweep(self, run_one: F) -> Result where F: Fn(&[Scalar]) -> RunReport + Sync, { let space = self.bp.param_space(); let ordered = resolve_axes(&space, &self.axes)?; let grid = GridSpace::new(&space, ordered) .expect("named layer pre-validates arity/kind/non-empty"); Ok(sweep(&grid, run_one)) } } /// Resolve named sweep axes to a positional `Vec>` in `param_space()` /// slot order. (Body filled in Step 3.) fn resolve_axes(space: &[ParamSpec], axes: &[(String, Vec)]) -> Result>, BindError> { let _ = (space, axes); todo!("resolve_axes") } ``` In `crates/aura-engine/src/lib.rs`, the re-export block at lines 40-43 currently reads: ```rust pub use blueprint::{ aliases_on, signature_of, BindError, Binder, BlueprintNode, CompileError, Composite, OutField, ParamAlias, Role, }; ``` Add `SweepBinder` (alphabetical, after `Role`): ```rust pub use blueprint::{ aliases_on, signature_of, BindError, Binder, BlueprintNode, CompileError, Composite, OutField, ParamAlias, Role, SweepBinder, }; ``` - [ ] **Step 2: Add all Task-1 tests, run, verify RED** In the `#[cfg(test)] mod tests` of `crates/aura-engine/src/blueprint.rs`, add an explicit import for the grid primitives the parity test needs (the test module does not import sweep symbols today), placed with the module's other `use`s (~:831-834): ```rust use crate::GridSpace; ``` Then add these tests: ```rust #[test] fn resolve_axes_named_equals_positional() { // named axes resolve to the positional Vec> in slot order, // order-independent on the binding side let space = vec![ ParamSpec { name: "sma_cross.fast".into(), kind: ScalarKind::I64 }, ParamSpec { name: "sma_cross.slow".into(), kind: ScalarKind::I64 }, ParamSpec { name: "scale".into(), kind: ScalarKind::F64 }, ]; let axes = vec![ ("scale".to_string(), vec![Scalar::F64(0.5)]), ("sma_cross.fast".to_string(), vec![Scalar::I64(2), Scalar::I64(3)]), ("sma_cross.slow".to_string(), vec![Scalar::I64(4), Scalar::I64(5)]), ]; assert_eq!( resolve_axes(&space, &axes), Ok(vec![ vec![Scalar::I64(2), Scalar::I64(3)], vec![Scalar::I64(4), Scalar::I64(5)], vec![Scalar::F64(0.5)], ]), ); } #[test] fn resolve_axes_empty_axis() { let space = vec![ParamSpec { name: "a".into(), kind: ScalarKind::I64 }]; assert_eq!( resolve_axes(&space, &[("a".to_string(), vec![])]), Err(BindError::EmptyAxis("a".to_string())), ); } #[test] fn resolve_axes_missing_knob() { let space = vec![ ParamSpec { name: "a".into(), kind: ScalarKind::I64 }, ParamSpec { name: "b".into(), kind: ScalarKind::I64 }, ]; assert_eq!( resolve_axes(&space, &[("a".to_string(), vec![Scalar::I64(1)])]), Err(BindError::MissingKnob("b".to_string())), ); } #[test] fn resolve_axes_per_element_kind_mismatch() { // a MIXED-kind axis: the second element mismatches; per-element check must // catch it (a first-element-only check would pass it through to a panic). let space = vec![ParamSpec { name: "scale".into(), kind: ScalarKind::F64 }]; let axes = vec![("scale".to_string(), vec![Scalar::F64(0.5), Scalar::I64(1)])]; assert_eq!( resolve_axes(&space, &axes), Err(BindError::KindMismatch { knob: "scale".to_string(), expected: ScalarKind::F64, got: ScalarKind::I64, }), ); } #[test] fn named_sweep_rejects_wrong_kind_axis_without_panic() { // builder path: an F64 axis bound to an I64 slot is rejected as a clean // BindError, never reaching GridSpace::new's .expect() — the run closure // must not be invoked. let (bp, _eq, _ex) = composite_sma_cross_harness(); let result = bp .axis("sma_cross.fast", [2.0, 3.0]) // F64 values for the I64 slot .axis("sma_cross.slow", [4]) .axis("scale", [0.5]) .sweep(|_: &[Scalar]| -> RunReport { panic!("axis pre-validation must reject before running") }); assert_eq!( result, Err(BindError::KindMismatch { knob: "sma_cross.fast".to_string(), expected: ScalarKind::I64, got: ScalarKind::F64, }), ); } #[test] fn named_axes_grid_parity_with_positional() { // named axes enumerate the SAME GridSpace points (same order) as the // positional grid over the sample param-space. let space = composite_sma_cross_harness().0.param_space(); let named = resolve_axes( &space, &[ ("sma_cross.fast".to_string(), vec![Scalar::I64(2), Scalar::I64(3)]), ("sma_cross.slow".to_string(), vec![Scalar::I64(4), Scalar::I64(5)]), ("scale".to_string(), vec![Scalar::F64(0.5)]), ], ) .expect("named axes resolve"); let positional = vec![ vec![Scalar::I64(2), Scalar::I64(3)], vec![Scalar::I64(4), Scalar::I64(5)], vec![Scalar::F64(0.5)], ]; let named_pts = GridSpace::new(&space, named).expect("named grid").points(); let pos_pts = GridSpace::new(&space, positional).expect("positional grid").points(); assert_eq!(named_pts, pos_pts, "named and positional grids must enumerate identically"); } ``` Run: `cargo test -p aura-engine resolve_axes_ named_sweep_rejects_wrong_kind_axis_without_panic named_axes_grid_parity_with_positional 2>&1 | tail -25` Expected: FAIL — every new test panics with `not yet implemented: resolve_axes` (the `todo!("resolve_axes")` stub; the builder/parity tests reach it via `SweepBinder::sweep` / direct call). - [ ] **Step 3: Implement `resolve_axes`, run, verify GREEN** In `crates/aura-engine/src/blueprint.rs`, replace the `resolve_axes` stub body from Step 1 with: ```rust fn resolve_axes(space: &[ParamSpec], axes: &[(String, Vec)]) -> Result>, BindError> { // Phase 1 — per axis in input order: claim slots by exact name (a, b, c, d). let mut claimed: Vec>> = vec![None; space.len()]; for (name, values) in axes { let matches: Vec = space .iter() .enumerate() .filter(|(_, p)| p.name == *name) .map(|(i, _)| i) .collect(); match matches.as_slice() { [] => return Err(BindError::UnknownKnob(name.clone())), // a [idx] => { if values.is_empty() { return Err(BindError::EmptyAxis(name.clone())); // c } if claimed[*idx].is_some() { return Err(BindError::DuplicateBinding(name.clone())); // d } claimed[*idx] = Some(values.clone()); } _ => return Err(BindError::AmbiguousKnob(name.clone())), // b } } // Phase 2 — slot walk in param_space() order: completeness (e) + per-element kind (f). let mut ordered = Vec::with_capacity(space.len()); for (i, p) in space.iter().enumerate() { match &claimed[i] { None => return Err(BindError::MissingKnob(p.name.clone())), // e Some(values) => { for v in values { if v.kind() != p.kind { return Err(BindError::KindMismatch { knob: p.name.clone(), expected: p.kind, got: v.kind(), }); // f — first offending element in axis order } } ordered.push(values.clone()); } } } Ok(ordered) } ``` Run: `cargo test -p aura-engine resolve_axes_ named_sweep_rejects_wrong_kind_axis_without_panic named_axes_grid_parity_with_positional 2>&1 | tail -25` Expected: PASS — all six new tests green. - [ ] **Step 4: Full workspace gate** Run: `cargo build --workspace 2>&1 | tail -5` Expected: success. Run: `cargo test --workspace 2>&1 | tail -15` Expected: all suites PASS (six new + all pre-existing). Run: `cargo clippy --workspace --all-targets -- -D warnings 2>&1 | tail -10` Expected: clean. (`resolve_axes` is called by `SweepBinder::sweep`; `axis`/`SweepBinder`/`sweep` are `pub`-re-exported; the previously-unconstructed `BindError::EmptyAxis` is now constructed in `resolve_axes`, so no `dead_code`.) ## Task 2: CLI — convert the sample sweep to `.axis(…).sweep(…)` **Files:** - Modify: `crates/aura-cli/src/main.rs:226-266` (`sweep_family`) and `:13` (import) - [ ] **Step 1: Convert `sweep_family()` grid construction to named axes** In `crates/aura-cli/src/main.rs`, replace the body of `sweep_family()` (lines 227-265 — the `let space = …` + `GridSpace::new(…).expect(…)` + `sweep(&grid, …)`) with the named form. Keep the per-point closure body **verbatim** (it still reads `space` for the manifest params); only the grid construction and the `sweep(&grid, …)` wrapper change: ```rust fn sweep_family() -> SweepFamily { let bp = sample_blueprint_with_sinks().0; let space = bp.param_space(); bp.axis("sma_cross.fast", [2, 3]) .axis("sma_cross.slow", [4, 5]) .axis("scale", [0.5]) .sweep(|point| { let (bp, rx_eq, rx_ex) = sample_blueprint_with_sinks(); let mut h = bp .bootstrap_with_params(point.to_vec()) .expect("grid points are kind-checked against param_space"); let prices = synthetic_prices(); let window = ( prices.first().expect("non-empty stream").0, prices.last().expect("non-empty stream").0, ); h.run(vec![prices]); let equity = f64_field(&rx_eq.try_iter().collect::>(), 0); let exposure = f64_field(&rx_ex.try_iter().collect::>(), 0); let params = space .iter() .zip(point) .map(|(ps, v)| (ps.name.clone(), scalar_as_param_f64(v))) .collect(); RunReport { manifest: RunManifest { commit: option_env!("AURA_COMMIT").unwrap_or("unknown").to_string(), params, window, seed: 0, broker: "sim-optimal(pip_size=0.0001)".to_string(), }, metrics: summarize(&equity, &exposure), } }) .expect("the built-in named grid matches the sample param-space") } ``` Then remove the now-orphaned `GridSpace` from the import block at line 13. The block currently reads: ```rust use aura_engine::{ f64_field, summarize, sweep, BlueprintNode, Composite, Edge, FlatGraph, GridSpace, Harness, OutField, ParamAlias, Role, RunManifest, RunReport, SourceSpec, SweepFamily, Target, }; ``` Remove `GridSpace, ` (it is the only symbol the conversion orphans — `sweep`, `SweepFamily`, `RunReport`, `RunManifest`, `summarize`, `f64_field` all remain used; `Scalar` is used elsewhere and is imported separately). Result: ```rust use aura_engine::{ f64_field, summarize, sweep, BlueprintNode, Composite, Edge, FlatGraph, Harness, OutField, ParamAlias, Role, RunManifest, RunReport, SourceSpec, SweepFamily, Target, }; ``` - [ ] **Step 2: Run the sweep goldens (both roots), verify GREEN** Run: `cargo test -p aura-cli sweep_report_renders_four_points_in_odometer_order 2>&1 | tail -8` Expected: PASS — the unit golden (`main.rs:541-544`) is unchanged; the named axes produce the same `"params":{"sma_cross.fast":N,"sma_cross.slow":M,"scale":0.5}` lines in odometer order. Run: `cargo test -p aura-cli --test cli_run sweep_prints_four_json_lines_and_exits_zero 2>&1 | tail -8` Expected: PASS — the integration golden (`tests/cli_run.rs:214`) is unchanged (the binary's first line still `"params":{"sma_cross.fast":2,"sma_cross.slow":4,"scale":0.5}`). - [ ] **Step 3: Full workspace gate** Run: `cargo test --workspace 2>&1 | tail -15` Expected: all suites PASS. Run: `cargo clippy --workspace --all-targets -- -D warnings 2>&1 | tail -10` Expected: clean (the `GridSpace` import was dropped; no unused-import warning).