juniper-model-core 0.2.0

Shared model-contract interfaces (TrainableModel / GrowableModel ABCs, the TrainingEvent vocabulary, ModelSerializer, the describe_topology() schema) plus a reusable conformance test kit for the Juniper ML platform.

juniper-model-core

The shared model-contract template for the Juniper ML research platform: the minimal interface the Juniper service layer needs from any learning model, plus a reusable conformance test kit that proves a model is pluggable.

It is the linchpin of the model/middleware refactor — the seam that lets a new neural-network model drop into the ecosystem (data → training → monitoring → serving) without the service layer knowing the model type. The contract is derived from two real implementers — the Cascade-Correlation network (a growable classifier) and the Δt-native Legendre Memory Unit (a fixed-order regressor) — never from one model alone.

Install

pip install juniper-model-core                 # the contract (no third-party runtime deps)
pip install "juniper-model-core[conformance]"  # + numpy/pytest, to run the conformance kit

import juniper_model_core pulls no third-party runtime dependency: the contract references numpy only in type annotations. numpy is needed only to run the conformance kit.

The contract

Element	What it is
TrainableModel (ABC)	fit / predict / metrics / describe_topology + task_type, input_shape, output_shape. numpy at the boundary; no argmax/accuracy in the generic surface.
GrowableModel(TrainableModel)	adds n_units / grow_step / freeze for constructive models (Cascade-Correlation, RCC, Growing-ESN). Fixed-topology models implement only TrainableModel.
TrainingEvent	the model-agnostic event vocabulary (training_start/end, epoch_end, unit_added, phase_change) every model maps its native events onto.
ModelSerializer (ABC)	a save/load strategy decoupled from the model; round-trips must be lossless.
describe_topology()	a model-agnostic {nodes, edges, meta} graph the front-end renders without knowing the model type.
juniper_model_core.conformance	the reusable pytest kit any implementer subclasses to prove compliance.

Shared behavior (metric/topology/event validation) lives in juniper_model_core.validation as inspectable free functions — the ABCs themselves are interface-only (first-principles, no black-box base classes).

Using the conformance kit

from juniper_model_core.conformance import TrainableModelConformance, tiny_regression_3d

class TestMyModelConformance(TrainableModelConformance):
    def make_model(self):      return MyModel(task_type="regression")
    def make_dataset(self):    return tiny_regression_3d()
    def make_serializer(self): return MySerializer()

pytest then runs every contract assertion (interface compliance, fit→predict→metrics, task-type-consistent metrics, renderable topology, lossless serialization, legal event order, and — for GrowableModel — grow_step incrementing n_units) against your model.

Design

See notes/JUNIPER_MODEL_CORE_INTERFACE_DESIGN_2026-06-14.md and notes/JUNIPER_MODEL_MIDDLEWARE_REFACTOR_DESIGN_AND_PLAN_2026-05-31.md (§2.3, §3.3) in the juniper-ml repository.

License

MIT — see LICENSE.