Developer guide¶

Use the table to locate the component that owns a change. Read its architecture contract before editing.

Change	Start here	Continue with	Verify with
Python declaration or validation	`packages/foamnordic/foamnordic/core/`	`packages/foamnordic/foamnordic/execution/`	`test_graph.py`, `test_plan.py`
Closure or equation boundary	`src/foamnordic/openfoam/closureHook.H`	`src/foamnordic/openfoam/models/`	Python contract tests, OpenFOAM build, solver smoke test
Generic field transform	`src/foamnordic/openfoam/fjordExchange.C`	`fieldBridge.C`, `operations/`	`test_graph.py`, `test_plan.py`, `tests/openfoam/`
Observation	`src/foamnordic/backend/adapter/observation.hpp`	`fieldProgramObservation.C`	`tests/backend/adapter/`, `test_run.py`
Exchange or data plane	`src/foamnordic/backend/communication/`	`src/foamnordic/backend/adapter/exchange.cpp`	`tests/backend/communication/`, `tests/backend/adapter/`
ModelHost execution	`src/foamnordic/backend/inference/`	`packages/bindnordic/`	`tests/backend/inference/`, `packages/bindnordic/tests/native/`
FNOM or scaler semantics	`packages/bindnordic/src/bindnordic/`	`packages/foamnordic/foamnordic/export.py`	BindNordic native and Python artefact tests
Launch or placement	`packages/foamnordic/foamnordic/execution/`	`src/foamnordic/runtime/`	`test_launch.py`, `test_slurm.py`, `tests/runtime/`

Change route¶

Locate the owning component and read its local README and architecture contract.
Change that component and add relevant behavioural coverage; avoid duplicating numerical or lifecycle logic.
Follow the verification guide and update affected API or usage documentation.

Stable boundaries¶

Keep equations in OpenFOAM, model execution in ModelHost and BindNordic, exchange in Fjord and Harbor, and orchestration in Longship. Observations remain non-blocking. The architecture principles define these boundaries.

Guides¶

Guide	Use it for
Field programmes and OpenFOAM	Closures, transforms, native algebra, observations and external solver adapters
OpenFOAM source style	Formatting and reviewing OpenFOAM-linked C++ without changing runtime design
Native runtime	Rune, Fjord, Harbor, ModelHost, Smedja, BindNordic and connectors
Verification	Selecting the smallest sufficient local, OpenFOAM, MPI and Roihu checks
Documentation site	Building and publishing the Zensical site on GitHub Pages