Every engine is specified subsystem by subsystem, alongside the cross-cutting
specs for the shared foundation and the report layer. These documents are the
authoritative definitions of Hydra’s behaviour. Where a spec and the
implementation disagree, the spec wins.
Document Scope
crates/common/src/spec.mdFoundation contracts: engine identity and registry, the reportable-output contract, and the element, quantity, result-variable, criteria and editing contracts crates/report/src/spec.mdReport templates, document model, and the txt/csv/html renderer formats
Document Scope
crates/engine-wds/src/model/spec.mdData model, unit system, model file formats crates/engine-wds/src/hydraulics/spec.mdHydraulic engine: GGA solver, sparse Cholesky, valves, demands crates/engine-wds/src/quality/spec.mdQuality engine: transport, mixing, reactions, source injection crates/engine-wds/src/simulation/spec.mdSimulation orchestrator: controls, timestep, accounting, session API crates/engine-wds/src/analysis/spec.mdPost-simulation analytics: demand reliability, service compliance, distributions, and the report-block catalog
Document Scope
crates/engine-uds/src/spec.mdCharter: scope, principles, correspondence to the predecessor, status crates/engine-uds/src/model/spec.mdData model and unit system crates/engine-uds/src/hydrology/spec.mdRainfall-runoff, infiltration, LID controls, snowmelt, groundwater, RDII, climate crates/engine-uds/src/hydraulics/spec.mdSection geometry, dynamic-wave routing, structures, street inlets crates/engine-uds/src/transport/spec.mdPollutant buildup, washoff, treatment, network transport crates/engine-uds/src/simulation/spec.mdControls, orchestration, accounting, statistics, session API crates/engine-uds/src/report_blocks/spec.mdPost-simulation analytics: report-block catalog, derivations, options crates/engine-uds/src/interop/spec.mdPredecessor file formats: INP import, interface files, OUT/RPT output, recognition